...Current ESnet development efforts are focused on version 3 of iperf (otherwise known as iperf3), which is available at:
https://github.com/esnet/iperf
http://software.es.net/iperf
Meanwhile, a third party has taken up development and maintenance of iperf2. As of this update (November 2017), this work can be found in the following repository:
https://sourceforge.net/projects/iperf2/