Install iperf
cd /usr/local/src
wget http://internap.dl.sourceforge.net/sourceforge/iperf/iperf-2.0.4.tar.gz
tar xvfz iperf-2.0.4.tar.gz
cd iperf-2.0.4
./configure && make && make install
Test your server's bandwidth
To test the bandwidth between your server and IPerf.wiscnet.net with an interval of every two seconds and a total of twenty second of testing:
iperf -c IPerf.wiscnet.net -i2 -t 20
------------------------------------------------------------
Client connecting to IPerf.wiscnet.net, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 38.99.248.82 port 33408 connected with 205.213.110.244 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0- 2.0 sec 1.35 MBytes 5.67 Mbits/sec
[ ID] Interval Transfer Bandwidth
[ 3] 2.0- 4.0 sec 1.50 MBytes 6.29 Mbits/sec
[ ID] Interval Transfer Bandwidth
[ 3] 4.0- 6.0 sec 1.53 MBytes 6.42 Mbits/sec
[ ID] Interval Transfer Bandwidth
[ 3] 6.0- 8.0 sec 1.56 MBytes 6.55 Mbits/sec
[ ID] Interval Transfer Bandwidth
[ 3] 8.0-10.0 sec 1.49 MBytes 6.26 Mbits/sec
[ ID] Interval Transfer Bandwidth
[ 3] 10.0-12.0 sec 1.50 MBytes 6.29 Mbits/sec
[ ID] Interval Transfer Bandwidth
[ 3] 12.0-14.0 sec 1.56 MBytes 6.55 Mbits/sec
[ ID] Interval Transfer Bandwidth
[ 3] 14.0-16.0 sec 1.52 MBytes 6.36 Mbits/sec
[ ID] Interval Transfer Bandwidth
[ 3] 16.0-18.0 sec 1.52 MBytes 6.39 Mbits/sec
[ ID] Interval Transfer Bandwidth
[ 3] 18.0-20.0 sec 1.51 MBytes 6.32 Mbits/sec
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-20.0 sec 15.1 MBytes 6.32 Mbits/sec