In this article we are going to see how we can use iperf3.

What is iperf3?

Iperf is a network speed test utilities. It is more accurate than speedtest-cli and you can define your server to test with.

  • Default iperf3 server listens on TCP port 5201
  • Iperf has client mode & server mode
  • Client mode create request to test with server.
  • Server mode runs in background to receive request for speed test.

Why iperf3?

  • Network speed test in cli
  • Intranet speed test
  • Testing speed among different type of network in same organization or in different part of the world.


  • Install via APT

       sudo apt-get update &&  sudo apt-get install -y iperf3       	
  • Manually install, download from here

Run iperf3 server

	iperf3 -s 

Run iperf3 server in Background

	iperf3 -s D

Run iperf3 client to test

	iperf3 -c ip_or_address_of_server

Iperf3 Testing Example

	iperf3 -c


Create iperf3 service in linux

Create a file iperf3.service at /etc/systemd/system/ or $HOME/.config/systemd/user/iperf3.service location

# /etc/systemd/system/iperf3.service
# User service: $HOME/.config/systemd/user/iperf3.service

Description=iperf3 server auditd.service

ExecStart=/usr/bin/iperf3 -s


And run the service :

sudo systemctl daemon-reload
sudo systemctl enable iperf3.service
sudo systemctl start iperf3
sudo systemctl status iperf3

if you want log for this service (optional) :

sudo journalctl -f -u iperf3

More Options

There are more CLI options, here is the whole list.

Usage: iperf [-s|-c host] [options]
	   iperf [-h|--help] [-v|--version]

Server or Client:
  -p, --port      #         server port to listen on/connect to
  -f, --format    [kmgKMG]  format to report: Kbits, Mbits, KBytes, MBytes
  -i, --interval  #         seconds between periodic bandwidth reports
  -F, --file name           xmit/recv the specified file
  -A, --affinity n/n,m      set CPU affinity
  -B, --bind      <host>    bind to a specific interface
  -V, --verbose             more detailed output
  -J, --json                output in JSON format
  --logfile f               send output to a log file
  -d, --debug               emit debugging output
  -v, --version             show version information and quit
  -h, --help                show this message and quit
Server specific:
  -s, --server              run in server mode
  -D, --daemon              run the server as a daemon
  -I, --pidfile file        write PID file
  -1, --one-off             handle one client connection then exit
Client specific:
  -c, --client    <host>    run in client mode, connecting to <host>
  -u, --udp                 use UDP rather than TCP
  -b, --bandwidth #[KMG][/#] target bandwidth in bits/sec (0 for unlimited)
							(default 1 Mbit/sec for UDP, unlimited for TCP)
							(optional slash and packet count for burst mode)
  -t, --time      #         time in seconds to transmit for (default 10 secs)
  -n, --bytes     #[KMG]    number of bytes to transmit (instead of -t)
  -k, --blockcount #[KMG]   number of blocks (packets) to transmit (instead of -t or -n)
  -l, --len       #[KMG]    length of buffer to read or write
							(default 128 KB for TCP, 8 KB for UDP)
  --cport         <port>    bind to a specific client port (TCP and UDP, default: ephemeral port)
  -P, --parallel  #         number of parallel client streams to run
  -R, --reverse             run in reverse mode (server sends, client receives)
  -w, --window    #[KMG]    set window size / socket buffer size
  -C, --congestion <algo>   set TCP congestion control algorithm (Linux and FreeBSD only)
  -M, --set-mss   #         set TCP/SCTP maximum segment size (MTU - 40 bytes)
  -N, --no-delay            set TCP/SCTP no delay, disabling Nagle's Algorithm
  -4, --version4            only use IPv4
  -6, --version6            only use IPv6
  -S, --tos N               set the IP 'type of service'
  -L, --flowlabel N         set the IPv6 flow label (only supported on Linux)
  -Z, --zerocopy            use a 'zero copy' method of sending data
  -O, --omit N              omit the first n seconds
  -T, --title str           prefix every output line with this string
  --get-server-output       get results from server
  --udp-counters-64bit      use 64-bit counters in UDP test packets
  --no-fq-socket-pacing     disable fair-queuing based socket pacing
							(Linux only)