Anyone know how to load balance outbound web traffic across multiple nics on a linux server? Each nic would be attached to the same switch and network connection; the goal is to increase bandwidth capacity in case of dos attack and to provide nic redundancy. Thanks.

Apache automatically listens on all available IP addresses (so network interfaces), unless configured not to.

In truth, you are very unlikely to get any benefit at all from multiple NICs, especially if one is part of the mainboard. The chances of just the NIC failing on it's own are very low (none if a NIC is part of the mainboard). You are unlikely to be able to saturate a 100 Mbps interface unless it serves very large files and/or has very large numbers of simultaneous connections. All NICs are attached to the same (PCI) bus on a standard system, as well.

I think that the better solution to the issues you're mentioned are to have multiple boxes and use a round-robin DNS entry to split the traffic between them. The base line spec for Web serving is literally a 486, so the boxes can be as big or small as you like. A simple script can keep the files on multiple servers identical.

you could do ether-channel (channel-bonding)

as for round robin dns... to slow

I had posted a method to get perfect load balancing on another forum a while back. You might find it useful
http://forums.fedoraforum.org/showthread.php?p=835704

To use some specific iptables features, you may have to re-compile it. This link will help
http://mndar.phpnet.us/tutorials/Lin...s_goodies.html

Any clues whether Linux supports multichassis bonding?

Check out this book:
Linux Enterprise Cluster

http://www.amazon.com/Linux-Enterpri...2565376&sr=8-1

You could accomplished that by having a cluster. A cluster is not replacement for bandwidth though , instead it will enable to have failover and to load balance traffic among several linux boxes.

Good luck.
Angel