I have just installed Debian. Never before used it. Only to find that there is no network device files. i.e eth0.

Do ethernet devices go by another name in Debian or is something wrong?

They go by the ethX naming. Did you configure the network during install, or install straight from cd? If the latter, edit the file /etc/network/interfaces then bring the device up with ifup (or dhclient). Is the card detected by lspci -v?

I have done the following:

1. Run lspci -v: It said the following.
   
   Code:

   00:13.0 Ethernet controller: Silicon Integrated Systems [SiS] SiS900 10/100 Ethernet (rev 02)
       Subsytem: Silicon Integrated Systems [SiS] SiS900 10/100 Ethernet Adapter
       Flags: bus master, medium devsel, latency 64, IRQ 12
       I/O ports at e400 [size=256]
       Memory ay e8000000 (32 bit, non-prefetchable) [size=4k]
       Expansion ROM at e7000000 [disabled] [size=128k]
       Capabilities: [40] Power MAnagement version 2

   I'll assume that means that it can see it.
2. I checked the /dev/ directory. It contains no ethXX device files.
3. I edited the interfaces file to the following:
   
   Code:

   auto lo, eth0
   
   iface lo inet loopback
   iface eth0 inet dhcp

   For obvious resons it did not work, as there is no device file called eth0.

I did install straight from the CD. I do not understand why installing the server distro of debian, network support isn't included by default.

Networking support is included by default you are however expected to configure the system to load the proper modules if it is not already built into the kernel. Try this as root in a console or console window modprobe sis900 if the module loads correctly then /etc/init.d/networking restart this will restart the networking and now that the module was loaded it should be able to get the DHCP lease from whatever server you have that gives you your IP. You may want to check in your /etc/resolv.conf and make sure that you have at least one nameserver in there or you will not be able to resolve internet addresses. To make the change permanent edit the file /etc/modules as root and put the sis900 module name on a line by itself and it will be loaded at boot. BTW what does uname -a say you are running for a kernel if this does not work.

On using modprobe it said it was unable to locate the module. I'm assuming this means I need to obtain the source for the Sis900 driver and compile it into the kernel?

Yes if it is available for the 2.2 kernel that you must be running in my firewall's old kernel config which was using the 2.4.18-bf2.4 kernel which would have been installed if you used that option the module is compiled into the kernel so you should be able to use your network card if you are running that kernel so what does uname -a in a console window tell you?
You should be able to install a 2.4.18 kernel from the CD(s) that you have and get the required support for the card.

Thanks for the all the help. I have compiled the latest kernel 2.4.23 and made sure I included the SiS900 support. After a bit of tweaking I have got it working - for the moment though I have had to set the interfaces file up as follows:
Unfortunatly using the dhcp option causes them not to work - the dhcp server does not give them ip addresses.

Again, thanks for all the help. Debian is very different from RedHat :s so I might need some more guidance.