Hi!
You might recall that Tor has been restricting the possible amount of Tor relays per IP address to 2, mainly for Sybil prevention reasons.[1] We bumped that limit to 4 earlier this year[2] to make better use of available resources and considered back then bumping that limit further to 8 relays per IP address.
I've good news for everyone looking forward to raising that limit further: after an investigation into the effects of allowing 4 relays per IP address[3] we think it is overall beneficial for the network and our users to raise it further to 8.
This change (by having set `AuthDirMaxServersPerAddr 8` on a majority of them) is in effect since a couple of hours and you can run more than 4 relays per IP address now.
This is not meant to be a permanent change, though, but only a stopgap solution to work around missing multithreading support in Tor until relays in Arti will be available and deployed (which is still some years away from now).
For more details, information and discussion see: tor#40744.[4]
Thanks to everyone who helped making this change happen,
Georg
[1] proposals/109-no-sharing-ips.txt · main · The Tor Project / Core / Tor Specifications · GitLab
[2] [tor-relays] 4 relays per IP address are allowed from now (Feb 2023) on
[3] Analyze the results of bumping the max allowed relays per IP address to 4 (#51) · Issues · The Tor Project / Network Health / Analysis · GitLab
[4] Increase the amount of allowed relays per IP address to 8 (#40744) · Issues · The Tor Project / Core / Tor · GitLab