New release: Tor 0.4.1.5 nickm August 20, 2019

After months of work, we have a new stable release series! If you build Tor from source, you can download the source code for 0.4.1.5 on the website. Packages should be available within the next several weeks, with a new Tor Browser in early September.

This is the first stable release in the 0.4.1.x series. This series adds experimental circuit-level padding, authenticated SENDME cells to defend against certain attacks, and several performance improvements to save on CPU consumption. It fixes bugs in bootstrapping and v3 onion services. It also includes numerous smaller features and bugfixes on earlier versions.

Per our support policy, we will support the 0.4.1.x series for nine months, or until three months after the release of a stable 0.4.2.x: whichever is longer. If you need longer-term support, please stick with 0.3.5.x, which will we plan to support until Feb 2022.

Below are the changes since 0.4.0.5. For a list of only the changes since 0.4.1.4-rc, see the ChangeLog file.

Changes in version 0.4.1.5 - 2019-08-20

  • Directory authority changes:
    • The directory authority "dizum" has a new IP address. Closes ticket 31406.
  • Major features (circuit padding):
    • Onion service clients now add padding cells at the start of their INTRODUCE and RENDEZVOUS circuits, to make those circuits' traffic look more like general purpose Exit traffic. The overhead for this is 2 extra cells in each direction for RENDEZVOUS circuits, and 1 extra upstream cell and 10 downstream cells for INTRODUCE circuits. This feature is only enabled when also supported by the circuit's middle node. (Clients may specify fixed middle nodes with the MiddleNodes option, and may force-disable this feature with the CircuitPadding option.) Closes ticket 28634.