Test If a Port is Open with Bash

If netcat isn’t available on your machine and you don’t have the priviledge to install it you can use this trick to test if a port is open or not. It will throw a connection refused message if a port is closed.

$ : </dev/tcp/127.0.0.1/80

And you can use it in a script like this:

(: </dev/tcp/127.0.0.1/80) &>/dev/null && echo "OPEN" || echo "CLOSED"

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