Detecting listening network ports on Linux

It is importand to check for ports that are open and there are not needed.

For a list of network ports that are open you can use the following commands:

netstat -tulp or
lsof -i -n | egrep ‘COMMAND|LISTEN|UDP’

Or, you are not limited to netstat or lsof but you can always use a port scanner, telnet or nc to list open/close ports.