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We have an Ubuntu 10.04 LAMP server running on site (Apache is on port 80). It is running fine through the LAN, but I cannot access it using its external IP address through the Netopia 3000 Series modem by which it is connected to the internet. I have tried using what Netopia calls "Pinholes" (Port Forwarding) to make the server accessible, but a telnet to the external address just gives me "connect to address x.x.x.x: Operation timed out." I have also tried enabling "Services" and "IP Passthrough" on the router, but it gives the same result as above.

How can I enable the server to be accessed through its external IP address? Because it connects fine locally, it would seem to be a problem with the Netopia router.

Update: Booting the server in GUI mode instead of text mode solved the problem instantly. Any ideas why?

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You'll probably want to close all ports that you don't want open in a hurry, especially if you're going to be broadcasting your public IP in a public Internet forum. – squillman Aug 20 '11 at 2:36
Which Netopia model number are you using? – quanta Aug 20 '11 at 2:36
1) Did you telnet to port 80 on the external IP? (2) Did you try it from outside? The Netopia might not allow you to connect to the external IP from the LAN. (3) The Netopia doesn't seme to be the problem, the configuration of the Netopia seems to be the problem. ;) – TessellatingHeckler Aug 20 '11 at 3:02
@TessellatingHeckler, yes to the first two questions--same result; your right about the third point, that's what I meant (I'm a bit tired :). – mindoftea Aug 20 '11 at 3:22
@quanta, the model number is 3347NWG-VGx. Thanks. – mindoftea Aug 20 '11 at 3:31

2 Answers

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This sounds like it may be a case where there is a SOHO-level NAT (maybe the Netopia?) not capable of looping traffic that originates from its LAN to the WAN and then back into the LAN. It's pretty common. This is also referred to as NAT hairpinning as well.

You might check your NAT equipment to see if there are any "advance" settings which might deal with "loopback" or maybe even "hairpinning" for its WAN functionality. Some manufacturers may offer firmware revisions which overcome this limitation.

In lieu of the NAT equipment being able to support the configuration/functioning, you just cannot call your internally hosted resources by the external/WAN IP when you are on the LAN side of the NAT.

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Thanks for your answer answer, I would agree except that I have tried accessing the server from other connections--it is still unresponsive. Sorry I didn't make it more clear. – mindoftea Aug 20 '11 at 13:00
From the WAN side? If that is the situation, then you may consider setting another system forward, so to rule out the NAT equipment vs. the target system. – user48838 Aug 20 '11 at 17:22
See the edit to the original post. – mindoftea Aug 21 '11 at 14:04
"Booting the server in GUI mode instead of text mode solved the problem instantly." That being the case, you may want to closely audit the GUI vs. CLI configurations. Chances are that the one of the startup configurations is either adding or disabling a firewall or routing rule which is impacting the system from answering non-local traffic. – user48838 Aug 21 '11 at 18:38
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  • Follow this guide to enable port forwarding.
  • Access canyouseeme to verify port 80 is open.
  • Use a proxy server to test your website via public IP.
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I enabled port forwarding already using a method very similar to the one above, but will certainly try again using this specific tutorial when I can. – mindoftea Aug 20 '11 at 15:15

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