Quick curl command to test a TCP port
SUCCESS - connected to port 443
[root@SERVER1 mail]# curl -v telnet://9.23.7.7:443
* About to connect() to port 443
* Trying 9.23.7.7... * connected
* Connected to 9.23.7.7 (9.23.7.7) port 443
FAILED - failed connection to port 443
[root@SERVER1 mail]# curl -v telnet://9.23.7.7:443
* About to connect() to 9.23.7.7 port 443
* Trying 9.23.7.7... * Connection refused
* Closing connection #0
curl: (7) couldn't connect