ncat tricks/examples

ncat.md

ncat trick #1

Run these in 2 terminals, after ncat is installed:

$ ncat -l -p 9999

And on the other one:

$ echo Hello | ncat localhost 9999

ncat trick #2

$ ncat -l -p 9999

This command tells ncat to listen on port 9999. We could have chosen any port between 1025 and 65535 that another program isn't already listening on.

In another terminal:

$ cat ~/.bashrc | ncat localhost 9999

This command sends the contents of your ~/.bashrc file over a TCP connection to your computer's port 9999 -- which of course your first terminal is listening on.

Bonus: tcpdump

To view this traffic flow over the (loopback) network interface, use tcpdump:

$ sudo tcpdump -vXxns 0 -i lo 'port 9999' 

ncat trick #3: visit a website

$ echo -e 'GET / HTTP/1.1\r\n\r\n' | ncat checkip.dyndns.org 80

Notice that if you visit http://checkip.dyndns.org in your browser, then right-click and View Source, you'll see that the body of the web page you visited matches the end of ncat's output