Red Hat Linux ships with very few drivers built into the kernel. Instead, most drivers, including Ethernet drivers, are provided in the form of dynamically loadable modules. When you set up networking during Red Hat Linux installation, the installation program adds appropriate entries to the text file /etc/modules.conf. These entries tell the modprobe command what modules to load. For Ethernet drivers, the important entries are lines that define the driver aliases eth0, eth1, and so on. If you have only one Ethernet card, the alias eth0 should be set to the name of the driver for your Ethernet card (refer to Table D-1 for a list of cards and their corresponding drivers).
For example, my PC has a 3Com 3C905C PCI Ethernet card. For this card, the installation program adds the following alias entry in the /etc/modules.conf file:
alias eth0 3c59x
For some older Ethernet cards, you may need another entry in the /etc/modules.conf file to specify various options, such as I/O port address and interrupt number (IRQ) for your Ethernet card. For example, the following line in /etc/modules.conf specifies an IRQ of 5 and an I/O port address of 0x300 (hexadecimal 300) for the 3Com 3C503 card:
options 3c503 irq=5 io=0x300
For PCI and EISA Ethernet cards, it is safe to let the driver probe for various parameters of the card. Consult the files in /usr/src/linux-2.4/Documentation/networking for the options various Ethernet driver modules accept.