Roger Dingledine:
It looks like around 844 Guard relays are listening on port 443 right now, out of the 1858 available Guard relays.
guard probability for all guards having ORPort on 80 or 443: 45.99%
guard probability per ORPort:
+---------+-------------------+ | or_port | guard_probability | +---------+-------------------+ | 443 | 44.4 | | 9001 | 39.1 | | 80 | 1.5 | | 9002 | 1.3 | | 8080 | 1.1 | | 8443 | 0.9 | +---------+-------------------+
(onionoo data as per 2018-07-05 07:00 UTC)
(*) Actually, before Tor starts attempting to reach Guards, it first needs to bootstrap the consensus document from either the directory authorities or the fallback directory servers -- but they have a pretty similar distribution of ports they listen on.
unfortunately onionoo does not have fallbackdir data, so I can't provide the same table as above for fallbacks without creating it myself first