tcpdump uses the libpcap library to capture packets.

Intercepter-NG is a multifunctional network toolkit for various types to recover interesting data from the network stream and perform different kinds of MiTM …

PRTG is a network monitoring tool that helps you to ensure that your computer systems are running smoothly and that no outages occur.

Kismet is a wireless network detector, sniffer, and intrusion detection system.