When I was last working on Kings of Space (“KoS”) I implemented a master server, i. e. a server list that is centrally held, using RakNet’s Lightweight Database which – after some problems – worked reasonably well. There is only the problem that I don’t really have the resources for always running a custom server.

I then decided to convert the code to using HTTP with a few PHP scripts on the server side. That way it’s possible to use Apache on the server side which is running anyway. Although RakNet is solely UDP based, it fortunately has a TCP plugin (“TCP Interface”) which can be used to make HTTP requests. I proceeded with implementing this “master server” and everything went fine, a local Apache correctly added servers, removed servers and sent clients a list of servers.

But when I uploaded the PHP scripts to a remote server (actually the server you’re using right now), it simply stopped working. On the client side it looked like the connection attempt had been successful, but when sending a message to the server the client would hang forever and the server wouldn’t even get an HTTP request. Running netstat on the server showed that the TCP connection was in the state SYN_RECV which obviously means that the connection hadn’t yet been fully established. Waiting for something to happen didn’t help because nothing would happen.

Finally, I got the idea that the problem might not be my code or the server’s firewall, but my router here at home. It’s a Speedtouch 585, one of these integrated DSL modem + router + switch things. So I looked through the configuration and found something called Web Browsing Interception, I switched it off and suddenly everything worked the way it should.

This Web Browsing Interception is normally only visible when the router doesn’t have an active internet connection and you try to access a webpage anyway. It then delivers a page to the browser describing the problem instead of letting the browser find out about the problem itself. I guess I can live without this “feature”.

I’m currently working on getting KoS so far that I can make a public tech demo available on this website.

Tags: http, kos, raknet, speedtouch, syn_recv, tcp

This entry was posted on Tuesday, June 10th, 2008 at 13:27:51 and is filed under kos. It has 1,157 views. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.