vnStat - vnStat is a console-based network traffic monitor for Linux and BSD that keeps a log of network...
iftop - iftop does for network usage what top(1) does for CPU usage.
IPtraf-ng - iptraf-ng is a fork of original iptraf-3.0.0.
darkstat - darkstat is a packet sniffer which runs as a background process, captures network traffic...
nload - Monitor network traffic and bandwidth usage in real time
Zabbix - Track, record, alert and visualize performance and availability of IT resources