-f, --format

[kmKM] format to report: Kbits, Mbits, KBytes, MBytes

-i, --interval

# seconds between periodic bandwidth reports

-l, --len

#[KM] length of buffer to read or write (default 8 KB)

-m, --print_mss

print TCP maximum segment size (MTU - TCP/IP header)

-p, --port

# server port to listen on/connect to

-u, --udp

use UDP rather than TCP

-w, --window

#[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

# set TCP maximum segment size (MTU - 40 bytes)

-N, --nodelay

set TCP no delay, disabling Nagle's Algorithm

-V, --IPv6Version

Set the domain to IPv6

-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 #[KM]

for UDP, bandwidth to send at in bits/sec (default 1 Mbit/sec, implies -u)

-c, --client

<host> run in client mode, connecting to <host>

-d, --dualtest

Do a bidirectional test simultaneously

-n, --num

#[KM] number of bytes to transmit (instead of -t)

-r, --tradeoff

Do a bidirectional test individually

-t, --time

# 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 #

port to recieve bidirectional tests back on

-P, --parallel

# number of parallel client threads to run

-T, --ttl

# time-to-live, for multicast (default 1)

-h, --help

print this message and quit

-v, --version

print version information and quit

[KM] Indicates options that support a K or M suffix for kilo- or mega-

The TCP window size option can be set by the environment variable TCP_WINDOW_SIZE. Most other options can be set by an environment variable IPERF_<long option name>, such as IPERF_BANDWIDTH.