2.19.3.8. NetCat

NetCat (or nc) is a utility that allows you to create TCP and UDP connections. Functionally similar to telnet. Available by default on Unix and macOS, not available on Windows.

1. Open terminal on macOS or Linux.
2. Run the command:

   nc -v example.com 80

   In a team: example.com — IP or address of the site to which you want to connect (specify without http:// or https:// at the beginning and / at the end); 80 — the port on which the connection should be made. There are several useful keys to use the utility:

   • -v — detailed output of information in the course of work.
   • -t — ensuring compatibility with the Telnet protocol.
   • -u — connection via UDP protocol. The default is TCP.
3. Wait for the connection results:
   • If the connection is successful, the following message will appear:

     Connection to example.com 80 port [tcp/http] succeeded!

     Instead http the protocol by which the connection was made will be displayed.

   • If the connection fails, an error message will appear:

     connect to example.com port 80 (tcp) failed: Connection refused

     The error in the response may differ depending on the reason for the termination of the connection.

To get out of nc click Ctrl+C.