iperf-3.19 2025-05-16

• Notable user-visible changes

  • iperf3 now supports the use of Multi-Path TCP (MPTCPv1) on Linux with the use of the -m or --mptcp flag. (PR #1661)

  • iperf3 now supports a --cntl-ka option to enable TCP keepalives on the control connection. (#812, #835, PR #1423)

  • iperf3 now supports the MSG_TRUNC receive option, specified by the --skip-rx-copy. This theoretically improves the rated throughput of tests at high bitrates by not delivering network payload data to userspace. (#1678, PR #1717)

  • A bug that caused the bitrate setting to be ignored when bursts are set, has been fixed. (#1773, #1820, PR #1821, PR #1848)

  • The congestion control protocol setting, if used, is now properly reset between tests. (PR #1812)

  • iperf3 now exits with a non-error 0 exit code if exiting via a SIGTERM, SIGHUP, or SIGINT. (#1009, PR# 1829)

  • The current behavior of iperf3 with respect to the -n and -k options is now documented as correct. (#1768, #1775, #596, PR #1800)

• Notable developer-visible changes

  • iperf3 now supports a callback function to get the JSON output strings. (#1711, PR #1798)

  • iperf3 now builds correctly with gcc-15 (#1838, PR #1805)

  • Various memory leaks were fixed (#1881, PR#1823, #1814, PR#1822)

  • A potential segfault crash was fixed (#1807)

  • Improved warning messages when reading malformed JSON messages (PR #1817)

  • The Github CI configuration was changed to use a more up-to-date set of runners (PR #1864)