Can't access server use domain name, got tcp flag RST

Question

I have a http sever provide service to internet, so I configured port forward in router. It’s fine for users access server outside company (URL: _http://mydomain.com:80/). But if the user is inside company, use above url to access the server is not work. The only way to access server is use inner ip like _http://192.168.1.213:80/.

network map picture: http://i56.tinypic.com/20i8dmr.jpg

I use wireshark captured tcp packets when I telnet mydomin.com 80，the result is can’t connect to server.

wireshark captured packet picture: http://i51.tinypic.com/zsl8ox.png

In wireshark captured packets, No 2-3 show the domain name resolution is success. No 4 my computer(192.168.1.37) access server using server outer ip(116.232.154.50). No 7 show the port foward is ok, the reply ip is server inner ip(192.168.1.213). No 8 the connection is reset (TCP Flag RST) .

Anybody know what’s the reason?

Answer 1

Your port forwarding is most probably only listening for requests on the public interface (internet side). Depending on the brand of your router you can configure to listen to both sides.

So we'll need more info the help you any further.

Answer 2

The usual solution to this problem is to use split-dns. You need to configure your DNS server to return different IP address for your server name depending on where the query comes from. How you do this will depend on what DNS server you use, but it is a common setup.

So on the inside of your network:

servername.company.com -> 192.68.1.213

But for outside queries:

servername.company.com -> 116.232.154.50