iperf flags & options

-s, --server

Run in server mode, listening for connections.

iperf3 -s

-c, --client

Run in client mode, connecting to a server.

iperf3 -c 192.168.1.100

-p, --port

Set the server port. Default is 5201.

iperf3 -s -p 9000

iperf3 -c 192.168.1.100 -p 9000

-t, --time

Set the test duration in seconds. Default is 10.

iperf3 -c 192.168.1.100 -t 30

-P, --parallel

Run multiple parallel streams.

iperf3 -c 192.168.1.100 -P 4

-R, --reverse

Reverse the test direction (server sends, client receives).

iperf3 -c 192.168.1.100 -R

-u, --udp

Use UDP instead of TCP.

iperf3 -c 192.168.1.100 -u

-b, --bandwidth

Set target bandwidth. Default is 1 Mbit/s for UDP, unlimited for TCP.

iperf3 -c 192.168.1.100 -u -b 100M

-i, --interval

Set the reporting interval in seconds.

iperf3 -c 192.168.1.100 -i 0.5

-J, --json

Output results as JSON.

iperf3 -c 192.168.1.100 -J