Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.
Fping (open source) - fping is a program to send ICMP echo probes to network hosts, similar to ping, but much better performing when pinging multiple hosts.
Eusing Free IP Scanner - Free IP Scanner: a very fast IP scanner and port scanner.
NetCrunch Tools - Our free network tools offer ping scanning, SNMP scanning, port and network service scanning, and more.
Angry IP Scanner - Open-source and cross-platform network scanner designed to be fast and simple to use
NetTK - NetTK, Network Tool Kit, is an Open Source alternative for monitoring and troubleshooting your...