Based on how packets travel and how connections are made, you need to actually have these IPs in order to use them, otherwise you won't have any luck making a connection at all.

One more thing: why do you need do this? SPAM comes to mind.

first, to clarify why i need this. SPAM is exactly why. I am testing against a tool that does spam detection. That is why i need to connect to it from multiple IPs. sure the easiest way would be to get mulitple computers (and their ip address) Thats great but in our enviornment we cant tie up that many computers for our automated testing. This is why I have had such a hard time findign info for this. I have been workign with creating ip alias, but those only seem to want to work on incoming not outgoing. This isnt so much a how to do it in perl question, but more of a, can i do in perl(even if it means doing some system commands first).