Adding a network card to Linux

Last Updated on December 4, 2015 by Dave Farquhar

I said yesterday I didn’t remember exactly how to add a network card to Linux machines. I found instructions today. They weren’t entirely correct. So here are instructions (hopefully more correct–I have access to exactly one Linux box right now) for adding a NIC in Linux.
First, determine which module your NIC uses, then install it temporarily with the following:

insmod [module name]

For example:

insmod rtl8139

In RPM-based distributions (Red Hat, Mandrake, Caldera, TurboLinux, UnitedLinux), edit the file /etc/modules.conf or /etc/conf.modules to add an alias for the module. In Debian-based distributions, edit the file /etc/modutils/aliases and then run the command update-modules. In any case, the format of the line to add is the same:

alias eth0 rtl8139

More likely, you’re adding a second NIC, in which case the line would look more like this:

alias eth1 rtl8139

In RPM distros, next you create an interface config file in /etc/sysconfig/network-scripts. The file is called ifcfg-[interface]. Here are a couple of example ifcfg-eth0 files:

# Static IP
DEVICE=eth0
IPADDR=192.168.0.33
NETMASK=255.255.255.0
BROADCAST=255.255.255.255
ONBOOT=yes

# DHCP
DEVICE=eth0
BOOTPROT=dhcp
ONBOOT=yes

In Debian, all network configuration info is kept in /etc/network/interfaces. Here’s a sample configuration:

iface eth0 inet dhcp

iface eth1 inet static
address 192.168.1.1
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255

SuSE is likely to be a bit different. Slackware is virtually guaranteed to be different. I haven’t looked at SuSE in three years and Slackware in five. Hopefully they’re similar enough that this can give you a start.

I’m sure there’s a graphical way to do this in some, if not all distributions, but I prefer to hit the configuration files directly. It’s much easier to explain, and the knowledge is much more portable.

Dave Farquhar

David Farquhar is a computer security professional, entrepreneur, and author. He has written professionally about computers since 1991, so he was writing about retro computers when they were still new. He has been working in IT professionally since 1994 and has specialized in vulnerability management since 2013. He holds Security+ and CISSP certifications. Today he blogs five times a week, mostly about retro computers and retro gaming covering the time period from 1975 to 2000.