listening port with netcat not working

Question

I am trying to listen to port 8080 using netcat. It was working fine, suddenly I an getting this. Any idea?

root@kali:~# nc -vv -l -p 8080
retrying local 0.0.0.0:8080 : Address already in use
retrying local 0.0.0.0:8080 : Address already in use
retrying local 0.0.0.0:8080 : Address already in use
retrying local 0.0.0.0:8080 : Address already in use

Answer 1

Some other process is using the port. use ps command to find the list of running processes it would list the list of active processes and also command name. Find and kill the process responsible for using the port 8080.

Answer 2

TL;DR This means another service is using that port, and only one service at a time can use that port. Could be your web browser, proxy, or a couple other possibilities. You can use netstat -an | grep 8080 to see what else is running on that port.

Try listening on another port, such as 4444.

Port 8080 is usually reserved as a sort of secondary HTTP port, or for web proxies (e.g. Burp Suite).

Answer 3

Doesn't that mean that this port is currently used, try

netstat -antp

to see what is using the port 8080

using other port may help you to not enter in other problems