# Find Unused Unix Ports

**Problem**

You need to bring up another Unix web server but port 443 is already in use. How do you find another unused Unix port?

Solution

Use the [netstat](https://man7.org/linux/man-pages/man8/netstat.8.html) command to discover which ports are already used

`netstat -ln | grep LISTEN | awk '{print $4}' | grep ":" | sort | uniq`

Breakdown of commands

`netstal -ln` : List all the numerical Unix ports that are listening for network traffic

`grep LISTEN` : Display the output lines that are in LISTEN status

`awk '{print $4}` : Print the fourth column of the output that has the port numbers that Unix processed are LISTENING

`sort | uniq` : Sort the output and only show unique values

You will get an output similar to

> 0.0.0.0:443
> 
> 0.0.0.0:5353  
> 0.0.0.0:68  
> 0.0.0.0:80  
> 10.0.2.15:123  
> ::1:10089  
> ::1:123

The number after the last colon is the port in use, e.g. 443, 80, 123, 5353.  Pick any Unix port not already in use and assigned.