SSH service is traditionally configured to listen on port 22 because it is the default port for SSH connections. Changing the port number from the default 22 to a different port, such as 4453, requires modifying the SSH configuration file (/etc/ssh/sshd_config) and restarting the SSH service.
In the situation described, even though the configuration file was updated to use port 4453 and the firewall was modified to allow connections through that port, the SSH service is still listening on port 22. This could be due to a few reasons:
1. The SSH service may not have been properly restarted after making the configuration changes. It is important to ensure that the SSH service is restarted correctly to apply the new configuration.
2. The firewall rules may not have been applied correctly or are not taking effect. Make sure that the firewall rules are properly enabled and allow connections on the new port.
3. Another process or service may be interfering with the SSH service and causing it to continue listening on port 22. Check for any other services that may be using port 22 and stop or disable them if necessary.
4. There may be a caching issue or a delay in the changes taking effect. Sometimes it can take a little bit of time for changes to be reflected in the system.
To troubleshoot the issue, you can try restarting the SSH service again, double-checking the firewall rules, ensuring that the SSH configuration file is correct, and checking for any other processes using port 22. You can also try restarting the server to see if that resolves the issue.