iperf(1) perform network throughput tests


iperf -s [ options ]

iperf -c server [ options ]

iperf -u -s [ options ]

iperf -u -c server [ options ]


iperf is a tool for performing network throughput measurements. It can test either TCP or UDP throughput. To perform an iperf test the user must establish both a server (to discard traffic) and a client (to generate traffic).


-f, --format
[kmKM] format to report: Kbits, Mbits, KBytes, MBytes
-h, --help
print a help synopsis
-i, --interval n
pause n seconds between periodic bandwidth reports
-l, --len n[KM]
set length read/write buffer to n (default 8 KB)
-m, --print_mss
print TCP maximum segment size (MTU - TCP/IP header)
-o, --output <filename>
output the report or error message to this specified file
-p, --port n
set server port to listen on/connect to to n (default 5001)
-u, --udp
use UDP rather than TCP
-w, --window n[KM]
TCP window size (socket buffer size)
-B, --bind <host>
bind to <host>, an interface or multicast address
-C, --compatibility
for use with older versions does not sent extra msgs
-M, --mss n
set TCP maximum segment size (MTU - 40 bytes)
-N, --nodelay
set TCP no delay, disabling Nagle's Algorithm
-v, --version
print version information and quit
-V, --IPv6Version
Set the domain to IPv6
-x, --reportexclude
[CDMSV] exclude C(connection) D(data) M(multicast) S(settings) V(server) reports
-y, --reportstyle C|c
if set to C or c report results as CSV (comma separated values)


-s, --server
run in server mode
-U, --single_udp
run in single threaded UDP mode
-D, --daemon
run the server as a daemon


-b, --bandwidth n[KM]
set target bandwidth to n bits/sec (default 1 Mbit/sec). This setting requires UDP (-u).
-c, --client <host>
run in client mode, connecting to <host>
-d, --dualtest
Do a bidirectional test simultaneously
-n, --num n[KM]
number of bytes to transmit (instead of -t)
-r, --tradeoff
Do a bidirectional test individually
-t, --time n
time in seconds to transmit for (default 10 secs)
-F, --fileinput <name>
input the data to be transmitted from a file
-I, --stdin
input the data to be transmitted from stdin
-L, --listenport n
port to receive bidirectional tests back on
-P, --parallel n
number of parallel client threads to run
-T, --ttl n
time-to-live, for multicast (default 1)
-Z, --linux-congestion <algo>
set TCP congestion control algorithm (Linux only)


Controls the size of TCP buffers.


This section needs to be filled in.


Exit statuses are inconsistent. The threading implementation is rather heinous.


Iperf was originally written by Mark Gates and Alex Warshavsky. Man page and maintence by Jon Dugan <jdugan at x1024 dot net>. Other contributions from Ajay Tirumala, Jim Ferguson, Feng Qin, Kevin Gibbs, John Estabrook <jestabro at ncsa.uiuc.edu>, Andrew Gallatin <gallatin at gmail.com>, Stephen Hemminger <shemminger at linux-foundation.org>