Multiplayer Engine

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6 comments, last by sevensix 18 years, 11 months ago
Hello, I'm new to networking and multiplayer game development. I read a lot of articles regarding different architectures that gaming network provides (p2p or client/server and hybrid) but i was curious as to what kind of firewall issue there is that i need to worry about. If my client application was running in a computer behind a strict firewall such as universities or coporations, is there anything in design that i need to worry about? Any insight would be greatly appreciated. Also I'm hoping to start a good discussion regarding other multiplayer game design issues as well. Thanks!
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Eh? You read the articles. You know how firewalls work. The implications should then be pretty straight-forward.

If you don't know how firewalls work, take a few minutes to research that. They aren't too magical, even these days.
Well sorry about misleading. I read articles regarding network gaming and firewall. So let me try to rephrase the question. If firewall only allows certain ports to be opened for communication between client and server, is there anything in developer that can do to bypass it? I guess I don't have detail understanding of firewall. Here's a scenario. Let's say all of ports are closed and only port allowed for traffic is port 80 (http). (I think this is typical firewall scenario.) So in this case, can game packets be submitted through port 80 with out any problems? If this is the case, then why doesn't all games or other online application use port 80 for any network traffic? Do you see what I'm trying to describe here?
Because that is "not right". Not right being the tradition of leaving different apps for their own ports. It also prevents the game server from also running a web server for example. For all practical purposes, only one process can listen on a given port at a time.

That said, you can run your game over whatever port you wish. Running ssh or game servers on port 80 isn't exactly unheard of because of the scenario you describe.

Though I'd caution against that. http is an easy protocol to monitor, and any game activity will set off alarms on any protocol analyzer [or intrusion detection system] watching the link.

But [imo] this isn't something the game or protocol design should even consider. The port you use is just a parameter in a config file. It influences nothing.
ok i am not a network wizard but as far as i understand the port is the "program" that you acess / send pacets too.

Witch means browers operate on port 80. so if you send game pacets the brower will get the.


i think the standard configuration on firewalls make it so that if you start a connection the correct ports will open and be aviable for communication.
So the main concern is if the server is behind a firewall then i makes a problem not else. So the one controlling the server must configure the firewall to open up the game server port.


just my thoughgs a limited knowledge. Hope it helps some.
-Truth is out there-
That's great to hear because I was under an impression that developer can make application firewall friendly or not.

Are there other multiplayer design issues that beginner should be aware of?

hehe there are very many multiplayer design issues. The largest ones i think is deadrecogning and nat's ( people behind routers ). And then there is latancy issues and how to pack the data.

I would suggest you try to write a few minor applications like we did in our course. we hade for example make a chat server ( take a message and broadcast it to connected clients ) and we had make a network pong game.

donno how much you know already but you will lern faster and more stable taking small stepps.


Good luck mate.
-Truth is out there-
Thanks for the tip. Yea i was heading that direction. I figure i can ask questions and get some feedbacks to see what i'm getting myself into :)

Thanks!

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