Analyse TCP/UDP traffic with netcat

Sometimes you want to see what data you get through a TCP or UDP connection.
For example, you want to know how a HTTP Request look like.

It's very easy with netcat Show archive.org snapshot .

Example to listen on port 80 and the output gets to stdout.

sudo nc -kl 80

It's also possible write it into a file:

sudo nc -kl 80 > output.txt

If you use Ports higher than 1000 you don't need to be root (sudo).