NAT punch through

It's un-clear what the problem even is. Are you running a residential gateway or firewall at home? If so, you need to set the actual server machine into a DMZ, or you need to port forward 6464 to your server through the firewall.

computer A is behind a fire wall, and is hosting my game server. computer A registeres it self with a master server on the internet, but via port 80.

My game uses port 6464 to connect.

Now a computer B comes along, gets a list of ip's from the master server, then attempts to connect to one. The ip is computer A's internet address, so attempts to connect on port 6464.

The connection fails, and my guess is that because my server has not punched through the nat on port 6464, the router/dsl modem/nat wont know how to foward packets comming in on that port.

So, i'm thinking i need to punch a connection through on port 6464 to some server on the internet so the NAT knows how to foward the packets. Problem is you cant open up an connection on a random port (6464) to my webserver.

So i'm wondering what the solution is, with out the user going to configure thier routers to foward that port to thier PC....

Quote:

Original post by supagu So, i'm thinking i need to punch a connection through on port 6464 to some server on the internet so the NAT knows how to foward the packets. Problem is you cant open up an connection on a random port (6464) to my webserver.

Well, first, I'm assuming this is UDP. Punching through NAT is most easily accomplished with it, as far as I understand.

The problem with your approach is that after connecting to the Internet server on port 6464 the NAT is only going to forward packets originating from the internet server on that port. That's why a client is not going to be able to do anything with this approach.

So what you actually need is to try sending a packet to the client from your NATed server, so that the NAT knows to forward packets from that client to your server. Of course, you may run into an issue where the client is also behind a NAT, in which case it also has to send a packet out to your server to punch through it's NAT. This is going to require both the server and client being connected to the internet server to coordinate the punching through process.

I've been reading on this recently, so its possible of got something wrong. But as far as I can tell this is how it is done.

I don't think you understand the requirements for punch-through. For punch-through to work, you have to register on the same port as you will be using, and you have to have an actively participating matchmaker server. The Forum FAQ has several links to NAT punch-through documents. Also, if you're trying to do this with TCP, you should know that TCP punch-through support is quite spotty. UDP punch-through support is much more widespread.