The State of IPv6 support on the Tor network

In our last article, published in RIPE's website, we described the work that happened in 2020 related to giving IPv6 support to the Tor network.

Tor 0.4.5.1-alpha is the first release that includes all the work described in the RIPE article. Relays running 0.4.5.1-alpha are the first to report IPv6 bandwidth statistics.

 

As of December 2, 2020, 54% of the relays on the network run a version of Tor that supports IPv6. Of the 6852 relays in the network, 3587 are running version 0.4.4 and 8 relays are running the latest Tor version 0.4.5. From all those, 1588 are announcing an IPv6 address and port for the OR protocol. 1587 relays are reachable on IPv6 by the directory authorities. 626 permit exiting to IPv6 targets.

 

 The latest consensus published in November contains:

• 6538 relays:
  • 1562 of these (36.39% TCW) have an IPv6 ORPort.
  • 1067 of these (24.86% TCW) support at least partial IPv6 reachability checks.
  •  55 of these (1.90% TCW) support full IPv6 reachability checks.
• 2527 "usable guards" and Wgd=0.
  • 641 of these (29.73% UGCW) support IPv6 clients.
  • 446 of these (21.33% UGCW) support at least partial IPv6 reachability checks.
  • 36 of these (2.92% UGCW) support full IPv6 reachability checks.

 

 

The IPv6 stats that we are collecting are:

• the number of Tor relays that support IPv6 reachability checks (full versus partial).

• the number of Tor relays that have an IPv6 ORPort.

• the number of connections, and consumed bandwidth, using IPv4 and IPv6. 

• IPv6 bandwidth statistics.

 

Reminder that for relays to report IPv6 bandwidth statistics, they would have to set the option ConnDirectionStatistics to 1 and leave the ExtraInfoStatistics option enabled (it is on by default) to be able to report IPv6 bandwidth statistics. This is the relay operators’  decision, since relays are operated by volunteers. We will keep the statistics code in the codebase for when 0.4.5 is released and relays start reporting it.