Glossary
Listener
The program the tester runs to receive an incoming reverse shell connection, commonly netcat, ncat, or socat.
A listener is the receiving end of a reverse shell: the program the tester runs to accept the target's inbound connection and provide an interactive session. The canonical example is netcat:
nc -lvnp 443
The listener must match the payload: a TLS payload needs a TLS listener, and a staged payload needs a full handler rather than plain netcat. Listener-vs-payload mismatch is one of the most common reasons a shell connects and immediately dies — see choosing a listener.