Loading Network Drivers

The first step in configuring a network card is to load the appropriate drivers. As described in Chapter 1, Kernel Network Configuration, drivers may reside on your system in one of two forms: as an integral part of your Linux kernel, or as separate kernel module files. In the first case, the task of loading network drivers is easy, because it's done when the kernel loads. For some cards, though, you may need to pass parameters to the driver via kernel boot options. If you use LILO, these can be passed with an append option in /etc/lilo.conf . For instance, the following /etc/lilo.conf line, as part of a kernel definition, tells the kernel to look for the eth0 device (the first Ethernet card) at I/O port 0x240:

 append="ether=0,0,0x240,eth0" 

You can include several options within the quotes after append= by separating them with spaces. You can use this trick to force a particular Ethernet card to link itself to a particular network card on a multi-interface system by identifying the I/O port used by a specific card. In most cases, you won't need to pass any options to a driver built into the kernel; the driver should detect the network card and make it available without further intervention, although you must still activate it in some other way.

If your network card drivers are compiled as modules, you can pass them parameters via the /etc/modules.conf file (which is called /etc/conf.modules on some older distributions). For instance, this file might contain lines like the following:

 alias eth0 ne options ne io=0x240 

This pair of lines tells the system to use the ne driver module for eth0 , and to look for the board on I/O port 0x240. In most cases, such configurations will be unnecessary, but you may need to make the link explicit in some situations. This is especially true if your system has multiple network interfaces. The GUI configuration tools provided by many distributions can help automate this process; you need only select a particular model of card or driver from a list, and the GUI tools make the appropriate /etc/modules.conf entries.

When you've created an entry in /etc/modules.conf , Linux will attempt to load the network drivers automatically whenever it detects an attempt to start up a network interface. If you should need to do this manually for any reason, you may use the insmod command to do the job:

 #  insmod ne  

This command will load the ne module, making it available for use. If kernel module auto-loading doesn't work reliably, you can force the issue by placing such a command in a startup script such as /etc/rc.d/rc.local or /etc/rc.d/boot.local .

If your connection uses PPP, SLIP, or some other software protocol for communicating over serial, parallel, or other traditionally nonnetwork ports, you must load the drivers for the port itself and for the software protocol in question. You do this in the same way you load drivers for a network card ”by building the code into the kernel file proper or by placing it in a module and loading the module. In most cases, you'll need to attend to at least two drivers: one for the low-level hardware and another for the network protocol. Sometimes one or both of these will require additional drivers. For instance, a USB modem may require you to load two or three drivers to access the modem.