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In my apartment, the management provides the building with a network connection. I have my computer plugged into the ethernet coming out of the walls, and my friend who also lives in the apartment building has his computer connected to a separate ethernet jack.

As far as I know our two computers are not within a LAN, and ipconfig shows that we only have external ip addresses.

The problem, then, appears when we attempt make direct communication between our computers. I have some hosting server set up on my machine, and my friend is unable to connect to it via my ip address. Other people who do not live in the apartment can connect fine.

Ethernet adapter Local Area Connection:

   IPv4 Address. . . . . . . . . . . : 204.29.113.41
   Subnet Mask . . . . . . . . . . . : 255.255.254.0
   Default Gateway . . . . . . . . . : 204.29.112.1

His ip: 204.29.113.104

Using a fulltunnel vpn doesn't help.

Tracert:

E:\Users\User>tracert 204.29.113.104

Tracing route to x.113.29.204.web-pass.com [204.29.113.104]
over a maximum of 30 hops:

  1  User-PC.web-pass.com [204.29.113.41]  reports: Destination host unreachabl
e.

Trace complete.
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Can he ping your server's IP address? –  goblinbox Mar 7 '11 at 0:08
    
No, he can't. I cant ping his either. –  Razor Storm Mar 7 '11 at 0:36
    
What does a tracert from his machine to yours (and vice versa) show? –  Craig H Mar 7 '11 at 3:50
    
Tracert shows destination host unreacheable. =/ –  Razor Storm Mar 7 '11 at 4:34

1 Answer 1

up vote 1 down vote accepted

Since you can both get on the Internet but you cannot ping each other and you're on the same subnet, I suspect a configuration error in your network's router.

It's probably returning a null tracert result because it doesn't know how to trace a route to itself, since it knows that both your IP and your friend's IP are directly connected.

You will probably need to speak with the netadmin on this one.

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I'm not sure if that's a possibility, I haven't been able to find contact information, is there some form of workaround possible? For instance direct our connections through a third party. A full tunnel vpn didn't work for some reason. –  Razor Storm Mar 7 '11 at 4:47
    
You can't ping or tracert to each other, which means that you cannot communicate. That's why your VPN failed. This is a configuration problem that only the network administrator will be able to solve, since it involves traffic on the LAN, inside the network. The only "workaround" would be for either you or your friend to get on another network. Perhaps there's a wireless signal one of you can use instead of the apartment's LAN. –  goblinbox Mar 7 '11 at 5:09
    
I see, that makes sense. What about a proxy? Since we can both connect to a third party, and any third party can connect to both of us. If my friend sends his packets to the proxy (which works) and then has it routed to me (which works) that'd theoretically solve the problem right? –  Razor Storm Mar 7 '11 at 5:44
    
It sure would; I'd certainly give it a try! I have been thinking, too, that it might be policy to keep all of the computers in your building isolated from one another, and that even if you could find the right phone number, you might not get any resolution. –  goblinbox Mar 7 '11 at 5:47
    
Hey I tried that, and it worked! We still cant ping each other, but he can connect to my server. So maybe the router is blocking pings, but that's ok. thanks! –  Razor Storm Mar 7 '11 at 18:46

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