Hi, I'm quite new to Linux networking. I'm setting a machine RedHat 9.1 to work as firewall and gateway to ADSL and LAN connection. The trouble is: if ADSL is up, LAN doesn't work and viceversa. ADSL uses eth0 (a fictitious ethernet card created by modem driver) and LAN using eth1 (a 3Com ethernet card). This is the message I get from command "ifconfig" when ADSL is up:

eth0 Link encap:Ethernet HWaddr 00:30:DA:1E:20:58
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1265 errors:0 dropped:0 overruns:0 frame:0
TX packets:1439 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:332817 (325.0 Kb) TX bytes:142528 (139.1 Kb)

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:658 errors:0 dropped:0 overruns:0 frame:0
TX packets:658 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:68256 (66.6 Kb) TX bytes:68256 (66.6 Kb)

ppp0 Link encap:Point-to-Point Protocol
inet addr:81.36.72.162 P-t-P:192.168.153.1 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1492 Metric:1
RX packets:373 errors:0 dropped:0 overruns:0 frame:0
TX packets:334 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:212728 (207.7 Kb) TX bytes:65067 (63.5 Kb)

Anyone can help to set eth1 as convinient to make ADSL and the LAN working simultaneously? Any little help is heartly welcome!

Do you have a USB DSL modem? No experience with one. However here are some ideas.

Since device ID's usually start at zero the OS might be trying to configure your NIC as eth0 too. What does the file /etc/modules.conf show for your NIC?

If it has an eth0 then change it to eth1. Not familar with the RH GUI tools but then configure eth1 for the local network. netconfig is a command line tool try:
netconfig eth1