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I have a CentOS VPS running Tomcat on port 80 and HTTP on port 81. I didn't know how to configure DNS. I searched and figured out there are websites that give you DNS. So I got DNS address from cloudflare.com and set it up on my domain. Now I can access my websites running on tomcat.

Everything works fine but I can't access other ports by typing domain names like: 

example.com:81

But I can do it by typing: 

192.0.2.1:81

So I want to know is there any way to access other ports by domain names or simply that is not possible and if not why?

kasperd
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armin momeni
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  • What is the error you got when trying with MyDomain.com:81 ? – krisFR Sep 24 '17 at 14:22
  • @krisFR nothing happens. just loading on browser – armin momeni Sep 24 '17 at 14:27
  • Is that somehow related to [this](https://support.cloudflare.com/hc/en-us/articles/200169156-Which-ports-will-Cloudflare-work-with-)? Try to use port 8080 instead of 81 and test again. – Thomas Sep 24 '17 at 14:28
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    My guess is the service you found is not actually a DNS service. If your VPS has IP address `192.0.2.1` and you got the domain name `example.com` hosted on a DNS service and pointing to your VPS, that would mean `example.com` resolves to `192.0.2.1`. If that was the case `http://example.com` would probably produce the same result as `http://192.0.2.1`. That's why I am guessing the service you found is not DNS but rather a proxy. And likely `example.com` resolves to a proxy such as `198.51.100.1` which only listens on port 80 and forwards the requests to `192.0.2.1`. – kasperd Sep 24 '17 at 19:53
  • If your question provided real addresses, it would be possible to provide a definitive answer to the question and not just guesses. – kasperd Sep 24 '17 at 19:54

1 Answers1

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So this seems to be related to that Cloudflare does proxying even DNS queries and only allows a limited amount of ports.
The available ports are listed on the Cloudflare page.

Thomas
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