Visit Our Sponsors:		Table of Contents: The MailBag Help Wanted & Article Ideas General Mail News Bytes Distro News News in General Software Announcements The Answer Guy , by James T. Dennis More 2-Cent Tips 0800-LINUX: Creating a Free Linux-only ISP, Part II , by Carlos Betancourt HelpDex , by Shane Collinge Interview with Ronnie Ko of 32BitsOnline , by Fernando Ribeiro Corrêa Journal File Systems , by Juan I. Santos Florido How To Make A Hotkey On The Linux Console , by Bryan Henderson The Deep, Dark Secrets of Bash , by Ben Okopnik Bluefish HTML Editor , by Martin Skjøldenrand Building a Secure Gateway, part II , by Chris Stoddard Regular Expressions in C , by Ben Tindale An Introduction to Object-Oriented Programming in C++ , by Michael Williams The Back Page About This Month's Authors Not Linux

TWDT 1 (gzipped text file) TWDT 2 (HTML file) are files containing the entire issue: one in text format, one in HTML. They are provided strictly as a way to save the contents as one file for later printing in the format of your choice; there is no guarantee of working links in the HTML version.
Linux Gazette, http://www.linuxgazette.com/ This page maintained by the Editor of Linux Gazette, Copyright © 1996-2000 Specialized Systems Consultants, Inc.

Answers to these questions should be sent directly to the e-mail address of the inquirer with or without a copy to [email protected]. Answers that are copied to LG will be printed in the next issue in the Tips column.

This section was edited by Michael Williams <> aka. "Alex".

Before asking a question, please check the Linux Gazette FAQ to see if it has been answered there.

Wed, 31 May 2000 10:48:35 +0100
From: "Anne Parker" <>
Subject: kppp playing up

I'm running RedHat 6.0, with KDE as my user desktop and fvwm as my root
desktop.
I have set up ppp and can activate it successfully through the Network
Configurator when logged in as root. When I go to my user desktop, I can dial up my ISP (ClaraNET) and collect email, surf, etc - providing I have already started the relevant apps. Once I have logged on, I can't start new apps because kppp has (I think) started playing with resolve.conf. If I go to a terminal and log on as a different user, it says that my hostname is, e.g. du-208.clara.co.uk, which is presumably my dynamic IP address. It doesn't even reset it after I've logged off - I have to su root and type
"hostname localhost"
before KDE will talk to me again. I'm know I've successfully set up kppp in the past, but the various examples I've seen in books tend to assume that your machine has its own name and IP address, so I may have chosen some incorrect settings in kppp this time. Can anyone help with the correct kppp settings for a plain standalone box (localhost, 127.0.0.1) dialing on a regular phone connection to an ISP that assigns a dynamic IP address?
Thanks

Anne

Thu, 1 Jun 2000 09:15:38 +0530
From: "karthik subramanian" <>
Subject: HELP!!! Keyboard Problems

Hi,
i'm running Red Hat 6.2 on a Pentium-MMX(233MHz.). i get crazy problems with my keyboard... after i work with my computer for about 20 minutes or so, i start missing keystrokes and sometimes keystrokes are duplicated. then Linux throws this error at me:
"Keyboard: too many NACKs -- noisy keyboard cable?"
if i'm running X (i use KDE), and i exit, i see this message too:
"QGDict: Look: Attempt to insert null item"
it's so bad that i can hardly get any work done on my PC...
the typematic rate setting option in BIOS is disabled - enabling it and fiddling with the rates does not help either. i don't know what's happening, could somebody please help!!!!

thanks,
karthik

Fri, 2 Jun 2000 10:01:38 +0530
From: "Karthik" <>
Subject: Startx Blues

I am a LINUX newbie. I have installed it on a Pentium II 233 Mhz machine.I have a S3 TrioV2 DX/GX video card and Samsung Samtron 4Bni (14") monitor. I can boot up an login into root but when i issue the command the command startx to get into X, my screen flashes and I get a blank screen. Can anyone please help me with this problem.

Thanks.

[Have you tried running 'Xconfigurator' (remember, it's case sensative)? Did you set up your graphics card properly during setup? It sounds to me that you've made an error during the X setup section of your installation. -Alex]

Fri, 23 Jun 2000 06:25:22 GMT+08:00
From: "Michael Smith" <>
Subject: RH Upgrade Problems


Dear Sir/Madam,
I am having a problem with my computer...
I did an upgrade installation of Redhat 6.2 on my machine; which now,after booting and loading Linux, would reach the text login prompt, then supposedly Linux would start X11, but X11 never appears, my screen is blank with some fuzzy, jagged white lines flashing across my screen every
few seconds. Ctrl+Alt+Backspace and Ctrl+Alt+F1-6 don't seem to work as
they normally do. Before I upgraded, I was happily running Mandrake 6.0 (which is a beefed
up version of RH as I understand) on my 166 Mhz, 64 MB Ram home PC. If you know what the problem is and how to fix it, great, I would like to hear from you! But even information on how to stop X11 (if it is X11) from loading would be appreciated. Any other ideas?
Thanks,
Michael Smith ([email protected])

P.S. Pls keep in mind that I have only been using Linux for 3 or so months so am not an expert at everything.

Fri, 23 Jun 2000 04:43:01 +0530
From: "Dipankar Mitra" <>
Subject: how to use wav file on diskless linux.

hello,
I want to put a diskless linux m/c & want to use wav file on those diskless m/c
Can any one help me how to do that , giving me step by procedure for
that.

Tue, 20 Jun 2000 14:24:48 +0100 (BST)
From: Paul Nettleship <>
Subject: The answers gut - File formats!!!

Hello,

I was just having a quick look through your magazine and the 'answers guy' sections really intrested me,
and prompted this question....
So, I've always wondered about file formats for exe and obj files. I guess there is all sorts of
intresting data hiding away in there. Symbol tables, mark up info and god knows what else.
Is there some standard for these! Or is it completely compiler dependant?

Just out of interest, Paul.

[Well, it's not strictly a Linux question, but yes, there are [obviously] standards for all executable files and object files. The compiler couldn't just throw together a load of rubbish now could it? -Alex]

Mon, 19 Jun 2000 21:07:47 -0400
From: "Gary R. Cook" <>
Subject: Signaling application running in xterm window of mouse click event

If I am running an application in an xterm window (e.g., xterm -e myapp) and I click on that window, making it my active window, how can I notify my application of that event?

Thanks!!

Mon, 19 Jun 2000 11:16:34 +0200
From: "Angus Walton (EEI)" <>
Subject: Grep

Hi,
I'm quite new to Linux, but I want to learn as much as possible. Here's my question (not really a problem, it would just be interesting to find out how to do this):
Lets say I do a 'finger' and heaps of users are spewed up onto the screen. I only want to see the users which are preceeded with the text 'potatoe'. So, I do the command 'finger | grep "potatoe" ' .But, some users, for example tomatoe_man, are connected to the computer 'potatoe.shellaccount.mycomputer.com', which means that they come up
aswell. Without making finger not display the 'Where' column, how would I weed out these users?

Keep up the good work on the gazette.

Aengus Walton

Sat, 17 Jun 2000 22:10:27 -0500
From: Ivan Gauthier <>
Subject: linux crash

dear sir,

i would like to know if there is solution for the following problem:
when Linux crash due for example to an electric blackout, on the next boot it tries to repair the file system (in this case the hard disk has 2 partitions, on the 1st. the complete operating system is installed, including boot, home, root etc., the 2nd. partition is used for user programs files and database data. Linux is RedHat 6.0 and Mandrake 6.0 (nad 7.0) but most of the time it cannot repair and give a message like:

** e2fsck cannot automatically repair file system. please do e2fsck
manually without the -a or -p options. **

(type control-d to continue or type root passwd ..)

here my questions:
1- if one types control-d nothing happen (well linux tries to repair but it finished as before..)
2.- when manually repairing the file system a LOT of files are lost, including important ones like inetd.conf, and not only on this partition but on the 2nd. one. is this normal? . and what can be done..

this question is not really a problem but an option i would like to have. do you know how to get the "hour clock" or "glass clock" on KDE after doble clicking an icon on the desktop. (like Corel Linux is doing with KDE )
many thanks

ivan gauthier
venezuela

Thu, 15 Jun 2000 16:25:23 +1000
From: "Nick Adams" <>
Subject: Port 80 Telnet

Hello,
Quick question.
I want to change my port to accept telnet connections to port 80. This enables me to connect from behind my proxy at work. How do I do this?
Thanks,

Nick Adams

Wed, 14 Jun 2000 17:05:20 +0100
From: David Whitmarsh <>
Subject: Second X server and Redhat 6.2/gdm

Following up on Bob Hepple's tip on running a second X server, I tried to to the same on my Redhat 6.2 box. I found that I could start a new X server on the command line, but it gave me only the basic X-server screen (fine grey check with the X cursor), and no login screen. Same problem with Xnest.
I could however run two X servers at once by placing a second entry in the gdm.conf file and restarting gdm.
It would be nice to only have the overhead when I want the second server though. Any thoughts on how to get the login screen?
Regards,

David Whitmarsh

Tue, 13 Jun 2000 11:03:17 +0800
From: "michaelkwan" <>
Subject: Sendmail Question

Hi,
I have setup the RedHat6.1 with sendmail 8.9.3. All the clients use IMAP4 to connect to the server using Outlook Express 4.
The problem I found is, there will be several processes for the same user running the [imap]. As a result, the user cannot receive or delete any mail in their mailbox. I have to 'kill' the 'extra' processes otherwise the mailbox will be read only. Is there any thing I can do with this?
Thanks!

Michael Kwan

Mon, 12 Jun 2000 11:32:28 -0300
From: Eduardo Spremolla <>
Subject: Pentium III boot problem

I have here a Pentim III machine and when it boot ~= 4 out of 5 times it
locks with a mesage:
387 failed, traying to reset.
I comes from the bugs chequing module. Is there some issue with PIII and the check? or did I got a faulty CPU ?
Thanks in advance.

Eduardo Spremolla
Montevideo,Uruguay

Sat, 10 Jun 2000 01:12:02 +0200
From: "almighty" <>
Subject: Graphics card setup

hi i'am a new lunix user but i want to know how can i make lunix set my graphic card:
(intel (r) 810 Chipset graphics driver pv1.1)
it's could be fun if you can send me a solution to enjoy linux
thanks a lot

P.S:sorry for my english because i'am french

Fri, 9 Jun 2000 10:20:33 -0700 (PDT)
From: "Timothy McPherson" <>
Subject: TERM Variable

Hi,
Hoping someone might have an solution for me. I have a Solaris system
with a number of Wyse 60 terminals connected to it. I have a Corel Linux PC on a LAN with the same Solaris box. I believe I have compiled the terminfo wyse60 entry correctly on the Linux PC (as it did NOT have one originally).
Basically I took the output from the command "infocmp wy60" on the
Solaris box and used "tic" to recompile it on my Linux PC. So far so good. The entry is now in /etc/terminfo/w/wy60 and "infocmp wy60" is identical to the Solaris one. I set my TERM variable to wy60 but it doesn't look to healthy either through an xterm session, a console text login or a telnet on either. Any ideas? Am I going about this the wrong way? Basically if I can get this working properly I can scrap Windows in favour of Linux on all PCs on the LAN:) Thank you for any help you can offer.
-Timothy

Wed, 07 Jun 2000 12:11:48 -0500
From: Brian Finn <>
Subject: Linux Webserver and AS/400 Database?

Hi,
I was just curious if any good readers have any success stories about using a Linux server running the Apache web server as a front end for a DB2 database on an IBM AS/400? I'd like to know what solutions there are (or should be) for accessing DB2 data from a Linux box.
Thanks!

Tue, 6 Jun 2000 10:46:13 -0700
From: "Christine Rancapero" <>
Subject: hi

Do you have an issue regarding the advantages and disadvantages of migrating linux mail server to an MS exchange? Your help is gratefully appreciated....thank you very much =)

Mon, 05 Jun 2000 14:34:43 -0500
From: Noah Poellnitzh <>
Subject: linux booting

I was wondering if you have ever heard of anyone booting up a system with a linux boot floppy. The system previously lacks the ability to boot from a CD , but after installing linux, uses the CD drive to install another operating sytem which at teh same time will write over the Linux system.

Sun, 4 Jun 2000 09:09:23 +0100
From: "Graham" <>
Subject: mother board help desperately needed

Hello there,

I have added a video card and sound card to a GMB-P56SPC mother board (ESS I think) I have managed to disable the sound chip ( both sound and video were both onboard with SIS 5596 video and SiS 1868 sound chips) with jumper JP13 unfortunately I cannot find a video jumper.
Please help how do I disable the onboard video?
Many thanks in advance

Sat, 03 Jun 2000 12:04:54 -0400
From: James Dahlgren <>
Subject: modprobe: can't locate module ppp-compress-21

First I want to thank you and all the people at Linux Gazette for all
the fine work you are doing. Many of the services running on my Linux box wouldn't be running without the help I've gotten from your fine site.

I'm assuming this is trivial, but it still bothers me. I've usedSlackware, RedHat, and Mandrake distributions of the 2.2.x kernel. I'm not sure which pppd version the Slackware and Mandrake had but the RedHat has pppd 2.3.7. Iv'e use the 2.2.5,10,13,14,15 kernel revisions. With all of them I get error messages when pppd starts:

Jan 15 17:54:40 paxman modprobe: can't locate module ppp-compress-21
Jan 15 17:54:41 paxman modprobe: can't locate module ppp-compress-26
Jan 15 17:54:41 paxman modprobe: can't locate module ppp-compress-24

Fri, 2 Jun 2000 11:48:21 -0600
From: "Doug" <>
Subject: IPX, RH 6.2, socket: Invalid argument

I am a sorta newbie on Linux. I have Red Hat 6.2, am running Samba and DHCP and ftp server on a peer-to-peer Windoze network with ethernet. All of the above works fine. I am trying to get netbios working over ipx for a port I am doing from DOS. My initial install was RH 5.2, then I upgraded to 6.2. My linuxconf does give me a Segmentation fault (core dumped) message when I try to run it, which it didn't do before I upgraded to 6.2. My main problem is this:
When I try to run 'ipx_interface add eth0 802.3', I get the following:

'ipx_interface: socket: Invalid argument'

Any clues as to what is going on? How to fix it? Places to go for more
info
on netbios over ipx?

Thanks,
Doug

Fri, 2 Jun 2000 11:48:21 -0600
From: "Allen Tate" <>
Subject: Getting Linux to see my network card during bootup

I have recently installed Phat Linux (which by the way is an excellent Linux distribution for beginners) and for the life of me, I can't find which boot script I need to edit to get the system to see my network card during bootup. Can someone point me to the correct boot script or the correct HOWTO file? The strange thing is that the KDE System tool can see the Ethernet card and tells what the IRQ and I/O are. Please email me privately at and I'll explain in better detail about what I'm talking about.

Alan wrote back and said:

Never mind, I figured it out. I transposed 3c509 for 3c905. That didn't work so I used the 3c59x driver and it came right up. I love it when I figure it out on my own.

Fri, 2 Jun 2000 11:48:21 -0600
From: Tom Russell
Subject: How to run Windows programs on Linux

Whether or not Microsoft is successful in their appeal to the US High Courts on technical grounds, the facts remain that after a lengthy and involved legal process, they were found guilty of breaking the laws of their country, and secondly of using their monopoly powers to hold up innovation in what is still a developing industry.

As a believer in religious principles, and the laws and morals of my country, I find it unethical and personally abhorrent to continue to use or recommend products and services produced by Microsoft.

I recently read that Corel are using a Linux Windows emulator to enable their Windows office suite to operate successfully in the Linux environment without the need for any Microsoft products or services.

Could you please let me and other concerned readers know how to do this for other non Microsoft products, so we are no longer forced to be immoral and unethical by association with a guilty party.

31 May 2000 18:24:10 +0200
From: Jan-Hendrik Terstegge <>
Subject: Re: Linux Gazette - German Translation [LG #54, General Mail]

Hi guys!

In LinuxGazette 54 you printed under General Mail my eMail from 29 Apr 2000, concerning my question for a german translation of LinuxGazette. Today the new issue came out and I created a translation of the article "Building a Secure Gateway System". Hoping that more Linux guys will help me to translate more articles, I copied it to my webpage. The german LinuxGazette Mirror-Page can now be found under http://www.linuxgazette.de.

I hope that after my call someone will help me to get more and more articles online.

[We also have a Spanish translation now at http://gaceta.piensa.com. -Ed.]

Mon, 26 Jun 2000 08:49:51 -0700
From: Heather Stern <>
Subject: Kudos to our translators

Pass my thanks to our translators everywhere. It's a tough and usually unsung job.

[And as an amateur translator myself, I'll add that it's quite time-consuming. -Ed.]

Wed, 14 Jun 2000 01:05:46 +0300
From: Charles Kibue <>
Subject: Thanks!

Hi! Here's from a very happy Linux user in Kenya...... Your magazine is very informative as well as interesting to read. I got some issues on my disk from the SuSE installation of the LDP and I sure look forward to reading more issues from you. Thanks to you all and you sure will be hearing a lot more from me. Cheers.

Composed on a Digital HiNote VP562 Series Laptop...powered by... SuSE Linux 6.3!

Tue, 20 Jun 2000 17:22:37 +0100
From: Steve Emms <>
Subject: Who controls the Linux Media ?

I run LinuxLinks.com - a linux portal and recently we added a personalised calendar service to our web site. We submitted an article to LinuxToday (owned by internet.com) and it was published only to be pulled almost immediately. The reason given was that website enhancements are no longer news. However a similar service offered by another website was published. And who owns that website ? Why internet.com of course.

OK, this calendar isn't state of the art - but it is a free service and it does complement the existing facilities on the site. And sure, it is up to LinuxToday what they think is newsworthy and so post. But wait a minute, this sort of thing has made the news before - linuxstart announced a similar calendar service - take a look at

http://linuxtoday.com/news_story.php3?ltsn99-07-13-015-10-PR

What's the difference ? Well, Linuxstart are owned by internet.com

This opens up a number of questions about how we judge the news we read. Linux is becoming big business and there are vested interests. Web sites are merging and being taken over by large conglomerates. Who determines the impartiality of the news we read ? Who determines what is news and what is advertising ?

LinuxToday is one of the major daily linux newsites and they determine that enhancements to major Linux websites like LinuxLinks is not important. But LinuxLinks is independent - it isn't owned by internet.com and it isn't owned by VA Linux. Is it and sites like it being penalised because they don't have a monopoly in the Linux media ? And is this really in the spirit of the Linux movement ?

Wed, 14 Jun 2000 23:37:41 +0530
From: Vikrant Dhawale <>
Subject: subscription info.

I have read the current issue of the linux gazette and found it very interesting and informative. Is it available as a e-mail letter which I can subscribe and recieve in email since reading it online wastes a lot of online time as it is spread over pages.

[See the LG FAQ, questions 2-4. The Gazette is too big to send via e-mail. To minimize online time, download the FTP version of each issue and read it from your hard drive rather than via the web. -Ed.]

Sun, 4 Jun 2000 19:24:00 +0530 (IST)
From: LUG Account <>
Subject: Claims of First Indian OS: Aryabhatt Linux

Press Release
in response to articles on `Aryabhatt Linux' as
the first Indian Operating System.

We introduce ourselves as the Linux Users Group, Bombay Chapter (ilug-bom.org.in). We are a non-profit voluntary organisation actively involved in promoting open source software. Our activities include mailing lists for users, training, workshops, open source projects etc. Our group constitutes more than 400 man years of Linux experience vested in its members.

We draw your attention to the following articles which have appeared in the publications mentioned below.

1. "Made-in-India Linux to go global", Express Computer dated 29/05/2000, page 1.

2. "Linux Technologies launches Aryabhatt Linux", Times Computing dated 31/05/2000 page 5.

3. "Aryabhatt Linux", PC Quest dated June 2000 page 174.

... and several others.

In these articles there are numerous inconsistencies, false claims and trademark violations made by the company Linux Technologies Pvt. Ltd. We have evaluated their Linux distribution Aryabhatt Linux and compared it with other currently available distributions such as Red Hat, SuSE, Mandrake etc. Listed below are some of the findings:

1. RedHat Trademark Violation?: The packaging of Aryabhatt Linux distribution mentions that it is "Based on RedHat Linux 6.1", but fails to comply with RedHat's Licensing policy, as is evident from the following excerpt taken from http://www.redhat.com/about/trademark_guidelines.html

" C. You may state that your product "is based on Red HatŪ Linux X.X," but you must do so in a fashion that indicates that "Red Hat Linux" is not the name or brand of your product and that Red Hat is not a source or sponsor of your product. Some guidelines to follow on this point include:

" You must clearly indicate how your product differs from Red HatŪ Linux. This includes listing the packages that you deleted from Red HatŪ Linux and those that you added to your product, as well as indicating any and all other changes you made. This information must be clearly and prominently presented in all packaging, advertisements and other marketing materials for your product in a typeface no smaller than the typeface you use for the words "Red HatŪ Linux."

" The use of "Red HatŪ Linux" must be in a typeface (which includes appearance, size and color) no larger than one-third the size of the typeface used for the name of your product.

" The typeface you use for the words "Red HatŪ Linux" must be the same typeface you use for other written text to describe your product. You may not use a unique typeface for "Red HatŪ Linux" in order to set it off from the other text included on your product.

" You may not do anything at all to state or imply that your product is an official product of Red Hat, Inc. and may not do anything else to create confusion in the market between your product and the products of Red Hat, Inc.

" You must include the following statement in a prominent place in your product packaging and in all marketing and promotional efforts for your product:

"Red HatŪ is a registered trademark of Red Hat, Inc. This product is not a product of Red Hat, Inc. and is not endorsed by Red Hat, Inc. This is a product of [name of publisher] and we have no relationship with Red Hat, Inc."

2. Linux trademark violation?: Linux is a registered trademark of Linus Torvalds who was the original developer of the Linux kernel. He has permitted use of this trademark subject to an explicit mention of his ownership. Neither their web site nor the product packaging mentions this fact.

3. It is not an original Indian Linux distribution: The Aryabhatt Linux is a distribution based on another Linux distribution viz Red Hat Linux 6.1 as mentioned on the product packaging.

4. Misrepresentation of License: Most of the programs distributed in Red Hat Linux are licensed as GPL (General Public License). This licensing policy permits anybody to go through the source code and modify as per their requirements. It also explicitly requires the GPL to be mentioned clearly. Arybhatt Linux does not seem to have been licensed under GPL since the GPL copy on the CD is issued by Red Hat and not by Linux Technologies Pvt. Ltd.

5. GPL requires distribution of source code as well as free download of source code: Under GPL it is mandatory to distribute source code FREE OF COST either on CD's or on ftp sites. As on date Linux Technologies has not made any provisions for the same. The company also does not have any ftp sites.

6. The Graphics Driver for SiS6215: Graphics Drivers for SiS6215 card were developed by SuSE GmbH (suse.com) and XFree86 (xfree86.org) and copyrighted under GPL. Linux Technologies Pvt. Ltd. falsely claims to have developed the same.

7. Misuse of Linux Logo: The Linux logo which depicts a penguin has been affectionately referred to for a long time as Tux by the entire Linux community. It also appears on most of the web sites, publications and articles pertaining to Linux. Other Linux distributions also feature Tux on their packaging. By writing Peggy across the penguin and registering it as their own trademark, Linux Technologies Pvt. Ltd. has attempted to cash in on the popularity of Tux and deeply hurt the sentiment of Linux users.

8. The picture on product packaging box: The product packaging box as well as the step by step User Guide of Aryabhatt Linux depict a picture of peggy surrounded by networked computers. This picture was designed and copyrighted by Jassubhai Digital Media and was published in the August 1999 issue of CHIP magazine, CHIP Linux special and Network Computing.

9. Most of the applications in any Linux Distribution are developed by GNU (www.gnu.org). Linux Technologies Pvt. Ltd. does not acknowledge the same.

10. Though Aryabhatt Linux is claimed as "customized for the Indian user", as on date, it does not support any Indian Language. And the claimed hardware support for the locally assembled hardware already exists in other distributions of Linux.

11. On going through the step by step guide, we found numerous inconsistencies and wrong information.

As Indians we would love to have an Indian Linux distribution but we are thoroughly disappointed and disgusted with Aryabhatt Linux's blatant attempt to hijack the efforts of the open source and free software community. This ruthless exploitation of free, open source software will tarnish the image of the Indian software industry. We therefore urge you to set the record straight as regards the claims of Linux Technologies Pvt. Ltd., if you have published articles related to Aryabhatt Linux. For others who have not published any reports, pleas consider this as information.

This message is released in public interest, and in the interest of Open Source Software by the following active members of the Indian Linux Users Group, Bombay Chapter:

Aditya Kulkarni [email protected] Apurva Shah [email protected] G.Sagar [email protected] Kiran Jonnalagadda [email protected] Kishor Bhagwat [email protected] Mitul Limbani [email protected] Nagarjuna.G [email protected] Parag Mehta [email protected] Philip Tellis [email protected] Prakash Advani [email protected] Prakash Shetty [email protected] Rajen Parekh [email protected] Rakesh Tiwari [email protected] Sandesh Rao [email protected] Terrence D'Souza [email protected] Vikas Pawar [email protected]

Contact Address: GNU/Linux User Group of India, Bombay Chapter [email protected] http://www.ilug-bom.org.in

Mailing Address: Dr. Nagarjuna G. Homi Bhabha Center for Science Education TIFR, V.N. Purav Marg, Mankhurd, Mumbai 400088 INDIA Phones: 091-22- 556 7711, 555 4712, 555 5242 Fax: 091 - 22 - 556 6803.

Richard Stallman <> replies:

It sounds like this company is violating the GPL in the use of some FSF-copyrighted software. If that is true, we can try to enforce the GPL. Would you please double-check for us that FSF-copyrighted programs are included on their CD and on their ftp site, and send us the names of the specific programs you identified? We also need to know the URLs and the official name of the product.

Also, could you tell me how to contact them? We need the company name, snail addresses, email addresses, etc. With this information, we can have lawyers contact them to object.

Meanwhile, one more item you can add to your list is that they're calling the whole operating system "Linux". Linux is actually the kernel, one of the important pieces of the system. That is what Linus wrote in 1991.

At that time, we had been working on the GNU operating system for almost a decade, and it was almost complete enough for self-hosting; the only major piece missing was the kernel. Combining Linux with GNU produced a complete free operating system, versions of which are now integrated by Debian, Red Hat, and others. Everyone is free to redistribute it, but they ought to call it GNU/Linux and give us a share of the credit. It isn't a legal requirement, but it is the right thing to do.

See http://www.gnu.org/gnu/linux-and-gnu.html for more explanation.

Regarding the idea of an "Indian operating system": I think that kind of nationalism is not a good thing for world peace.

But India should not feel left out. The GNU system has been an international project since the very beginning; no single country originated it. Humanity originated it. And India is part of humanity.

This page written and maintained by the Editor of the Linux Gazette. Copyright © 2000,
Published in Issue 55 of Linux Gazette, July 2000

"Linux Gazette...making Linux just a little more fun!"

Contents: Distro News News in General Software Announcements

July 2000 Linux Journal

The July issue of Linux Journal is on newsstands now. This issue focuses on Science & Engineering.

