To check open ports in Linux using the command line interface (CLI), you can use the “netstat” command. This command will show you all the active network connections, including information about the protocol (TCP or UDP), the local and remote addresses and ports, and the state of the connection.
To check all open ports, use the following command:
sudo netstat -tulnp
This will show you all the TCP and UDP connections, the process ID and name of the program that is using the port, and the state of the connection.
You can also use the “lsof” command to check for open ports. This command lists all open files and the processes that have opened them. To see a list of all open network ports, use the following command:
sudo lsof -i
This will show you a list of all open network ports and the processes that have them open.
Another tool to check open ports is nmap, which is a network exploration tool and security scanner. You can use nmap to check for open ports on a specific host or IP address. To scan a host for open ports, use the following command:
sudo nmap [hostname or IP address]
It will show all the open ports and the services running on them.