iperf3 Project News

2024-05-13: ipef-3.17.1 released

SHA256: 84404ca8431b595e86c473d8f23d8bb102810001f15feaf610effd3b318788aa

iperf-3.17.1 fixes some issues with version numbers in various places. It is otherwise identical to iperf-3.17.

2024-05-10: iperf-3.17 released

SHA256: 077ede831b11b733ecf8b273abd97f9630fd7448d3ec1eaa789f396d82c8c943

iperf 3.17 contains a fix for a minor security vulnerability related to iperf3’s authentication feature and its use of RSA-encrypted credentials. The release notes contain more details on this breaking change, and how to revert to older, less secure behavior if needed for backward compatibility with older versions of iperf3.

This version also contains a new streaming JSON output format (enabled with the –json-stream) option, and a number of other bug fixes.

2023-12-01: iperf-3.16 released

SHA256: cc740c6bbea104398cc3e466befc515a25896ec85e44a662d5f4a767b9cf713e

iperf 3.16 uses multiple threads to serve parallel tests for improved throughput on high-speed links. It also includes support for OpenSSL 3. More details are provided in the release notes.

2023-09-14: iperf-3.15 released

SHA256: bdb77c11f72bce90214883159577fa24412013e62b2083cf5f54391d79b1d8ff

iperf 3.15 fixes that could cause an iperf3 server process to hang waiting for input on the control connection. For more information, please see:


This version of iperf3 also includes several other minor bug fixes, which are summarized in the release notes.

2023-07-07: iperf-3.14 released

SHA256: 723fcc430a027bc6952628fa2a3ac77584a1d0bd328275e573fc9b206c155004

iperf 3.14 fixes a memory allocation hazard that allowed a remote user to crash an iperf3 process (server or client).

More information on this specific fix can be found at:


This version of iperf3 also includes a number of minor bug fixes, which are summarized in the release notes.

2023-02-16: iperf-3.13 released

SHA256: bee427aeb13d6a2ee22073f23261f63712d82befaa83ac8cb4db5da4c2bdc865

iperf 3.13 is primarily a bugfix release.

2022-09-30: iperf-3.12 released

SHA256: 72034ecfb6a7d6d67e384e19fb6efff3236ca4f7ed4c518d7db649c447e1ffd6

iperf 3.12 is principally a bugfix release, although it includes an updated version of cJSON and adds a few new features.

2022-01-28: iperf-3.11 released

SHA256: de8cb409fad61a0574f4cb07eb19ce1159707403ac2dc01b5d175e91240b7e5f

iperf 3.11 is principally a bugfix release. Also GitHub Discussions are now supported.

2021-06-02: iperf-3.10.1 released

SHA256: 03bc9760cc54a245191d46bfc8edaf8a4750f0e87abca6764486972044d6715a  iperf-3.10.1.tar.gz

iperf 3.10.1 fixes a problem with the configure script that made it make not work correctly in some circumstances. It is functionally identical to iperf 3.10.

2021-05-26: iperf-3.10 released

SHA256: 4390982928542256c17d6dd1f56eede9092649ebfd8a97c8cecfad12d238ad57  iperf-3.10.tar.gz

iperf 3.10 is principally a bugfix release. A few new features have been added (--time-skew-threshold, --bind-dev, --rcv-timeout, and --dont-fragment). More information on these new features can be found in the release notes.

2020-08-17: iperf-3.9 released

SHA256: 24b63a26382325f759f11d421779a937b63ca1bc17c44587d2fcfedab60ac038  iperf-3.9.tar.gz

iperf 3.9 adds a --timestamps flag, which prepends a timestamp to each output line. A new --server-bitrate-limit flag has been added as a server command-line argument, and allows an iperf3 server to enforce a maximum throughput rate. More information on these new features can be found in the release notes.

2020-06-10: iperf-3.8.1 released

SHA256: e5b080f3273a8a715a4100f13826ac2ca31cc7b1315925631b2ecf64957ded96 iperf-3.8.1.tar.gz

iperf 3.8.1 fixes a regression with make install in iperf 3.8. It is otherwise identical to iperf 3.8.

2020-06-08: iperf-3.8 released

SHA256: edc1c317b0ae31925e5eb84f0295faefbaa1db3229f4693e11d954d114de4bcd  iperf-3.8.tar.gz

iperf 3.8 contains minor bugfixes and enhancements.

2019-06-21: iperf-3.7 released

SHA256: d846040224317caf2f75c843d309a950a7db23f9b44b94688ccbe557d6d1710c  iperf-3.7.tar.gz

iperf 3.7 adds the --bidir flag for bidirectional tests, includes some minor enhancements, and fixes a number of bugs. More details can be found in the release notes.

Note: Documentation for the --bidir flag was inadvertently omitted from the manual page. This will be fixed in a future release.

2018-06-25: iperf-3.6 released

SHA256: de5d51e46dc460cc590fb4d44f95e7cad54b74fea1eba7d6ebd6f8887d75946e  iperf-3.6.tar.gz

iperf 3.6 adds the --extra-data and --repeating-payload options and fixes some minor bugs.

