netstat -tunlp

netstat is a command line tool used in Unix-based operating systems to display network connections

routing tables

interface statistics

masquerade connections

and multicast memberships. The -tunlp option is used to display TCP

UDP

and Unix socket connections along with the process IDs (PIDs) and names of the processes that are listening on those connections.

When you run the netstat -tunlp command

it will display a list of all the active TCP

UDP

and Unix socket connections on your system. This information can be useful for troubleshooting network connectivity issues

identifying potential security risks

and monitoring network activity.

The output of the netstat -tunlp command includes the following columns:

- Proto: The protocol used by the connection (TCP

UDP

or Unix)

- Local Address: The IP address and port number of the local endpoint of the connection

- Foreign Address: The IP address and port number of the remote endpoint of the connection

- State: The state of the connection (e.g.

ESTABLISHED

LISTENING

TIME_WAIT)

- PID/Program name: The process ID (PID) and name of the process that is listening on the connection

By analyzing the output of the netstat -tunlp command

you can identify which processes are using network resources

troubleshoot network connectivity issues

and detect unauthorized or suspicious network connections.

It is important to note that the netstat command may require root or administrator privileges to display certain information

especially process names and PIDs. Additionally

some Unix socket connections may not have associated process names or PIDs

as they are used for inter-process communication within the system.

Overall

the netstat -tunlp command is a powerful tool for monitoring network activity

identifying potential security risks

and troubleshooting network connectivity issues on Unix-based operating systems. By analyzing the output of this command

you can gain valuable insights into the network connections and processes running on your system.