Installation of iperf-1.2: # tar zxvf iperf-1.2.tar.gz # cd iperf-1.2 # make # make install This puts iperf exes into /usr/local/bin/. Then do the tests: On ouhep1: # cd tests # ./server On ouhep2: # cd tests # ./client tests ouhep1 ouhep2 Worked; now, change TCP buffer size: # echo 1048576 > /proc/sys/net/core/wmem_max # echo 1048576 > /proc/sys/net/core/rmem_max # cat /proc/sys/net/core/?mem_* To make those sizes permanent, add previous two lines to /etc/rc.d/rc.local And start iperf server on ouhep1: # iperf -s -D -w 2M -m > /var/log/iperf_tcp_server.log # iperf -s -D -w 2M -m -u > /var/log/iperf_udp_server.log To test connection (on ouhep2): # iperf -c ouhep1 -w 2M # iperf -c ouhep1 -w 2M -u Works fine. The default port seems to be 5001 for both TCP and UDP.