IPv6 for obfs4 bridges
In the last weekly meeting there was a conversation on how many censors bloc only IPv4 traffic and using IPv6 might be useful for circumvention. But currently we only have IPv6 for vanilla bridges and not for obfs4 ones.
The bridge authority
cached-extrainfo files contain the IPv4 address of the obfs4 transport but no IPv6, while
networkstatus-bridges does include both IPv4 and IPv6 addresses for the vanilla bridge. The problem comes from tor not allowing to have multiple lines in the TransportListenAddr (tpo/core/tor#11211) so only the IPv4 is specified. But in practice binding to 0.0.0.0 implies also binding into IPv6 (tpo/core/tor#12138 (comment 2762221)), so we could assume any bridge that has an IPv6 address in bridge-descriptors might have a working obfs4 on the IPv6 and same port that is published for IPv4.
How do want to move forward to use IPv6 obfs4 bridges?