Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.

Zabbix - Track, record, alert and visualize performance and availability of IT resources

AirGrab WiFi Radar - AirGrab WiFi Radar is a WiFi scanning tool that is used for showing information about Apple AirPort based stations and other WiFi connections and access points.

Abusix - Abusix is a network security company that offers email threat protection and network abuse handling solutions to ISPs, Telcos, and Cloud/Hosting Providers to stop the rapidly growing problem of email-borne threats and other kinds of network abuse.

Lizard Systems WiFi Scanner - Lizard Systems WiFi Scanner is a multi purpose WiFi scanner and WiFi troubleshooting tool designed for dealing with all WiFi related issues conveniently.

FastNetMon - FastNetMon is a very fast DDoS analyzer with sflow/netflow/mirror support.