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.

Qualys - Qualys helps your business automate the full spectrum of auditing, compliance and protection of your IT systems and web applications.

netcat - Netcat is a featured networking utility which reads and writes data across network connections...

Nessus - Nessus Professional is a security platform designed for businesses who want to protect the security of themselves, their clients, and their customers.

Ettercap - Ettercap is a suite for man in the middle attacks on LAN.

AlienVault USM (from AT&T Cybersecurity) - AlienVault USM Anywhere delivers powerful threat detection, incident response, and compliance management for cloud, on-premises, and hybrid environments.