To make that clearer:

using screen open 2 terminals.

In the first one, run "nc -lnvp <port number>", where the port number should be an available one.

In the 2nd one, run the binary with the same port: ./suconnect <port number>

Now: return to the 1st one and type level20's password, and the suconnect command in the other terminal will return the next level password.