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Nighthawk X6 R7900 port forwarding only works partially
I'm using the Nighthawk X6 R7900 having firmware version V1.0.1.12_10.0.17. I am setting up a small web server on one of the computers that is wired into the nighthawk. The web service is using p...
I spent a bit of time looking up possible reasons why CENTOS might not send ACK in reply to SYN. A number of potential causes came up, none of which addressed my particular failure.
I have another server that is running CENTOS 7. When I installed the web server on that machine, the port forwarding worked just fine. Somehow, the port forwarding does not interact well with CENTOS 6.
Since things are working on my CENTOS 7 machine, I'll consider the issue resolved - though at some point it would be nice to understand what is going on so that I can do port forwarding to my older servers.
If that tcpdump was captured on the server, then it seems to me that the server received the TCP SYN from canyouseeme.org, proving that port forwarding worked. The server failed to respond to it. Therefore, you need to troubleshoot the server. Look for anything in /var/logs/... that may shed light. You may have to enable additional logging.
I spent a bit of time looking up possible reasons why CENTOS might not send ACK in reply to SYN. A number of potential causes came up, none of which addressed my particular failure.
I have another server that is running CENTOS 7. When I installed the web server on that machine, the port forwarding worked just fine. Somehow, the port forwarding does not interact well with CENTOS 6.
Since things are working on my CENTOS 7 machine, I'll consider the issue resolved - though at some point it would be nice to understand what is going on so that I can do port forwarding to my older servers.