How can I appear to be coming from a certain IP address?

Question

I have a friends IP and I want to appear to be coming from his specific IP to the outside world. How can I do that besides actually taking over his computer?

Thanks!

Answer 1

If your friend is cooperating with this endeavor then they could install a proxy on their machine and let you connect through it. I am guessing this is not the case though and you are trying to impersonate them.

If you are on the same network (such as the same dorm or house network), then setting your IP to theirs would probably do it, though be disruptive to both of you.

Assuming a non-shared-network scenario, if your ISP is lax then you'd be able to send packets 'from' your friends ip address, but you would not receive the result as they would go to your friends machine. In practice this means at best you can send unidirectional UDP packets, and there isn't much practical use for this. A good ISP will prevent this behavior though.

So, as a practical matter, you can't.