Linux Network Monitoring and Tuning
nload - http://www.roland-riegel.de/nload/ and http://www.cyberciti.biz/networking/nload-linux-command-to-monitor-network-traffic-bandwidth-usage/
nmon - http://nmon.sourceforge.net/pmwiki.php
mtr - http://www.bitwizard.nl/mtr/
Socket Stats - ss command. http://www.cyberciti.biz/tips/linux-investigate-sockets-network-connections.html