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Ok I have setup a VNC server, I have port forwarded TCP/UDP for both 5900 and 5800. Everything works fine all ports are open according to (http://canyouseeme.org/). But i still cannot access it using the external ip address. It works fine with the internal ip address but somehow not the external. Any ideas?

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Are you behind NAT/ the router (whatever is requiring you to use port forwarding) and trying to access the VNC server externally this way? –  ekaj Dec 10 '12 at 3:32
    
I am behind a router and trying to access the vnc outside of my router. –  enginefree Dec 10 '12 at 3:35
    
You are behind some other router and trying to access the VNC that is behind your own router, using your router's external IP address? If you're behind the same router, you can't access it using the outside IP address using port forwarding, only using hairpin. If you only setup port forwarding, it's not supposed to work. (Port forwarding only applies to connections from the outside, not from the inside.) –  David Schwartz Dec 10 '12 at 3:39
    
Yes, I am behind a different router trying to access my VNC. Is there anyway that I could just have the vnc server like any other "website." –  enginefree Dec 10 '12 at 3:40
    
So the setup is this: [machine you're trying to access from] <-> [router] <-> Internet <-> [router doing port forwarding] <-> [machine you're trying to access]? –  David Schwartz Dec 10 '12 at 3:41

1 Answer 1

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You'll need a router that supports hairpin NAT (sometimes called "lookback NAT", a form of dual NAT where both the source and destination addresses are rewritten) to access a forwarded service from the inside using the outside IP address. This answer explains why port forwarding won't work unless the connection originates from the Internet side of the router. Most SoHo routers can't do loopback NAT with their factory firmware.

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