Emulate internet conditions with 3 computers

[sholex]

Hello,

I am trying to connect 3 computers (A, B and C) like this,

A --> B --> C

so A can send data to C through B. B runs application for forwarding packets, causing packet drop, corruption, latency... emulating real life conditions.

The question is, how do I connect them? Should I use a switch and connect all of them to it? If I do that, I must address packets from A to B, and packets from B address to computer C... Is there any elegant way to connect them and send packets from A directly to C and have B intercept those and modify them (like real internet)? Can I put two ethernet cards in B?

Thanks

 

[Emerald]

two NIC in B with different IP schemes