CertiGuide to Network+  9  Chapter 0110: Network Operating Systems (NOS)       9  VI  Linux

Distributions 1 Linux (UNIX) File Permissions

One task that’s less user-transparent in most Linux distributions than it is in Microsoft Windows is system configuration – telling the NOS what hardware is connected to the system.

When it comes to making a NIC work in Linux, as with all operating systems, a driver (interface between the O/S and the network card) must be loaded. How that is done depends on the LINUX/UNIX flavor or distribution. The primary choice is, “is the driver being used as a loadable module or is it compiled directly into the kernel of the operating system?” Actually, it’s not much of a choice any more, as loadable kernel modules are the wave of the future. The old way of doing things was to compile the driver into the OS kernel, which had the down side of causing the OS not to recognize your NIC if it was an unusual one for which a driver wasn’t already included in the OS kernel.

Currently, most Linux offerings use loadable (modular) drivers, a technology similar to Windows DLL’s (dynamic link libraries), which is a more flexible alternative. Typically these loadable drivers are stored in the /lib/modules folder. In the case of PCI cards, the module usually will detect the NIC(s) installed automatically. In the case of older ISA cards, this cannot happen and details such as the Interrupt ReQuest (IRQ) and I/O base address must be supplied. This information is typically stored in the /etc/conf.modules file:

options ne io=0x240,0x300

(Unlike DOS the 0x MUST be in front of the I/O address).

If the kernel is an older version that is not capable of handling two cards on one option line, when looking in the /etc/conf.modules file, you may find data similar to:

alias eth0 ne (or some other cryptic NIC model label, I.E. 3c501)

alias eth1 ne

options eth0 –o ne io=0x280 irq=5

options eth1 –o ne io=0x320 irq=7

This example uses the –o option to give each module a unique name for each ISA card.

Distributions 1 Linux (UNIX) File Permissions