iperf is free open-source command-line utility for measuring network performance. It is available for Linux, Windows and macOS. It can be used in both client and server mode.

Install iperf

• Ubuntu: sudo apt-get install -y iperf
• macOS: brew install iperf
• Windows: download here

Server mode

To run iperf in server mode, run the following command:

iperf -s

It listens to TCP port 5001 by default. You change this by specifying the -p parameter.

If you are doing wireless network performance monitoring, then you probably want to run iperf in server mode on a device with a wired ethernet connection.

Client mode

To run iperf in client mode, run the following command:

iperf -c <SERVER_IP>

The default behavior is that the client will send and the server will receive. You can change this behavior by specifying the -R parameter.

Options

There are plenty of options you can use. Use iperf --help to list all available options.

Below some useful options are listed.

Server

• -p specify the port to listen to.
  Example: to have iperf listen on port 5551, use iperf -s -p 5551

Client

• -t specify the duration of the test.
  Example: iperf -c <SERVER_IP> -t 10
• -i specify the interval between reports.
  Example: iperf -c <SERVER_IP> -t 30 -i 5
• -R reverse the test so that the server receives and the client sends.