Linux Journal has articles that appear "Strictly On-Line". Check out the Table of Contents at http://www.linuxjournal.com/issue75/index.html for articles in this issue as well as links to the on-line articles. To subscribe to Linux Journal, go to http://www.linuxjournal.com/subscribe/index.html.

For Subcribers Only: Linux Journal archives are available on-line at http://interactive.linuxjournal.com/

Best

SOT has released their Best Linux operating system to Russian-speaking users for the first time. The new version is also available in English, Swedish and Finnish, and includes the brand new XFree 4.0, kernel version 2.2.14 and integrated office solution Star Office(tm) by Sun Microsystems.

The Best Linux 2000 boxed set includes some new features never seen before in Linux--like lifetime installation support. The boxed set also contains a 400 page manual, an installation CD, a source code CD, a Linux games CD and a software library CD providing an easy way for consumers and business desktop users alike to start using a complete Linux system.

Founded in 1991, SOT is based in Finland, where it builds and maintains the Best Linux distribution. SOT counts among their customers large organisations such as Nokia, Sonera and the Finnish Board of Education.

Caldera

OREM, UT-June 6, 2000-Caldera Systems, Inc., today announced that free support is available for OpenLinux users in Europe. Registered OpenLinux users will receive free 30-day phone and 90-day e-mail support in German, French, Italian and English.

In Germany, registered OpenLinux users may dial 030 726238 88 or visit [email protected]. Registered users needing support in English, French or Italian may dial +353 61 702033 or visit [email protected].

http://www.calderasystems.com

Space is limited. For more information or to register for the tour, visit http://www.calderasystems.com/partners/tour .

Lute

LuteLinux at the Technical Certification Expo 2000 revealed not only their new LuteLinux Lite software, but also their training and certification plans . In addition to offering certification for various levels from user to specialist, LuteLinux will also offer Trainer Certification. This will include training on teaching and public speaking, classroom techniques for beginner to advanced users, as well as common classroom scenarios and bridging the gap between the classroom environment to the real world. Their certification not only qualifies you as a LuteLinux trainer, but many of the techniques and lessons are easily transferable to other training environments.

LuteLinux is taking a new approach to certification. They recognize that multiple choice and even most simulation environments only provide for one right answer, and most examinations don't respond to non-standard approaches to a problem: something that is required on a daily basis in the real world. LuteLinux is fixing that explains Mr. Daunheimer, "our on-line LuteLinux simulation responds to multiple approaches to a problem. There is more than one answer to the questions, just as there is more than one way to solve a problem in the real world. There will be an ongoing assessment of responses during the examination, and the questions which are presented are chosen by a system that takes into account your last response." Although it's easy to talk about results, at LuteLinux they guarantee them. If any client is not satisfied with their training, or feels unprepared to apply new skills on the job, they will retrain them - for free. Examinations will be available both in-house at one of their training centers, and on-line via their web site.

Red Hat

PITTSBURGH, PA - June 19, 2000, /PRNewswire/ -- Advanced Computer & Network Corporation has received Red Hat Linux 6.2 certification and is now included on Red Hat's Hardware Compatibility List for RAID storage systems. http://www.acnc.com/product_jetstorii_lvd.html.

SuSE

SuSE, the international technology leader and solution provider in open source operating system (OS) software, has opened their new Latin America headquarters office in Caracas, Venezuela. Xavier Marmol, well known to the Latin American Linux Community, has been chosen to run SuSE's Latin America presence.

Xavier Marmol is highly regarded in the Latin American Linux community. He was previously the Network Administrator at the University of Zulia Academic Network. As an active Linux advocate since 1995, he successfully implemented Linux OS for the Universities network of several hundred computers. As founding President of VELUG (Venezuela Linux User Group) in 1997, he led the initiative to include VELUG achievements at the Latin American LinuxWeek, the first Spanish-speaking Linux event. Marmol was also the first content manager of the Spanish LinuxStart.com Web site.

SuSE will release the first fully engineered version of Linux for the Apple PowerPC, IBM RS 6000 and Motorola PreP in mid-June. [It was unclear to LG at press time whether it has been released yet. -Ed.] In addition to databases, firewall scripts, web servers and mail programs, there are also such interesting applications as the video editing system Broadcast 2000, or the powerful image processing program, GIMP.

Of great interest to Mac users and professionals is the inclusion of the Virtual Machine (MOL) MAC on LINUX in the distribution, making it possible to start the MacOS in Linux and switch from one program to the other. In addition, the Mac user also has the option of using standard PCI hardware, such as network cards or TV cards.

Storm

Vancouver, BC., June 20, 2000 - Stormix Technologies Inc. and StarNet Communications Corp., today announced an agreement to include a fully- functional copy of StarNet's X-Win32 PC X server Version 5.0 with Storm Linux 2000 Deluxe Edition. This allows Windows workstations to connect to Linux servers. Storm Linux 2000 customers will receive a free one-year license for X-Win32. This product is normally listed at approximately $200.00US.

http://www.stormix.com

Upcoming conferences & events

La Gaceta de Linux--Spanish Linux Gazette

May 31st., 2000. Mexico City, Mexico. Bufete Consultor de Mexico - Piensa Systems has announced the launch of the new web site entitled La Gaceta de Linux as a Spanish version of the very well known electronic magazine Linux Gazette, effective this June 1st.

"We are searching for volunteers to enrich and enhance La Gaceta de Linux in every aspect."; said Monique Ollivier, image and content managing editor of the Spanish edition, "in first place, we need lots of support to translate, in a monthly basis, the original articles in foreign languages; mostly English; to ours, and maybe even more important, we want La Gaceta de Linux to be an open forum to whomever wants to write about Linux or just publish their work."

"After the site launch, we will add more features and services to La Gaceta de Linux, providing special benefits to the ones that contribute to the site with a bit of their time as well as additional services to the general public."

, Bufete Consultor de Mexico, S.A. de C.V., CEO and General Director: "We want all this free and open technologies and the broad experience that the global Linux community has acquired, to be leveraged at the maximum by all those Spanish speaking individuals and companies that across the globe."

"Having a tool like La Gaceta de Linux and, of course, the web, allows us to very efficiently promote Linux and all related technologies to be used in real life industry, businesses and corporate use; for instance; in Latin America, most of small to medium sized businesses do require IT services and systems that really do work, and work well but, not at the very high cost of the current "systems" that are well known to all company owners ... It is our experience that Linux is an excellent alternative."

"Another very important readers and users group for La Gaceta de Linux is the academic one. That's where tomorrow's IT people are and, we have to let them know about Linux and what this new technology can provide. Educating people at every level is the key and that is the most important goal of La Gaceta de Linux."

About Bufete Consultor de Mexico, S.A. de C.V. (BCM): BCM, founded in 1994 is a private Mexican Information technology consulting firm. BCM has wide experience in the implementation of mission critical systems in customers of various sectors across Latin America. "Piensa Systems" and "piensa.com" are BCM registered trademarks.

[The original press release read "the official Spanish version". I changed it to "a Spanish version" to make clear that LG has no affiliation with BCM and does not wish to endorse one Spanish translation over another. Nevertheless, we are grateful to BCM for making LG accessible to the Spanish-speaking, as we have long desired. -Ed.]

Adomo--technology for the automatic house

"Adomo wants a place in your home. Not on top of your TV, or as a firewall or gateway hiding in a closet. What Adomo wants, is to fill your home with a network of low-cost, easy-to-use information appliances. All over the place. And they will all have Linux inside..." This is from LinuxDevices' technical overview paper about Adomo.

An Adomo spokesman calls it "kind of like a Cobalt Qube for the home".

[This reminds me of the children's science-fiction story, Danny Dunn and the Automatic House, as well as Ray Bradbury's (?) story "There Will Come Soft Rains", and Bill Gates' home entertainment system/art gallery. -Ed.]

Linux on Compaq handheld

Compaq announced it has ported the Linux operating system to its iPAQ handheld computer. The goal of the port and the supporting program is to enable developers and researchers looking to explore applications and uses for handheld computing to experiment with Compaq's iPAQ handheld by gaining access to the Linux-based source code for the device.

Telephony switch

6th June 2000, SUPERCOMM 2000, Atlanta, USA. Axtar Limited, a UK-based developer of programmable communications solutions for public network operators and service providers, has announced OneSwitch, the industry's first standards-based Central Office programmable telephony switch to use both the Red Hat Linux operating system and the compactPCI (cPCI) form factor. Value-added communications services that can be supported by the OneSwitch include: web-based call centre services, personal numbering, pre-paid calling card, Internet Call Waiting services and 1xxx services. The product will start shipping Q3 2000.

Linux NetworX News

SANDY, UTAH, JUNE 23, 2000 - Linux NetworX, Inc., a provider of large-scale cluster computer solutions for Internet, industry and research fields, announced the launch of its new Web site (www.linuxnetworx.com). The site provides information about the company's products and services as well as other useful information about computer cluster technology.

Individuals who browse the site will find it updated with information concerning cluster computer solutions. Along with extended company information and event calendar, the site includes an informational cluster tour and a comprehensive newsroom containing computer cluster news.

Principle products include ClusterWorXHardware and Software Control, a hardware-based cluster management system controlling up to thousands of nodes, independent of specific motherboards or chipsets.

FreeDesk selects Tarantella Software

Santa Cruz, CA (June 21, 2000) The Tarantella Division, an independent business unit of The Santa Cruz Operation, Inc., today announced that FreeDesk.com has chosen Tarantella software to replace Citrix MetaFrame as the key technology to centrally manage and deliver applications via the web. FreeDesk.com is switching to Tarantella to get better application performance over the web.

Linux newsletter in Atlanta

I am the editor and manager for a free local publication entitled Atlanta Linux Newsletter. We have been freely distributing this publication for over a year. In that time, we have increased our distribution from 500 to 5,000, and we are now increasing that number to 10,000.

The publication is distributed throughout the Atlanta Area. This refers to Downtown, Midtown, Buckhead, as well as some of the surrounding areas: Roswell, Decatur, Alpharetta, etc. Our new channel for distributing our newsletter will be with Computer User magazine. In addition, we give copies of the Newsletter to all of our Customers as well as any User Group Meetings, seminars and showcases that we attend.

We have been working on our content so as to focus towards the new Linux community. Our customers, and the Linux community, in the past has been hackers and hobbyists. However, with the new surge of Linux users, we are beginning to focus on the business solutions side of Linux as well as the novice. We aim our content to reflect this type of audience.

Our advertisers consist of Linux companies, design companies, web companies, etc. These advertising supporters are assisting in the promotion of the newsletter whether in printing costs, distribution costs, etc.

-Kate Cotrona, Senior Editor & Manager, Atlanta Linux Newsletter

http://www.linuxgeneralstore.com (Click on the logo to enter, then choose "Newsletter" from the menu.)

kaivo.com, a new Open Source marketplace

DENVER (June 14, 2000) -- Kaivo, Inc., today performed the initial launch of the first vendor-neutral marketplace for Open Source products and services. Located at kaivo.com, the Kaivo site is the only service designed to connect IT executives interested in the Open Source revolution with vendors who can design, build, and maintain Open Source solutions.

The Kaivo.com Open Source Marketplace features three primary elements:

• Solutions Locator: a catalog of products and services allowing customers to find the perfect Open Source solution to specific business problems.
• Provider Locator: a resource for buyers in search of the right solution provider, and a tool for partners to find complementary technologies and providers.
• Opencyclopedia[TM]: an encyclopedia of topics relevant to Open Source, written specifically for the business community.

In addition to its Open Source Marketplace, Kaivo will deliver professional services consulting and education and training programs to users of Open Source solutions.

Kaivo is the ancient Finnish word for "source".

The Editor asked Kaivo's PR man Anthony Benedetti <> how Kaivo is different from Cosource and SourceXchange, and he replied:

While Cosource, SourceXchange and Kaivo all have common elements, Kaivo's focus and its audience are different from the others. Both Cosource and SourceXchange excel at helping manage the development process of custom Open Source applications by bringing project managers and development talent together.

Kaivo, on the other hand, is about delivering the full world of Open Source into a corporate setting. Our end-user audience, IT executives, is assumed to be not as hands-on technical as the primary audience of the other sites.

We believe that our market has a need to understand what Open Source solutions exist (in contrast to proprietary models) and desires a simplified channel in which to procure those solutions. So ours is a market place for software, hardware, services and solutions. Kaivo is also designed as an educational site.

In many ways, Cosource, SourceXchange and Kaivo are complementary.

Alpha Processor news

Concord, Mass., June 1, 2000 - API, (Alpha Processor, Inc.), announced the UP1100, the latest addition to its Ultimate Performance Series motherboards. The UP1100 offers Alpha Linux developers a complete, cost-efficient, entry-level Alpha board for Beowulf clusters, Web servers, development systems and rendering solutions.

API's high I/O and memory bandwidth technology, combined with the UP1100's new features and the open source Linux software, enables system integrators to build high-performance, scalable and reliable systems. The low profile UP1100 features the Alpha 21264 processor on the UP1100 motherboard, allowing the overall cost of systems to be reduced. This provides research institutions, computer graphics companies and enterprises a cost-effective system for powering compute-heavy applications.

Doubling disk I/O performance over the UP1000, the UP1100 uni-processor planar design includes on-board integrated sound and Ethernet on a standard ATX form factor, providing a more robust Alpha solution for developers. The on-board Ethernet and sound preserves maximum configurability of system PCI I/O slots, simplifies cluster configuring and lowers the overall solution cost.

The UP1100 will begin shipping in July.

Concord, Mass., Bristol, United Kingdom, June 1, 2000 -- API, (Alpha Processor, Inc.), a leading architect of high-performance solutions for high-bandwidth and compute-intensive applications, today announced its collaboration with Quadrics Supercomputers World (QSW), a leading provider of supercomputer technology in Europe, to develop high-performance supercomputers for Linux. QSW now can offer customers high-performance scaleable supercomputers with the flexibility to support a wide range of parallel programming models on the Linux platform.

Using API's 64-bit platform and the Linux open-source operating system, QsNet, a high-bandwidth, ultra low-latency interconnect for commodity SMP nodes, offers some of the highest possible system interconnect performance and scalability available. The solution, based on QSW's third-generation "Elan and Elite" ASICs and API's UP2000 Ultimate Performance Series motherboards, consists of a network interface and a high-performance multi-stage data network. The system is managed using QSW's Resource Management System.

Linux R&D Facility Opens

TCS' Linux Research and Development facility will be located in Round Rock, Texas. Over the course of several months, TCS will recruit highly skilled employees to assist with the development of Linux related products for existing and new clients located worldwide, including Dell. TCS' recruitment effort will include an aggressive outreach to Texas universities and from within the local community.

Available exclusively at the TCS website-- http://www.tcs.com--the test harness and suite, called TAAL (Testing And Analysis tooL) benefits businesses and consumers who use Red Hat Linux 6.X by evaluating the Linux operating system.

TCS is a software technology consultancy company that provides information technology and management consulting services to organizations in over 50 countries across the globe.

Transmeta's Crusoe Processor and NetWinder, and Rebel the ISP

Ottawa, Canada - June 27, 2000 - Rebel.com Inc. announced its intention to adopt Transmeta's Crusoe processor family in a future line of residential and small business gateways that will add to its NetWinder OfficeServer line of products.

Linux Links

BASCOM's Open Source Equipment Exchange will match those donating computer equipment with open source developers in need.

The TERMinator is a glossary of PC technical terms.

News articles:

• Linux Grows Up. Is the open-source market maturing? To IPO or not to IPO? (E-Commerce Times)
• Europe leads desktop revolution. SuSE's CEO Roland Dyroff says that Linux has penetrated European desktops at a higher rate than in the US. (ZDnet UK)
• Pick a Distro claims "there are more [Linux] distributions than ever" but "choosing one that's right for a specific task is getting easier." (ZDnet)
• The Linux Dating Game is not a program to help you find your mate, nor is it gossip about famous Linux personalities. Instead, it's an attempt to predict which Linux companies would make complementary mergers. (Anchordesk UK)
• Linux Rising: Linux Games Come of Age is about the state of Linux gaming. It mentions that Xfree86 4.0 includes 3D graphics as a standard component. There's also a nostalgic look at the past of Linux gaming. (Gamespot UK)

Linux Graphics Programming with SVGAlib is a book that shows both beginners and advanced users how to make graphics applications without X. The URL also features other books on Linux/Open Source products.

Firstlinux has added five articles to its collection of overviews titled "I've installed Linux: What Next?" New topics include MP3, games, scientific/mathematical programs, PIMs (personal information organizers), and CD writing. The site also has a web-based personal calendar in 13 languages. There is also a news site, FirstLinux Network News.

The Maximum RPM book (version 2) is available for download at www.rpm.org in Postscript format. This is a work in progress.

The Linux Security Knowledge Base is SecurityPortal.com's collection of, um, Linux security articles. Writers and translators are needed. All documents are under the GNU Free Documentation License.

Magic Software subsidiary Access Data Corporation will deliver a comprehensive public safety records management solution for all agencies within the State. The solution will include a centralized database of criminal activity to be created using statistical and investigative information. One hundred installations are expected to take place over the next two years.

ITsquare.com has launched Linux Square, a web application to help companies find serious, reliable Linux development firms.

Server-Based Java Programming by Ted Neward is a practical guide which teaches the fundamental concepts of server-based Java. On-line samples are at http://www.manning.com/Neward3/Contents.html and http://www.manning.com/Neward3/chapters.html

Funny articles from Humorix. June's features: corporations buy up almost all the 2-letter country domains; Windows vs Linux holy war in Yakima, Washington; banner ads infest Linux; how Microsoft's anti-piracy policy (not including a Windows CD with new computers) will cause more piracy; "Won't somebody please think of the Microsoft shareholders' children?"; a computer survives the Blue Screen of Death!; and who designed those Blue Screens anyway? (Humorix via Linux Today)

New Warez Distribution Addresses Ease of Use Issues (Another funny story from Segfault via Linux Today)

[Adults only] Linux Loving Sluts must be Linux's first porn site. Scantily-dressed women sport the Tux logo on their clothing and tattoos. Captions read "powered by Linux", "penguin power", "sexy chicks choose Linux", and Linus's oft-cited quote, "Software is like sex--it's better when it's free."

MySQL now GPL

C.O.L.A software news

Berlin, the windowing system that's not X-Windows has released version 0.2.0 after a year of work. Download it at http://download.sourceforge.net/berlin/Berlin-0.2.0.tar.gz. Licence: LGPL.

StrongARM version of Stalker's CommuniGate Pro mail server

MILL VALLEY, CA - May 15, 2000 - With this release, Stalker expands the number of supported Linux architectures: besides the "regular" Intel-based systems, CommuniGate Pro can be deployed on PowerPC, MIPS, Alpha, Sparc, and now StrongARM processors running the Linux(r) operating system.

The highly scalable messaging platform can support 100,000 accounts with an average ISP-type load on a single server, and the CommuniGate Pro unique clustering mechanisms allow it to support a virtually unlimited number of accounts. For office environments and smaller ISPs, CommuniGate Pro makes an ideal Internet appliance when installed on MIPS-based Cobalt Cubes(r) and, now, Rebel.com's NetWinder(r) mini-servers.

Key Features: full redundancy and load balancing on clusters, over 18 platforms supported, IMAP/HTTP access to mail including unique IMAP multi-mailbox features, personal web page publishing, mailing lists with web searching, web administration, anti-spam features, etc.

A free trial version is available at http://www.stalker.com/CommuniGatePro/.

Lineo Ships Embedix SDK for X86

LINDON, Utah - June 5, 2000 - Lineo, Inc. today began shipping Embedix SDK for x86, a software development kit that simplifies the development of embedded devices and systems. This tool set allows developers to include only the components of Linux and other software needed for the specific solution at hand. Embedix SDK is designed to reduce the system requirements, development time and overall cost of deploying embedded solutions.

Embedix SDK provides the unique tools and technologies necessary for deploying Linux across the full range of embedded devices and systems, from tiny microcontrollers through multidisk backplane servers providing high availabilit y services. Embedix SDK couples the benefits of the Open Source Linux community with Lineo's embedded tools, technologies and professional services.

Embedix SDK is available immediately for $4995 for an initial development seat, which includes a one year upgrade and maintenance agreement. Multi-user licenses are also available.

http://www.lineo.com

Lutris/Enhydra news

SAN FRANCISCO - JavaOne Conference and Exhibition, June 5, 2000 - Lutris Technologies, Inc. announced the first release of Enhydra Enterprise code to the developer community. The release of the product source code is an important step in the development of the Enhydra Enterprise application server and represents the first availability of an enterprise-level, Java/XML open source application server. Enhydra Enterprise is the direct result of joint development projects between noted open source supporters BullSoft and France Telecom, and the current Enhydra developer community, all of which contributed significant source code and expertise to the project.

Lutris Enhydra Professional 3.0 includes the Open Source PostgreSQL and the all-Java InstantDB and databases for abbreviated configuration time and fast prototyping. Inclusion and integration with Borland* JBuilder Foundation 3.5 allows developers to work within their preferred environment.

Pricing for Lutris Enhydra Professional 3.0 is $499.00 and includes technical support.

"By joining The Open Group, Lutris Technologies will be able to participate and keep abreast of the latest security issues and ensure that the Enhydra Application Server platform continues to provide robust security support," said Paul Morgan, chief technology officer of Lutris Technologies.

Omnis Studio: drag-and-drop WAP, more developers, etc.

Omnis Software confirmed some of the functionality to be available in the forthcoming release of their Rapid Application Development tool, Omnis Studio. A highlight is the incorporation of a powerful drag and drop WML (Wireless Markup Language) editor to simplify direct connectivity between server based data and remotely located WAP (Wireless Application Protocol) 'phones. WML is based on XML and was developed for specifying content and user interface for devices such as phones and pagers.

WAP phones are driving a market which needs to supply and modify relevant information quickly and clearly. With the WAP generator and one of the many available WAP phone emulators, you can quickly build and test cards and decks that can interface with existing data sources, wherever they may be located.

Omnis Studio is a high-performance visual RAD tool that provides a component-based environment for building GUI interfaces within e-commerce, database and client/server applications. When used with the company's WebClient plug-in technology, Omnis Studio allows the development of client/server relationships over the Internet using popular web browsers, giving fast, secure, scalable solutions in a minimum of development time. Development and deployment of Omnis Studio applications can occur simultaneously in Linux, Windows, and Mac OS environments without changing the application code.

The company cites three reasons for this growth: these include the increasing adoption of the Linux operating system, a reduction in Studio's price, and increasing awareness of the power and speed of the development tool.

Games!!!

Spiderweb Software and Boutell.com proudly present Exile III: Ruined World, an epic fantasy role-playing game for Linux.

• Involving, intricate plot, with 200,000 words of story!
• An enormous, changing world. Do nothing, and things evolve around you. Refugees move from town to town. Villages will be destroyed. Characters will die. Monsters will gain territory.
• Detailed, open ended system. Don't want to go on adventures? Do odd jobs. Save up and buy a house. Go on one of dozens of side missions. Explore an enormous outdoors with well over a hundred dungeons and towns. Just go through peoples' houses and rummage through their stuff!
• Pleasing, professionally done graphics and sound.
• Carefully designed interface, with comprehensive online help, adventure journals, and the ability to enable you to do everything you want with the minimum amount of fuss.

Exile III for Linux will be released Summer, 2000. You can find information and a large demo at http://www.spiderwebsoftware.com/exile3/linuxexile3.html.

http://www.spiderwebsoftware.com. Port By: http://www.boutell.com.

Loki has released a beta of the Linux SDK for use with Quake III Arena.

Loki also announced plans to bring Interplay's Descent 3 to Linux by July 2000. Descent has a Rock 'n' Ride simulator that moves a gamer and their monitor up 55 degrees. Up to 16 gamers can play together at one time via the Internet.

Loki will bring CogniToy's MindRover: The Europa Project to Linux by early fall 2000. MindRover is a 3D game that enables players to create autonomous robotic vehicles and compete them in races, battles and sports.

As if that wasn't enough, Loki also signed a deal with QLITech Linux Computers Computers to bundle several games with QLITech's Advanced Multimedia Workstations. Title include Civilization: Call to Power, Heavy Gear II and a Loki Games Demo CD with a full install of Eric's Ultimate Solitaire.

GoAhead embedded web server

BELLEVUE, Wash., May 24, 2000 - GoAhead(R) Software, the leading provider of off-the-shelf service availability software for Internet infrastructure, today announced the release of GoAhead WebServer(TM) 2.1, the latest version of GoAhead's open source, royalty free, standards-based embedded Web server.

By 2002, there will be more than 42 million devices connected to the Internet (International Data Corporation). Embedding a Web server gives manufacturers access to their devices even after they are shipped. GoAhead WebServer is the only open source embedded Web server currently on the market. It provides a secure, flexible and free way to access remote devices and appliances via standard Internet Protocols. GoAhead WebServer 2.1 now includes support for Secure Socket Layering (SSL) and digest access authentication (DAA).

GoAhead WebServer 2.1's new features were made possible in part through the active developer community that has emerged in support of the product. More than 500 developers download GoAhead WebServer source code each month.

The source code is currently available for download from GoAhead Software's Web site at http://www.goahead.com/webserver/wsregister.htm.

GoAhead Software, Inc.

iTools

iTools--a suite of tools to dramatically simplify Apache configuration & maintenance

Santa Barbara, CA, June 6, 2000. Tenon Intersystems's iTools extends and enhances Linux's networking performance, efficiency, ease-of-use, and functionality with a family of tools essential to serious, commercial content delivery and eCommerce. iTools is based on open-source implementations of Apache, DNS, FTP, and sendmail, created and maintained by software developers worldwide. Using the Linux open source internet software as a point-of-departure, Tenon's iTools extends the underlying architecture with a point & click interface and a rich set of new features.

In addition to extensions and enhancements to Apache, DNS and FTP, iTools includes a WEBmail server, an SSL encryption engine to support eCommerce, a sophisticated search engine, and both FastCGI and mod_perl support to provide high-performance Perl and CGI execution. All of the tools are supported using a point & click, browser-based administration tool.

The price is $199. A free demo is at http://www.tenon.com/products/itools-linux

Other software

Chili!Soft has a new version of ASP and a new product, SpiceRack, for developers working with Active Server Pages. ASP 3.5.2 runs on more distributions than the previous version, and has new database support and an improved installation routine for both experienced administrators and novices. SpicePack 1.0 offers additional ASP objects for sending mail (SMTP), receiving mail (POP3) and uploading files. Evaluation copies are at http://www.chilisoft.com/downloads/. Chili!Soft is a subsidiary of Cobalt Networks, Inc.

XPloy from Trustix AS is a GUI for Linux system administration. Manage your Linux servers graphically from a Linux or Windows workstation.

Proven Software, Inc. has created separate divisions for its single- and multi-user accounting software, citing differing market forces and user demands between the two. BestAcct is a "desktop" program for small organizations and individuals. Proven CHOICE Accounting is for value-added resellers and their clients with multi-user requirements. BestAcct sells for an astounding US$29.95, but includes much more than "checkbook programs" at that price. Proven Software has been developing business applications for over 15 years, exclusively for Linux for over 5 years.

Financial Accounting Systems, Inc. develops Linux accounting software for loan servicing, savings accounting, CD (certificate of deposit) accounting and safe deposit box accounting.

Hypercosm offers next-generation 3D authoring technology to Linux users that had previously been available only for Windows users.

