[TriLUG] Iptables help

[Greg Kuhn]

Hello all, 
      I have what is probably a simple question, I just don't have the answer. Here is the situation, I am currently enrolled in wake techs high performance computing program, and this semester I am taking their linux security class among others. The instructor wants as the last part of our current lab to do the following:

from machine 1 ping machine 2 and have the ping forward to machine 3, so it looks like the ping is actually coming from machine 2.

I set up machine three to log the activity, when i ping machine 3 directly from 1 or 2 it logs it, but my forwarding/masqing rules don't seem to be working, when I try to ping 3 thru 2 from 1.

I tried using the rules from  my server at home but something is missing.

So if you could please send the iptable rules needed to accomplish this task.

Thanks, Greg