Who is using the port?

Find which process is using tcp port

Linux
netstat -anp | grep LISTEN

AIX
lsof -i:portnumber
The above command will list the processes and pids.
grep using the pid to know the config
ex: ps -ef | grep httpd | grep pid

Windows
netstat -an |find /i "listening"
netstat -an |find /i "9443"

netstat -no
netstat -ao
netstat -a