LinkScan 7.2 allows webmasters and quality-assurance engineers to build fast, accurate, scalable and automated test suites for web sites. Four versions are offered--from Workstation to Enterprise--at a price range of US$300-5000. (Electronic Software Publishing Corporation (ELSOP))

WebKing 2.0 is another website-testing program. WebKing takes traditional testing techniques such as white-box, black-box, and regression testing and applies them to Web development. In addition, ParaSoft is introducing a new testing technique called Web-box testing, which is a form of unit testing essential to Web development. http://www.parasoft.com or http://www.thewebking.com. Pricing is US$3495, or $2995 before July 31, 2000.

Metro Link, Inc. has released Open Motif with Metro Link enhancements and bug fixes, available for free FTP download at http://www.metrolink.com/openmotif/ or http://www.opengroup.org/openmotif/.

HELIOS EtherShare 2.6 offers a high-performance Unix implementation of AppleTalk networking. PCShare 3.0 is a high-performance Windows-compatible file and print server for Unix servers, with support for Windows 2000 clients.

Active Concepts (San Francisco, CA) will use VA Linux servers and Linux-Mandrake released and beta versions as a testbed for its flagship Funnel Web prouct, to keep it synchronized with technological advances in all the major Linux distributions. Funnel Web costs US$1199-3499.

Xi Graphics Inc. has released as v1.1 the first major update to its new 3D graphics product line for Linux. The update, which is free to registered owners of the product, provides significant performance improvements and increased stability.

Progressive Development Systems, Inc. markets Level5 Pro, a total database software solution for wholesale distributors. Their newest product is WAM, a Web Access Module. The company is committed to offering its products on the Linux platform.

This page written and maintained by the Editor of the Linux Gazette. Copyright © 2000,
Published in Issue 55 of Linux Gazette, July 2000

Contents:

¶: Greetings From Heather Stern

Wrong Support Center, Folks

• problems with my card --or--
  Missing VXDs? Don't Use MS Windows!
• winmail.dat and (Former) Friends
• CD problems ...with a car
• update ...webTV, we're not.

YOU can help the Answer Gang

• Strip Library Files --or--
  Anyone out there know more?
• seeking translation for Denmark query

Procmail Arguments

Random Numbers --or--

Getting Random Values in sh

Limiting exported symbols --or--

More on Exporting Symbols from Shared Libraries

re Corel Linux and Blank Passwords

subshells in ksh, etc.

Windoze on 2d Hard Drive --or--

A Usable Example lilo.conf for 2 Drive Dual Boots

Multi- Boot LINUX, NT and WIN98

Lilo --or--

Boot Stops at LI

Can't get into telnet --or--

Accessing Shakespeare's Lear: Get Thee to a Help Desk!

How can I disable anonymous login to my ftp server --or--

Disabling Anonymous FTP

Login as root problem --or--

Remote Login as 'root': Don't do it! (Except using SSH or ...)

Linux DEVFS --or--

Linux devfs (Device Filesystem)

FW: Linux --or--

Multiple append= Directives in /etc/lilo.conf

question --or--

Getting Addresses Routed: Use IP Masquerading or Application Proxies

Linux as a firewall/router --or--

FTP Through a "Firewall"

Simple Shell and Cron Question

Uninstalling red hat --or--

Left in the Lurch
or: Uninstalling Linux the Hard Way

help....need to delete a linux partition

UVFAT --or--

Getting UVFAT

Find the source for specific program.

Greetings from Heather Stern

I'd like to especially thank Michael for stepping up to the wizard's hat early. Also we have a few answerbubbles this month which I think people will enjoy.

I'd like to please discourage people from sending us questions on both plaintext and HTML versions. The HTML produced by mailers is just not of publishable quality, and the mime attachment just makes our mail clunkier. Thanks for the thought, but just text will be fine.

That said, I had an interesting time this month. USENIX Annual Technical was in San Diego, and a number of core linuxers, *BSD developers, and other open source developers were there. There's been a crossover for ages but with their Freenix track it's a little more obvious. Last year the Freenix track book was half as thick as the normal proceedings. This year it's just as thick. I suspect it's a really good thing that Atlanta Linux Showcase (ALS) is partnered with USENIX now, because I think there is a lot more research to publish where those came from... I'll be there of course.

Now, on to the editorial. I thought of this mid-month. I told my friends to look for it. I didn't really expect it would become a slashdot flamewar and so on but I still think it needs to be said. So I'll add a disclaimer which many of you will consider obvious, but others may need to have clear:

• I am not a lawyer, I don't even play one on the net.
• I am not religious, I hope not to offend, but I think the comparison is worthy.
• speaking of religion, I already have my own opinion in this matter; the point here is to make you think, so that the open source choices you make are your own.
• If the following makes you hungry, don't say I didn't warn you.

Solved thousands of years ago, still argued today

Looking outside the tiny little box in front of me, and indeed outside the open source world, we have one of the most hotly debated arguments about what is, and what isn't okay to use. We should follow its model, as it appears to have stood the test of time while most of its strongest adherents have not starved to death.

I am, of course, referring to kosher food.

Many of you may think this cannot possibly relate to computing except insofar as the usual meal preceding a product release is nightly orders of pizza until it's a go. Or chinese food or whatever else it is the managers and engineers share a yen for. Last I recall vegetarian pizza is kosher (though not pareve) and the usual Meat Lover's Special definitely is not. Neither is oyster sauce.

We can think of food in this context because it covers mixing code, as well as dynamic linking. I can take a slice of good Jewish rye, and dynamically link in some corned beef. Yum, still kosher. If I also dynamically link on some swiss cheese, um, no. Still removable? Ask your rabbi if the touched meat remains trafe. Most customers wouldn't be able to tell if this had been done in the kitchen. If I make that a hot sandwich, I statically linked it, guess I should get a new one.

A big fuss in the GPL seems to be about the sentence fragment which, paraphrased, is something like "the whole of derivitive works shall be under the GPL". One of its more common allergies is what to do about things which require linkage against something that is under some other license. (I refuse to label other licenses more or less restrictive, without a context to apply.)

But the fact is, that the rules of kosher food are not about preventing jewish kids from enjoying cheeseburgers with their schoolfriends. They're about health. It just isn't safe to eat crustaceans from the wrong part of the sea, pork that may be undercooked, and a number of other things. Conversely our concern over licenses is about our health. If a company, or a coalition of friends, that is responsible for maintaining a product stops answering their email forever, what am I as a user of their product able to do with it? Even if I don't personally read its source code, under the DFSG compliant licenses, I can always hire some programmer to solve my problems with it and make derivitive works. This truth is made more useful by the fact that it was also legal for me to glom a copy of the source code and keep it around.

It's perfectly normal for me to buy products at the store, in neat packaging even, which are not directly consumer-level food. At least, I know very few people who buy a bag of flour in order to scoop handfuls of it into their mouth and call it lunch. It's normally statically linked against some dairy products or water, leavened with yeast, and made into sandwich fixin's or (with more linkages) sweets. Ooo, I almost forgot. Leavening it means it's not kosher for passover. Do some people eat in this "more kosher" fashion all the time? I suspect some do.

There are other products, like cereal, which we normally expect to be dynamically linked (milk please!) but which are sometimes prepared in other ways (eg. rice krispie bars) and yes, I know kids who eat cereal straight out of the box.

So this is what I was thinking when the debate was re-awakened: Is the K project kosher? I think so. Others don't have to think so. Right now, the "Harmony" project (http://harmony.ruhr.de/ ? I can't read German, and couldn't find code) which would claim to also meet Qt's API, isn't enough to make even little bitty sandwiches with. But one of the Harmony crew feels that the QPL is kosher enough for him (read his letter to LWN at http://lwn.net/1998/1203/a/jd-harmony.html) so it may be a bit of work. I think I'll go get me a nice, thick, not-kosher-for-passover, corned beef sandwich on rye.

Wrong Support Center, Folks

Most non-Linux questions don't get published here, or answered at all. Nonetheless, best of luck in your quest for knowledge...

Missing VXDs? Don't Use MS Windows!

From megabad on Tue, 06 Jun 2000

hello please my i have 5 mins of you time.

Since I have installed by Sis 6326 card when I start my computer it says missing 5591agp.vxd and then missing 5600agp.vxd please help cos i have not got a clue

thanks paul

Those sound like MS Windows problems. You're system has been infected with the infamous and widespread "Redmond" virus and you should wipe out the whole system and install Linux.

Alternatively you should contact a vendor that support Microsoft products. I don't.

(BTW: VXD is the extension used for "virtual extension drivers" or something along those lines. The were introduced in MS Win 3.1 or so IIRC. The AGP stuff is some sort of "advanced graphics port" --- a type of slot in newer PC motherboards. I presume that this error is to tell you to install a new video driver).

winmail.dat and (Former) Friends

From iwomack on Wed, 07 Jun 2000

Dear Answer guy!

Why is it that, whenever I send a word document file to one of my many contacts, the file is received on his end as a winmail.dat file? I am using Microsoft outlook and I am sending a word Document. Please Help?

IAN WOMACK

First, let me contratulate you on NOT sending me a 'winmail.dat' file.

winmail.dat is a file attachment that Microsoft's Outlook mail client attaches to most mail so that it can contain any of MS' extensions to mark up the text of your mail. So the basic text of your message, with no highlighting or special formatting is supposed to comprise the main body of your e-mail, while 'winmail.dat' is supposed to contain all of the formatting and other fluff that makes it look the same to another MS Windows user as it did to you.

I personally find winmail.dat files to be mildly annoying.

However, I find that mail sent to me in proprietary formats (such as MS Word .doc) to be highly irritating. Basically people have to pay me to read those. If you're not a customer or my boss and you send me something as an attachment in any format that I can't readily read --- your mail goes into the bit bucket faster than you can say "delete."

Of course it would be unfair to single out Microsoft in this regard. I don't like Netscape's "vcard" attachments any less obnoxious than "winmail.dat" and I find Netscape's previously default behavior of appending HTML formatted copies of the body text to all outgoing e-mail to be almost as bad as appending .doc or other binary formats. (At least I can read between the tags if I care to).

Of course I'm a curmudgeon in this regard. I think that plain old unadulterated text is a fine tool for communications and I don't like to see a lot of formatting fluff to confuse the issue. I still use Lynx for most of my web browsing, and I still work from text mode consoles more often than not. (Although I've made it a point to stay in X most of the time on my new laptop, mars, and on my latest home desktop client, canopus. I still use a big xterm running a copy of 'screen' for almost all of my work).

Anyway, If you want to learn how to send mail that is likely to be most effective and least irritating to the broadest range of correspondents, then eschew all of the fancy formatting, and learn to write!

As for configuring your mail client to behave itself, I don't know. I don't use any MS products and certainly wouldn't use a GUI mail client. Perhaps Microsoft offers some sort of support with their products. Last I heard they run a 900 (pay-by-the-minute) telephone service. Perhaps that could answer your questions more thoroughly for a few quid.

(On the other hand, you could switch to Linux, which would make Outlook basically unavailable to you. Then you'd also be protected from the next few outbreaks of the "Melissa" and "Love Bug" viruses among others. Indeed you'd be immune from that whole class of plagues).

CD Problems

From Sheree_Shannon on Thu, 08 Jun 2000

Hi, I purchased a 1998 Chrysler Town & Country van recently that has a cd player. When I try to put a cd in, it immediately comes back out. Someone told me another cd must be stuck in there. How can I find out, and how do I get it out?

Thanks. Sheree'

I know this is going to sound shocking, but did you look in the owner's manual or contact a factory dealership?

I suppose you could try the "Ask Chrysler" CGI program at:

http://ask.chrysler.com

Or take it down to your favorite neighborhood car stereo shop and have them take a look at it. Of course all of those venues will try to sell you a new CD player, or a new car, or something.

I won't try to sell you anything. I just answer Linux questions for this online magazine called the "Linux Gazette." They picked "The answer guy" as a name for my column which is presumably how you got tricked into mailing this question to me.

O.K. I lied. I'll try to sell you something. You could try replacing that CD player with an automotive MP3 player. That would mean that you'll "rip" your CDs on you home computer, download them into a little computer in your car and use that to play them.

Here's a few links on that idea:

Open Directory - Computers: Software: Operating Systems: Linux: Music

http://www.dmoz.org/Computers/Software/Operating_Systems/Linux/Music

(BTW: the Open Directory Project, dmoz, is very cool. Think, community driven Yahoo!)

Knight Rider MP3 Player

http://knightrider.linuxave.net

Slashdot:IBM and Mp3

http://slashdot.org/articles/99/04/04/1530213.shtml

Slashdot:Doing the Quickee Boogie

http://slashdot.org/articles/99/01/13/226240.shtml

update

From texastootles on Mon, 12 Jun 2000

WebTV Support Line? NOT!

For 3 days I get this update when i try to get on webtv I have let them but they just never seem to finish what shall I do?

~tootles~

This is not the WebTV tech support line.

Perhaps they offer some sort of customer service with the product they sold you and the "service" to which you are subscribed.

[Rolls eyes heavenward! Sighs!]

YOU can help the Answer Gang

One or more questions may be posted here, as well as any that need translation before the Gang can answer. Got any answers for these? Send them to

Anyone out there know more?

From David Lee on Thu, 22 Jun 2000

Hello,

I would like to have a question about stripping binary and library files.

Actually I am building a Linux boot/root floppy disk. I need to fit in some huge shared library files, especially libc-2.1.1.so.6. (I am using Linux Mandrake 6.1). Reducing file size is necessary.

I think either objcopy or strip can be used. However, the Linux Bootdisk HOWTO says that only debug symbols should be removed (--strip-debug). What would happen if everything is removed (--strip-all)? I have tried and the resulting boot/root disk seems to be OK. However, something must be wrong ...

Thanks for your help.

David.

Seeking translation for Denmark query

From hilsen kasper on Thu, 22 Jun 2000

Dav jeg syntes at det er en gode side du har med en masse gode brugbare råd . men det er ikke det jeg vil , je har et problem som du måske kan hjælpe mig med . Jeg har en 450 mhz p3 cpu som jeg gerne vil have overclocket jeg har et asus bundkort model :p2b/f1440bx agp atx. Jeg ved ikke om at jeg skal have noget extra køling på når det kun er til 500 mhz da mit bundkort ikke kan tage mere.en anden ting er at jeg ikke ved hvordan jeg gør så jeg håber at du vil hjølpe mig. JEg håber at du vil hlælpe mig med mine spørgsmål.

hilsen kasper

Procmail Arguments

From D. Scott Lowrie on Mon, 19 Jun 2000

hi,

I've been able to use procmail when I send the mail to &myuserid+keyword.

Where I assign a variable (say PLUSARG=$1).

I can use the variable PLUSARG to base some procmail recipes. So what's the question??? well it seems if I us and alieas set up for me and the "+keyword" syntax that procmail doesn't pass the "+keyword" in as the $1 parameter. E.G. $1 is found when I use myid+keyword but not with alieasId+keyword. thanks,

Scott Lowrie

I think that your mailer (sendmail) is actually the culprit. I think that the MTA is stripping out everything from the + to the @ since (since that's how it figures out which mailbox is the intended recipient with the old "plusaddressing" convention).

It seems to be that the ^TO macro in procmail does expose the header address (which retains the + extension) while the envelope address is being passed to your PLUSARG.

Try using the ^TO pattern.

procmail arguement list

From D. Scott Lowrie on Tue, 20 Jun 2000

thanks for the suggestion ... I really appreciate your help.

Scott FYI I'll let you know what we are doing with the "+arguement" -

its not all that clever but in our case makes for an easy way to add things to our online documentation. Perhaps some other user may find this useful for simple/quick documentation.

The simple idea is that we have a userid called "caddoc" and if you have an email that others may find useful (perhaps like the tip you just gave me!) then we just would send/forward/cc/bcc to "caddoc+mailtips". The procmail script then processes the caddoc to signify you want to document something; the +mailtips to signifiy you want it in our "mailtips" archive area; and then uses "mhonarc" to add this email in html format to the data area defined in the "mhonarc" call. So with just a simple addition of "caddoc+mailtips" we get the info tucked away for future reference. The alternative of swipping the data; putting this data in a file in the mailtips area; updating the index.html would also work but the reality is "our natural laziness" makes it unlikely to happen.

Scott Lowrie

Getting Random Values in sh

From Devil Man on Thu, 08 Jun 2000

Hello answer guy I was wondering and have been unable to find any info about a shell scripting utility or command that can be used to generate a random number such as if I wanted to create a shell script to generate a random number between 1-20 or so. It dose not have to be a all in one basically how do you generate random numbers and the command line?

Thanks randomly speaking

Well the easiest way, under bash is to simply use the predefined "magic" shell variable: $RANDOM. So the following might work for you:

RANDOM=$$$(date %+s) function d20 () { d=$[ ( $RANDOM % 20 ) + 1 ] }

... The first line just seeds bash' random number generator using your current process ID (PID) and the current time/date expressed as the number of seconds since 1970 (the UNIX epoch). This should prevent RANDOM from generating the same predictable sequence every time you run it. (You can set bash' RANDOM to new seed values, but if you ever 'unset' it --- it will lose its special "magic" property for the life of that shell/process. This is true of a couple of bash' "magic" variables).

Note that this form of random seeding is common but not adequate for proper cryptography, or high stakes gambling. For that we probably wouldn't be using the shell, we certainly wouldn't be storing things in environment variables, and we'd probably want to read a bit of entropy out of the Linux /dev/urandom or /dev/random devices (depending on the relative importance of speed versus "quality of entropy" required).

Shell function, which I've named after the gamer's conventional abbreviation for their favorite polyhedral (dice), simply takes a $RANDOM value modulo 20 (modulus is the remainder of a division, and thus gives us a number between 0 and 19) and then I add one to just this from the range 0-19 up to 1-20.

This method (take a modulus of a number and add a base) is commonly used by programmers to get random values within a specific range. If you want the numbers to follow a specific curve you can use additional arithmetic operations and additional random values. For example to get a nice bell curve that reasonably approximates a natural population where lots of entities are "average", a few are "exceptional" or "bad" and a very few are "super" or "woeful" you can use a sum of several random numbers.

The classic "Dungeons & Dragons (TM)" 3d6 gives such a curve which is why they don't simply use a single d20 for each ability score. It's also why simple percentile rolling on a pair of d10s or d20s doesn't give the "right" distribution of results.

You can get some really wacky curves if you take one random value and divide it with another (round down to the nearest int). For example a d6/d4 gives a number from 0 to 6 with only a 1 in 24 chance of getting a 6, and 25% chance of getting nothing, just over %30 of getting a 1, etc. But I digress.

Of course my example here depends on bash. So it's not very portable.

Here's a method that's somewhat more portable:

r=`fortune | cksum | cut -f1 -d" "` d=`expr \( $r % 20 \) + 1 `

Those are shell backtick (command substitution) operators. That's an older syntax which is supported by very old shells (and is still supported by new ones). I use that on the command line sometimes, but I prefer to use the newer syntax $( ... ) in scripts and when explaining shell programming. It's easier to read and it's easier to write clearly on a whiteboard. (Of course both forms mean the same thing, execute the enclosed command(s) capturing the output from them, and paste that output into parent expression as a replace for the whole "backtick" expression).

The 'fortune' command is included with most versions of UNIX and is commonly installed. It's just a little program that randomly chooses a "fortune cookie" --- a random quotation or aphorism --- and prints it. Lots of people see those every time they log in, and some of the X screensavers (like Mr Nose) use them. In this case we get a random phrase and feed it to the cksum (BSD/SysV checksum program). The checksum of a random strings should be random. (I don't have a rigorous mathematical proof of that handy --- but I'm pretty sure it's true; though it may not give a very even distribution). (That's another advantage to the $(...) form. It's nestable, you can have $( foo $( bar ... ) ) without ambiguity or error).

So I use another line and the old 'expr' command to scale $r to the desired range. I have to use two lines in this case, since the old "backtick" form cannot be "nested" (or at least the kinds of quoting tricks that might allow one to nest such a beast would probably not be very portable and would certainly be less readable.

Note that the 'expr' command is fairly picky --- so we must separate our operands and operators with spaces so that it sees each as a separate command line argument. Also note that I must quote/escape the parentheses in my arguments to 'expr' since I need for 'expr' to see them, so I have to prevent the shell (specifically the subshell that's executing my backtick command) from seeing those parentheses as a "subshell" operator. You could also wrap each of those parens. in quotes, single (hard) or double (soft). However you should NOT try to just wrap the whole expression in single or double quotes, because then 'expr' will see it all as one big (string) argument rather than as a sequence of numbers and operators. Sorry that's so complicated. That's how 'expr' works. In general it's much easier to use a more recent ksh, bash, or zsh which supports the internal 'let' command as well as $(( .... )) and/or $[ ... ] syntax for arithmetic operations.

Obviously if you want you script to be very portable, and you can't guarantee that your users will have a 'fortune' command installed, or that they'll have a recent version of a decent shell then you'll have to work at some other way to get a random number.

As long as you have expr, cksum, and ps (and/or w and/or who), date (and/or the time command), cut (or awk) it should be possible to cook up small random numbers suitable for dice games, etc.

The trick is to run some of those commands in a subshell, piping their combined output into cksum and cut out the checksum value. Any commands that are very likely to give different, even slightly different information when run from one second to the next are suitable as input to your checksum. Thus one new process or one that dies or changes state give different ps output. Every second the idle time reported by the 'w' (who) command will be updated. Of course the 'date' command will be different every second, as well.

Of course once you have a seed value (based on something non-deterministic, or something that is usually going to be different each time your program runs) then you can use your own arithmetic operations to perturb that seed value.

Here's a link to a discussion of "simple psuedo-random number generation":

http://www.sct.gu.edu.au/~anthony/info/C/RandomNumbers

The examples can be adapted to sh pretty easily:

Set initial value:

seed=`( echo $$ ; time ps ; w ; date ) | cksum | cut -f1 -d" " `

Use it:

echo $seed
seed=` expr \( $seed \* 9301 + 4929 \) % 233280 `

... note I have to escape my "*" 'expr' operator to prevent it from being expanded (into a list of files) due to shell globbing.

Also note that this must be run in the current shell context --- putting the seed=... line in a shell script wouldn't work because the shell script runs in its own shell, updates its own value of the seed, and then exits. That would leave our copy of the seed unchanged.

So, if this calculation (the linear congruential method) is to be stored in a shell script it must be invoked with the shell's "dot operator" or the 'source' built-in command. That will execute it within the context of the current shell, allowing the lines therein to modify the values of your current shell's variables.

I came across another nice article on the "linear congruential" calculation of psuedo-random numbers at:

http://www.acm.inf.ethz.ch/ProblemSetArchive/B_US_NorthCen/1996/prob_f.html

This apparently was in the context of a programming assignment, challenge or contest of some sort.

It should be noted that the values of your L, I, and M (the numbers you multiple, increment and modulo your current/seed value with at each iteration) can't be arbitrarily chosen. There are some some values for these that give "good" psuedo-randomness (an even distribution of return values across the spectrum of available numbers) while others will give very bad numbers.

Frankly I think all that stuff is two complicated. So I'm glad I use Linux where I can just use:

dd if=/dev/urandom count=1 2> /dev/null | cksum | cut -f1 -d" "

... to get all the randomness I want.

So, I hope that's more than you wanted to know about generating psuedo-random numbers using the shell.

Random Numbers

From Devil Man on Mon, 12 Jun 2000

Just a Note see below.

And thanks for all the wonderful info and the quick response...

-- The Linux Gazette Answer Guy <> wrote:

Getting Random Values in sh

>Hello answer guy I was wondering and have been unable to find
>any info about a shell scripting utility or command that can be
>used to generate a random number such as if I wanted to create a
>shell script to generate a random number between 1-20 or so. It
>dose not have to be a all in one basically how do you generate
>random numbers and the command line?

>Thanks randomly speaking

Well the easiest way, under bash is to simply use the predefined "magic" shell variable: $RANDOM. So the following might work for you:

RANDOM=$$$(date %+s)

shouldn't the date command be (date +%s)

Yep. That was a typo.

More on Exporting Symbols from Shared Libraries

Answered By dps on Thu, 08 Jun 2000

There are valid reasons other than those evil one you give for wanting to limit the exported symbols---prime examples are big jobs split into multiple source files, which export symbols that implement the feature. Normally one would not want to export these symbols after linking the library.

IF anyone wants to use undocumented functions that for advanatge over the competition then removing it also stops them linking those functions. A little reading of the binutils man page will reveal, for example the -L optionm in objcopy

      -L symbolname, --localize-symbol=symbolname
           Make symbol symbolname local to the file, so that it is
           not visible externally.  This option may be given more
           than once.

which seems to fit the bill. (Several symbols in the resolver code became local in the glibc 2.0 yto glibc 2.1, breaking various programs that used the undocumented behaviour of those symbols.)

The main differences is that M$ dll's seem to require you to explicitly list what is externally visible, unlike most unicies and their shared libraries.

I didn't think I characterized it as "evil." I just didn't think it would be very useful.

However, you've shown me a new trick. I hope my earlier correspondent checks back if he or she still needs this tidbit.

Limiting "Public Interfaces" on Share Libraries

Answered By Steven G. Johnson on Tue, 30 May 2000

Hi, noticed your answer regarding "public interfaces" in shared libraries in the latest Linux Gazette, and I had a couple of comments. (I am a programmer, and have written several libraries and shared libraries under Linux.)

There are at least two good reasons to hide functions from public interfaces:

1. If a function is internal to the library, and it may well disappear or change incompatibly without warning in future versions, so that you don't want to be worry about people using it.
    
   Any library will almost certainly contain a large number of such internal functions, and the code would be utterly unmaintainable if you couldn't change them between releases because people depended on them.
    
   Of course, it is usually sufficient to simply not document those functions or declare them in your header files, so that programmers who find out about them should know that they use them at their own risk. (Some programmers are foolish enough to do so, even though it is almost never a good idea. e.g. there was a well-known case where StarOffice had depended upon internal glibc functions and therefore broke when glibc was upgraded.)
2. If you don't want to pollute the namespace.
    
   If I have an internal function in my library called something generic, like print_error, I run the risk of accidentally conflicting with a function of the same name in a calling program, with unpredictable results. One way around this is to prefix the function with the name of my library, calling it e.g. foo_print_error if my library is libfoo. But this can be awkward to do for every little internal function you write, and it is often preferable to simply hide them from the linker.

There is a solution, however, provided by ANSI C: simply declare your functions with the "static" keyword, and they will only be visible/callable within the file they are defined in. This isn't perfect, I suppose, because they also aren't visible to other files in the same library. However, it covers the case where foo_ prefixes are most annoying: little utility functions that are only called within one file.

Cordially,
Steven G. Johnson

re Corel Linux and Blank Passwords

Answered By Dave Cotton on Wed, 31 May 2000

This is just a long shot. I have only loaded Corel once or twice to see what it looked like. His name does not tell me, is he using a US keyboard, or a non US one? I have found that before the system is loaded on some distros you are in US keyboard layout, afterwards it runs your native keyboard. I got caught by this, I had numbers in the password, in the US they're unshifted in FR they're shifted!

Keep up the good work
Dave Cotton
France

subshells in ksh, etc.

Answered By Bill Rausch on Thu, 1 Jun 2000

All? of the popular free sh-like shells (pdksh, bash, etc.) have the bug you mentioned in http://www.linuxgazette.com/issue54/tag/11.html. It is documented somewhere; I've seen a reference a couple of times (pdksh man page I think, maybe other places as well).

