Hi guys I'm the programmer of fiercegear.combovideos.com that is a program that try to add network playing to a game that doesn't have it. Now I've just implemented the network part of the project and everything go in the right way. The only problem that afflict my mind is that I want to provide a scheme that will not let user of version x.x.x of the program play with x.x.y one. The solution I provide for now is a little hand-shaking phase that is performed in the first moments of the peer-to-peer (and server-client) connection in wich every client send the version number. But I don't know if this is the right way to do. Do you think that a special field in the header of my packet sent everytime is a better thing? like: [x.x.x][frame-spawn][gamedata] How do you, game-programming gurus, solve this problem?

I'd hardly be a network guru, but I'd say a single handshake at the beginning would be perfectly OK if you're using TCP. If you're rolling your own using UDP, it may be worth sending it per packet just to make sure that you always know what version you're dealing with, but then again it may not, as long as you have a checksum on each packet, and you have a client ID or some such in the header.

thanks for the quick answer. The game that I hacked (big word) for on-line play is a 2D figthing game so only 1/0 client is connecting at an X time and it use UDP cause I try to implement all the things I can to defeat lag that is very annoying in a game like that. I'm not very sure of the security that is implicated with the hand-shaking and send-every-time methods. I've passed hours thinking about a possible manner to break my net-code. I don't want cheaters, security is the first thing to assure. A 32 bit added to my packet must not break-down the net performance cause the packet for now is very small (64 bit).