Back in college, when the network admins added rules to the routers in the dorms to drop UDP broadcasts, we wrote an application to perform re-broadcast on different leaf's to allow for our games to work. All we wanted was some Counter-Strike, and Unreal action.
So turns out that effort was not totally for naught with the recent PSN outage. Most game only have PSN support, but luckily our current game du jour, Red Dead Redemption, also still has support for LAN gamers. Alas, trying to create a VPN without heavily modifying our home networks can be quite cumbersome. So I decided to analyze the traffic for the game and write a 1-off server so my brother and I can take care of some outlaws. I mean, they're not going to kill themselves.
Analyzing the traffic, I found that when entering LAN mode the game would broadcast a series of packets to the LAN on UDP to port 11112. Whipping up a client/server to handle this was simple enough. So far the client has sent its broadcast requests to the server, and the server has responded, but the client does not seem to like the responses. So I tried to dig a little deeper and see if anything stood out in the protocol. So far, the only item of note is the first 16-bits of the UDP payload is the size of the message being sent. The contents of all the messages does not change from both the client and the server. So this leads me to believe that maybe some timing is being performed to detect if its *really* a LAN connection.
As remote protocol RE'ing can be quite difficult, I tried a scan around the Inter-tubes to see if anyone else had shed any light on this subject. All I was able to turn up was a link about smattering of ports and another broad swath of ports that includes the PSN/Voice Chat ports
Hopefully I can get 2 PS3s on my LAN to see how the traffic works out, otherwise I'm stabbing in the dark. If you have any information on this, or would like to help, drop me an e-mail.