2018-03-02: iperf-3.5 released

SHA256: 539bd9ecdca1b8c1157ff85b70ed09b3c75242e69886fc16b54883b399f72cd5  iperf-3.5.tar.gz

iperf 3.5 fixes a bug that could over-count data transfers (and hence measured bitrate).

2018-02-14: iperf-3.4 released

SHA256: 71528332d751df85e046d1944d9a0269773cadd6e51840aecdeed30925f79111  iperf-3.4.tar.gz

iperf 3.4 fixes a number of minor bugs and adds a few enhancements.

2017-10-31: iperf-3.3 released

SHA256: 6f596271251056bffc11bbb8f17d4244ad9a7d4a317c2459fdbb853ae51284d8  iperf-3.3.tar.gz

New minor release of iperf 3.3, fixing a number of minor bugs.

2017-06-26: iperf-3.2 released

SHA256: f207b36f861485845dbdf09f909c62f3d2222a3cf3d2682095aede8213cd9c1d  iperf-3.2.tar.gz

New minor release of iperf 3.2, with new features, bugfixes, and enhancements.

2017-06-06: iperf3 update, June 2017


2017-04-27: iperf3 update, April 2017


2017-03-06: iperf-3.1.7 released

SHA256: a4ef73406fe92250602b8da2ae89ec53211f805df97a1d1d629db5a14043734f  iperf-3.1.7.tar.gz

This version of iperf3 contains two documentation fixes, but is otherwise identical to the prior release.

2017-02-02: iperf-3.1.6 released

SHA256: 70f0c72d9e60c6ecb2c478ed17e4fd81d3b827d57896fee43bcd0c53abccb29d  iperf-3.1.6.tar.gz

This version of iperf3 contains two minor fixes. Notably, one of them unbreaks JSON output with UDP tests.

2017-01-12: iperf-3.1.5 released

SHA256: 6e1a6200cd38baeab58ef0d7b8769e7aa6410c3a3168e65ea8277a4de79e5500  iperf-3.1.5.tar.gz

This version of iperf3 makes some improvements to the fair-queue-based pacing and improves the selection of the default UDP packet size. Users who use either of these aspects of iperf3 are encourage to review the release notes for this version.

2016-10-31: iperf-3.1.4 released

SHA256: db61d70ac62003ebe0bf15496bd8c4b3c4b728578a44d0a1a88fcf8afc0e8f76  iperf-3.1.4.tar.gz

This release fixes a few minor bugs, including a (non-security-impacting) buffer overflow fix ported from upstream cjson.

2016-06-08: Security Issue: iperf-3.1.3, iperf-3.0.12 released

SHA256: 60d8db69b1d74a64d78566c2317c373a85fef691b8d277737ee5d29f448595bf  iperf-3.1.3.tar.gz
SHA256: 9393d646e4e616f0cd7864bc8ceacc379f5d36b08003a3d8d65cd7c99d15daec  iperf-3.0.12.tar.gz

These releases address a security issue that could cause a crash of an iperf3 process (it could theoretically lead to a remote code execution). Although the risk for common use cases is believed to be low, all users are encouraged to update to these versions or newer as soon as possible. More information on the security vulnerability can be found in the following ESnet Software Security Advisory:


iperf-3.1.3 also includes support for fair-queueing, per-socket based pacing of tests on platforms that support it (currently recent Linux distributions), as well as several other fixes.

2016-02-01: iperf-3.1.2 released

SHA256: f9dbdb99f869c077d14bc1de78675f5e4b8d1bf78dc92381e96c3eb5b1fd7d86  iperf-3.1.2.tar.gz

This release fixes a couple of minor bugs, including one that results in invalid JSON being emitted for UDP tests.

Older News

2015-11-19: iperf-3.1.1 released

SHA256: 62f7c64eafe19046ba974b3ef2d962a5597194d6fbbddde328a15a5e74110564  iperf-3.1.1.tar.gz

This release fixes a few minor bugs.

2015-10-16: iperf3 Development Status

Beginning with the release of iperf 3.1, ESnet plans to support iperf3 in “maintenance mode”. At this point, we have no definite plans for further iperf3 releases, and ESnet will be providing a very limited amount of resources for support and development, going forward. However, ESnet could issue new iperf3 releases to deal with security issues or high-impact bug fixes.

Requests for support, enhancements, and questions should best be directed to the iperf-dev mailing list. ESnet would be open to adding project members/committers from the community, in case there are developers who are interested in doing more active work with iperf3 and/or supporting the user base.

2015-10-16: iperf-3.1 released

SHA256: 4385a32ece25cb09d4606b4c99316356b3d2cb03b318aa056b99cdb91c5ce656  iperf-3.1.tar.gz

This release adds support for SCTP on supported platforms, better feature detection on FreeBSD, better compatibility with various platforms, and a number of bug fixes.

2015-01-09: iperf-3.0.11 released

SHA256: e01db5be6f47f67c987463095fe4f5b8b9ff891fb92c39104d042ad8fde97f6e  iperf-3.0.11.tar.gz

This maintenance release adds a -1 flag to make the iperf3 execute a single test and exit, needed for an upcoming bwctl release. A few other bugs are also fixed.