I got bit porting some scripts from HP-UX to Linux. Took a while to figure out what was busted. The particular construct I was using was piping a command through a "while read loop".

The original ksh is now available from ATT but with some kind of goofy license. I don't know if it will catch on or not.

Bill

[ They explain it a little bit in their ATT Source License FAQ:

http://www.research.att.com/sw/download/faq.license.html

Essentially, the goofiest thing about it is making sure everyone is clear that further recipients have to actively agree to the license; active agreement is why they don't have a normal FTP site to get these toys from.
-- Heather. ]

A Usable Example lilo.conf for 2 Drive Dual Boots

Answered By David Uhring on Thu, 22 Jun 2000

Using lilo's mapping facility does not attempt to fool Windows; it fools the BIOS. Linux Mandrake's installer generates a lilo.conf file similar to this one, actually in use on my system:

boot   = /dev/hda
map     = /boot/map
install = /boot/boot.b
vga     = normal
default = linux
read-only
linear
prompt
timeout = 150
message = /boot/message

  image  = /boot/vmlinuz
  label  = linux
  root   = /dev/hda14

  image  = /boot/vmlinuz.suse
  label  = suse
  root   = /dev/hda14

  other  = /dev/hdb1
  label  = dos
  table  = /dev/hdb
  map-drive=0x80
    to=0x81
  map-drive=0x81
    to=0x80

  other = /dev/hda1
  label = obsd
  table = /dev/hda

  other = /dev/hda2
  label = sun
  table = /dev/hda

  other = /dev/hda3
  label = fbsd
  table = /dev/hda

The Win98SE installation, BTW, is remarkably stable. I've been using it for about four months with only two BSOD's. Course, with four flavors of UNIX available, I really don't use Windows all that much.

Dave

Multi- Boot LINUX, NT and WIN98

From ng chin kar on Sat, 17 Jun 2000

Hi answerguy,

I'm an novice to linux and had just installed Linux redhat 6.0 to my system and like to configure to multi-boot to my WINNT4.0, WIN98 and DOS. How to counter act this problem. Pls Advice. Thanks

Regards LINUX NOVICE

Multi- Boot LINUX, NT and WIN98

From Michael Williams on Sat, 17 Jun 2000

It's difficult to answer this problem since you do not give enough details about your problem. Answer these questions, and I can help you out:

1. Do you have LILO installed? 2. What partitions and drives are all the OS's on?

Mike

Fwd: Re: Multi- Boot LINUX, NT and WIN98

From ng chin kar on Tue, 20 Jun 2000
Answered by Michael Williams

Hi there,

Current;y I'm able to have the multi-boot option. But I had another question to seek your advise that is I install another linux (Corel Linux) and the installation goes smoothly but when at the login screen, the screen starts to brink and it starts when try to start the KDE display manager. Pls advise.

Regards and thanks

Right, here's a solution. As far as I can tell, all you need to do is edit your /etc/lilo.conf file to include the following text:

boot=/dev/hda
read-only
prompt
timeout=50
vga=ext

#Windows 98
other=/dev/hda1
label=dos
table=/dev/hda

#Linux
image=/boot/linux   #Put the name of your kernel here
root=/dev/hda3
label=linux

#Windows NT
other=/dev/hda2
label=winnt
table=/dev/hda

You can edit it by typing:

pico /etc/lilo.conf

Then type:

lilo

To install lilo to the MBR

Obviously, you can use any text editor. That should solve your problem, unsless of course something else is wrong

Mike

Boot Stops at LI

From pha17 on Wed, 07 Jun 2000

My linux computer freezes when i try to boot, it just says " LI " then hangs.

I have got into the system with a boot disk and checked the lilo.conf file and run lilo which returns " Added Linux * " but lilo still will not boot

Can you tell be whats wrong ?

In the documentation for LILO there is a description of this problem. The LILO boot loader prints each of the characters: "L ... I ... L ... O" (LILO) at a different point in the processs of reading/parsing the partition table, loading the secondary boot loader code, locating and loading its maps (which it uses to locate and load kernels and optionally a initial ram disk --- initrd--- images).

When the system stops at LI then that tells you that the process failed before it could reach the part of that sequence where it would have printed the second "L".

Usually this means that you have a mismatch in the way that LILO and the BIOS are trying to access specific parts of a drive. One may be using CHS (cylinder, head, sector) co-ordinates while the other might be expecting LBA (linear block address) offsets. So, try adding the "linear" directive to the global section of your /etc/lilo.conf (and re-running the /sbin/lilo command to build and install a new boot loader from that conf file, of course).

Alternatively, try changing your PCs CMOS Setup options. Look for an option like "LBA" or "UDMA" mode and disable it. Note that this may not work with newer large capacity drives.

Search the back issues of LG on the term "LILO" for many other discussions of this sort of issue and explanations about what LBA and CHS mean, and some commentary on the historical reasons why IDE has evolved through all these EIDE, LBA, UDMA iterations.

Also note that it's still a good idea to make a small (16 - 32 Mb) "boot" partition at or near the beginning of any hard drive on which you install Linux. That should be entirely below the 1024 cylinder line. Newer versions of LILO can work around that infamous limit in most cases --- but it's still a good idea. Most people mount this partiton on /boot. It is the best place to put your kernels, initrd images, and their System.map files. (If you have MS-DOS or some other Microsoft OS installed in a large partition at the beginning of a drive, such that you can't put a small partition below cylinder 1024, consider using LOADLIN.EXE instead of LILO).

It may also be a good time to look at GRUB (the GNU grand unified bootloader). I haven't played with this yet; but I've heard that some people are very happy with it.

You can find out more about GRUB at its home page on the Free Software Foundation's (FSF) web pages:

http://www.gnu.org/software/grub/grub.en.html

Accessing Shakespeare's Lear: Get Thee to a Help Desk!

From TRANS on Tue, 06 Jun 2000

I'm having trouble getting into telnet from an off campus computer. I've

tried to access my shakespeare account, lear, using the email express tab on the IUB homepage, but everytime I try to connect a little dialog box pops up and says connection failed. I know that my modem is working, so I don't know what the problem is. I would appreciate any help you could offer. Thanks,

Nellie Khalil

Unfortunately you message doesn't contain enoough information to troubleshoot the problem.

It sounds like you're trying to access an account under the name of 'lear' on a host named 'shakespeare' from some other system which is "off campus." I guess you're looking at the web pages at "IUB" which I presume is some university or college, and you're clicking om some link that this web page provides (which is labelled "email express" or something like that).

So, you think your modem is working (presumably becuase you can use your browser to access some web page). It's not clear why you think telnet is involved in any of this. Is the link you are clicking of the form "telnet://shakespeare..."?

However, there are way too many variables here. Most likely the system you are trying to access is behind some sort of firewall or on some network that is not routable from where you're connected to the net. It is also likely that the link on this IUB page shouldn't be visible from the outside world. Of course it's also possible that you have a broken browser, don't have a telnet client installed, are looking at a broken link or that I've completely failed to guess at what your question really meant.

In any event it is VERY unlikely that this is a Linux question and it is VERY likely that you should contact the help desk at whatever campus you're talking about.

It also seems like you might won't to take some extra classes in communications skills. It amazes me that anyone could write a message such as this with an apparent total ignorance of how much it assumes of the reader.

How many people out on the internet know what you mean by IUB? How many other meanings of IUB might collide with that? What campus? What "tab"? Where would I look to see that "tab" and how were you "using" it (clicking, I guessed)? What put up that little dialog box? (Your browser? MS Windows? Linux GNOME or KDE?) etc.

I probably should just delete messages like this. It's clear that I spend far more time and energy trying to understand them than the writers put into composing them.

However, there's a part of me that hopes that some of the people that read this rant will think about it. Maybe they'll re-read what they've written to some tech support guy out there and ask themselves: "Have I provided enough information that this correspondent could possibly answer my question?"

Disabling Anonymous FTP

From Aung Win Thu on Tue, 06 Jun 2000

Dear Dennis

I have installed Linux Redhat 6.0 on my intel machine. I want to disable anonymous login to my ftp site. how can i do it? Thaks for your help.

Aung

Traditional FTP daemons used the existence of an account named "ftp" (an ftp:... entry in the /etc/passwd file) as a flag to enabled anonymous FTP.

If you're using a plain old BSD port of ftpd you could just remove that user. There are various other FTP daemons such as WU-ftpd (originally from Washington University in St Louis, wustl.edu), NCFTPd (by Mike Gleason, author of the ncftp client) and ProFTPd (http://www.proftpd.net). Each of those supports some way of enabling anonymous FTP --- so all you have to do is reverse those steps to "disable" it.

I also recommend that you use TCP wrappers (edit your /etc/hosts.allow and /etc/hosts.deny files) to limit whence FTP connections are accepted. In other words, start with ALL: ALL in your /etc/hosts.deny and add the networks and IP address patterns (and/or domain name patterns) from which you will allow you users to access your site.

Personally I'd like to see FTP fade away in favor of SSH or more secure protocols. (Although it may be more of a race between the secure protocols at the applications level and the transparently secure protocols in IPSec FreeS/WAN).

Remote Login as 'root': Don't do it! (Except using SSH or ...)

From michael.rees on Wed, 07 Jun 2000

Hi, Sorry to bother you but could you help me with the following??

i am running red hat linux 6.1 and am encountering some problems i can login as root from the console but not from anywhere else

i have to login as webmaster on all other machines on ntwk

from nowhere, including the console, can i su once logged in as webmaster

any help would be appreciated

Regards, Michael

Your system is enforcing a very reasonable policy by preventing direct 'root' logins from over the network.

The best way to circumvent this policy is to use one of the implementations of SSH (the original SSH by Tatu Ylonen, now owned and commmercially available from DataFellows Inc http://www.datafellows.com, or OpenSSH http://www.openssh.com --- which is ironically at a .com rather than a .org domain, or the GPL'd lsh at http://www.net.lut.ac.uk/psst).

Any of these should allow you to access your system through cryptographically secured authentication and session protocols that protect you from a variety of sniffing, spoofing, TCP hijacking and other vulnerabilties that are common using other forms of remote shell access (such as telnet, and the infamous rsh and rlogin packages).

If you really insist on eliminating these policies from your system you can edit files under /etc/pam.d that are used to configure the options and restrictions of the programs that are compiled against the PAM (pluggable authentication modules) model and libraries. Here's an example of one of them (/etc/pam.d/login which is used by the in.telnetd service):

#
# The PAM configuration file for the Shadow `login' service
#
# NOTE: If you use a session module (such as kerberos or NIS+)
# that retains persistent credentials (like key caches, etc), you
# need to enable the `CLOSE_SESSIONS' option in /etc/login.defs
# in order for login to stay around until after logout to call
# pam_close_session() and cleanup.
#

# Outputs an issue file prior to each login prompt (Replaces the
# ISSUE_FILE option from login.defs). Uncomment for use
# auth       required   pam_issue.so issue=/etc/issue

# Disallows root logins except on tty's listed in /etc/securetty
# (Replaces the `CONSOLE' setting from login.defs)
auth       requisite  pam_securetty.so

# Disallows other than root logins when /etc/nologin exists
# (Replaces the `NOLOGINS_FILE' option from login.defs)
auth       required   pam_nologin.so

# This module parses /etc/environment (the standard for setting
# environ vars) and also allows you to use an extended config
# file /etc/security/pam_env.conf.
# (Replaces the `ENVIRON_FILE' setting from login.defs)
auth       required   pam_env.so

# Standard Un*x authentication. The "nullok" line allows passwordless
# accounts.
auth       required   pam_unix.so nullok

# This allows certain extra groups to be granted to a user
# based on things like time of day, tty, service, and user.
# Please uncomment and edit /etc/security/group.conf if you
# wish to use this.
# (Replaces the `CONSOLE_GROUPS' option in login.defs)
# auth       optional   pam_group.so

# Uncomment and edit /etc/security/time.conf if you need to set
# time restrainst on logins.
# (Replaces the `PORTTIME_CHECKS_ENAB' option from login.defs
# as well as /etc/porttime)
# account    requisite  pam_time.so

# Uncomment and edit /etc/security/access.conf if you need to
# set access limits.
# (Replaces /etc/login.access file)
# account  required       pam_access.so

# Standard Un*x account and session
account    required   pam_unix.so
session    required   pam_unix.so

# Sets up user limits, please uncomment and read /etc/security/limits.conf
# to enable this functionality.
# (Replaces the use of /etc/limits in old login)
# session    required   pam_limits.so

# Prints the last login info upon succesful login
# (Replaces the `LASTLOG_ENAB' option from login.defs)
session    optional   pam_lastlog.so

# Prints the motd upon succesful login
# (Replaces the `MOTD_FILE' option in login.defs)
session    optional   pam_motd.so

# Prints the status of the user's mailbox upon succesful login
# (Replaces the `MAIL_CHECK_ENAB' option from login.defs). You
# can also enable a MAIL environment variable from here, but it
# is better handled by /etc/login.defs, since userdel also uses
# it to make sure that removing a user, also removes their mail
# spool file.
session    optional   pam_mail.so standard noenv

# The standard Unix authentication modules, used with NIS (man nsswitch) as
# well as normal /etc/passwd and /etc/shadow entries. For the login service,
# this is only used when the password expires and must be changed, so make
# sure this one and the one in /etc/pam.d/passwd are the same. The "nullok"
# option allows users to change an empty password, else empty passwords are
# treated as locked accounts.
#
# (Add `md5' after the module name to enable MD5 passwords the same way that
# `MD5_CRYPT_ENAB' would do under login.defs).
#
# The "obscure" option replaces the old `OBSCURE_CHECKS_ENAB' option in
# login.defs. Also the "min" and "max" options enforce the length of the
# new password.

password   required   pam_unix.so nullok obscure min=4 max=8

# Alternate strength checking for password. Note that this
# requires the libpam-cracklib package to be installed.
# You will need to comment out the password line above and
# uncomment the next two in order to use this.
# (Replaces the `OBSCURE_CHECKS_ENAB', `CRACKLIB_DICTPATH')
#
# password required       pam_cracklib.so retry=3 minlen=6 difok=3
# password required       pam_unix.so use_authtok nullok md5

This is from my Debian laptop (mars.starshine.org) and thus has far more comments (all those lines starting with "#" hash marks) than those that Red Hat installs. It's good that Debian comments these files so verbosely, since that's practically the only source of documentation for PAM files and modules.

In this case the entry that you really care about is the one for 'securetty.so' This module checks the file /etc/securetty which is classically a list of those terminals on which your system will allow direct root logins.

You could comment out this line in /etc/pam.d/login to disable this check for those services which call the /bin/login command. You can look for similar lines in the various other /etc/pam.d files so see which other services are enforcing this policy.

This leads us to the question of why your version of 'su' is not working. Red Hat's version of 'su' is probably also "PAMified" (almost certainly, in fact). So there should be a /etc/pam.d/su file that controls the list of policies that your copy of 'su' is checking. You should look through that to see why 'su' isn't allowing your 'webmaster' account to become 'root'.

It seems quite likely that your version of Red Hat contains a line something like:

# Uncomment this to force users to be a member of group root
# before than can use `su'. You can also add "group=foo" to
# to the end of this line if you want to use a group other
# than the default "root".
# (Replaces the `SU_WHEEL_ONLY' option from login.defs)
auth       required   pam_wheel.so

Classically the 'su' commands on most versions of UNIX required that a user be in the "wheel" group in order to attain 'root' The traditional GNU implementation did not enforce this restriction (since rms found it distasteful).

On my system this line was commented out (which is presumably the Debian default policy, since I never fussed with that file on my laptop). I've uncommented here for this example.

Note that one of the features of PAM is that it allows you to specify any group using a command line option. It defaults to "wheel" because that is an historical convention. You can also use the pam_wheel.so module on any of the PAMified services --- so you could have programs like 'ftpd' or 'xdm' enforce a policy that restricted their use to members of arbitrary groups.

Finally note that most recent versions of SSH have PAM support enabled when they are compiled for Linux systems. Thus you may find, after you install any version of SSH, that you have an /etc/pam.d/ssh file. You may have to edit that to set some of your preferred SSH policies. There is also an sshd_config file (mine's in /etc/ssh/sshd_config) that will allow you to control other ssh options).

In generall the process of using ssh works something like this:

1. Install the sshd (daemon) package on your servers (the systems that you want to access)
2. Install the ssh client package on your clients (the systems from which you'd like to initiate your connections).
3. Generate Host keys on all of these systems (normally done for you by the installation).

.... you could stop at this point, and just start using the ssh and slogin commands to access your remote accounts using their passwords. However, for more effective and convenient use you'd also:

4. Generate personal key pairs for your accounts.
5. Copy/append the identity.pub (public) keys from each of your client accounts into the ~/.ssh/authorized_keys files on each of the servers.

This allows you to access those remote accounts without using your passwords on them. (Actually sshd can be configured to require the passwords AND/OR the identity keys, but the default is to allow access without a password if the keys work).

Another element you should be aware of is the "passphrases" and the ssh-agent. Basically it is normal to protect your private key with a passphrase. This is sort of like a password --- but it is used to decrypt or "unlock" your private key. Obviously there isn't much added convenience if you protect your private key with a passphrase so that you have to type that every time you use an ssh/slogin or scp (secure remote copy) command.

ssh-agent allows you to start a shell or other program, unlock your identity key (or keys), and have all of the ssh commands you run from any of the descendents of that shell or program automatically use any of those unlocked keys. (The advantage of this is that the agent automatically dies when you exit the shell program that you started. That automatically "locks" the identity --- sort of.

There are alot of other aspects to ssh. It can be used to create tunnels, through which one can use all sorts of traffic. People have created PPP/TCP/IP tunnels that run through ssh tunnels to support custom VPNs (virtual private networks). When run under X, ssh automatically performs "X11 forwarding" through one of the these tunnels. This is particularly handy for running X clients on remote systems beyond a NAT (IP Masquerading) router or through a proxying firewall.

In other words ssh is a very useful package quite apart from its support for cryptographic authentication and encryption.

In fairness I should point out that there are a number of alternatives to ssh. Kerberos is a complex and mature suite of protocols for performing authentication and encryption. STEL is a simple daemon/client package which functions just like telnetd/telnet --- but with support for encrypted sessions. And there are SSL enabled versions telnet and ftp daemons and clients.

Another issue where I talked a bit about crypto software available for Linux:

http://www.linuxgazette.com/issue35/tag/crypto.html

Another issue where I answer questions about remote root logins:

http://www.linuxgazette.com/issue35/tag/remoteroot.html

Linux devfs (Device Filesystem)

From Nathan F. on Thu, 08 Jun 2000

Hello! Excuse the beginner question, but I was wondering how in the heck to install and run DEVFS in my RedHat 6.2 linux OS?

Short Answer: get 2.4.0test* and use that!

Before I say anything else I should point out that I haven't been using Red Hat for the last few revisions. So I don't know the details of their 6.2 release.

That said I can answer the general question about devfs.

I never saw the option under menuconfig, and whenever I try to do something like "mount -t devfs none /devfs" it says that the kernel doesn't support it.

[For our readers who may not have heard of it: devfs is a "virtual filesystem" like /proc, but for dynamically representing devices instead of processes. /proc and devfs are sort of like RAM disks, they exist in memory rather than on a physical disk or partition. Each represents ways for the kernel to present its internal state to userspace using a common directory/file hierarchical abstraction. Richard Gooch has been working on devfs for a couple of years, and Linus recently accepted it into the mainstream developmental kernels]

1. how do I go about adding it during the kernel compile (or during RedHat Setup)?

I suspect that 6.2 is shipping with a 2.2.15 or so kernel. devfs was not included in mainstream kernels prior to 2.3.46 or so. So, you'd have to either use a development/test kernel (2.4.0test1-ac10 is what I'm using at the moment), or download Richard Gooch's patches for the earlier kernel versions.

[ RedHat shipped with 2.2.14. A 2.2.16 kit is posted in their updates area, including i586 and i686 specific flavors for uniprocessor or smp. You definitely want to find a mirror site to do the download from, though.
-- Heather. ]

You can learn all about Richard's work at his web site:

http://www.atnf.csiro.au/~rgooch/linux/kernel-patches.html

2. is there something to add in the makefile?

The patch includes changes to the make files so that the new options will appear in 'make menuconfig' and its ilk.

last but not least,

3. What is the variable that is used during boot up that determines whether or not to use devfs?

You're probably asking for:

"devfs=nomount"

The patch, and some of the 2.3.46+ series of kernels had this really irritating default. They would mount the filesystem over /dev as the kernel booted, thus over-riding your normal device list. This would make the system essentially unusable if you had not made all of the correct adjustments to all of your rc scripts, /etc/fstab and other files. (There was a warning about this in the configuration help in 'menuconfig' and in other places).

In the latest kernels (2.4.0test1) this is NOT the default. You can enable devfs support when you build a kernel and then play with it at your leisure.

For example I have devfs mounted on /devfs on mars (my laptop). Here's a (partial) list of the devices that I currently have recognized/active thereunder:

/devfs/.devfsd
/devfs/cpu
/devfs/cpu/mtrr
/devfs/misc
/devfs/misc/apm_bios
/devfs/misc/psaux
/devfs/mem
/devfs/kmem
/devfs/null
/devfs/port
/devfs/zero
/devfs/full
/devfs/random
/devfs/urandom
/devfs/tty
/devfs/console
/devfs/vc
/devfs/vc/1
/devfs/vc/2
   ....
/devfs/vc/63
/devfs/vc/0
/devfs/ptmx
/devfs/pty
/devfs/pty/m0
/devfs/pty/m1
  ....
/devfs/pty/m254
/devfs/pty/m255
/devfs/pty/s0
 ....
/devfs/pty/s7
/devfs/pts
/devfs/vcc
/devfs/vcc/0
/devfs/vcc/a
/devfs/vcc/1
/devfs/vcc/a1
 ....
/devfs/vcc/7
/devfs/vcc/a7
/devfs/rd
/devfs/rd/0
 ....
/devfs/rd/15
/devfs/ide
/devfs/ide/host0
/devfs/ide/host0/bus0
/devfs/ide/host0/bus0/target0
/devfs/ide/host0/bus0/target0/lun0
/devfs/ide/host0/bus0/target0/lun0/disc
/devfs/ide/host0/bus0/target0/lun0/part1
/devfs/ide/host0/bus0/target0/lun0/part2
/devfs/ide/host0/bus0/target0/lun0/part4
/devfs/ide/host0/bus0/target0/lun0/part5
/devfs/ide/host0/bus0/target0/lun0/part6
/devfs/ide/host0/bus0/target0/lun0/part7
/devfs/ide/host0/bus0/target0/lun0/part8
/devfs/ide/host0/bus1
/devfs/ide/host0/bus1/target0
/devfs/ide/host0/bus1/target0/lun0
/devfs/ide/host0/bus1/target0/lun0/cd
/devfs/cdroms
/devfs/cdroms/cdrom0
/devfs/discs
/devfs/discs/disc0
/devfs/scsi
/devfs/tts
/devfs/tts/0
/devfs/tts/1
/devfs/cua
/devfs/cua/0
/devfs/cua/1
/devfs/root
/devfs/floppy
/devfs/floppy/0u1440
/devfs/floppy/0u1680
/devfs/floppy/0u1722
/devfs/floppy/0u1743
/devfs/floppy/0u1760
/devfs/floppy/0u1920
/devfs/floppy/0u1840
/devfs/floppy/0u1600
/devfs/floppy/0u360
/devfs/floppy/0u720
/devfs/floppy/0u820
/devfs/floppy/0u830
/devfs/floppy/0u1040
/devfs/floppy/0u1120
/devfs/floppy/0u800
/devfs/floppy/0
/devfs/printers
/devfs/printers/0

I go that by using the command:

mount -t devfs /devfs /devfs

... since I'm just playing with devfs for now.

thx in adv!
-ion

That should help. It's probably best for you to upgrade to 2.4... and play with it. That's likely to have the most stable support for devfs.

Keep in mind that you should consider this feature and the whole 2.3 and 2.4.0test* kernel series to be experimental. You should get a few months (or at least weeks) of testing on them done before deploying them in a production server role.

Multiple append= Directives in /etc/lilo.conf

Answered By Carl Davis on Thu, 08 Jun 2000

Thanks Jim, but I have solved the mystery................

The problem was that lilo does not like multiple "append" statements in /etc/lilo.conf. I fixed this by putting all the statements on the one append line, separated by commas and of cotatement2, statement3" You may wish to add this snippet to the list of 2cent tips.

Regards Carl Davis

Actually those should probably be separated with spaces and not commas. The commas may work in your case --- but it might cause problems in other cases.

Anyway --- this response will make it into the search engines, so the tip will be published that way.

Getting Addresses Routed: Use IP Masquerading or Application Proxies

From Future Systems Today on Thu, 08 Jun 2000

ok, here it is... I have a suse linux 6.3 server that is using a cable modem and has a static ip address from my isp which is 63.92.157.x. The isp also is being used as my dns and gateway on my first nic on that server. Everytime i change the ip address of my second nic to something other than 63.92.157.x I have no internet connection. What should i do or how do i trouble shoot this also i tried to connect my other ms pc's through this box to the internet but since i am trying to go through the ip address that the isp is giving me then i am getting a error message.

Is there a way to get internet access through my server which has the ip address that the isp gave me and make it look like it is connecting rather than a ip address that i gave a machine.

Thanks Joe

(Short answer: use IP masquerading or SOCKS).

What you're asking for is called "IP Masquerading" or "network address translation" (NAT). Technically IP masquerading is a particular form of network address/port translation.

I've written about this on a number of occasions, and a search on LG (http://www.linuxgazette.com/search.html) shows over 120 matches on the phrase (ip;masq).

Here's a link to an LG article by Mark Nielsen and Andrew Byrd "Private Networks and Roadrunner using IP Masquerading LG #51" (http://www.linuxgazette.com/issue51/nielsen.html) that's probably just what you need to get started.

Also the LDP (Linux Documentation Project) has a reasonably up-to-date HOWTO on this topic:

http://www.linuxdoc.org/HOWTO/IP-Masquerade-HOWTO.html

... so you should read those and see if that explains it. (I can understand why one wouldn't know the magic keywords for this concept, and thus wouldn't have been able to find this).

If you get stuck on some of the assumptions that these articles and HOWTOs will make then you might want to read my article on "Routing and Subnetting 101" (http://www.linuxgazette.com/issue36/tag/a.html) which goes into related topics in some detail.

Keep in mind that you could also configure your Linux box as a "proxy" server (more formally it could be an "applications level proxy"). In this case your other machines never talk "directly" to the Internet, but the applications talk to a "proxy" application/server on your router (your Linux box). That proxy then performs the Internet requests on behalf of your applications and relays the results back to you.

There are many freely available proxy packages for Linux including NEC Socks 5, Dante, Delegate (all using the SOCKS standards), and specific proxies for specific applications (like squid which is a caching proxy). You could do a search on "proxy" or "applications;proxy" to read more about that.

The reason that IP masquerading has become somewhat more common and popular than applications proxying is that it is more transparent. When using applications proxying you have to configure each system and many individual applications to use the proxy. On the other hand proxying is technically a better, cleaner and probably more secure way to build a good network.

