netstat实时查看TCP和UDP的端口How to Watch TCP and UDP Ports in Real-time

https://www.tecmint.com/watch-tcp-and-udp-ports-in-linux/

$ sudo watch netstat -tulpn
OR
$ sudo watch ss -tulpn

-t – enables listing of TCP ports.
-u – enables listing of UDP ports.
-l – prints only listening sockets.
-n – shows the port number.
-p – show process/program name.