Cheat Engine

NINTENDO · Posted: Thu Aug 13, 2009 3:58 pm Post subject: Client to client communication.

Is it possible for a client to contact another client without a server?

Slugsnack · Posted: Thu Aug 13, 2009 4:19 pm Post subject:

not sure about other protocols but using winsock there must be one process somewhere running the client and one with server

Flyte · Posted: Thu Aug 13, 2009 5:01 pm Post subject:

If you are doing the connections over the internet, there is no way to do a to do a direct client-client connection without first accessing a server (unless of course you know at least one of the clients IP addresses before hand, and you know it won't change).

If you are doing this over LAN, you could do a UDP broadcast in order to initiate communication.

DanielG · Posted: Thu Aug 13, 2009 5:48 pm Post subject:

Ehm, yes.

Any TCP connection between 2 computers would constitute as a "client to client" connection.

But if you are talking about how (multiplayer) games work, then it would have to be built in the game otherwise it wil most likely not be possible.

Flyte · Posted: Thu Aug 13, 2009 8:06 pm Post subject:

BanMe · Posted: Thu Aug 13, 2009 8:24 pm Post subject:

Connectionless Protocols...UDP..
where as one is neither server or client but both?

Anden100 · Posted: Thu Aug 13, 2009 9:53 pm Post subject:

Flyte · Posted: Fri Aug 14, 2009 12:47 am Post subject:

DanielG · Posted: Fri Aug 14, 2009 8:17 am Post subject:

Polynomial · Posted: Fri Aug 14, 2009 8:44 am Post subject:

You can use UDP Multicast (or Broadcast) to send a UDP packet to everyone on the same subnet. This allows you to broadcast your location (i.e. send a UDP packet containing some unique identifier for the application and your IP address) to everyone on your subnet (e.g. 192.168.1.xxx). It's how LAN games identify other players on the network.

As regards client to client communication outside the subnet, you'd need some form of acquiring the IP of the other client. This is where you'd need the server to pass the IP between you. However, if you can communicate between each other using some other method (email, MSN, IRC, phone, face to face, etc) you can manually tell the other person your IP.
If you're developing an application and don't want to shell out for hosting or a server, why not use some obscurely named pastebin subdomain to post IP addresses that link to usernames? That way, when a client "logs on", you can post their username and IP in a new pastebin entry. When they log off, you simply submit an entry saying "<username> offline". To find the other user's IP, you just type in their username into your program and it will enumerate the entries in Pastebin to find the IP, then connect to it. This isn't very elegant, but it'd work.