Listen to port continuously and dump data to file

Question

I use this command to listen to port and dump data to file:

while :  ; do nc -l 0.0.0.0 10000 > log.txt & done

First request works perfect, it's dumped in log.txt but after first request, the nc is no longer listening but stopped.

Can someone point me to what I do wrong?

I just want this to run in the background continuously and log any request from this port to log.txt file...

Answer 1

You must add an option to nc. The option depends on the version of nc you are running. For instance, in my case (Kubuntu), the option is -k. From the man page,

-k Forces nc to stay listening for another connection after its current connection is completed. It is an error to use this option without the -l option.

I cannot promise -k works (unless you are n Ubuntu, of course), you will have to search for something similar. For instance, on my Debian, -k does not exist, but you find:

-q seconds after EOF on stdin, wait the specified number of seconds and then quit. If seconds is negative, wait forever

Edit:

To check that it works, on one pc:

  nc -k -l 0.0.0.0 10000 > out.txt

On a second pc:

  echo Hello | nc IP_address_of_first_pc 10000

Issue the command above a few times, then interrupt the nc command on pc1, check number of lines in out.txt.