Release of the New Stable Tor 0.4.5 Branch

The Tor Project has announced the release of Tor 0.4.5.6, the toolkit used to operate the anonymous Tor network. Version 0.4.5.6 is the first stable release in the 0.4.5 branch, which has been in development for the past five months. The 0.4.5 branch will be maintained according to the standard support cycle—updates will end either nine months after release or three months after the launch of the 0.4.6.x branch, whichever comes first.

Long-term support (LTS) is provided for the 0.3.5 branch, with updates available until February 1, 2022. Support for branches 0.4.0.x, 0.2.9.x, 0.4.2.x, and 0.4.3 has ended. Support for the 0.4.1.x branch will end on May 20, and for the 0.4.4 branch in June 2021.

Main Updates in Tor 0.4.5

• Tor can now be built as a statically linked library for embedding into other applications.
• Significant improvements in detecting relays that support IPv6. The Address option in torrc now allows specifying IPv6 addresses.
• Relays now automatically bind to IPv6 for ORPorts specified, except those explicitly marked with the IPv4Only flag. The reachability of ORPort over IPv6 is now tracked separately from IPv4.
• Relays supporting IPv6, when connecting to another relay, include both IPv4 and IPv6 addresses in the cell list and randomly select which one to use for the connection.
• A new “MetricsPort” mechanism is available for relay operators to monitor node performance. Node statistics are accessible via an HTTP interface, currently supporting output in Prometheus format.
• Added support for the LTTng tracing system and user-space tracing in USDT (User-space Statically Defined Tracing) mode, which involves building programs with special static tracepoints enabled.
• Performance issues have been resolved for relays running on the Windows platform.

For more information, visit the official Tor Project website.