After installing a new Linux system or after configuring a new network services/server, you may need to verify which ports are listing on systems network interface including binding.
Use any one of the following command to find this information:
Code:
lsof -i
nmap localhost
netstat -an
netstat -tulpn
nmap -sT -O localhost
If you find or see unwanted open port, it can be confirmation of an intrusion or cracker in your system.
For more advance usage or adventure with these commends read man pages of corresponding commands.