This is the old, Iperf 2 code base. The primary development has moved to Iperf 3 which is hosted on Google Code. You can find it here: http://code.google.com/p/iperf/.
Iperf was developed by NLANR/DAST as a modern alternative for measuring maximum TCP and UDP bandwidth performance. Iperf allows the tuning of various parameters and UDP characteristics. Iperf reports bandwidth, delay jitter, datagram loss.