Problem networking linux

[awakening]

Hey guys here is what i have done...i recently purchased a Dlink DFE-530TX nic to add to my integrated one in my dell poweredge server running linux. What i want to do is allow the internet connection from my broadband modem to come in one nic and share that connection with a switch and other computers out of the second nic. Both nic's can be used to access the internet fine on my server but it will not allow me to activate the other network interface if one is on. i.e. if broadband is coming in one of my nics and ETH0 is active it will not allow me to activate ETH1 to share my conection with the rest of my network.

Heres a diagram
___________________________Debian Linux Server_____________
Internet----Broadband Modem----[Nic 1]-[Nic-2]----switch----pc1,pc2,pc3

i can use nic 1 and 2 individually to connect to the internet but i cannot share my connection. Any help at all is greatly appreciated and i thank you for being a troubleshooter and helping with my issue here.

[awakening]

Hiello, its me again. Does anyone know what to do in the above situation to fix it? Thanks a lot guys!

[paleadin]

hello I'm a newbee but I think you need ipchains to do the ip masquerade
not much help but its a place to start
if you are just wanting a firewall machine look at coyotee it boots from a floppy (no HD required) and has minimal sys req and even has a winbloz configuration gui. I don't remember if it does ip masq

[TruthSeeker]

Not sure but I think you need to take a look at the "bridge-utils" package...

man brctl

[smolloy]

I had a similar problem that was solved on this thread.