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Cannot connect two computers


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#1 Tank202   Members   -  Reputation: 176

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Posted 05 March 2014 - 02:27 PM

Hello everyone,

 

I'm currently learning to work with high-level game networking libraries. Problem is that I can't connect two computers. When I use local host(127.0.0.1) it works perfectly. I've tried disabling firewall and open ports, but that didn't make any good. 

 

I've tried ENet, OpenPlay, and SFML libraries but they all can't connect.

Please help ! biggrin.png

 

OS: Windows 8.1 x64bit (I think the problem will be related to the OS as I hate it biggrin.png)


Edited by Tank202, 05 March 2014 - 02:28 PM.


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#2 Angus Hollands   Members   -  Reputation: 707

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Posted 05 March 2014 - 03:37 PM

If you're using UDP, are you binding the server to the external ip? In Python, that entails leaving the address field blank, instead of "localhost" or 127.0.0.1



#3 Tank202   Members   -  Reputation: 176

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Posted 05 March 2014 - 10:57 PM

Well, I'm a bit confused. Do you need to bind server to some external IP? I thought that server uses IP of the host computer, and you need to use that when connecting.

 

Also SDK precompiled demos would have done this if that was so fundamental, but they didn't work either.

 

Finally, I prefer UDP, but I think I could do with TCP too, so in the mean time I'll try the TCP protocol. But still this question is very important to me, so if you have suggestions I would be very gratefull to hear them.

 

And I would also like to point out that I use C++.



#4 frob   Moderators   -  Reputation: 19766

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Posted 05 March 2014 - 11:34 PM

Specifying your ports is something some beginners mess up. Usually the host machine listens on a specific port of a specific interface. The client machine attempts to connect with a specified outbound IP+port pair, but usually leaves its own side blank, allowing the system to connect on any open interface and any open port that it thinks best.  The combined tuple { SrcIP, SrcPort, DestIP,  DestPort } needs to be unique so it is usually a bad idea to specify all four when you are establishing a connection.  Specify only one pair of IP/Port and allow the system to figure out the other two.

 

As for the firewall possibility:

 

If both machines are inside your own local network, you can connect directly by their LAN IP address.  Often this is 192.168.0.x, but can be other values. This corresponds with a netmask of 255.255.255.0, which means anything on the last byte is assumed to be directly connected. Double-check the IP addresses and netmasks of the machines if you need to. If both machine's addresses are in the same range within the netmask, and your machines are otherwise able to see each other, and it still isn't connecting, then yes it might be firewalls or antivirus tools on either machine. This can sometimes be tiresome to figure out.  You can troubleshoot by disconnecting your NAT from your ISP to reduce infection risk, then turn off all the firewalls and AV tools, and connect again.

 

If both machines are inside your own local network and you are trying to connect using an external IP address, that is generally not going to work. For example, connecting from a local machine to a public IP address, which is actually the IP address of your home's connection, pointing back in to your network and being port forwarded to a machine, it probably won't work. This is called a "hairpin route", since just like a physical hairpin it loops back on itself from inside the NAT to outside the NAT to right back inside the NAT. Few consumer devices support this.


Edited by frob, 05 March 2014 - 11:41 PM.

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#5 3TATUK2   Members   -  Reputation: 729

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Posted 08 March 2014 - 08:27 AM

Probably a router/firewall setting issue.

 

Before messing with assuring actual code works - try running some simple free server program like smallftpd or whatever.... Then verify you can connect. If not, you need to fix settings before YOUR OWN code will actually work.






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