In either case you should be sure that you don't pick addresses "out of the blue." There are sets of addresses that are reserved for use behind proxying and IP masquerading firewalls and routers, and on other "disconnected" networks (those that will never interconnect to the Internet). Those are defined in RFC 1918. (RFCs are "request for comment" documents; proposals to the corpus of the Internet about how things should be done. They are basically drafts that become Internet standards).

RFC 1918 basically assures us that the IANA (Internet assigned numbers authority) and its delegates (like ARIN, the American Registry for Internet Numbers) will never issue the following address blocks to any organization on the Internet:

    192.168.*.*
    172.16.*.* through 172.31.*.*
    10.*.*.*

So those are available for use on "disconnected" networks. (This also explains by most examples in textbooks and online technical discussions about IP use the 10.* and 192.168.* address ranges; most people don't remember the 172.... Class B set).

FTP Through a "Firewall"

From Jonathan Marshall on Thu, 08 Jun 2000

I'm having an issue in which im not sure why ftp ing isn't going through the linux firewall to our isp that handles all the files. What should I check and look for to make sure ftping works through this linux firewall.

I have no clue thanks

Jonathan Marshall

Short form: Probably blocking all incoming TCP/IP connections and failing to use "passive" FTP clients.

It probably means that your firewall is improperly configured.

I'm going to guess that you can do some web browsing, and/or that ping or some other form of TCP/IP traffic is working between your client(s) and the target host (the FTP server).

In other words I'm going to assume that you are asking specfically about why FTP is NOT working because other stuff is working. If not then the problem could be anywhere in the realm of addressing routing, link layer and lower level networking.

The most common problem where "everything is working except FTP" has to do with the way that FTP works. Normal FTP (now sometimes called "active" FTP) works something like this:

• Your client connects to the FTP server. It sends TCP packets to port 21 of the remote. That connection is used to control the FTP session. Your commands (like 'ls' and 'get') are sent over that connection.
• The server makes connections back to your client every time it wants to send a stream of data. Thus the 'ls' listing that you asked for comes back over a separate TCP channel from the control connection.

This technique plays hell with simplistic packet filtering and is why "firewalls" are more complicated than just packet filtering.

You mention that you are using a Linux "firewall/router." Notice that the term "firewall" is pretty vague. It implies that you have this system configured to enforce some sort of policies about what sorts of traffic it will route into and out of your network.f However, that could be anything from some simple ipfwadm or ipchains rules through a gamut of different applications proxies, "stateful packet filtering" systems, and other software.

These days a lot of people refer to Linux systems which are simple IP masquerading routers as "firewalls." That's really a stretch. It seems quite likely that you are running through masquerading. If that's the case you should be aware that Linux requires a special loadable module in order to support normal FTP through a masqueraded route. It may be that the module isn't their, or that the kerneld/kmod (dynamic module loading mechanisms) aren't properly running or configured, etc. You should have your sysadmin check the error logs on this "firewall" and look for a file like:

/lib/modules/.../ipv4/ip_masq_ftp.o

... or for error messages in the logs that refer to such a beast. That little gizmo handles the active back "PORT" connections from that might be coming from your ISPs FTP server.

So, it sounds like you need to get someone to properly configure the firewall if you want to use traditional FTP. It also sounds like you have an ISP that has lackluster support (since any decent sysadmin should have been able to explain this to you).

Another option is to use "passive mode" FTP. This still stills two connections (control and data, as before). However, it basically means that the client requests that the server accept all of the connections --- so that no new connections will be "inbound" back to the client. Most newer FTP clients will support passive mode. If you're using the old "shell mode" FTP command try just issuing the command 'passive' at the FTP command's prompt. If it responds with a message like: "passive mode on" then you should be able to go from there.

Under ncftp (a popular FTP client that's almost more common on Linux than the old Berkeley shell mode program) you would try the command 'set passive on'

In any case search your man pages for "passive" and/or "PASV" (the protocol keyword) to see if that helps.

Note that most web browsers default to passive mode for all FTP transactions. So one of the common symptoms of this problem is that FTP works through a browser and fails otherwise.

There are a number of places where you can read more about Linux firewalls. One place to check is:

Linux Administrators FAQ List: Firewalling

http://www.kalug.lug.net/linux-admin-FAQ/Linux-Admin-FAQ-9.html

... and, of course:

Firewall and Proxy Server HOWTO

http://www.linuxdoc.org/HOWTO/Firewall-HOWTO.html

... and the home page of the:

Freefire Projekt Startpage, English, Bernd Eckenfels

http://sites.inka.de/sites/lina/freefire-l/index.en.html

... and Dave Wreski's:

Linux Security Administrator's Guide

http://www.nic.com/~dave/SecurityAdminGuide/SecurityAdminGuide.html

... and a bit about the Sinus Firewall package (which is under the GPL):

SINUS Firewall Page

http://www.ifi.unizh.ch/ikm/SINUS/firewall

... and the Juniper Firewall Toolkit (from Obtuse):

Juniper

http://www.obtuse.com/juniper

... and I'm sure that most of those links lead to many others.

So, your sysadmin and our ISP have no excuse for not learning more about firewalls, packet filtering and how to support simple requests and solve simple problems such as this.

Simple Shell and Cron Question

From Amir Shakib Manesh on Thu, 08 Jun 2000

Dear ANswer Duy, I want to write a shell script, in which every 15 minutes it run a simple command, let say 'top -b'. Would you help me?

Well one way would be to make a cron entry like:

*/15 * * * *  top -b

... which you'd do by just issuing the command: 'crontab -e' from your shell prompt. That should put you in an editor from which you can type this command.

Also is there any way to prevent from auto-log out in unix?

Sincerely,

Amir Shakib-Manesh

UNIX and Linux don't have an "auto-log out" mechanism by default. So if you are getting logged out after some period of inactivity then the details of how you'd bypass that depend on the mechanism that's being used by your sysadmins. Ask them.

(Other than that one of the possibilities is that they are setting a special variable in your shell, like TMOUT in bash. Read the bash man pages and search on TMOUT to see on that works. There are similar features in some other shells. That's a pretty common and relatively harmless way to encourage users not to leave their prompts unattended. Other methods involve some daemon like "idled" which runs as 'root' and watches for inactivity, pouncing on line hogs with 'kill' signals).

Left in the Lurch

or: Uninstalling Linux the Hard Way

From Kevin Lampert on Mon, 12 Jun 2000

answer guy,

i have been going through your suggestions off the web for uninstalling red hat, but i have an even bigger problem, i have no resecue disk and i have no way of getting into red hat. The problem orginated because a former employee loaded red hat on a pc and no one knows anyway to gain access into the pc now since no one knows any of the user names or paswords that he set. So, my question is "how do I get rid of red hat with no rescue disk or no access into red hat?" Any suggestions you have will be greatly appreciated.
kl

Well, here's a couple of ideas:

First you could break into the system. I've described "recovering lost passwords" on a few occasions and you can search the back issues or the FAQ for details on that. Here's the short form:

1. Reboot the system. (Try [Ctrl]+[Alt]+[Del], then try [Ctrl]+[Alt]+[Backspacel] followed quickly by [Ctrl]+[Alt]+[Del]. If those fail you, power cycle it).
2. As it boots after the BIOS messages and the initial keyboard LED flashes, toggle the [scroll lock] and/or [caps lock] keys. (That should bring up the LILO prompt, even if it wasn't showing up before --- unless it's been configured specially).
3. At the LILO: prompt hit the [Tab] key. A list of boot "labels" should appear. Usually one of them will be named "Linux" or "linux" or something like that. Choose any one of those and type its name (case-sensitive) following by the following string:

   init=/bin/sh rw

4. Hit [Enter]

Now, if all of that went O.K. you should see the Linux kernel starting up. However, instead of going though the usual init process and running a whole mess of rc* scripts, it should just start a shell.

If you wanted to change the password and regain control of the system at this point you'd type the following commands (ignoring any errors for the moment --- some of them are just to account for common configurations that might not match yours):

mount /usr
passwd # and create a new password...
sync
mount -o remount,ro /
umount /usr
exec /sbin/init 6

... and wait for the system to shutdown and reboot (with your password setting safely saved).

However, you've said that you want to blindly remove Linux from this box. So, at the shell prompt you can type something like:

dd if=/dev/zero of=/dev/hda #DANGEROUS!!!!

... which will zero out the whole primary IDE hard drive.

... of course that's overkill. You could just add count=1 to that command to limit the damage to the MBR (master boot record) which is sufficient that any other OS you try to install should then consider this drive to be empty.

Of course there might be some glitches to this approach. Your former employee might have been a security nut and might have protected the boot sequence with a CMOS/Setup password. He or she might also have put in a LILO password. He or she might not have been using LILO at all -- there are a few alternative boot loader for Linux.

In the worst case you could use a screw driver, open the case, take out the hard drive and temporarily put it into another system, and use that to erase the drive. If you do have to go to that extreme, I suggest you take the drive, or the whole system, down to "PC Repair-o-rama" (any place that repairs PCs --- like CompUSA, Fry's, etc). They should be able to do the job for about $70 (and it would take way more than $70 of my time to explain all the possible complications of removing a drive, and temporarily installing it in another computer; especially since I don't even now if that system is SCSI, IDE, or something old or exotic like ESDI, SMD, or ST506 --- RLL/MFM).

A whole other approach would be to download a copy of Tom Oehser's Root/Boot (or any of several other mini-distributions of Linux that fit on a single floppy or a couple of floppies).

You could get Tom's Root/Boot image from http://www.toms.net/rb ... and he does have a .ZIP file with the Linux image, a RAWRITE.EXE utility and instructions on creating a Linux rescue diskette from an MS-DOS prompt.

If you use the root/boot diskette on this errant Red Hat system, (assuming that it doesn't CMOS/Setup passwords that prevent you from doing a floppy boot), then you can use that to wipe out the data on your hard drive using the same 'dd' command I described above. Notice that you should NOT use that command if there is ANYTHING on that hard drive that you want to save.

You can also use Tom's root/boot to change the passwords on your system --- and thereby regain control of it. To do that you'd insert the following commands before my "mount /usr" command above:

         mount /dev/hda? /mnt
          cd /mnt
          chroot . /bin/sh

... where hda? might be hda1, hda2 or something like sda1, sda2

etc. (Explaining that would take a bit longer. hd* are all of the IDE drives, hda is the master on the primary IDE interface, hdb is the slave, hdc is the master on the secondary IDE, etc.; those might include the CD-ROM. sd* are all the SCSI hard drives on the system sda through sdz (if you had that many). However, SCSI CD-ROM are NOT included in that list, they get names like scd0, scd1 etc.).

... The command examples I'm giving here are not the BEST way to do this; they are simply the easiest set to explain such that they are most likely to work on the widest variety of systems.

With about 20 million copies of Linux installed, I guess the this knowlege has become de riguer even for NT, Netware, and MS Windows help desk specialists.

help....need to delete a linux partition

From Mark Dellaquila on Mon, 12 Jun 2000

Jim-

Is there any possible way to delete all linux partitions? I want to get

rid of them and reinstall the Mandrake Linux 7.0. Any help would be great. Thanks!

Mark Dellaquila

Boot into Linux (preferably using a rescue diskette or CD; possibly using Mandrake's installation CD and switching to VC 2 (the second virtual console on most Linux installation packages is a command prompt).

Then, for each drive you can run fdisk -l like:

       fdisk -l /dev/hda
        fdisk -l /dev/hdb
        fdisk -l /dev/sda

... etc.

Look for Linux and Linux Swap partitions in each of these listings. On any of them that list a Linux or Linux Swap partition, run fdisk in interactive mode (just leave out the -l option), and delete those partitions.

If you want to wipe out a whole drive (e.g. you don't have any non-Linux stuff on it that you wish to preserve) you can use the 'dd' command with script zeros over all of it, or just the MBR. Here's a couple of example commands:

      dd if=/dev/zero of=/dev/hda count=1 bs=512  ## just wipe the MBR
      dd if=/dev/zero of=/dev/hda                 ## blank everything!

... that's basically all there is to it.

Getting UVFAT

From AaronWL on Sun, 18 Jun 2000

hi..

do you know where i could get a working uvfat for linux 2.2.x? i cant find any info on it anywhere.. and im getting desperate..

aaron

I presume you're looking for UMSDOS/VFAT support from your kernel. In other words you want to access Win '9x long file names and you want to be able to store UNIX/Linux meta-data (permissions, ownership and group association) on your MS-DOS filesystems.

The uvfat code is included with the mainstream Linux kernel sources. So, just compile a new kernel, and select "Y" and/or "M" (module) for the UMSDOS and VFAT support options.

Be sure to read the "The Linux Kernel HOWTO" (http://www.linuxdoc.org/HOWTO/Kernel-HOWTO.html) for details on building new kernels.

Find the source for specific program.

From The Answer Gang on Mon, 19 Jun 2000

Hi,

Is there any way to find out what package that s specific program belongs to? And where to download the source to build it? For example, I am trying to figure out how and where to find the source or package for mount program. I check the fileutils & sh-utils and can't find it within them.

Any help will be highly appreciated.

Meiji

That would be a "whence" command (which used to exist in some forms of UNIX and even in the old Yggdrasil distributions).

If you're using an RPM based system such as Red Hat, SuSE TurboLinux, etc, then you can use the following command to find the "owner" or "provider" of a given file:

     rpm -qf $FILEPATH

Note that this should use the full name of the file. So in your case try:

    rpm -qf $( which mount )

... (you can use backticks for the $(...) expression, this is just a less ambiguous syntax under most fonts).

On a dpkg (Debian-based) system such as Debian, Corel, Stormix, LibraNet etc, then you can use the following command:

    dpkg -S $FILEPATH

... or you can simply do a grep -l /var/lib/dpkg/info/*.list

"Linux Gazette...making Linux just a little more fun!"

Netscape 2c tip

You can get a two-column printout from netscape by using the psutils packages. For letter-sized printouts, just change your "Print Command" in netscape to

pstops -q -w8.5in -h11in -pletter "2:[email protected](8.in,-0.1in)[email protected](8.in,4.95in)"  |  lpr -h

The PSUtils are avalable at http://www.dcs.ed.ac.uk/home/ajcd/psutils/index.html

You will have to edit the Makefile and set PAPER=letter if you live in North America.

Mandrake and memory

Here's something I stumbled across while installing Mandrake 7.1 this weekend. While the installer correctly detects that the machine has more than 64 MB RAM (in my case 128). However - it does _not_ adjust lilo or grub, which it installs as default.

So when you start up with manually editing the config files you only get 64 MB. Which may not be readily apparent (my 700 Mhz machine is like lightning even on 64 MB).

Naturally you may need to add "mem=8m" to your lilo or grub config file.

[See the Mailbag and 2-Cent Tips of the past few issues for a discussion of adding
append = "mem=128M"
to /etc/lilo.conf. Sometimes it's required and sometimes it isn't, depending on the BIOS. -Ed.]

vi and escape

Hello gazette!

2-cent tip for new vi users: If you have to move your left-hand to hit all the time, you can give Control-[ a try (if you didn't notice this posibility already.)

bye

Intel i810

[Forwarded from The Answer Guy column. -Ed.]

Searching for more information about the i810 chipset I came across your [The Answer Guy's] discussion about it and Linux.

I had a similar problem with my Linux installation, where as Linux installed fine and I could utilize the command line wihtout a problem. However I had no graphics support, that is to say no XFree86.

The soultion to this porblem is to be found at support.intel.com, under the i810 fourm site. They have the X server and Kernel module and complete instrcutions for how to install and use the software. You must however read the fourm posts as there are a few tricks to the setup procedure.

That being said, I would like to know when/if kernel support will be provided for the i810 chipset. Actually I would rather learn how to find this information for myself. If you teach a man to fish, etc....

Disk-space usage of Red Hat 6.0 & 6.2

Here are the disk usage numbers for a kitchen-sink Red Hat Linux 6.0 installation. I got these numbers by installing every package the system installer had to offer on a pair of stock Gateway E-3200's, then pulling the hard drive from one and attaching it in place of the other's CD-ROM drive (that's at hdc). The operating system on the transplanted hard disk was never booted, so as to preserve the exact post-install, pre-boot state of the installation. I fired up the box, mounted hdc, changed the current directory over and did du --max-depth=1 in "/" and "/usr". Then I did it all over again with a different pair of E-3200's to make sure my numbers were consistent. They were. (I was mildly surprised.) My main reason for doing all this is so that I can make educated decisions about my hard disk partitioning (I've had bad experiences following other people's advice on this subject), but of course the data is interesting even in a purely academic sense.

                           Disk Usage  Percentage                                        Disk Usage  Percentage       Percentage
Directory                 (recursive)  of Installation        Directory                 (recursive)  of Installation  of /usr
/lost+found                     12 KB    0.00%                /usr/X11R6                  72,925 KB    7.06%            7.62%
/dev                           111 KB    0.01%                /usr/bin                    92,961 KB    9.00%            9.71%
/etc                          2621 KB    0.25%                /usr/dict                      404 KB    0.04%            0.04%
/tmp                            17 KB    0.00%                /usr/doc                   156,448 KB   15.15%           16.35%
/var                        22,858 KB    2.21%                /usr/etc                         1 KB    0.00%            0.00%
/proc                            1 KB    0.00%                /usr/games                      48 KB    0.00%            0.01%
/bin                          5448 KB    0.53%                /usr/include                11,129 KB    1.08%            1.16%
/boot                         6581 KB    0.64%                /usr/info                     6357 KB    0.62%            0.66%
/home                         3131 KB    0.30%                /usr/lib                   266,192 KB   25.77%           27.81%
/lib                        30,454 KB    2.95%                /usr/local                      20 KB    0.00%            0.00%
/mnt                             3 KB    0.00%                /usr/man                    25,169 KB    2.44%            2.63%
/root                            8 KB    0.00%                /usr/sbin                   11,142 KB    1.08%            1.16%
/sbin                         4364 KB    0.42%                /usr/share                 243,235 KB   23.55%           25.41%
/usr                       957,156 KB   92.68%                /usr/src                    51,959 KB    5.03%            5.43%
/.automount                      1 KB    0.00%                /usr/libexec                  1141 KB    0.11%            0.12%
/misc                            1 KB    0.00%                /usr/i386-glibc20-linux     12,319 KB    1.19%            1.29%
/                        1,032,768 KB  100.00%(1)             /usr/i386-redhat-linux         237 KB    0.02%            0.02%
                                                              /usr/cgi-bin                    39 KB    0.00%            0.00%
                                                              /usr/i486-linux-libc5         5429 KB    0.53%            0.57%
                                                              /usr                       957,156 KB   92.68%(1)       100.00%(1)

(1) As the result of round-off error, the sum of the individual entries in this column (these columns) in fact comes to 0.01% shy of what it should be.

Note that in the case of both tables, the sum of the component entries in the Disk Usage column (the subdirectories of "/" and "/usr", respectively) is one kilobyte less than the total (the "/" and "/usr" directories, respectively). I thought round-off error, did du --block-size=1 --max-depth=1 and found that the numbers still disagreed. On intuition, I subtracted the --block-size=1 sums from the --block-size=1 totals and found that the sums were exactly 1,024 bytes less than the totals. Aha! I conclude that the two directory contents listings themselves take up a kilobyte each, and this is supported by the fact that "/proc", "/.automount", "/misc" and "/usr/etc" are all four empty, but are reported by du to occupy one kilobyte each. Where does the kilobyte value come from? Dividing the du --block-size=1 entries each by 1,024, I found that they are all evenly divisible. (That's why I ended up making the tables in kilobytes instead of bytes... there is no round-off error here.) Noting that du measures disk usage and not actual file size, I expect that one kilobyte is the cluster size on my disks, but I don't know much about that. If so, that beats Hell out of FAT32... isn't FAT32 four-kilobyte clusters minimum? My curiosity stopped at this point, but if I was to go on, I'd say the next step would be to start exploring the ext2 file system structure... if directory contents listings take up space alongside "regular" files, then there is probably no file allocation table, and I'd be curious to poke around on an ext2 file system with a disk editor. :-)

Here are the disk usage numbers for a kitchen-sink Red Hat Linux 6.2 installation.

                           Disk Usage  Percentage                                        Disk Usage  Percentage       Percentage
Directory                 (recursive)  of Installation        Directory                 (recursive)  of Installation  of /usr
/lost+found                     16 KB    0.00%                /usr/X11R6                  85,540 KB    6.19%            6.50%
/proc                            4 KB    0.00%                /usr/bin                   108,556 KB    7.85%            8.25%
/var                        15,256 KB    1.10%                /usr/dict                      408 KB    0.03%            0.03%
/tmp                            32 KB    0.00%                /usr/doc                   164,712 KB   11.91%           12.51%
/dev                           124 KB    0.01%                /usr/etc                         4 KB    0.00%            0.00%
/etc                          5896 KB    0.43%                /usr/games                      52 KB    0.00%            0.00%
/bin                          5760 KB    0.42%                /usr/include                18,200 KB    1.32%            1.38%
/boot                         2452 KB    0.18%                /usr/info                     6776 KB    0.49%            0.51%
/home                       10,388 KB    0.75%                /usr/lib                   412,912 KB   29.86%           31.37%
/lib                        21,232 KB    1.54%                /usr/local                      80 KB    0.01%            0.01%
/mnt                            12 KB    0.00%                /usr/man                    20,280 KB    1.47%            1.54%
/opt                             4 KB    0.00%                /usr/sbin                   16,860 KB    1.22%            1.28%
/root                           28 KB    0.00%                /usr/share                 384,752 KB   27.82%           29.23%
/sbin                         5184 KB    0.37%                /usr/src                    70,132 KB    5.07%            5.33%
/usr                     1,316,324 KB   95.19%                /usr/libexec                  2100 KB    0.15%            0.16%
/.automount                      4 KB    0.00%                /usr/i386-glibc20-linux     14,052 KB    1.02%            1.07%
/misc                            4 KB    0.00%                /usr/i386-redhat-linux         252 KB    0.02%            0.02%
/tftpboot                       48 KB    0.00%                /usr/kerberos                 5152 KB    0.37%            0.39%
/                        1,382,772 KB  100.00%(1)             /usr/boot                        8 KB    0.00%            0.00%
                                                              /usr/i486-linux-libc5         5492 KB    0.40%            0.42%
                                                              /usr                     1,316,324 KB   95.19%(1)       100.00%

(1) As the result of round-off error, the sum of the individual entries in this column (these columns) in fact comes to 0.01% off of what it should be.

Note that in the case of both tables, the sum of the component entries in the Disk Usage column (the subdirectories of "/" and "/usr", respectively) is four kilobytes less than the total (the "/" and "/usr" directories, respectively). I did du -b --max-depth=1 and found that the sums were less than the totals by exactly 4,096 bytes. The directories "/proc", "/opt", "/.automount", "/misc" and "/usr/etc" are all five empty, but are reported by du to occupy four kilobytes each. This is peculiar... if I am correct about cluster size being the relevant issue, why does Red Hat 6.2 use four-kilobyte clusters on the same hardware on which Red Hat 6.0 uses one-kilobyte clusters?

Tips in the following section are answers to questions printed in the Mail Bag column of previous issues.

ANSWER: Missing root password

Just use a boot floppy to boot up the machine into single user mode. From there you can edit /etc/lilo.conf to your liking and run lilo, and also from there you can delete the encrypted password from either /etc/passwd or /etc/shadow (the latter if you're using shadow passwords). Then when you login as root, there will be no password, just hit enter. Be sure to immediately run passwd and give root a new password.

Pierre Abbat <> writes:

Get a rescue disk like tomsrtbt, mount the root partition, and edit /etc/passwd manually, removing the root password or setting it to the same as on another computer (it's hashed). Then reboot using the boot disk you made when you installed Linux, log in as root, and edit /etc/lilo.conf and run lilo.

ANSWER: Limiting "Public Interfaces" on Share Libraries

Hi, noticed your answer regarding "public interfaces" in shared libraries in the latest Linux Gazette, and I had a couple of comments. (I am a programmer, and have written several libraries and shared libraries under Linux.)

There are at least two good reasons to hide functions from public interfaces:

1) If a function is internal to the library, and it may well disappear or change incompatibly without warning in future versions, so that you don't want to be worry about people using it.

Any library will almost certainly contain a large number of such internal functions, and the code would be utterly unmaintainable if you couldn't change them between releases because people depended on them.

Of course, it is usually sufficient to simply not document those functions or declare them in your header files, so that programmers who find out about them should know that they use them at their own risk. (Some programmers are foolish enough to do so, even though it is almost never a good idea. e.g. there was a well-known case where StarOffice had depended upon internal glibc functions and therefore broke when glibc was upgraded.)

2) If you don't want to pollute the namespace.

If I have an internal function in my library called something generic, like print_error, I run the risk of accidentally conflicting with a function of the same name in a calling program, with unpredictable results. One way around this is to prefix the function with the name of my library, calling it e.g. foo_print_error if my library is libfoo. But this can be awkward to do for every little internal function you write, and it is often preferable to simply hide them from the linker.

There is a solution, however, provided by ANSI C: simply declare your functions with the "static" keyword, and they will only be visible/callable within the file they are defined in. This isn't perfect, I suppose, because they also aren't visible to other files in the same library. However, it covers the case where foo_ prefixes are most annoying: little utility functions that are only called within one file.

ANSWER: calculate cpu load

I would like to know how one can calculate cpu load and memory used by processes as shown by 'top' command. It would be nice if anyone can explain me how you could do these by writing your own programs, or by any other means.

In linux, a lot of information about the processes and the system in general is found in the /proc directory. To get the load average as output by top, use

cat /proc/loadavg

Information about the memory used by particular processes can be found in /proc//stat. Details on this are listed in the manpage of proc, cf. 'man 5 proc'.

ANSWER: Linux and the love bug

Well, Alex's reply is partly right, but I *have* seen a 'lovebug.sh', so if you would allow your browser to execute it, it could do some damage. Maybe; I have not tried it. Assuming you are careful and do not read your email as 'root' the damage that the virus can do is limited. That's what file permissions are meant to accomplish.

ANSWER: resolution

My comuter under linux redhat xwindow will only run 300x200 graphics. Even if I hit CTRL ALT + , it wont change. I have a SiS620 Card with 8mb. Can you please help. I have spent a lot of time on the internet, It seems other people have the same problem but no one can help.

You need to properly configure your video card. Definitely easier said than done. You can run Xconfigurator, but I assume you've already done that. A few tips might help though.

* Instead of running startx, run startx 2>&1 | tee startx.txt This will tell you which modes were accepted and rejected by X at startup.

* Make *sure* that you tell Xconfigurator the proper values for your max and min horizontal and vertical scan rates. Using the defaults will yield the low performance figures you are probably getting now.

* There's a pretty good writeup on how to configure X in Running Linux from O'Reilly.

* A lot of the SiS cards are not standard. i.e., one card may be different from another card of the same model. The point is that if the card is properly configured, it still may not work. In that case, see if you can find yourself a good Matrox card. A Millenium II is cheap on e-bay these days and I consider it to be rock solid. That card probably came as a default in your PC. Don't feel bad; you had to buy a real modem too to replace that WinModem that came with it.

ANSWER: Getting the most from multiple X servers - using startx script

Bob Hepple's tip on using multiple X servers when using an XDMCP session manager was interesting and informative. I had never even heard of Xnest and it definitely looks worth investigating.

