How to ensure a given port is open
by NotionCommotion from LinuxQuestions.org on (#5KS15)
I have a 1&1 virtual Centos7 server. 1&1 has a firewall that sits above my virtual machine and I need to open ports on it as well as the local firewalld. The ports are open on both firewalls but some of them (993, 1338, 5432, 7869) show as being closed when I telenet from my PC or use https://www.yougetsignal.com/tools/open-ports/. To rule out an issue on my end, I have stopped the firewalld service, but no change. I contacted 1&1 and they said it was not on their end. I asked if was possible to disable their server and politely got a no. I would like to completely rule out an issue on my end.
Do I need to do more that just stop the firewalld service? 1&1 suggested I reboot the server and even though I knew it wouldn't work tried it and sure enough no difference. Is it possible there is another firewall running, and if so how could it be identified? I looked at /var/log/firewalld which showed nothing (which prompted this post). Some of the ports show as having some service running on them (lsof -i:5432 shows postgres) but others do not. Is there a different way to check if a port is open if a service is running on it?
Is there anything else I should do before going back to 1&1. Thanks
Do I need to do more that just stop the firewalld service? 1&1 suggested I reboot the server and even though I knew it wouldn't work tried it and sure enough no difference. Is it possible there is another firewall running, and if so how could it be identified? I looked at /var/log/firewalld which showed nothing (which prompted this post). Some of the ports show as having some service running on them (lsof -i:5432 shows postgres) but others do not. Is there a different way to check if a port is open if a service is running on it?
Is there anything else I should do before going back to 1&1. Thanks