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I have a local ip (xxx.xxx.xxx.xxx) and also a public ip (yyy.yyy.yyy.yyy) for my local server. I host a website in the local server on port 5555. I can open my website from the local ip (http://xxx.xxx.xxx.xxx:5555) but I can't open it from my public ip (http://yyy.yyy.yyy.yyy:5555).

I'm not the server admin, but I was operating under the assumption that I should be able to access the port that is open in the local IP through the public IP. Apparently I am wrong; how can I determine what the cause of this problem is?

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closed as off-topic by EEAA, MDMarra, Wesley, Dennis Kaarsemaker, Iain Sep 24 '13 at 6:57

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Contact your system administrator. –  Michael Hampton Sep 24 '13 at 1:59
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Port 5555 needs to be forwarded from the public ip to the private ip. This is done on your firewall or router. –  joeqwerty Sep 24 '13 at 2:17
    
Are you trying to access the server by its public IP from inside the same local network where the server is? That won't work unless your router has specific support for hairpin (or loopback) NAT. Port forwarding will not do this. –  David Schwartz Sep 24 '13 at 3:01
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2 Answers

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There can be several things going on.

First, it sounds like you are may be talking about accessing your public IP from within your private network, attached to the private IP side of your server. That requires two things to be working: your server software needs to be attached to the public IP, and your private IP needs to forward to your public IP (and back).

So, the first thing to do is figure out which of those is not working. Go to another Internet access point, outside your local network, and try accessing your public IP. That will tell you if your server software is attaching to your public IP address, and that your firewall is allowing outside connections through that IP.

If that works, try connecting to some other publicly-accessible port on your server from inside your local network. If that fails, there can be a range of issues, from your firewall blocking access, to NAT not passing packets one way or the other.

Following those instructions, you should at least get closer to your solution. If you post your findings, along with some more details about your configuration, and we can help further.

On the other hand, if not being the server administrator means that you don't have access to the logs or firewall configuration, you will need to speak with the person who does.

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You will need to make sure that your modem allows for port forwarding. Then you can port forward all :5555 to your local server. If you have a router, you can place your modem in bridemode to make things easier. In some cases this is required.

Contact your ISP and modem documentation for more.

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