2014-12-16: iperf-3.0.10 released

SHA256: a113442967cf0981b0b2d538be7c88903b2fb0f87b0d281384e41b462e33059d  iperf-3.0.10.tar.gz

This maintenance release fixes building on MacOS X Yosemite, as well as making the -w option work correctly with UDP tests.

2014-10-14: iperf-3.0.9 released

SHA256: 40249a2b30d26b937350b969bcb19f88e1beb356f886ed31422b554bac692459  iperf-3.0.9.tar.gz

This maintenance release fixes an issue for a situation in which attempting a UDP test with pathologically large (and illegal) packet sizes could put the iperf3 server in a state where it would stop accepting connections from clients, thus causing the clients to crash when interrupted.

2014-09-30: iperf-3.0.8 released

SHA256: 81b8d91159862896c57f9b90a006e8b5dc22bd94175d97bd0db50b0ae2c1a78e  iperf-3.0.8.tar.gz

This maintenance release is functionally identical to 3.0.7. It incorporates updated license verbage and a minor compilation fix.

2014-08-28: iperf-3.0.7 released

SHA256: 49510e886f9e876cd73dcd80414bfb8c49b147c82125585e09c2a6e92369d3f2  iperf-3.0.7.tar.gz

This maintenance release fixes several minor bugs. Of particular note:

  • A bug that caused some problems with bwctl / perfSONAR has been fixed.

  • A bug that made it possible to disrupt existing, running tests has been fixed.

2014-07-28: iperf-3.0.6 released

SHA256: 3c5909c9b286b6503ffa141a94cfc588915d6e67f2aa732b08df0af73e21938  iperf-3.0.6.tar.gz

This maintenance release includes the following bug fixes:

  • Several problems with the -B option have been fixed. Also, API calls have been added to libiperf to extend this functionality to API clients.

  • Some portability fixes for OpenBSD and Solaris have been merged from the mainline.

As always, more details can be found in the RELNOTES.md file in the source distribution.

2014-06-16: Project documentation on GitHub Pages

iperf3 project documentation can now be found at:

This is a GitHub Pages site. In an ongoing series of steps, content will be migrated from the iperf3 wiki to GitHub Pages.

2014-06-16: iperf-3.0.5 released

SHA256: e1e1989985b17a4c03b0fa207004ad164b137e37ab0682fecbf5e93bcaa920a6  iperf-3.0.5.tar.gz

This is the third maintenance release of iperf 3, with few more enhancements and bug fixes. Highlights:

  • A timing issue which caused measurement intervals to be wrong with TCP tests on lossy networks has been fixed.

  • It is now possible to get (most of) the server-side output at the client by using the --get-server-output flag.

  • A number of bugs with --json output have been fixed.

A more extensive list of changes can always be found in the RELNOTES.md file in the source distribution.

Note: An iperf-3.0.4 release was planned and tagged, but not officially released.

2014-06-10: New iperf3 download site

iperf3 downloads are now hosted on a new server at ESnet:

Going forward, new releases will be made available in this directory. Older releases will, at least for now, continue to also be available at the previous location.

2014-03-26: iperf-3.0.3 released

SHA256: 79daf3e5e5c933b2fc4843d6d21c98d741fe39b33ac05bd7a11c50d321a2f59d  iperf-3.0.3.tar.gz

This is the second maintenance release of iperf 3.0, containing a few bug fixes and enhancements, notably:

  • The structure of the JSON output is more consistent between the cases of one stream and multiple streams.

  • The example programs once again build correctly.

  • A possible buffer overflow related to error output has been fixed. (This is not believed to be exploitable.)

More information on changes can be found in the RELNOTES.md file in the source distribution.

2014-03-10: iperf-3.0.2 released

SHA256: 3c379360bf40e6ac91dfc508cb43fefafb4739c651d9a8d905a30ec99095b282  iperf-3.0.2.tar.gz

Note: Due to a mistake in the release process, the distribution tarball referred to above is actually not compressed, despite its .tar.gz extension. Instead it is an uncompressed tar archive. The file checksum is correct, as are the file contents.

This version is a maintenance release that fixes a number of bugs, many reported by users, adds a few minor enhancements, and tracks the migration of the iperf3 project to GitHub. Of particular interest:

  • Build / runtime fixes for CentOS 5, MacOS 10.9, and FreeBSD.

  • TCP snd_cwnd output on Linux in the default output format.

  • libiperf is now built as both a shared and static library; by default, the iperf3 binary links to the shared library.

More information on changes can be found in the RELNOTES.md file in the source distribution.

2014-02-28: iperf migrated to GitHub

The new project page can be found at:


2014-01-10: iperf-3.0.1 released

SHA256: 32b419ef634dd7670328c3cecc158babf7d706bd4b3d248cf95965528a20e614 iperf-3.0.1.tar.gz

During development, there were various distributions of the source code unofficially released carrying a 3.0.0 version number. Because of the possibility for confusion, this first public release of iperf3 was numbered 3.0.1.