2 NICs

**elovkoff** · 03-01-2002, 12:06 PM

I've got 2 nics on the rh7.2. First nic is ip-less, no ip bound to nic, second has ip address.
System ALWAYS tries to ping from the first nic - and never oings cause there is no ip. The funny thing is that when it pings from the first nic and doesn't succeed it doesn't cut over to the second nic to try to ping from there.
When I revert the configuration and make first nic with ip and second without ip , then everything works fine and ping works.
(i gotta have one nic with no ip for sniffing packets)
Any ideas system doesn't try the second nic for pinging?

**Feztaa** · 03-02-2002, 11:49 AM

The funny thing is that when it pings from the first nic and doesn't succeed it doesn't cut over to the second nic to try to ping from there.

That's not funny at all. If you never told it to use that nic, it won't ever use it.

When I revert the configuration and make first nic with ip and second without ip , then everything works fine and ping works.
(i gotta have one nic with no ip for sniffing packets)
Any ideas system doesn't try the second nic for pinging?

Is ping the only program that is having trouble? I think what you want to do is set up your routing tables to have all traffic go through the second nic with the ip by default. Try 'man route' to see what that's about. You might also look into iptables, but I doubt that's what you're looking for...

**Compunuts** · 03-02-2002, 05:08 PM

System ALWAYS tries to ping from the first nic - and never oings cause there is no ip. The funny thing is that when it pings from the first nic and doesn't succeed it doesn't cut over to the second nic to try to ping from there.

Like Feztaa said, it's not funny at all...

What Linux ( any system for that matter ) will quit if the first try is unsuccessful. If it does, then you will have a system which try to use every available resource even though the first one is working right. And there is eth0 and eth1 for a reason called prioritizing.... It doesn't matter how your hardware are sitting in, you can have your system use the one you specify as a priority over another thus setting up as which one use eth0 and which one is eth1. As long as you abide by that rule, you will have no problem at all.

**elovkoff** · 03-02-2002, 09:10 PM

Is ping the only program that is having trouble? I think what you want to do is set up your routing tables to have all traffic go through the second nic with the ip by default. Try 'man route' to see what that's about. You might also look into iptables, but I doubt that's what you're looking for...
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First nic doesn't have ip, it is only brought up using 'ifup eth0' during the startup from rc3.d - I don't think routing is possible between two nics when one of them is ip-less. Am I wrong here?