Use netstat on linux to view the current service and listening port

The netstat command is commonly used in network monitoring. You can use this command to view the services and established services monitored by the current system, as well as the corresponding ports and protocols.

The netstat command is commonly used in network monitoring. You can use this command to view the services and established services monitored by the current system, as well as the corresponding ports and protocols.

Netstat parameter description

Although there are many netstat parameters, they are not commonly used, mainly including the following parameters:

netstat -[atunlp]

• -A: all: lists all connections, Service listeners, and Socket information.
• -T: tcp, used to list tcp services
• -U: udp, which lists udp services.
• -N: port number. the port number is displayed.
• -L: listening: used to list the current listening service.
• -P: program: list the PID of the Service program

For more information, see man netstat.

Netstat command test

netstat -atunlp

The output result is as follows:

Netstat command demonstration

Where

• Proto: network transmission protocol, mainly tcp and udp
• Local Address: Local ip: port
• Foreign Address: ip Address of the remote host: port
• State: The connection status, mainly including the listener (LISTEN) and the established (ESTABLISED)
• PID: service process ID
• Program name: service name

The last row of the above status is ESTABLISED because I am currently using putty to connect to this host.