Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have set up a website in iis which runs on port 5000

Now when I type I get that page.

Now, I do port forwarding with my Belkin Router using

Now, I find my IP using and I found it to be 117.x.x.x

Now, in my browser when I type 117.x.x.x:5000, fiddler throws me this message

[Fiddler] Connection to 117.x.x.x failed.
Exception Text: A connection attempt failed because the connected party did not
properly respond after a period of time, or established connection failed because
connected host has failed to respond 117.x.x.x:5000
share|improve this question

migrated from Jul 7 '11 at 20:01

This question came from our site for system and network administrators.

Try accessing your web server from outside your network. Many (most?) routers ship without "routeback" (possibly a vendor-specific term, I'm not sure, sorry) enabled, if they even support it, which is necessary for routing an internal connection attempt back into the internal network.

I have yet to see an off-the-shelf consumer-grade router with an option to enable this feature.

So what does this mean to you? It means that from within your network, you must use your server's internal IP (; from outside your network, you must use your router's external IP (117.x.x.x).

A quick-and-easy check can be made using the Open Port Check Tool, although this only tells you if the connection on port 5000 is being accepted, not that it is correctly serving you web site. For that, you can try the HTTP/HTTPS Header Check; if it gets a valid response, you're in business!

share|improve this answer
What you're describing is also known as a U-Turn NAT. – SpacemanSpiff Jul 7 '11 at 17:26
@Kromey every (consumer) router I've owned's worked fine... – Michael Lowman Jul 7 '11 at 18:37
@Tom The IETF refers to this as "hairpin NAT" or "NAT hairpinning" in the RFCs/BCPs (RFC 5382 (BCP 142), RFC 4787 (BCP 127)). – Spiff Jul 7 '11 at 21:42
@Michael Every consumer router I've owned has not supported/not enabled this feature -- sure, it technically works fine, but it can't/doesn't do "hairpin NAT". These days, though, I use low-end PC hardware running Linux, with Shorewall, where enabling this feature is as easy as turning on the "routeback" option for the internal interface. – Kromey Jul 7 '11 at 21:53
Yeah, most if not all consumer routers do not support hairpins. – surfasb Jul 7 '11 at 22:33

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.