How to check which ports are occupied in Linux?

In Linux, commands like netstat, ss, and lsof are often used to view occupied ports.

• ss -tuln — shows all listening TCP and UDP ports with numbers and addresses.
• netstat -tuln — similar, but may be absent in newer distributions.
• lsof -i :<port> — shows processes using a specific port.

Example command to view all occupied ports:

ss -tuln

To find out which process is occupying port 8080:

lsof -i :8080

These tools help identify which ports are occupied and by which processes.