Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.
SolarWinds IP Address Tracker - SolarWinds IP Address Tracker software, an all-in-one network monitoring utility, provides you with all the visibility you need into what’s connected to your network.
HaCi - HaCi is an IP address / network administration tool with IPv6 support.
Progress WhatsUp Gold - Progress WhatsUp Gold is an all-in-one Network monitoring utility that now offers even more features and functionality to help you monitor your servers, network, and IP address.
Port Authority - A handy systems and security-focused tool, Port Authority is a very fast Android port scanner.
ipplan - IPplan is a free (GPL), web based, multilingual, TCP IP address management (IPAM) software and...