I'm not a Linux expert, but here is how to see if your NIC (network interface card) is detected and working. This example is from Red Hat 7.0 installed on a Pentium 3 machine with one NIC, and the NIC is labeled eth0 on the system.  (newer versions probably have prettier GUI's and better tools) In X-Windows, open an xterm window and, as root user, enter the following command:

$ /sbin/ifconfig

You should see  this:

etho     Link encap:Ethernet   HWaddr  00:50:56:85:00:23
           inet  addr:192.168.0.135  Bcast:192.168.0.255  Mask:255.255.255.0
           UP LOOPBACK RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:50 error:0 dropped:0 overruns:0 frame:0
           TX packets:0 error:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           Interrupt:9 Base address:0x1000

lo         Link encap:Local Loopback
           inet addr:127.0.0.1  Mask:255.0.0.0
           UP LOOPBACK RUNNING  MTU:16436  Metric:1
           RX packets:6 error:0 dropped:0 overruns:0 frame:0
           TX packets:6 error:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0 

If you don't see the eth0 line, then Linux did not recognize your NIC, or it is not enabled.  Check if the NIC is enabled by entering this command:

$ ifconfig eth0   -- (you can also try: $ ifconfig eth0 up) -- where eth0 is the name of your NIC.

You should see something similar to this outputted:

eth0        Link encap:Ethernet    HWaddr  00:A0:CC:24:BA:02

              inet addr:192.168.203.2  Bcast:192.168.203.255
                Mask:255.255.255.0

              UP BROADCAST RUNNING  MT:1500  Metric:1 .....

If you don't see the "inet addr..." and "Bcast:..." IP numbers then you need to install a NIC that is supported by your version of Linux (the easiest route for newbies...but costs a few dollars if you don't have one), or go to your NIC's manufacturer's website (or other driver sites) and see if they have a driver for your NIC and version of Linux.

(To see which version of Red Hat supports which NIC'S, check here)

You need to know the make/model of your installed NIC, so you can check to see if there is a driver loaded for it.  Open an xterm window, and as root user, enter the following command:

$ linuxconf-auth

You should see this:

(If you need to install a driver, HERE is a generic text file describing the process for a 3com NIC driver install)

[more instructions coming soon...under construction...]

Sample Views Of Red Hat Network Configurator GUI Tool:

To use this tool (in X-Windows), start an xterm window and, as root user, type the following command:

  $ netcfg

This is what you should see:

The "Names" button displayed:

The "Hosts" button displayed:

The "Interfaces" button displayed:

The "Routing" button displayed: