iftop - iftop does for network usage what top(1) does for CPU usage.
iperf - A TCP, UDP, and SCTP network bandwidth measurement tool
ntop - ntopng High-Speed Web-based Traffic Analysis and Flow Collection ntopng is the next generation version of the original ntop, a network traffic probe that monitors network usage. ntopng is based on …
netperf - Netperf is a benchmark that can be used to measure the performance of many different types of networking. It provides tests for both unidirectional throughput, and end-to-end latency. - HewlettPack...
IPtraf-ng - iptraf-ng is a fork of original iptraf-3.0.0.
TamoSoft Throughput Test - TamoSoft Throughput Test is a utility for testing the performance of a wireless or wired network.