Usually the more familiar methods are netstat and lsof, but what else is there?
1.netstat or ss command
netstat -anlp | grep 80
2.lsof command
This command is to view which files the process occupies
lsof -i:80
3.fuser command
The fuser command is the opposite of lsof, which is to check which process a certain file is occupied. In Linux, everything is a file, so you can view ordinary files, socket files, and file systems. The socket file contains the port number. For example, view port 22.
fuser 22/tcp -v
USER PID ACCESS COMMAND
22/tcp: root 1329 F.... sshd
root 1606 f.... sshd
4.nmap tool
By default, nmap always scans ports. It is very convenient to scan the local port.
nmap localhost
Starting Nmap 5.51 ( http://nmap.org ) at 2018-03-03 18:00 CST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.0000020s latency).
Other addresses for localhost (not scanned): 127.0.0.1
Not shown: 998 closed ports
PORT STATE SERVICE
22/tcp open ssh
25/tcp open smtp
Nmap done: 1 IP address (1 host up) scanned in 0.06 seconds