P2P and desync recovery

Discussion about the game and its default mods.
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Unit158
Posts: 20
Joined: Wed Feb 12, 2014 10:05 pm

P2P and desync recovery

Post by Unit158 »

I was reading on lockstep today and my eye was caught by some of the properties of the model.

It is perfect for a peer to peer system because it requires synchronization between the clients, some further research shows me that servers and lobbies can be reduced to middlemen to help punch a hole through NAT. I am not sure how useful this would be, but I might be willing to implement such a feature. We might be able to reduce the amount of hetzner servers needed in this case, and remove a possible point of latency.

Another point that may be worth looking into is desync resolution in games with more than two players or by defaulting to what the host has.


This has probably been brought up before, but I felt I might as well bring it up while I was looking at it.

Matt
Posts: 1144
Joined: Tue May 01, 2012 12:21 pm
Location: Germany

Post by Matt »

Not really sure what you mean with peer to peer system. Also we support UPnP to punch holes through NAT.

Having a real dedicated server, not just a headless client, would be a cool feature I guess.

I believe desync recovery was never implemented on purpose, because that would hide programming errors and allows people to cheat/exploit and get away with it.

Unit158
Posts: 20
Joined: Wed Feb 12, 2014 10:05 pm

Post by Unit158 »

What I was looking into was made for UDP. Whoops. Part of the research still applies anyway.


You can fool some NAT systems into making a connection to a blocked port on a desired remote client, then sending that info about the blocked port to the server. The server sends this info to the remote client, who sends a packet back to the first client. The packet acts as an acknowledgement and starts a connection between the two clients because both clients initiated connections to eachother.

AFAIK this only works for two computers, but I still have more research to do.

deniz1a
Posts: 31
Joined: Thu Jan 16, 2014 2:21 pm

Post by deniz1a »

How could it be used to cheat?

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