IP Networking

In a college's internet laboratory:

1. Network has 2 different ISP net-connections.
2. I want the both net-connections to be available to all clients.
3. My Linux-server has 3 LAN cards:
eth0 : connected to ISP1
eth1 : connected to ISP2
eth2 : I want to to circulate internet received in eth0 & eth1 to my intranet.
HOW CAN I DO?
4. I do not know how to combine 2 ISP connections into one.

It's up to your routing table. /sbin/route -n

It's easy to have both available, but probably only the first one in the routing table will get used if they're both considered catchalls since it has to be able to tell them apart somehow -- i.e. some destinations only accessible through one gateway, other destinations only used through the other. It should be consistent, too, otherwise you'll mess up TCP connections.

with iproute2, you can deal that kind of topology. It's not perfect but it works

Routing for multiple uplinks/providers