How can you find out which process is using a specific port?

To determine which process is using a specific port, using lsof -i :port_number is the most effective option. The lsof command stands for "list open files," and it can be used to view all files or network connections that are currently open on the system. When used with the -i option followed by the specific port number, it shows the processes that are using that port for networking purposes.

This command provides detailed information, including the process ID (PID), the user running the process, and the command associated with it. This level of detail is specifically tailored to network connections, making lsof a powerful tool for troubleshooting and managing network resources.

Other methods like using netstat -a do show the state of network connections but do not indicate which specific process is using a particular port. The ps -aux command displays a list of running processes but doesn’t include port information. Similarly, fuser :port_number can identify processes using the given port, but it might not provide as comprehensive information as lsof. Thus, lsof is the most suitable tool for directly correlating processes with port usage.