What are the different ways to check for listening ports in Linux?

There are several ways to view listening ports in Linux.

1. Use the netstat command: The netstat command can display the currently listening ports and the processes associated with them. Common options include:
2. -a: displays all ports (including listening, established connections, and ports waiting for connections)
   -t: shows ports related to the TCP protocol
   -u: shows ports related to the UDP protocol
   -l: only shows listening ports
   -p: displays the process ID associated with the port.
3. For example, the following command can display all TCP ports that are currently being listened to along with the processes associated with them:
4. Show all active TCP connections and listening ports.
5. By using the ss command, you can quickly check the status of port listening, as an alternative to the netstat command. Common options for the ss command include:
6. -t: Display ports related to the TCP protocol
   -u: Display ports related to the UDP protocol
   -l: Show only ports that are currently listening
   -p: Display the process ID associated with the port
7. For example, the following command can list all TCP ports that are currently being listened to and the processes associated with them:
8. List all the current connections with their addresses and ports.
9. One common way to use the lsof command is to display a list of open files and processes on the system, including the ability to view port listening status. Commonly used options include:
10. -i: display files and processes related to the network, can be used in combination with port numbers
    -n: display hosts and ports in numerical form, without resolving host names and service names
    -P: display service names in the form of port numbers, without resolving service names
11. For example, the following command can be used to list all TCP ports that are currently listening and the processes associated with them:
12. Show me a list of all processes currently listening on TCP connections.

You can choose to use these commands as needed to view the ports that are listening on a Linux system and the processes associated with them.