Multiple source IP addresses from one server

Some applications (like irssi) let you bind to a certain source address. Others are hard coded to always use the default interface (which is usually the interface closest to the exit point in the routing table (if your default gateway is an address on the same network as eth0, the default would be to bind to eth0)).

wget(1) has a –bind-address option, that I think does what you're saying.

Yup, exactly what I need. I just discovered netcat's -s option, which I think should work wonders.

Edit: also, seems PHP's socket_bind() should work and not require running an external program.

if you're using curl to query something: (in php at least)

curlsetopt($ch, CURLOPTINTERFACE, $ip);

Thanks, Esoterik, that'll be even easier not to have to deal with raw sockets. Good thing I've been lazy and haven't started coding this yet. :)