1IPERF3(1) User Manuals IPERF3(1)
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6 iperf3 - perform network throughput tests
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9 iperf3 -s [ options ]
10 iperf3 -c server [ options ]
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14 iperf3 is a tool for performing network throughput measurements. It
15 can test TCP, UDP, or SCTP throughput. To perform an iperf3 test the
16 user must establish both a server and a client.
17 The iperf3 executable contains both client and server functionality.
19 An iperf3 server can be started using either of the -s or --server com‐
20 mand-line parameters, for example:
21 iperf3 -s
23 iperf3 --server
25 Note that many iperf3 parameters have both short (-s) and long
27 (--server) forms. In this section we will generally use the short form
28 of command-line flags, unless only the long form of a flag is avail‐
29 able.
30 By default, the iperf3 server listens on TCP port 5201 for connections
32 from an iperf3 client. A custom port can be specified by using the -p
33 flag, for example:
34 iperf3 -s -p 5002
36 After the server is started, it will listen for connections from iperf3
38 clients (in other words, the iperf3 program run in client mode). The
39 client mode can be started using the -c command-line option, which also
40 requires a host to which iperf3 should connect. The host can by speci‐
41 fied by hostname, IPv4 literal, or IPv6 literal:
42 iperf3 -c iperf3.example.com
44 iperf3 -c 192.0.2.1
46 iperf3 -c 2001:db8::1
48 If the iperf3 server is running on a non-default TCP port, that port
50 number needs to be specified on the client as well:
51 iperf3 -c iperf3.example.com -p 5002
53 The initial TCP connection is used to exchange test parameters, control
55 the start and end of the test, and to exchange test results. This is
56 sometimes referred to as the "control connection". The actual test
57 data is sent over a separate TCP connection, as a separate flow of UDP
58 packets, or as an independent SCTP connection, depending on what proto‐
59 col was specified by the client.
60 Normally, the test data is sent from the client to the server, and mea‐
62 sures the upload speed of the client. Measuring the download speed
63 from the server can be done by specifying the -R flag on the client.
64 This causes data to be sent from the server to the client.
65 iperf3 -c iperf3.example.com -p 5202 -R
67 Results are displayed on both the client and server. There will be at
69 least one line of output per measurement interval (by default a mea‐
70 surement interval lasts for one second, but this can be changed by the
71 -i option). Each line of output includes (at least) the time since the
72 start of the test, amount of data transferred during the interval, and
73 the average bitrate over that interval. Note that the values for each
74 measurement interval are taken from the point of view of the endpoint
75 process emitting that output (in other words, the output on the client
76 shows the measurement interval data for the client.
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