listing-ports.md

Listening ports and applications using lsof command

Let us run the following to check open TCP and UDP ports using the lsof command:

sudo lsof -i -P -n | grep LISTEN

Where,

• i : Look for listing ports
• P : Inhibits the conversion of port numbers to port names for network files. Inhibiting the conversion may make lsof run a little faster. It is also useful when port name lookup is not working properly.
• n : Do not use DNS name
• | grep LISTEN : Again only show ports in LISTEN state using the grep command as filter.

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