Wireshark is an open source network sniffing utility to analyze network traffic.

Cain & Abel is a password recovery tool for Microsoft Operating Systems.

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

tcpdump uses the libpcap library to capture packets.

Acrylic WiFi is a free WiFi scanner designed to scan wireless networks and view WLAN channels, signal, traffic and security.