Personally I stay away from the XDMCP session managers. I like being able to use my computer without the overhead of a GUI, and I find the text mode easier on my eyes. I still end up using the GUI quite a bit and find times when running multiple X sessions, either using different bit depths and/or resolutions, or for different users, is desirable.

The default startx script from the RedHat distributions has display 0 hardcoded into it. I think this is the default script from the people who make X, but not being sure, this may not apply if you're not running RedHat.

There is a line in the startx script which reads:

display=:0

Replace it with:

let DISP=0
while ls -a /tmp/ | grep -q ".X$DISP-lock" ; do
        let DISP+=1
done
echo "Using Display:$DISP.0"
display=:$DISP

This checks the locks that X sets when it starts up, and uses the next available display. The echo line isn't needed, but I like feedback.

When an X session is running, use Ctl-Alt plus one of the Function keys to go to an available terminal, log in and run startx and a new X session will start. Use the Ctl-Alt Function key combinations to go back and forth between the various terminal and X sessions. You can even start a new X session by running startx from an xterm ( or equivalent ) from within X, but this makes the new X session a child of the original one, and when the first one is closed, it brings the second one down.

ANSWER: 300x200 graphics

My comuter under linux redhat xwindow will only run 300x200 graphics. Even if I hit CTRL ALT + , it wont change. I have a SiS620 Card with 8mb. Can you please help. I have spent a lot of time on the internet, It seems other people have the same problem but no one can help.

Off-hand, I can think of two possible causes:

1. the "DontZoom" option is set 2. You have only configured the 300x200 resolution.

Both of these problems can be fixed by editing the XF86Config file. I don't use Red Hat myself, so I don't know exactly where it is. Normally, typing "locate XF86Config" should tell you the location.

Inside this file, you should look for:

Option "DontZoom"

If you find this, place a # in front of it.

If you don't find this line, it means your X server is set up to use only 300x200 as screen resolution. I think the best way to fix this, is to use Red Hat's X configuration tool, and to add the resolutions you want.

ANSWER: Energy star support

Last year I bought one of these cheap(er) east-asian PC computers (like many of us ?) with the Energy Star feature (i.e. No more need to press any button to power off).

But this feature is implemented with M$ Win... and I've no idea of the way they manage the hardware behind this process.

So, as I recently installed a Corel distribution, I would like to know if there is any mean to power off directly from Linux, and not Shutdown-And-Restart, Open-M$Windows and Quit-From-There (and Decrease-My-Coffee-Stock ;-} )

What is the LAST thing you see when you shut down your computer? It should be "System halted" or "Power down.". If it is "System halted", then auto-off is disabled in the kernel, and you need to recompile it. If it is "Power down.", but it doesn't, I'm not sure what the problem is, but I've seen it.

If it says "The system is halted", but does not then say "System halted" or "Power down.", something else is wrong. One of my computers crashes half the time, and hangs the other, on shutdown.

ANSWER: How to properly configure mail on home machines

How to configure the typical home PC for mail services via your ISP? This information, though widely available, is not well-known. Many popular Linux books gloss over the subject, suggesting that Netscape (and Netscape alone) is the way to go. Unfortunately, this eliminates many fun, geeky, options like emacs' Rmail.

Most distibutions set up Sendmail and Fetchmail--but configure Sendmail for a "typical" host machine.

But a home user _can_ figure out how to modify this combination for home requirements without learning all of Sendmail. And it is relatively painless. My advice? Read the following short document thoroughly; and follow its instructions exactly http://www.linuxdoc.org/HOWTO/mini/Sendmail-Address-Rewrite.html

Then select the mail client of your choice and mail like the big guys!

Have Fun!

ANSWER: TOP Calculations

Look at the files and directories under /proc. These are "virtual" files that are updated by the kernel. As I understand it, most programs that provide process info and the like merely decode and present info gleaned from the /proc files.

ANSWER: Success story (Was: DNS for home mail not working)

Hello! My letter with a title "DNS for home mail not working" was printed in # 52 "Mail Bag". I appreciate the help and attention, but I believe that problem was really with my service provider. Because my request for help was ignored by provider we choosed another and installed the leased line. And here is success story. I laid the printouts of JC Pollman and Bill Mote articles before me, followed along - and all was working. Fetchmail got the mail from our mailboxes, procmail and imap delivered mail, sendmail handled outbound mail. Thank you, Linux Gazette, Mr. Pollman and Mr. Mote for my first linux success.

This page written and maintained by the Editor of the Linux Gazette. Copyright © 2000,
Published in Issue 55 of Linux Gazette, July 2000

"Linux Gazette...making Linux just a little more fun!"

It has been a very exciting month. Since the previous article about this project in June's issue of Linux Gazette, I have received over 40 replies, a virtual host to set up a web page and mailing list, and an Invitation to Global Linux 2000 in Seoul, Korea! Thanks to all of you who wrote and have helped out with resources, ideas and enthusiasm. I have learned a lot and have a more clear vision of the actions to take in order to achieve our goals. Also new dangers have arisen, or at least I have acknowledged, to the Linux community, so now I have a deep sense of urgency and total commitment to the project. New services ideas are on the works and some companies are starting to join. From the e-mail I have received to the friends and contacts I made in Global Linux 2000, I'm impressed to see how many people want this project to come true. THANK YOU!

News and Report from Korea

• Pascal Bleser, from ATOS, has offered to host the project's home page at http://open-isp.linuxbe.org He has also set up a mailing list to host further discussion on creating a Linux-only ISP. To subscribe send a message to: with the message:

  subscribe open-isp

  The web page is the place to go for news related to the project, announcements, statistics about dial-up growth in different countries, and core documents of the project. We are setting up a web discussion forum, so you can leave your comments on the web site.
• 
  
  
• Jakob Borg, from Denmark, voluntarily created and submitted the Open ISP Logo:
  Original site: http://open-isp.linuxbe.org/gfx/logo2.jpg
• 
  
  
• Carlos (me) got married on June 10th. Now I'm inside The circle of the Ring.
  Well, we didn't have time for honeymoon, as I flew to Korea the next day. Back from Seoul on June 17th, with a killing case of jet-lag, wedding party all day long on 18th and then honeymoon for one week in Barcelona, Spain, the next day. Very intense month. Believe me.
• 
  
  

New services Ideas

No Internet, No Linux: The Phantom Menace

• How many different ISPs have you used to the present?

• How many do you think you will have to switch to in the future?

• How is an Operating System going to attract new people if you can't connect to the Internet?

• How is the general public going to be aware of the Free Software movement and participate in it if they can't use Linux?

Course of Action

• The first step to move forward creating the Open ISP, is to create a non-profit organization, to have a legal status, so that companies can start donating hardware, money and resources to the project. This is going to consume a lot of paperwork and brainwork. Please, join us with your experience, advises and ideas to reach this goal. Hilaire Fernandez will send me by snail-mail documents on how to set-up a non-profit organization in Belgium and the United States. Bertrand Guiheneuf, from France, knows a good deal of people in France with experience on the subject and suggested to put me in contact with them.
  
  
• Design the hardware and telecommunications foundations of the Open ISP, in a standardized way compliant with ISO-9000 standards if possible, to guarantee:
  - Ease of replication around the world.
  - High Quality service.
  - Flexibility: utilization of all different kinds and brands of donated hardware.
  
  In order to reach achieve it, we must create an Engineering Task Force, to discuss and develop the technical issues.
  
• 
  
• Enhance the web site, providing more statistics, and set up a user survey, in order to estimate the number of dial-up users, how much is people spending on communications costs, how many actual Linux users would be willing to switch to the new Open ISP, etc.
  Provide more information about different countries' market conditions and ISP offers available. A good starting point is the EuroISPA (Internet Service Providers Association of Europe) and the Internet Associations and Organizations directory. Please, don't hesitate on sending more pointers to relevant information.

Final Thoughts

Copyright © 2000, Carlos Betancourt
Published in Issue 55 of Linux Gazette, July 2000

"Linux Gazette...making Linux just a little more fun!"

More HelpDex cartoons are on Shane's web site, http://mrbanana.hypermart.net/Linux.htm.

Copyright © 2000, Shane Collinge
Published in Issue 55 of Linux Gazette, July 2000

"Linux Gazette...making Linux just a little more fun!"

OLinux: Make a short introduction about yourself (carreer, job, name, age, and where you live)

Ronny Ko: I'm the Editor-in-Chief for 32BitsOnline.com. I'm in my twenties and living in Vancouver, BC, Canada

OLinux: what was the group that started 32bits online and where they came from (how did they get united?)? this group had other online businesses by then ? what were the main ideas by then? who are they: can you describe them, their background?

Ronny Ko: The magazine was actually started as a home page. Back then, it was called Ronny's Review Page. Basically, it dealt with my personal software reviews. As more and more people came to the site, the number of contributors increased. As it grew and given its OS/2 nature then, I decided to name it OS/2 Computing! Magazine.

The amount of content that OS/2 Computing! was able to published was directly proportional to the amount of activity in OS/2. OS/2 was quickly losing ground to Windows 95.

Because of this, we decided to change to 32BitsOnline.com. The focus is to be the best alternative technical publication anywhere.

OLinux: Describe your daily task and routine as an editor? What are your main news and articles resources: Are there many volunteers or instead how many employees work for 32? How hard it is to present a quality content every day?give us an idea.

Ronny Ko: It takes a lot of hard work. This is especially hard in web journalism. My job as Editor-in-Chief is to oversee editorial direction. Along with a dedicated team, 32BitsOnline is its people.

OLinux: How did evaluate since 1996? What was its initial focus in terms of OS and has changed? How often are upgrades (layout, new features) made How much editorial has changes since linux became a major player and drew attention from the world?

Ronny Ko: 32BitsOnline had already entered the Linux space before Linux became a viable solution against Windows in the enterprise space.

OLinux: How is 32 marketing strategy and key alliances to keep and promote itself on the internet?

Ronny Ko: 32BitsOnline strives to create key alliances but first and foremost, 32BitsOnline first responsiblity is to our readership.

OLinux: How profitable can be advertisement via Web? Can a website survive or have profits through advertisement?

Ronny Ko: If content is paramount on the web, then it is great but, the creation of original content take a lot of time and resources. In a world where success is valued by how much revenues a company generates, 32BitsOnline/Medullas is holding its own as a private company.

OLinux: Can you tell us about technical aspects: servers used, internet links, 32bits computing network, linux distribution and its programs used, databases?

Ronny Ko: We believe in Open Source. 32BitsOnline/PenguinApps are run on RedHat Linux servers. Database is based on MySQL with power outtage solutions built-in to prevent our service from being affected.

OLinux: How did 32 get involved with Linux International and how 32 works and helps this organization? How 32 bits online interact with GNU/Linux community? Does it participates actively in any other organizations?

Ronny Ko: 32BitsOnline strives to participate in every community event. By joining LI, we believe that a strong singular voice is more potent than each of our individual. Linux International was an easy decision.

OLinux: Does 32 take part in any important events like InstallFest, Expo and Conferences?

Ronny Ko: 32BitsOnline was a Media Sponsor in the last Linux World Expo. We're continuing to expand our support into other community events. If there are events which 32BitsOnline can sponsor, we welcome anyone interested to contact us at .

OLinux: How do you see and project linux growth for the next five years? There are already an uncountable number of commercial, companies and community linux distribution. Do you this fragmentation and excessive number of options raises consumer's fear while choosing it?

Ronny Ko: It is true that today, there are major fragmentation in terms of the number of distributions. What I can see will be a trend towards consolidation whereby the smaller distributions will consoldate into larger ones. In my opinion, this will be the only way to present possible Linux users that there's "one" Linux. If you walk to your local computer superstore, you'll see countless distributions. If I'm new to Linux, how am I supposed to pick one distribution?

Techinically, Linux is extremely united. Linus Torvalds has done an impressive job in keeping fragmention in check.

With variety, consumers have excellent diversity. Much like nature, natural selection will eventually select for the strongest while the weaker will slowly die or consolidate.

OLinux: Talk about PenguinApps: when was it started and what is the main idea behind it? Does it heavy a good traffic: give us some numbers. how often is it updated?

Ronny Ko: PenguinApps is still a very new product. We realized very early on that Linux users needed a site in which software should be easy to find. PenguinApps is updated daily. But more importantly, it is a complementary sister site for 32BitsOnline. When users read an article, users can expect to be able to download the software right here from PenguinApps.com.

Copyright © 2000, Fernando Ribeiro Corrêa
Published in Issue 55 of Linux Gazette, July 2000

"Linux Gazette...making Linux just a little more fun!"

INTRODUCTION

This article is the first in a series of two, where the reader will be introduced to the Journal File Systems:  JFS, XFS, Ext3, and ReiserFs. Also we will explain different features and concepts related to the new file systems above. The second article is intended to review the Journal File Systems behaviour and performance through the use of tests and benchmarks.

GLOSSARY

Internal fragmentation

The logical block is the minimum allocation unit presented by the file system through the system calls. That means that, storing fewer bytes than the logical block's within a file, would take a logical block's size of disk space to appear allocated. Therefore, if our block size doesn't divide a particular file (file size MOD block size != 0), the file system would allocate a new block that won't be completely full, causing a waste of space. That waste of space is internal fragmentation. Notice that the bigger the logical block is, the bigger the internal fragmentation should be.

External fragmentation

External fragmentation is a situation in which logical blocks of a particular file are scattered all over the disk, causing operations over that file to be slower, since more hard-disk header movements are needed.

Extents

Extents are sets of contiguous logical blocks used by several file systems and even database engines. An extent descriptor is something like beginning, extent size, offset, where beginning is the block address where the extent begins, the extent size is the size in blocks, and offset is the offset that the first byte of the extent occupies within the file.

Extents enhance spatial locality, since the blocks within an extent are all contiguous. That increase will lead to better scan times, as fewer header movements need to be performed. Realise that using extents reduces the external fragmentation drawback, since more blocks are kept spatially together. But notice that extents usage isn't always a benefit.  In case our applications request extents near in size to logical block's, we would lose the extents benefits, resulting in many small extents that would merely appear as logical blocks. To close the performance increase benefits, extents improve multi-sector transfer chances and reduce the amount of hard disk cache misses.

Finally, I would like you to realise that extents also provide for a way to organise large amounts of free contiguous space efficiently. Using extents will help us reduce the amount of disk space required to track free blocks, and will even enhance performance.

B+Trees

The B+tree structure has been used on databases indexing structures for a long time. This structure provided databases with a scalable and fast manner to access their records. B+tree stands for Balanced Tree. The + sign means that the Btree is a modified version of the original Btree, or more precisely, consists of maintaining pointers from each leaf node to the next, in order not to sacrifice sequential accesses. As Btrees and B+Trees have been inherited from database technology, we are going to use a database analogy to explain them.

The B+trees have two different types of nodes: the internal nodes and the leaf nodes. Both of them consist of sets of pairs like (key, pointer), ordered by the key value in an ascending manner and a final pointer which does not have a corresponding key. Whereas the internal node pointers are used to point to others' internal or leaf nodes, the leaf node pointers point to the final information directly. Every single pair's key is used to organise the information within the B+Tree. In databases, each record has a key field, a field where the value is used to distinguish that record from the same kind of records. Btrees take advantage of that key to index database records for better access times.

[In the diagram, the keys are file names. The bottom row above the red boxes contains a key for every file in the directory: these are the leaf nodes. Above these are the internal nodes, keys that have been chosen by the system to make finding other keys faster. -Ed.]

As we said earlier, an internal node pair (key, pointer) is used to point out either another internal node or a final leaf node. In both cases, the key that comes with the pointer will be greater than all the keys stored in the target node. Therefore, records with an equal key value to a certain pair's should be addressed by the next pair within the node. This is the main reason for a final pointer with no corresponding key to exist. Notice that once a key is used within a pair, there should be another pointer to address the records with that key value. That final pointer, is used in the leaf nodes to point to the next. That way, we can still visit the contents organised sequentially.

B+Trees also have to be balanced. That means the length of the path taking us from the tree's root to any leaf node should always be the same. Moreover, the nodes within a BTree must contain a minimum number of pairs in order to exist. Whenever a node's content gets below that minimum, the pairs contained would be shifted to another existing node.

In order to locate a specific record, we would do the following. Let's suppose we are looking for a record with a certain key, "K". We would begin at the root node, and then begin sequentially scanning the keys stored within. We scan throughout that node until we found a key that was greater than "K". Then we go to the node (internal or leaf; we don't know yet) pointed by the accompanying pointer. Once there, if we were taken to another internal node, we repeat the same operation. Finally, we get directed to a leaf node, where we scan sequentially until we found the desired key "K". As fewer blocks have to be retrieved to get the desired one, this technique is of lower complexity than sequential scanning, where in the worst case, we should visit all the entries.

UNIX File System (UFS)

The name of the file system SCO, System V and some other UNIXes used at the beginning. The Linux kernel includes optional support for UFS. Most UNIXes continue to use UFS, although now with custom minor enhancements.

Virtual File System (VFS)

A kernel layer that provides a unified application programming interface for file system services, irrespective of which file system a file resides in. All file system implementations (vfat, ext2fs, jfs, etc) must therefore provide certain VFS routines in order to be usable under Linux. VFS is the kernel layer that makes user applications able to understand so many different file systems, even file systems that are comercial.

THE JOURNAL

What is a Journal File System?

I think we all know what a write cache is; a buffer allocated in the main memory intended to speed I/O operations up. This kind of buffer is commonly used in file systems the disk cache and databases to increase overall performance. The problem appears if there is a system crash, before the buffers have been written to disk, that would cause the system to behave in an inconsistent way after system reboot. Think of a file deleted in the cache, but remaining in the hard disk. That's why databases and file systems have the ability to recover the system back to a consistent state. Although databases have recovered quickly for years, the file systems and more precisely UFS-like ones tend to increase their recover time as file system size grows. The fsck recover tool for ext2fs has to scan through the entire disk partition in order to take the file system back to a consistent state. This time-consuming task often creates a lack of availability for large servers with hundreds of gigabytes or sometimes terabytes. This is the main reason for the file systems to inherit database recover technology, and thus the appearance of Journal File Systems.

How does it work?

Most serious database engines use what is called a transaction. A transaction is a set of single operations that satisfy several properties. The so-called ACID properties of transactions stands for Atomicity, Consistency, Isolation and Durability. The most important feature for our explanation is the Atomicity. This property implies that all operations belonging to a single transaction are completed without errors or cancelled, producing no changes. This feature, together with Isolation, make the transactions look as if they were atomic operations that can't be partially performed. This transaction properties are held on databases, due to the problems related to keeping consistency while exploiting concurrency. Databases take advantage of this, logging every single operation within the transaction into a log file. Not only the operation names are logged in, but also the operation argument's content before the operation's execution. After every single transaction, there must be a commit operation, making the buffers be written to disk. Therefore, if there is a system crash, we could trace the log back to the first commit statement, writing the argument's previous content back to its position in the disk.

Journal file systems use the same technique above to log file system operations, causing the file system to be recoverable in a small period of time.

One major difference between databases and file systems journaling is that databases log users and control data, while file systems tend to log metadata only. Metadata are the control structures inside a file system: i-nodes, free block allocation maps, i-nodes maps, etc.

KNOWN PROBLEMS--SATISFYING THE SCALABILITY NEEDS

UNIX File System (UFS) and ext2fs were designed when hard disks and other storage media weren't as big in capacity. The growth in storage media capacity led to bigger files, directories and partition sizes, causing several file-system-related problems. These problems are a consequence of the internal structures those file systems laid over. Yet, although those structures were adequate for old files and directories' average sizes, they have proven inefficient for new ones.

There are two major problems with old structures:

• They are unable to cope with new storage capacities: as we said above, old fs were designed with certain file, directory and partition sizes in mind. File system structures have a fixed number of bits to store file size information, a fixed number of bits to store the logical block number, etc. As a consequence of that fixed number of bits, file sizes, partition sizes and the number of directory entries are limited. Old structures often lack the number of bits required to manage certain object sizes.
• They are inadequate to manage with new storage capacities: although old structures are sometimes able to manage with new object sizes, they are sometimes inadequate to manage with them for performance reasons. The main reason is that certain structures behave well with old sizes, but with the new ones lead to performance losses.

Solving the inability

Most new file systems have widened their number of bits for some fields, in order to overcome previous limitations. The new limits for those file systems are:
 

Actually, the maximum block device size limits the file system size to 2Tb, and there is also a VFS limit of 2GB for file sizes. The good news is that we now have file systems able to scale up, and once the 2.4 kernels come out, I am sure the limits will be extended. Notice also that JFS and XFS are commercial file systems ports; they were designed for other operating systems where these limitations didn't exist.

Avoiding inadequate use

The free blocks structure

Most file systems maintain structures where free blocks are tracked. The structures often consist of a list, where all the free blocks' numbers are kept. That way, the file system is able to satisfy the applications storage requests. UFS and ext2fs use what is called a bitmap, for free blocks tracking. The bitmap consists of an array of bits, where each bit corresponds to a logical block within the file system's partition. Each block's allocation state would be reflected in its related bit. Therefore, a logical "1" value could mean the logical block is being used, and a "0" could mean the block is free. The main problem with this kind of structure is that as the file system size grows, the bitmap would grow in size as well, since every single block within the file system must have a corresponding bit within the bitmap. As long as we use a "sequential scan algorithm" for free blocks, we would notice a performance decrease, since the time needed to locate a free block would grow as well (worst-case complexity O(n), where n is the bitmap's size). Notice that this bitmap approach isn't that bad when the file system size is moderate, but as size grows, the structure behaves worse.

The solution provided by the new-generation file systems is the use of extents together with B+Tree organization. The extents approach is useful since it can be used to locate several free blocks at a same time. Also, extents use provide a way to reduce the structure's size, since more logical blocks are tracked with fewer information. Therefore, a bit for each block is no longer needed. Furthermore, with extents use, the free block's structure size no longer depends on the file system size (structure size would depend on the number of extents maintained). Nevertheless, if the file system were so fragmented that an extent existed for every single block in the file system, the structure would be bigger than the bitmap approach's. Notice that the performance should be significantly increased if our structure kept the free blocks only, since fewer items had to be visited. Also, with extents use, even when they were organised into a list and sequential scan algorithms were used, the performance would be increased, since the structure would pack several blocks within an extent, reducing the time to locate a certain number of free blocks.

The second approach to overcome the free blocks problem is the use of complex structures that lead to lower-complexity scan algorithms. We all know there are better ways of organising a set of items that will need to be located later than the use of lists with sequential scan algorithms. The B+Trees are used since they are able to locate objects quickly. Thus, the free blocks are organised into B+Trees instead of lists, in order to take advantage of better scan algorithms. When several free blocks are requested by the applications, the file system would traverse the main "free blocks B+Tree" in order to locate the free space required. Also, there is a "B+Trees + Extents" approach, where not blocks but extents are organised within the tree. This approach makes different indexing techniques possible. Indexing by extent size, and also by extent position, are implemented techniques that make the file system able to locate several free blocks, either by size or by their location, quickly.

Large number of directory entries

All file systems use a special fs object called directory. The directories, from the file system view, is a set of directory entries. These directory entries are pairs (i-node number, file name), where the "i-node number" is the number of the i-node fs internal structure used to maintain file-relevant information. Once an application wants to look for a certain file within a directory, given its file name, the "directory entries structure" needs to be traversed. Old file systems organised the directory entries within a directory into a list, leading then to sequential scan algorithms. As a consequence, with large directories where thousands of files and other directories are stored, the performance would be really low. This problem, as the one described with the free blocks, is tightly related to the structure used. New-generation fs need better structures and algorithms to locate files within a directory quickly.

Solution provided: The file systems being reviewed use B+Trees to organise the directory entries within a directory, leading to better scan times. In those fs, the directory entries for every single directory are organised into a B+Tree, indexing the directory entries by name. Thus, when a certain file under a given directory is requested, the directory B+Tree would be traversed to locate the file's i-node quickly. Also, new fs usage of B+Trees is file system dependent. There are file systems that maintain a B+Tree for each single directory, while others maintain a single file system B+Tree for the whole file system directory tree.

Large files

Some old file systems were designed with certain patterns of file usage in mind. Ext2fs and UFS were designed with the idea that the file systems would contain small files mainly. That's why the ext2fs and UFS i-nodes look as they do. For those of you who still don't know what an i-node is, we are going to explain the i-node structure briefly.

An i-node is the structure used by UFS and ext2fs to maintain file-dependent information. The i-node is where the file permissions, file type, number of links, and pointers to the fs blocks used by the file are maintained. An i-node contains some direct pointers that are pointers (block addresses) to a file system's logical blocks used by the file it belongs to. i-nodes also contain indirect pointers, double-indirect pointers and even a triple-indirect pointer. Indirect pointers are pointers (addresses) to blocks where other pointers to logical blocks are stored. Thus, double-indirect pointers are pointers to blocks that contain indirect pointers, and triple-indirect pointers are pointers to blocks containing double-indirect pointers. The problem with this addressing technique is that as the file size grows, indirect, double-indirect and even triple-indirect pointers are used. Notice that the use of indirect pointers leads to a higher number of disk accesses, since more blocks have to be retrieved in order to get the block required. This would lead to an increasing retrieval time as file sizes grow. You could be wondering why ext2fs designers didn't use direct pointers only, as they have been proven faster. The main reason is that i-nodes have a fixed size, and the use of only direct pointers would take i-nodes to be as big in size as the number of direct pointers that could be used, wasting much space for small files.

In order to minimise the use of indirect pointers, we could think of using bigger logical blocks. This would lead to a higher information per block ratio, resulting in fewer indirect pointers usage. But, bigger logical blocks increase the internal fragmentation, so other techniques are used. The use of extents to collect several logical blocks together is one of those techniques. Using extents instead of block pointers would cause the same effect as bigger blocks, since more "information per addressed unit" ratio is achieved. Some of the reviewed file systems use extents to overcome the large file addressing problems. Moreover, extents can be organised within a B+Tree indexing by their offset within the file, leading to better scan times. New i-nodes usually maintain some direct pointers to extents, and in case the file needs more extents, those would be organised within a B+Tree. In order to keep performance high when accessing small files, the new-generation file systems store file data within the i-node itself. Consequently, whenever we get a file's i-node, we would also get its data. This is an especially useful technique for symbolic links, where the data within the file is really small.
 
 
 

(1) JFS uses a different approach to organise the free blocks. The structure is a tree, where the leaf nodes are pieces of bitmap instead of extents. Actually the leaf nodes are the representation of the binary buddy technique for that specific partition (Binary Buddy is the technique used to track and then collect together contiguous groups of free logical blocks, in order to achieve a bigger group). As we said when discussing the bitmap-based technique, every single bit on the bitmap corresponds to a logical block on disk. The value of a single bit could then be "1", meaning the block is allocated, or it could be "0", meaning the block is free. The pieces of bitmap, each of which contains 32 bits, could be understood as a hex number. Therefore, a value of "FFFFFFFF" would mean that the blocks corresponding to the bits on that sub-bitmap are all allocated. Finally, making use of that allocation number and other information, JFS builds a tree where a group of contiguous blocks of a certain size can be located quickly.

(2)This file system's core is based on B*Trees (an enhanced version of B+tree).The main difference is that every file system object is placed within a single B*Tree. That means there aren't different trees for each directory, but each directory has a sub-tree of the main file system one. That sort of use requires Reiserfs to have more complex indexing techniques. Another major difference is that Reiserfs does not use extents, though they are planned to be supported.

