iperf - A TCP, UDP, and SCTP network bandwidth measurement tool
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.
SmokePing - Smokeping is a tool for measuring latency.
NetworkMiner - NetworkMiner is a Network Forensic Analysis Tool (NFAT) for Windows.
PingPlotter - PingPlotter is a troubleshooting tool that helps IT professionals and neophytes identify, diagnose, and resolve network issues.
netcat - Netcat is a featured networking utility which reads and writes data across network connections...