iperf

Run on server

$ iperf [[-s|--server]]

$ iperf [[-u|--udp]] [[-s|--server]] [[-p|--port]] [5001]

$ iperf [[-c|--client]] [server_address]

$ iperf [[-c|--client]] [server_address] [[-i|--interval]] [2]

$ iperf [[-c|--client]] [server_address] [[-P|--parallel]] [5]

$ iperf [[-u|--udp]] [[-c|--client]] [server_address] [[-p|--port]] [5001]

iperf [-s|-c host] [options]

-s
    Run in server mode, listening for connections on a specified port.

-c host
    Run in client mode, connecting to the server at 'host'.

-p port
    Specify the port number to use. Default is 5201.

-u
    Use UDP instead of TCP.

-b bandwidth
    Set target bandwidth in bits/sec. (UDP only)

-t time
    Set the duration of the test, in seconds. Default is 10 seconds.

-i interval
    Set the reporting interval, in seconds. Default is 1 second.

-f format
    Format to report: 'k' (KBytes), 'm' (MBytes), 'g' (GBytes). Default is 'm' for TCP and 'k' for UDP

-n num
    Number of bytes to transmit (instead of -t).

-l length
    Set the length of read/write buffers. Default 8 KB.

-w size
    TCP window size (socket buffer size). Auto determines if not set.

-M MSS
    TCP maximum segment size (MTU - 40 bytes).

iperf is a widely used command-line tool for performing network throughput measurements.
It allows users to test the bandwidth between two nodes, one acting as a server and the other as a client.
iperf supports various protocols, including TCP, UDP, and SCTP, and offers options to adjust buffer sizes, window sizes, and transport settings.
This makes it a versatile tool for diagnosing network performance issues, identifying bottlenecks, and verifying network configurations.
With iperf, you can quickly assess the achievable bandwidth, packet loss, and latency of a network connection.
It is commonly employed by network administrators, developers, and researchers to ensure network stability and optimize data transfer rates.
Its simplicity and flexibility have made it a standard tool for network performance analysis across diverse platforms.

iperf provides a measurement of achievable bandwidth between two points. It does not guarantee actual application throughput, as many factors can influence the actual throughput of an application (e.g. application layer protocol overhead).

Ensure firewalls allow traffic on the selected port.
Run tests multiple times and average results to account for network variability.
For accurate UDP tests, consider adjusting the bandwidth parameter (-b) to avoid exceeding network capacity.

iperf was originally developed by NLANR/DAST as a tool for measuring network performance. It has evolved through various versions and is now maintained and distributed by different projects. The tool became popular and widely used for network benchmarking and troubleshooting.

tcpdump(1), netstat(1), ping(1)