(3)ReiserFS organizes every file system object within a B*Tree. Those objects, directories, file blocks, file attributes, links, etc. are all organised within the same tree. Hashing techniques are used to obtain the key field needed to organise items within a BTree. The best of it is that by changing the hashing method applied, we are changing the way the fs organises the items, and their relative position within the tree. There are hashing techniques that help maintain spatial locality for items related (directory attributes with directory entries, file attributes with file data, etc.).
 

OTHER IMPROVEMENTS

There are other limitations on "UFS-like" file systems. Amongst these are the inability to manage sparse files as a special case, and the fixed number of i-nodes problem.

Sparse files support

Let's suppose we create a new file, and write a couple of bytes at the beginning. Everything is okay until then. What about if we now write at offset "10000" within that file? The file system should now look for as many blocks as needed to cover the gap between offset 2 and offset 10000. That could take a while. The question now is, why should the fs allocate those blocks in the middle, if we were not interested in them? The answer to that question is the sparse file support provided by the new file systems.

The sparse file support is tightly related to the extent addressing technique for the file's blocks. The sparse file support takes advantage of the field "offset within the file" of extent descriptors. Thus, whenever the file system must look for free blocks just to fill the gap opened by a situation like the one described above, the file system just sets up a new extent with the corresponding "offset within the file" field. Thereafter, whenever an application tries to read one of the bytes within the gap, a "null" value should be returned, as there is no information there. Finally, the gap would be filled in by other applications that wrote at offsets within the gap. 
 

The ReiserFS internal fragmentation solution

When we discussed the internal fragmentation and file system performance, we said administrators often have to choose between performance and space waste. If we now look at the first table, we would see that new fs are able to manage blocks up to 64KB in size. That size of block and even smaller would produce a significant waste of space due to internal fragmentation. In order to make the use of big block sizes feasible, ReiserFS implements a technique that solves the problem.

As we said earlier, ReiserFS uses a B*Tree to organise the file system objects. These objects are the structures used to maintain file information access time, file permissions, etc. In other words, the information contained within an i-node-,  directories and the file's data. ReiserFS calls those objects, stat data items, directory items and direct/indirect items, respectively. The indirect items consist of pointers to unformatted nodes. Unformatted nodes are logical blocks with no given format, used to store file data, and the direct items consist of file data itself. Also, those items are of variable size and stored within the leaf nodes of the tree, sometimes with others in case there is enough space within the node. This is why we said before that file information is stored close to file data, since the file system always tries to put stat data items and the direct/indirect items of the same file together. Realise that opposed to direct items, the file data pointed by indirect items is not stored within the tree. This special management of direct items is due to small file support.

The direct items are intended to keep small file data and even the tails of the files. Therefore, several tails could be kept within the same leaf node, producing an important decrease of wasted space. The problem is that using this technique of keeping the file's tails together would increase external fragmentation, since the file data is now further from the file tail. Moreover, the task of packing tails is time-consuming and leads to performance decrease. This is a consequence of the memory shifts needed when someone appends data to a file. Anyway, the tails packing technique can be disabled if the administrator wants to do so. Consequently, it's once again an administrator choice.

Dynamic i-node allocation

One major problem of "UFS-like" file systems is the use of a fixed number of i-nodes. As we explained before, the i-nodes contain the information related to every file system object. Thus, a fixed number of i-nodes constrains the maximum number of objects that can be maintained within the file system. In case we used all the i-nodes of the file system, we would have to back up the partition, and then reformat with a higher number of i-nodes. The reason for this fixed number is that "UFS" uses fixed-size structures to track i-nodes state the same manner as free blocks. Also, "UFS" allocates i-nodes at well-known positions for the file system, so no i-node to logical blocks mapping is needed. The problem appears when system administrators have to guess the maximum number of objects their file systems should manage. Notice that it is not always a good policy to create the biggest number of i-nodes possible, since the disk space needed for the i-nodes is reserved (can't be used for other purposes), and this would waste much space.

To overcome that problem, dynamic i-node allocation appeared. The dynamic allocation of i-nodes avoids the need for system administrators to guess the maximum number of objects at format time. But the use of dynamic techniques leads to other problems: i-node to logical block mapping structures, i-node tracking structures, etc. The file systems reviewed use B+Trees to organise the allocated i-nodes of the file system. Furthermore, JFS uses "i-node extents" that form the leaf nodes of the B+Tree and keep up to 32 i-nodes together. There are also structures that help allocate i-nodes close to other file system objects. Consequently, the use of dynamic i-node is complex and time-consuming, but helps broaden old file systems' limits.
 
 

*(4) As we explained in "the ReiserFS internal fragmentation solution" section, ReiserFS makes use of stat_data items to store file-dependent information. The number of hard links, the file owner id, the owner group id, file type, permissions, file size, etc, are all stored within a stat_data item for the corresponding file. The stat_data item then replaces the inode's usage, except for the pointer to file blocks. Furthermore, the ReiserFS items are created dynamically and organised within the main file system B*tree, which leads us to dynamic inode allocation. Finally, every single file system item has a related key field, which serves to locate the item within the B*tree. This key has a number of bits at the end, dedicated to item-type identification and to let us know if the item is an stat_data, direct, indirect, etc. Therefore, we could say that inode organisation is performed by the B*tree usage.

*(5) Currently, ReiserFS sparse files support is not as fast as it was intended to be. This problem is scheduled to be fixed with ReiserFS release 4.

REFERENCES

File system home pages

• ext2fs
• ReiserFS
• xfs
• jfs

Bibliography

• JFS overview and layout white papers by Steve Best and Dave Kleikamp
• XFS: A Next Generation Journalled 64-Bit Filesystem With Guaranteed Rate I/O by Mike Holton and Raj Das. SGI, Inc.
• Scalability in the XFS File System by Adam Sweeney, Doug Doucette, Wei Hu, Curtis Anderson, Mike Nishimoto, and Geoff Peck. SGI, Inc.
• Scalability and Performance in Modern File Systems by Philip Trautman and Jim Mostek; ReiserFS web site papers.
• Design and Implementation of the Second Extended Filesystem by Rémy Card, Theodore Ts'o, Stephen Tweedie
• ReiserFS developers mailing list. To join, send e-mail to .
• JFS mailing list. To subscribe, send e-mail to with "subscribe" in the Subject: line and "subscribe jfs-discussion" in the body.
• Fundamentos de Bases de Datos by Henry F. Korth and Abraham Silberschatz. McGraw-Hill, 1993.

The author would like to thank Stephen C. Tweedie, Dave Kleikamp, Steve Best, Hans Reiser, the JFS and the ReiserFS mailing list guys for the fruitful conversations and answers.

Copyright © 2000, Juan I. Santos Florido
Published in Issue 55 of Linux Gazette, July 2000

"Linux Gazette...making Linux just a little more fun!"

Introduction

I'm a command line guy. I know on a modern Linux system, I can point and click my way through the world like I were illiterate, or a Windows user, but I'm most comfortable in a Linux virtual console with my Bash prompt. I was using Linux happily for two years before I ever installed X (which I did only when the Worldwide Web got to where it was unusable without a graphical browser). I used to keep my mouse on the floor.

But still, there are times when typing out commands is really annoying, like to read my mail twenty times a day. Infamous two-character Unix commands, aliases, and word completion can only go so far to ease the keystroke burden. So I set up my F2 key to bring up the mail in one touch. F1 edits a certain file to which I refer throughout the day. Other keys type out option strings, filenames, and directory names that I used to type a lot.

I can put any command or part of a command on any key on the keyboard, and with the Alt and Control shifts, plus that pointless numeric keypad, not to mention the F keys, there are plenty from which to choose.

If you don't know how to do this, read on; it's not hard. But I'm going to give a little background on keyboard stuff first.

Background - How keystrokes become a command

I've only worked with the IBM standard keyboard attached to an IBM (ISA) type computer, and some of the gritty details below may not apply to your keyboard. But I know the basic techniques work on any Linux keyboard.

Bash gets all of its commands (by "command," I mean your response to its command prompt) via the GNU Readline library. Readline is a subroutine library any program can use get a line of input from the keyboard. The advantage to a program of using Readline instead of just doing an ordinary file read of the terminal is that the Readline code lets the user do fancy editing of the line and perform a variety of magic to build up the line the way he wants before Readline passes it on to the program. All that command line editing that you do at a Bash prompt, such as backspace, delete word, history recall, and insert, are done not by Bash itself, but by the Readline subroutine that Bash calls.

Bash (also a GNU product) is the premier user of Readline and tends to get credit for all these fancy line editing functions (there are about sixty of them), and in fact they are described in the Bash man page. (And why not, if millions of users think amazon.com is a feature of AOL?) But all Bash does is call routines in the Readline library, and many other programs call the same routines and have the same line editing capability. Gdb, for example, and Postgresql's SQL prompt (Psql), and some Ftp clients.

Readline gets a stream of characters from the terminal (and it can be any old terminal — not just a Linux virtual console) and recognizes certain sequences and executes certain functions when it sees them. For example, when it sees E, it inserts E in the line you are building. When it sees Control-A, it backs the cursor up to the beginning of the line. When it sees Tab, it reads your mind (at least I think it does).

You get to choose what Readline does when it sees some character sequence via a Readline configuration file, which is normally called .inputrc in your home directory.

Making a hotkey

The Readline function we will be using is the one to insert a string into the line being built. To make the first example easy, we will do something ridiculous: Assign the string ps -a --forest to the character z. Once we do this, we will not be able to type the letter z in any command, so it is truly ridiculous.

To do this, we add the following to our ~/.inputrc (if it doesn't already exist, just make this the only line in a new file):

  "z":"ps -a --forest"

After doing this, you should find that when you hit the z key, the characters ps -a --forest appear in your command line buffer. Hit Enter and the ps command executes. You will find that you don't have to type z at the beginning of the line. Type echo z and you have typed echo ps -a --forest.

But let's be more reasonable and put this ps command on the F1 key. That's more complicated because pressing the F1 key does not cause a single typeable character to be sent to Readline. Instead, it causes a terminal-type-dependent sequence of characters to be sent. Let's concern ourselves with a Linux console only, and one that's using the default Linux console configuration. In that case, F1 sends the four characters Escape, [, [, and A.

But don't take my word for it. You can prove it by using Readline's quoted-insert function, which you should find bound to Control-V. quoted-insert means put the following character into the line instead of executing any function that might be assigned to it. You need this to keep Readline from trying to interpret that Escape character. So at a Bash prompt, type Control-V followed by F1. As Readline places the Escape and the three characters after it in the input line, it naturally echoes them so you can see them. The Escape character probably types out as ^[, which means Control-[, which is another name for Escape. This trick is the easiest way to find out the exact sequences generated by essentially any key on your keyboard.

Knowing that F1 sends Escape-[-[-A, we just need to put that into ~/.inputrc. Putting an Escape character into a file isn't pretty with any editor. Readline helps you out by accepting \e in the configuration file to represent Escape. So replace that z assignment above with the following in ~/.inputrc:

"\e[[A":"ps -a --forest"

Now if you're up for something more sophisticated than logging out and in again, just hit Control-X Control-R. That should reload the Readline configuration file. Now press F1 and you'll get ps -a --forest.

But having to hit Enter after F1 ruins everything. It's like having to get up to reach the TV remote.

Readline makes a special accomodation for this: End your inserted string with a Carriage Return (that's Control-M) and Readline submits the line to the caller (Bash) after it inserts the rest of the string. If you don't think this is a special accomodation, because Carriage Return is simply what one types to submit a command, think again. It's Readline that interprets a Carriage Return that you type and decides to submit the command. Readline interprets character sequences you type, not sequences that it inserts because you typed something else. You'll find that no other control characters in your insert string do anything other than insert a control character into the line.

It's too bad Readline doesn't provide a printable sequence like \s to say "submit this," because you'll have to figure out how to make your editor deal with a control character in your file. (Hint: in Emacs, check out Control-Q).

Anyway, put the following in your ~/.inputrc, reload, and you'll see that you have a one-touch ps command. ^M here means Control-M.

"\e[[A":"ps -a --forest^M"

For Alt and Control shifted keys, use the syntax C-x and M-x in ~/.inputrc (M is for Meta, a forerunner of the Alt key).

See the Readline User's Guide, available wherever fine Info documents are hyperlinked on your system, for all the details. The man page for the Readline subroutine also works.

Things That Don't Work

Now I should point out a few cases where things won't work as you expect because your keystrokes are interpreted at a level below Readline.

First of all, the tty device driver (that's a driver a level above the actual keyboard device driver) recognizes a few special characters, as controlled by the stty program. Readline turns off most of this tty interference by placing the console in raw tty mode, but Control-S, Control-Q, Control-C, and Control-Z are likely never to make it to Readline, being hijacked by the tty driver and acted on accordingly.

Then there's the keyboard driver. It lets you customize every key, and I don't mean at the same level as Readline. You can make the left shift key generate a q character if you're feeling a little psychotic. More important, the keyboard driver assigns certain console functions to certain keystrokes, which means those keystrokes will not generate anything that gets sent up to the tty driver, and then to Readline. For example, the driver normally associates Alt-F1 with "switch to Virtual Console 1." So don't even try to program Readline to insert the name of your Napster pirated music directory when you press Alt-F1.

Under X (in, say, an xterm window), the Linux keyboard device driver is mostly bypassed, with the X server substituting its own driver. So the keys won't necessarily generate the same character stream, to be seen by Readline, as you would see from a regular Linux virtual console.

More information

If you're interested in the wide world of keyboard mapping, start with the Keyboard-And-Console HOWTO and also read the Readline User's Guide and of course documentation for X.

Copyright © 2000, Bryan Henderson
Published in Issue 55 of Linux Gazette, July 2000

"Linux Gazette...making Linux just a little more fun!"

"There are two major products that come out of Berkeley: LSD and UNIX. We don't believe this to be a coincidence." -- Jeremy Anderson

Deep within the bash man page lurk terrible things, not to be approached by the timid or the inexperienced... Beware, Pilgrim: the last incautious spelunker into these mysterious regions was found, weeks later, muttering some sort of strange incantations that sounded like "nullglob", "dotglob", and "MAILPATH='/usr/spool/mail/bfox?"You have mail":~/shell-mail?"$_ has mail!"'" (He was immediately hired by an Unnamed Company in Silicon Valley for an unstated (but huge) salary... but that's beside the point.)

<Shrug> What the heck; I've already gone parasailing and scuba-diving this month (and will shortly be taking off on a 500-mile sail up the Gulf Stream); let's keep living La Vida Loca!

Parameter Expansion

The built-in parsing capabilities of bash are rather minimal as compared to, say, perl or awk: in my best estimate, they're not intended for serious processing, just "quick and dirty" minor-task handling. Nevertheless, they can be very handy for that purpose.

As an example, let's say that you need to differentiate between lowercase and capitalized filenames in processing a directory - I ended up doing that with my backgrounds for X, since some of them look best tiled, and others stretched to full-screen size (file size wasn't quite a good-enough guide). I "capped" all the names of the full-sized pics, and "decapped" all the tiles. Then, as part of my random background selector, "bkgr", I wrote the following:

fn=$(basename $fnm)                   # We need _just_ the filename
[ -z ${fn##[A-Z]*} ] && MAX="-max"    # Set the "-max" switch if true
xv -root -quit $MAX $fnm &            # Run "xv" with|without "-max"
                                      #   based on the test result

d=Digit
echo ${d}ize        # "Digitize"
echo ${d}al         # "Digital"
echo ${d}s          # "Digits"
echo ${d}alis       # "Digitalis"

${#parameter} - return length of the parameter value.
EXAMPLE: ${#parameter} = 10

${parameter#word} - cut shortest match from start of parameter.
EXAMPLE: ${parameter#*n} = uensis

${parameter##word} - cut longest match from start of parameter.
EXAMPLE: ${parameter#*n} = sis

${parameter%word} - cut shortest match from end of parameter.
EXAMPLE: ${parameter%n*} = amanue

${parameter%%word} - cut longest match from end of parameter.
EXAMPLE: ${parameter%%n*} = ama

${parameter:offset} - return parameter starting at 'offset'.
EXAMPLE: ${parameter:7} = sis

${parameter:offset:length} - return 'length' characters of parameter
starting at 'offset'.
EXAMPLE: ${parameter:1:3} = man

${parameter/pattern/string} - replace single match.
EXAMPLE: ${parameter/amanuen/paralip} = paralipsis

${parameter//pattern/string} - replace all matches.
EXAMPLE: ${parameter//a/A} = AmAnuensis (For the last two operations, if the pattern begins with #, it will match at the beginning of the string; if it begins with %, it will match at the end. If the string is empty, matches will be deleted.)

There's actually a bit more to it - things like variable indirection, and parsing arrays - but, gee, I guess you'll just have to study that man page yourself. Just consider this as motivational material.

So, now that we've looked at the tools, let's look back at the code -

[ -z ${fn##[A-Z]*} ]

Note that, since we're matching the entire string, ${fn%%[A-Z]*} would work just as well. If that seems confusing - if _all_ of the above seems confusing - I suggest lots and lots of experimentation to familiarize yourself with it. It's easy: set a parameter value, and experiment, like so -

Odin:~$ experiment=supercallifragilisticexpialadocious
Odin:~$ echo ${experiment%l*}
supercallifragilisticexpia
Odin:~$ echo ${experiment%%l*}
superca
Odin:~$ echo ${experiment#*l}
lifragilisticexpialadocious
Odin:~$ echo ${experiment##*l}
adocious

Parameter State

There are times - say, in testing for a range of error conditions that set different variables - when we need to know whether a specific variable is set (has been assigned a value) or not. True, we could test it for length, as I did above, but the utilities provided by bash for the purpose provide convenient shortcuts for such occasions: (Here, we'll assume that our variable - $joe - is unset or null.)

${parameter:-word} - If parameter is unset, "word" is substituted.
EXAMPLE: ${joe:-mary} = mary ($joe remains unset.)

${parameter:=word} - If parameter is unset, set it to "word" and
return it.
EXAMPLE: ${joe:=mary} = mary ($joe="mary".)

${parameter:?word} - Display "word" or error if parameter is unset.
EXAMPLE:
Odin:~$ echo ${joe:?"Not set"}
bash: joe: Not set
Odin:~$ echo ${joe:?}
bash: joe: parameter null or not set

${parameter:+word} - "word" is substituted if parameter is not unset.
EXAMPLE:
Odin:~$ joe=blahblah
Odin:~$ echo ${joe:+mary}
mary
Odin:~$ echo $joe
blahblah

Array Handling

Another built-in capability of bash, a basic mechanism for handling arrays, allows us to process data that needs to be indexed, or at least kept in a structure that allows individual addressing of each of its members. Consider the following scenario: if I have a phonebook/address list, and want to send my latest "Sailor's Newsletter" to everyone in the "Friends" category, how do I do it? Furthermore, say that I also want to create a list of names of the people I sent it to... or some other processing... i.e., make it necessary to split it up into fields by length, and arrays become one of the very few viable options.

Let's look at what this might involve. Here's a clip of a notional phonebook to be used for the job:

Name                     Category  Address                  e-mail
Jim & Fanny Friends      Business  101101 Digital Dr. LA CA [email protected]
Fred & Wilma Rocks       friends   12 Cave St. Granite, CT  [email protected]
Joe 'Da Fingers' Lucci   Business  45 Caliber Av. B-klyn NY [email protected]
Yoda Leahy-Hu            Friend    1 Peak Fribourg Switz.   [email protected]
Cyndi, Wendi, & Myndi    Friends   5-X Rated St. Holiday FL [email protected]

#!/bin/bash

# 'nlmail' sends the monthly newsletter to friends listed
# in the phonebook


# bash would create the arrays automatically, since we'll
# use the 'name[subscript]' syntax to load the variables - 
# but I happen to like explicit declarations.
 
declare -a name category address email

# Count the number of lines in "phonelist" and loop that 
# number of times 

for x in $(seq $(grep -c $ phonelist))
do
    x=$(($x))                           # Turns '$x' into a number
    line="$(sed -n ${x}p phonelist)"    # Prints line number "$x"
    name[$x]="${line:0:25}"             # Load up the 'name' variable
    category[$x]="${line:25:10}"        #  Etc.,
    address[$x]="${line:35:25}"         #       etc.,
    email[$x]="${line:60:20}"           #            etc.
done
# Continued below ...

# Continued from above ...
for y in $(seq $x)
do
    # We'll match for the word "friend" in the 'category' field,  
    # make it "case-blind", and clip any trailing characters.
            
    if [ -z $(echo ${category[$y]##[Ff]riend*}) ]
    then
        mutt -a Newsletter.pdf -s 'S/V Ulysses News, 6/2000' ${email[$y]}
        echo "Mail sent to ${name[$y]}" >> sent_list.txt
    fi
done

The array processing capabilities of bash extend a bit beyond this simple example. Suffice it to say that for simple cases of this sort, with files under, say, a couple of hundred kB, bash arrays are the way to go. For my own curiosity, I created a list of names that was just over 100kB, using the "phonelist" from the above example -

  for n in $(seq 300); do cat phonelist >> ph_list; done

Note that the above script can be easily generalized - as an example, you could add the ability to specify different phone-lists, criteria, or actions, right from the command line. Once the data is broken up into an easily-addressable format, the possibilities are endless...

Wrapping It Up

bash, besides being very capable in its role as a command-line interpreter/shell, boasts a large number of rather sophisticated tools available to anyone that needs to create custom programs. In my opinion, shell scripting suits its niche - that of a simple yet powerful programming language - perfectly, fitting between command-line utility usage and full-blown (C, Tcl/Tk, Python) programming, and should be part of every *nix user's arsenal. Linux, specifically, seems to encourage the "do it yourself" attitude among its users, by giving them access to powerful tools and the means to automate their usage: something that I consider a tighter integration (and that much higher a "usability quotient") between the underlying power of the OS and the user environment. "Power to the People!"

Until next month -
Happy Linuxing!

Quote of the Month

You owe the Oracle a twelve-step program."
--The Usenet Oracle

References

The "man" pages for bash, builtins

"Introduction to Shell Scripting - The Basics" by Ben Okopnik, LG #52
"Introduction to Shell Scripting" by Ben Okopnik, LG #53
"Introduction to Shell Scripting" by Ben Okopnik, LG #54

Copyright © 2000, Ben Okopnik
Published in Issue 55 of Linux Gazette, July 2000

"Linux Gazette...making Linux just a little more fun!"

A few months ago, I wrote a review of an HTML-editor ported from Windows: CoffeeCup. I found a quite a few bugs in that version, and don't actually know if a new one has been made available for Linux. I know that new Windows versions has been poping up regularly. So the search has been going on for a reliable and powerful HTML editor in which I can do all my HTML page construction. I can say I've found a good candidate for such a beast. It isn't Homesite--but then, it is isn't finished yet.

Bluefish is in version 0.3.4 as of this writing (early June 2000). So according to version number it is very early yet, but it is still a quite powerful editor.

As can be seen from the picture, it has all the button rows, tabs and menues one could ask for. The standard button row is for creating a new document, opening, saving, undo/redo, etc. All standard stuff. Then we've got a series of tabs which are generally well laid out but unfortunately not configurable at this time. Unfortunate, because the quick bar is supposed to contain the most used tags - but lacks the Heading tags, which are on the Fonts tab. While, structurally logical, it is not user-friendly. While I'm on about weird thing about the tabs, I'll mention an irritating bug that's been around for some versions: the Form wizard. It's long, very, very long. I have to scroll horizontally two screenfuls to find the close button. And while the other Wizards are pretty useful (New Page, Font, Tables, Frames, Lists, CSS, PHP, etc.), the Forms wizard is broken and should be avoided. Even if it were working, it creates only the opening and closing tags. While the button rows and wizards are good, you can also add tags using the menus. These are well laid out, and I believe they contain tags not available through the buttons and wizards. Another bug which has surfaced in this version is that the cursor disappears from time to time, making it hard to know exactly where you are in the text.

Regarding about menus, I can't say much about the help system. There isn't one, at least not in the version I am running (there was one earlier?). Even though that may be a disappointment, I didn't miss it much. One thing that is missing is Imlib support, which is necessary for the Image wizard. Imlib isn't installed standard on Red Hat. Without that you have to write you own image tags. Which is a pain. (Not as bad as writing your own table tags, but still a pain). Fortunately, you just install it off the CD and then you may happily create images in you HTML documents in no time.

To summarize, Bluefish is a very strong HTML editor, with nice looks as well. It will be interesting to see where this one is going. It is not Homesite (the well known Allaire editor for Windows) but it might get there.

Copyright © 2000, Martin Skjøldenrand
Published in Issue 55 of Linux Gazette, July 2000

"Linux Gazette...making Linux just a little more fun!"

Introduction

In the last article, we installed Linux with only those packages we absolutly needed. (If you have not read my previous article, you should do so now, as it is the base from which this is built on.) Now comes the detail work, turning your gateway into fortress. The first thing to understand is there is no way to be completely secure. There is just not enough time to do it all, Corporations employ huge IT departments, whose sole purpose in life is to secure their networks, and still they get cracked. Just accept it and get on with your life. Our real goal here is to keep honest people honest, keep the Script Kiddies out and slow the rest down, giving you opprotunity to discover them. Ideally, this should be done right after the clean install, before the system ever gets put on the Internet. This article assumes you know something about Linux, how to install it, how to edit various configuration files, and that you can log in as root.

I also assume you are setting up a firewall system and have no intention of running DNS, DHCP, web, ftp or telnet server. If you intend to run any of these services, of these services, I recommend setting up seperate machines. Setup a DMZ on your network, a system which is secured but allows connections from system outside your network. This way if an intruder does penetrate your server, he will have to start all over to penetrate your firewall system and you will hopefully discovered his breakin before he is able to get access to your internal network.

System Updates and Security Advisories

In the world of Computer Security, Knowledge is Power. Frankly the Security Experts are always one step behind the Crackers, most security issues are not discovered by the Experts, but by the Crackers and are plugged only after they have been exploited. You need to keep up to date on new problems, at the very least you should be updating the packages as they come out. Type "rpm -qa > packages.txt", this gives you a list of the packages and version numbers installed on your system, then go to Redhat's web site and download the updated packages. While you are there you should read the security advisories and implement any changes they suggest. If you are really proactive, subscribe to both the BugTraq and CERT mailing lists.

Physical Security

Since this article is aimed at the home cable modem user, I will assume physical security is not a problem. If you have child or a nosey baby sitter, consider using the BIOS password protection built into most computers.

User Accounts and Passwords

Besides the root account and the special accounts, which I'll go into in a moment, there should be only one user account. The user and the root accounts should have good passwords. A good password is one that is at least 8 characters long, has a mix of small letters, capital letters and numbers, and is not a dictionary word. It is also a good idea to change these passwords from time to time and do not write the passwords on a sticky note and put it on the monitor where everyone can see it. Use different passwords on each computer on your network, that way, if one system is cracked an intruder will still not have access to the other systems on the network. Again, because password cracking takes time, you will hopefully discover the cracker before he gets too far.

Along this same line, there are several special purpose accounts, which are installed by default with most Linux distributions, for our purposes these accounts are useless and pose a security risk, so we will remove them using the userdel command. The syntax for this command is "userdel username", substituting username with the appropriate account name. The accounts we want to remove are; adm, lp, sync, shutdown, halt, news, uucp, operator, games, gopher, and ftp. We also want to remove the associated groups with groupdel, the syntax is the same. Groups to delete are; adm, lp, news, uucp, games, dip, pppusers, popusers, and slipusers.

