A Tour of Network Devices

The kernel supports a number of hardware drivers for various types of equipment. This section gives a short overview of the driver families available, and the interface names used for them.

There are a number of standard names for interfaces in , which are listed below. Most drivers support more than one interface, in which case the interfaces are numbered, as in eth0, eth1, etc.

lo

The local loopback interface. It is used for testing pur- poses, as well as a couple of network applications. It works like a closed circuit in that any datagram written to it will be immediately returned to the host's networking layer. There's always one loopback device present in the kernel, and there's little sense in having fewer or more.

ethn

The n-th Ethernet card. This is the generic interface name for most Ethernet boards.

dln

These interfaces access a D-Link DE-600 pocket adapter, another Ethernet device. It is a little special in that the DE-600 is driven through a parallel port.

sln

The n-th SLIP interface. SLIP interfaces are associated with serial lines in the order in which they are allocated for SLIP; i.e., the first serial line being configured for SLIP becomes sl0, etc. The kernel supports up to four SLIP inter- faces.

pppn

The n-th PPP interface. Just like SLIP interfaces, a PPP interface is associated with a serial line once it is con- verted to PPP mode. At the moment, up to four interfaces are supported.

plipn

The n-th PLIP interface. PLIP transports IP datagrams over parallel lines. Up to three PLIP interfaces are supported. They are allocated by the PLIP driver at system boot time and are mapped onto parallel ports.

During the following sections, we will discuss the details of using the drivers described above.