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I live in an apartment which provides the internet connection (isp: webpass). In one wall socket, I plugged in a router, which serves all my machines in the living room. In my bedroom I have another machine plugged directly into the wall.

The router's external ip is different than that of my bedroom machine's. (Hence they aren't on the same LAN) However, both the router and my bedroom machine are on the same subnet (the entire apartment complex is on the same subnet).

I host a website out of my server which is connected to the living room router, so I wish to be able to develop my site from my bedroom machine. The problem is, I cannot ssh into my server. I tried browsing to my website both using the url and the external ip of my router, no good. Pinging the router's external ip does not work either.

Is there anything I can do to circumvent this problem, or is this something that can only be changed by requesting the apartment to modify on their end.

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Can you clarify what you mean when you say, "They aren't on the same lan (because the ips are different)" Are they both on the same subnet, with the same default gateway? I think it would help a lot if you just gave us 192.xx private ips in place of the actual ones with the subnet declarations of both the router and the bedroom host. Forgetting nat for a second, if they router and the bedroom are on the same shared lan, and are on the same subnet, they should be able to communicate. –  MattyB Oct 4 '10 at 1:11
    
Ok sorry for the confusion, here's a clarification. The bedroom and router are not in the same LAN (at least as far as I can tell). The bedroom's public ip is 204.28.112.176 whereas the router's public is 204.28.112.213. They are on the same subnet 112 –  Razor Storm Oct 4 '10 at 1:17
    
112 is not a valid subnet... what is the full subnet declaration? I am just wondering if they are using the same subnet declaration but are actually on different subnets, i.e the don't both share the same default router. you could test if they are on the same physical lan segment by checking for the mac address of the router, with arping from the bedroom computer. –  MattyB Oct 4 '10 at 4:04

2 Answers 2

Talk to the person who set it up. If they have different external IP's it is possible that they are doing BINAT. However my best guess is they block all incoming ports like HTTP/SSH and only allow traffic to come in if it was initiated by a packet to go out.

Now that of course precludes any mistake you could have done. Since your hosting multiple machines behind your living room I am guessing you NAT? If so did you enable port forwarding to a specific machine. Also is your router's firewall set up properly.

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My router is set up correctly. I port forwarded 80 and 22 to my server. Ssh into the server works fine from external machines. –  Razor Storm Oct 4 '10 at 0:01
    
All I can think of then if your setup is correct then and you get public IP's in your apt. is they must be firewalling every node from each other so you don't screw with your neighbors computer. Ask the company to allow all the machines in your apt to talk to each other I guess. –  PHGamer Oct 4 '10 at 3:03
    
Ok thanks I'll see if I can contact the sysadmins then. –  Razor Storm Oct 22 '10 at 7:24

Without knowing what subnet mask you are using, it's impossible (for us) to say if they're on the same subnet or not. They may be in the same "class C" network, but that (unfortunately) says nothing about the actual subnets involved.

It's also quite possible that the network provider is using "private VLANs" (essentially allowing only communication between access port and trunk port(s), not between access ports within the VLAN).

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