Configuration files

This is without a doubt the most important section. Poorly-maintained configuration files are the highest risk factor on any system. In this section you will be typing many of the same commands over and over again, this is a good opportunity to write a shell script to make this easier. What we want to do, after we are finished with each file, is to first make sure it's owned by root; second, that the only account which can read and write to it is root; and third, that it's unalterable even by root. This keeps the files from being accidentally deleted or changed and also prevents the file from being linked to, which could be a security risk. Type "touch secure-it", then type "chmod +x secure-it", now Open the file in your text editor of choice and put these lines in: (text version)

#!/bin/sh

# Change owner to root
chown root.root $1

# Change permissions so only root has access
chmod 600 $1

# Make the file unalterable
chattr +i $1

Now save the file and copy it to /usr/sbin by typing "cp secure-it /usr/sbin". Now when we are finished with a file we can lock it down simply by typing "secure-it filename".

/etc/exports

This file tells the system which system on you network are allowed to mount NFS drives from this system. This file should be empty, if it is not, delete it with "rm /etc/exports" and create a new empty one with "touch /etc/exports". Now lock the file down by typing "secure-it /etc/exports".

/etc/inetd.conf

This where many of the TCP/IP services start. Since the only service we want is ssh--which is not started by inetd--this file should be empty as well. So remove it, "rm /etc/inetd.conf", create an empty one with "touch /etc/inetd.conf". Lock it down with "secure-it /etc/inetd.conf".

/etc/hosts.deny

This tells the system which systems to deny access to your system's TCP/IP services. We want to deny everybody not listed in /etc/hosts.allow everything, so we edit this file so the following lines are the only thing in it, then we want to lock it down.

ALL: ALL

/etc/hosts.allow

This file tells the system which other system may access the services started in inetd.conf, Since inetd.conf is empty, this file should be emty as well. Remove it with "rm /etc/hosts.allow", create an empty one with "touch /etc/hosts.allow", and lock it down with "secure-it /etc/hosts.allow"

/etc/rc.d/rc.local

The next thing we want to do is keep your system from giving away too much information about itself through attempted logons and ICMP packets. First, delete the /etc/issue and /etc/issue.net files from the system. Next open /etc/rc.d/rc.local in your text editor and remove the following lines;

echo "" > /etc/issue
echo "$R" >> /etc/issue
echo "Kernel $(uname -r) on $a $SMP$(uname -m)" >> /etc/issue
cp -f /etc/issue /etc/issue.net
echo >> /etc/issue 

Before you save and close the /etc/rc.d/rc.local file, we want to keep the system from responding to ICMP requests, such as ping and traceroute, so we add the following lines right after the #!/bin/sh line:

echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all
echo 1 > /proc/sys/net/ipv4/tcp_syncookies

This will make your system all but invisible to the outside world; the Script Kiddies can't crack what they can't find. The second line helps protect your system from SYN Denial of Service Attacks. Go ahead and save the file and exit. Please note, this will also keep you from pinging the system, but should not interfere with other functions, such as ssh or IP forwarding. Finally, lock it down.

/etc/hosts.conf

While we are setting up defenses against outside attacks, we should add as the last line in /etc/host.conf the following;

nospoof on

This will cause the system to reject any requests coming from a source outside your network, claiming to be a system on the inside of your LAN, this type of a attack is called IP Spoofing. Go ahead and lock it down with secure-it. Other files we don't need to alter, but need to be locked down are, /etc/services, /etc/passwd, /etc/shadow, /etc/group and /etc/gshadow. If you plan to change your passwd or add a user you will have to run "chattr -i filename" on /etc/passwd, /etc/shadow, /etc/group and /etc/gshadow or you will get an error message.

/etc/fstab

This is where the system gets information about what drives and partitions should be mounted at bootup and where. If you configured your system with one large root partition or you did not setup a separate partition for /home and /tmp, you can skip this section and go on to setiing up disk quotas. /home and /tmp are important areas because they can be written to by users other than root. What we want to do is limit what a user can do on these partitions. In /home, we do not want the user to be able to create an SUID program or a device, additionally in /tmp we don't want any programs to be able to execute. We do this by changing the /etc/fstab. Mine looks like this and likely yours is similar.

/dev/hda1      /              ext2      defaults        1 1
/dev/hda1      /boot          ext2      defaults        1 2
/dev/cdrom     /mnt/cdrom     iso9660   noauto,owner,ro 0 0
/dev/hda5      /home          ext2      defaults        1 2
/dev/hda6      /tmp           ext2      defaults        1 2
/dev/sda1      /usr           ext2      defaults        1 2
/dev/hda7      /var           ext2      defaults        1 2
/dev/hda8      swap           swap      defaults        0 0
/dev/fd0       /mnt/floppy    msdos     noauto,owner    0 0
none           /proc          proc      defaults        0 0
none           /dev/pts       devpts    gid=5,mode=620  0 0

We want to change the /home and /tmp lines to read as follows:

/dev/hda5      /home          ext2        rw,nosuid,nodev 1 2
/dev/hda6      /tmp           ext2 rw,nosuid,nodev,noexec 1 2

Disk Quota

If you setup a seperate partition for /home, this step is optional. If, instead, you setup your hard drive as one large partition, you should use the disk quota system, this will limit the amount of drive space a user can consume and prevent an intruder who has stolen the account from filling up your hard drive. The default line in /etc/fstab will look something like this.

/dev/hda1      /              ext2      defaults        1 1

Change it to this,

/dev/hda9      /              ext2  defaults,usrquota   1 1

Add the following lines to /etc/rc.d/rc.local

/sbin/quotacheck -avug
/sbin/quotaon -avug

now type "touch /quota.user" and then "chmod 700 /quota.user" and reboot the system. There may have some error messages about quota; ignore them. Once the system is back up, you will need to set the quota for, what should be the only user account, type the following command, replacing "username" the the name of your user account, type "edquota -u username". This should bring up the vi text editor showing something similar to this.

Quotas for user username:
/dev/hda1: blocks in use: 7, limits (soft = 0, hard = 0)
    inodes in use: 6, limits (soft = 0, hard = 0)

By setting a block limit, you are limiting how much drive space the user can consume in KB, by setting the inodes you will be limiting the amount of files the user can have. Soft limits when exceeded will warn the user, hard limits are absolute. Unless you have a very good reason to set them higher, such as you plan on transfering MP3's to this machine, I suggest setting the limits fairly low, something like 10 MB of disk space and 100 files. Edit the lines so they look like like this, then save the file and exit.

Quotas for user username:
/dev/hda1: blocks in use: 7, limits (soft = 5120, hard = 10240)
    inodes in use: 6, limits (soft = 50, hard = 100)

This will set a soft limit of 50 files taking up 5 MB and an absolute limit of 100 files consuming 10 MB of drive space.

/etc/rc.d/init.d/*

Next we want to make sure all the startup scripts in /etc/rc.d/init.d have the proper permissions set, so type the following command, "chmod -R 700 /etc/rc.d/init.d/*".

SUID Programs

We must find all the SUID files on the system. These are programs which take on the identity of root when they are executed, this is a very large security risk. This makes these programs targets for buffer overflow attacks and replacement with Trojans. To find all the SUID programs on the system type "ls -alF `find / -perm -4000` > /root/suid.txt". Now open the suid.txt file and the output should look something like this.

-rwsr-xr-x 1 root root 35168 Sep 22 23:35 /usr/bin/chage
-rwsr-xr-x 1 root root 36756 Sep 22 23:35 /usr/bin/gpasswd
-r-xr-sr-x 1 root tty 6788 Sep 6 18:17 /usr/bin/wall
-rwsr-xr-x 1 root root 33152 Aug 16 16:35 /usr/bin/at
-rwxr-sr-x 1 root man 34656 Sep 13 20:26 /usr/bin/man
-r-s--x--x 1 root root 22312 Sep 25 11:52 /usr/bin/passwd
-rws--x--x 2 root root 518140 Aug 30 23:12 /usr/bin/suidperl
-rws--x--x 2 root root 518140 Aug 30 23:12 /usr/bin/sperl5.00503
-rwxr-sr-x 1 root slocate 24744 Sep 20 10:29 /usr/bin/slocate
-rws--x--x 1 root root 14024 Sep 9 01:01 /usr/bin/chfn
-rws--x--x 1 root root 13768 Sep 9 01:01 /usr/bin/chsh
-rws--x--x 1 root root 5576 Sep 9 01:01 /usr/bin/newgrp
-rwxr-sr-x 1 root tty 8328 Sep 9 01:01 /usr/bin/write
-rwsr-xr-x 1 root root 21816 Sep 10 16:03 /usr/bin/crontab
-rwsr-xr-x 1 root root 5896 Nov 23 21:59 /usr/sbin/usernetctl
-rwsr-xr-x 1 root bin 16488 Jul 2 10:21 /usr/sbin/traceroute
-rwxr-sr-x 1 root utmp 6096 Sep 13 20:11 /usr/sbin/utempter
-rwsr-xr-x 1 root root 14124 Aug 17 22:31 /bin/su
-rwsr-xr-x 1 root root 53620 Sep 13 20:26 /bin/mount
-rwsr-xr-x 1 root root 26700 Sep 13 20:26 /bin/umount
-rwsr-xr-x 1 root root 18228 Sep 10 16:04 /bin/ping
-rwxr-sr-x 1 root root 3860 Nov 23 21:59 /sbin/netreport
-r-sr-xr-x 1 root root 26309 Oct 11 20:48 /sbin/pwdb_chkpwd

As you can see right hand side shows the permissions of each file: anything with an "s" in it has its SUID bit set. By disabling SUID bit, only root will be able to run the program. What needs to be done now is decide which ones can have the SUID bit safely turned off--many of these programs require it for normal operations. Many, however, should be run only by root anyway. How you turn the SUID bit off is with the following command:"chmod a-s filename". My suggestions for this step are; /usr/bin/chage, /usr/bin/gpasswd, /usr/bin/wall, /usr/bin/chfn, /usr/bin/chsh, /usr/bin/newgrp, /usr/bin/write, /usr/sbin/usernetctl, /usr/sbin/traceroute, /bin/mount, /bin/umount, /bin/ping, and /sbin/netreport.

Checking system integrity

The last thing you want to do is setup your system to warn you of any changes to your system. If any intruders do get in and plant a Trojan or create a new account, we want the system to be able to tell what was altered. There are several good programs available for this, the easiest to implement that I've found is fcheck, which can be downloaded from, http://sites.netscape.net/fcheck/fcheck.html. Follow the instructions for installing and configuring the software, it is very straight forward. Once this is done, you will want it to run at least once a day and redirect the results to a file in the root directory. This can be done through crond, to setup a cron job, type "crontab -e" this will open vi, now type the following line:

1 0 * * * /usr/local/fcheck/fcheck -a > /root/fcheck.txt

Finished

It is relatively safe to put the system on the internet. Once this is done you will want to test your security. Gibson Research Corporation provides a port scanning service. In a perfect world, all the ports should be in stealth mode, meaning the ports do not respond to requests at all and will appear as though there is no system at your IP address. In a pinch the ports should be closed, meaning the port responds, but will not take requests; closed ports are still vulnerable to some types of attacks. Open ports are vulnerable ports, if any of your ports are open go back to the inetd.conf file, make sure it is empty, check to make sure apache, wu-ftpd or similar are not installed, also review your ipchains settings to ensure it is denying packets properly. It is a good idea to do this regularly to ensure an intruder has not opened a port for his personal use.

Again, as with my last article, I'd like to point out, this is not the end-all and be-all of Linux security, this is only a starting point. I have simplified this down to the very basics, there are many more things which could be done. Whether or not you should seek out these solutions, depends on what you are protecting. For a home user this will probably do just fine, however even a small business with more machines and data to protect, you should do more research and implement as much security as is possible. Better yet, hire a Network Security Consultant to implement it for you.

Copyright © 2000, Chris Stoddard
Published in Issue 55 of Linux Gazette, July 2000

"Linux Gazette...making Linux just a little more fun!"

Scope

In this series of articles I intend to explore the varying implementations of strings in languages that are common on the Linux platform. The first article will explore the regular expression library provided with GNU libc. In future articles I hope to look at other common libraries and languages - hashing functions in Java and strings in KDE versus string in Gnome.

Each language has its strengths and its weaknesses. I hope that by doing a little grunt work on your behalf, I'll be able to give you a brief overview of the abilities and weaknesses of the common languages and their libraries with respect to string handling.

I won't be talking about internationalization and localisation in this series of articles, since those subjects are worthy of volumes of study - not a short summary.

The Gnu C Library and Regular Expressions

The GNU C library is the most basic system element on any Linux installation from a programmer's perspective. Most higher level libraries are based on libc, and most of what we think of as the "C language" are really functions in libc.

Strings in C are just null terminated arrays of chars or wide chars. This is the simplest and most efficient implementation of strings in terms of computer resources, but probably the trickiest and least efficient implementation in terms of programmer resources. Since strings are either constants (ie literals) or pointers, the programmer has the power to manipulate the strings down to the bit level and has all kinds of opportunities to optimise their code (for example this snippet). On the other hand, null termination of strings and the absence of in-built length checking mean that problems such as infinite loops and buffer-overflows are inevitably going to appear in code.

The GNU C library is rich in string manipulation functions. There are standard calls to copy, move, concatenate, compare and find the length of a string (or a section of memory). In addition to these, libc also supports tokenization and regular expression searches.

Regular expressions are a powerful method for searching for text that matches a particular pattern. Most users will have first encountered the idea of regular expressions while using the command line, where characters such as '*' have a special meaning (in this case, matching zero or more characters). To illustrate the power of regular expressions and how they are used, we will implement a simple form of grep.

Mygrep.c

Mygrep.c uses the powerful regex.h library for the task of searching through a text file for a line that matches the given pattern.

        bash> ./mygrep -f mygrep.c -p int Line 17: int
        match_patterns(regex_t *r, FILE *FH) Line 36: printf("Line %d:
        %s", line_no, line); Line 52: printf("In error\n");
        bash>

Libc makes the use of regular expressions comparitively easy. Of course, it would be much easier to use a language with regular expression matching as part of its core definition (such as perl) for this example, but the C library does have the advantage of easy integration with existing code and maybe speed (although in languages such as perl the regular expression matching is highly optimised).

If you examine the program listing, you will see that mygrep.c consists of a main function that handles the user options and two functions that perform the actual regular expression matching. The first of these functions, logically, is the function do_regex(). This function takes in as its parameters a pointer to a regular expression structure, a string holding the pattern to search for and a string holding the filename. The first task that do_regex() performs is to "compile" the regular expression pattern into the format native to the GNU library by calling regcomp(). This format is a data structure optimised for pattern matching, the details of which are hidden from the user. Next, the file to be scanned is opened, then the file handle and the compiled regular expression are passed to match_patterns() to execute the search and output the results.

Match_patterns() scans through each line of the file, looking for patterns that match the regular expression. We begin scanning the lines one by one - note that we have assumed that the lines are less than 1023 bytes long (the array called "line" is 1024 bytes long and we need one byte for the null termination). If the input is more than 1023 bytes long, then the line is wrapped over and interpreted as a new line until the '\n' character is met. The function regexec() scans the line for a set of characters that match the user specified pattern. Every set of characters that matches the regular expression forces regexec() to return 0, at which point we print out the line and the line number that match. If a regular expression matches more than once, then the line is printed out more than once. The offset from the beginning of the line is updated so that we do not match on the same pattern again.

This example, while fairly trivial, illustrates how powerful the GNU C library can be. Some of the more salient features of the library that we have used include:

• The ability to automagically handle extremely long lines.
• Optimised data structures for particular functions.
• Standard, portable error handling.
• Standard, portable handling of command line options.

Copyright © 2000, Ben Tindale
Published in Issue 55 of Linux Gazette, July 2000

"Linux Gazette...making Linux just a little more fun!"

Snazzy title, eh? Well, not snazzy, but informative. As it suggests, this article (or tutorial, if you will) is all about OOP in the computer language C++. Okay, let's get to the intros. The name's Williams, Mike Williams. My mission? To teach novice programmers, such as yourselves about the art of programming. Through the months, I'm hoping to take you through a variety of programming techniques, starting right here, right now with C++. Are you sitting comfortably? Then I shall begin....

So what is OOP?

OOP is undoubtedly one of the most complex programming techniques to explain. In fact, it's not so much a 'technique' rather than a whole new method of looking at programming itself. There are entire books on the subject, and it's well beyond the scope of this article to introduce you to every philosophy and implication of OOP. To understand OOP, you must first understand what programming was like before OOP.

Back then, the basic definition of programming was this : a program is a sequence of logical instructions followed by the computer. And that's it. All well and good, but let's face it, it's hardly inspiring. Until now, that is. It's been hiding in the background for quite some time now, but OOP has finally taken off. In an OO programming language, the emphasis is placed far more on the data, or the 'objects' used and how the programmer manipulates them. Before OOP, numbers were simply an address in memory; a sequence of bytes that meant nothing. Now, however, through OOP they have become far more than that. The program is now a solution to whatever problem it is you have, but now it is done in the terms of the objects that define that problem, and using functions that work with those objects. Confused? Don't worry, you won't need to understand OOP to use it within your programs. Indeed, the best way to learn what OOP is all about is through using it in your programming.

What you'll need and who this is for

All the examples within this article can be compiled in the GNU C++ compiler. To invoke it, type:

g++ <filename>

at the BASH prompt. I'm assuming that you have a reasonably up to date compiler, although it shouldn't make too much of a difference if you don't. Oh, and by the way, you can't use the GNU C compiler - it won't work (just thought I'd mention that.) You will, of course, need a text editor. 'Emacs' is a very powerful editor, and I suggest you use that.

This article is aimed at people who already have a reasonably understanding of the C++ language, but want to further that understanding by learning about OOP in C++. If you're a complete beginner, I suggest you read one of the hundreds of C++ tutorials lying around on the internet. A good place to start would be http://www.programmingtutorials.com/.Good luck.

A Historical Interlude

Hundreds of years ago, in Britain (specifically England), there was civil unrest. People were angry - the poor people to be more specific. They noticed that some people were richer than them, they did not like it. What to do about this problem? How to keep the people happy? Religion had already gone some of the way, but even the promise of eternal utopia if the poor behaved themselves in life didn't seem to work. Capitalism already had sunk its powerful jaws into the world, and a new idea was needed to keep the masses happy. That idea became known as 'class'. The basis was that if everyone understood their place and role in society, they would feel secure and happy, and would not challenge the authority. It worked. There was the upper class (who were rich), the middle class (who were not so rich), and the poor sods class (who could barely afford to live). Quite unfair, but nevertheless it became reality. What has this got to do with C++ you ask? Well in C++, all Object Orientation comes in the form of classes. But enough of that; we're programmers, not social scientists.

Data types

Up to this point in your use of C++, you've used only the basic types of variables : int, float, bool, double, and so forth. These are called simple data types. However, they are very linear in what we can 'model' with them. Let's take an example. Let's say we wanted to represent a real life object, say a house. Obviously, we would have to examine the various attributes of a house : the number of rooms it has, its street number and whether or not it has a garden (okay, so there are more attributes, but I won't go into them now). In C++, we could show the house like this:

int number, rooms;
bool garden;

And it would work fine for this particular example. But suppose we wanted many houses? Suppose we wanted to make the program more complicated than this? Suppose we wanted to define our own data type to represent the house. C++ allows us to do this through the use of classes.

Classy!

Continuing with our example of the house, let's have a look at how we could 'model' a house using a C++ class:

class house
{
public:
    int number, rooms; 
        bool garden;
};

main()
{
        house my_house;
        my_house.number=40; 
        my_house.rooms=8;
        my_house.garden=1;
        return 0;
}

Let's take a look at what each line does. The second line declares a new class and calls it 'house'. We then open the class definition with the curly brace '{'. The next line declares that all the 'members' (any data type that belongs to the class) that follow it to be 'public (I'll explain what this means later). We then go onto declare two variables of the basic type 'int' (integer). The next statement declares the garden member to be of type bool (booleon- either a 1 or a 0). Finally, we end the class with closing curly brace '}' and a ;. We have now declared a new data type or class called 'house', which we can use within our program. To use it, we start the main() function, which is where the execution of the program begins and ends. The first thing we do in the function is to declare the variable my_house to be of type house, which is the class we defined at the beginning of the program. Now, we this variable gains new dimensions; it now has many more attributes than a simply int or float type. From our class definition, we gave the house class three variables : number, rooms and garden. The variable we just declared, my_house, has all of these attributes. In the second line of our main function, we define the number member of the object my_house to be of value 40. We then go onto define the values for the other three data members of my_house, before ending the function with the return value 0.

At this point, you're sitting there wondering what the big fuss is about these classes. After all, wouldn't it be simpler to use the non-OO method? Well, it would in this particular instance, since we're only talking about a very small program that does very little. However, once you start to write more and more complicated programs, you will find not only that classes are useful, but that they are essential.

Member Functions

It's all well and good being able to declare a some variables, but how do we make use of them? The answer comes of course in functions. In C++, classes can have member functions. These are declared in a similar fashion to member variables. To illustrate how they work, let's take an example. A square perhaps. First we must model the data based on the attributes of a square. It has a length, a width, and of course an area. Of course, you find the area of a square by multiplying the length by the width. To do this, we could use a member function:

class square
{
public:
        int length, width;
        int area()
        {
                return length*width;
        }
};

main()
{
        square my_square;
        my_square.length=5;
        my_square.width=2;
        cout<<my_square.area();
        return 0;
}

This example should output the number 10. The square class is very similar to the house class we saw earlier. Firstly, we declare two member variables of type int : length and width. We then go onto declare a function, area(), which will return a int value. You declare the function exactly as you would outside a class. In this case, we make area() return the value of the member variables length and width when multiplied. We then end the class, and start with the main function, which should pretty much explain itself.

Function Definitions Outside the Class Definition

Of course, if you had a lot of functions to put in the class, they would all become rather messy. To overcome this, we use something called the scope resolution operator. Let's say we wanted to declare the area() function outside of our original function definition. Firstly, we would declare the class square, and in it the function area, as shown above. However, we would not insert the function code in at this point, so the class definition would look like this:

class square
{
public:
        int length, width;
        int area();
};

To define the member function area() outside of the class defintion, we would write this:

int square::area()
{
        return length*width;
}

This would produce the same output.

Public or Private?

While we're on the subject of member function definitions, you should learn the difference between public and private members of a class. Members that are declared to be public can be accessed from any function within the entire program. The simplest way to explain is with an example. Suppose we declared the class square just like it was above, and tried to access the length variable from within the function main, which is not a member function of the class:

main()
{
        sqaure my_square;
        my_square.length=2;
        cout<<my_square.length;
        return 0;
}

The compiler would have no problem with this, and would output the value 2. However, let's say we change the square class so it looked like this, and all the members were private:

class square
{
private:
        int length, width;
        int area();
};

If we tried to run the function main() shown above, the compiler would generate an error. Private members can only be accessed through member functions.

Class Constructors

It gets a bit tedious declaring the value of each member variable of a class using the method shown below:

main()
{
        sqaure my_square;
        my_square.length=2
        my_square.width=3
}

For each member of mysquare, we have to seperately declare and initialize its value. Of course, not only is this tedious, but it's also easy to overlook the initialization of each member, particularly when your classes become more complex. One way around this is to use a class constructor. A class constructor is a function that is initialized whenever the class is used:

class square
{
public:
        int length, width;
        square(int length1, int width1)
        {
                length=length1;
                width=width1;
        }
        int area()
        {
                return length*width;
        }
};

main()
{
        square my_square(5, 2);
        cout<<my_square.area();
        return 0;
}
        

This would produce the output 10. Firstly, we declare the class constructor by giving it the same name as the class itself. >From now on, this function will execute itself whenever the class is used. We declare it so that it takes two values, both of type int. The next change comes in the function main(). Whenever we delcare an object to be of type square, we add a function definition. In this case, we gave the variables length1 and length2 the values 5 and 2. The constructor then takes these two variables, and assigns their values to the member variables length and width, and, as they say, the rest writes itself.

Arrays and Classes

It goes without saying that you can use arrays with classes. Obviously, this opens up scope for far declaring far more variables in a shorter time. There isn't a huge amount to go through on this subject, so let's take a simple example:

class person
{
public:
        int age, house_number;
};

main()
{
        person alex[5];
        for(int x(0); x<5; x++)
        {
                alex[x].age=x;
                alex[x].house_number=x;
                cout<<"Age is "<<alex[x].age<<endl
                        <<"House number is "<<alex[x].house_number<<endl;
        }
        return 0;
}

There's nothing really complicated within this example, so I won't go through it. Obviously, you can do a lot more with arrays, and it doesn't take a genius to work out other ways to use them.

In closing

Well that's all for this month. If I get a chance, next week I'll continue this very topic, and go further into OOP programming with C++ to look at ideas such as pointers, class desctructors, inheritance and organizing your program code into files. Happy programming!

Oh, and one more thang...

If you have any comments/criticisms/flames about this article [or life in general ] please send them to . I'll be more than happy to read them and respond, perhaps with childish name calling. Who knows.

Copyright © 2000, Michael Williams
Published in Issue 55 of Linux Gazette, July 2000

"Linux Gazette...making Linux just a little more fun!"

The Back Page

• About This Month's Authors
• Not Linux

Fernando Correa

Juan Ignacio Santos Florido

Bryan Henderson

Ben Okopnik

Martin Skjöldebrand

Chris Stoddard

Ben Tindale

Michael Williams

And now for something that's completely non-Linux.

My Ireland/UK trip was a blast. Dublin's bridges remind me of St Petersburg, and the streets are bustling at all hours. I saw The Business (an oi band), and then went to a 3-day scooter rally in Carlow (a hundred miles SW). Neither of these events were planned--I just happened to be at the right place at the right time. In Belfast I took the black taxi tour of the political murals, bought a book about the history of the Troubles, and hooked up with the singer of another oi band, Runnin' Riot. Then I skipped across the water to Scotland.

Edinburgh is amazing! I've been in six countries in Europe, but have seen no city that matches Edinburgh. There's a drained loch in the center of town, and next to it, high up on a hill, is the castle. I connected with an old friend and met several new ones. The four days I was in Edinburgh was not nearly enough.

Edinburgh also has a cybercafe that's open 24 hours, costs only 1 pound for 2-4 hours, and any minutes you don't use can be applied later using their anonymous logins. Plus it has five hundred PCs with LCD screens. I wouldn't mind seeing more cybercafes like that. But it must've cost the owner a bundle.

Then I spent a night each in Manchester and Cambridge, and five days in London. I'd been in London once before, so I knew what to expect. Still, the city was a bit big for me, and hard to get a handle on. I spent some time in Camden Town, took a picture of the Elephant & Castle statue , bought lots of clothes at The Merc and Lonsdale stores (cause you can't get that stuff in the States, at least not in the Northwest), and my two friends from Edinburgh and Cambridge came down one evening. Then I flew back to Vancouver and caught the train to Seattle. Just in time to begin the July Linux Gazette!

Michael Orr
Editor, Linux Gazette,

This page written and maintained by the Editor of the Linux Gazette.
Copyright © 2000,
Published in Issue 55 of Linux Gazette, July 2000