[The_King_Under_The_Hill]

So I was watching a video from Defcon titled 'Hacking MMO's for Fun (and Profit)' and they talk about altering packets client-side before they reach the server, thus allowing stuff like extra money etc.

This is not my intent, as MMO's have never interested me, but it seems an interesting concept and if anyone here has any knowledge on the subject I'd be grateful

[The Real Slim Shady]

Well, im not in the know on altering packets in real time... nor am i much at game cheating so im not sure in what other scenarios you would necessarily need that ability in.

That said, packet creation is very useful knowledge. Personally i use hping3 ( http://www.hping.org/ ). Very cool tool for network/computer hacking as you can craft custom packets to test whats allowed through a nat/firewall/etc. eg spoof source ip/ports, headers, specify destination ports. Supports pretty much the whole IP stack i believe (TCP/UDP/ICMP to say the least). Its been a couple years since ive used it, but i doubt anything much better has come along.