Wrong IP used from /etc/hosts
Be silly, miss-configure your /etc/hosts file, thus for a host named 'wrongtest' (thus "hostname -a" == wrongtest.wrongdomain" matches that), have in /etc/hosts/
Then have on the REAL interface (eth0) the real IP address 192.0.2.1.
Put in torrc (next to other semi-standard things):
DirPort 192.0.2.1:993 ORPort 192.0.2.1:443
Start tor using that, it will listen on the 192.0.2.1 IP (logs state that and netstat confirms), and then you will see:
[notice] Now checking whether ORPort192.0.2.66:443 and DirPort 192.0.2.66:993 are reachable... (this may take up to 20 minutes -- look for log messages indicating success) [warn] Your server (192.0.2.66 :443) has not managed to confirm that its ORPort is reachable. Please check your firewalls, ports, address, /etc/hosts file, etc.
Yes, for some mysterious reason 192.0.2.66 is used (which is only to be found in /etc/hosts), even though you specified the other address...
Now, stop tor. Fix /etc/hosts to the right IP (192.0.2.1) and restart Tor and everything works as it should.
Something is causing /etc/hosts to be used which should not even be involved at all, might want to figure out why.
(Of course I should not be silly and have old IPs in the configs left, but hey, can't blame me for that :)
Version not selected in Trac as this pertains to the current (today/last hour) git version and there is no 'tor git' option in the list, but there are a 50 other which are very old, and nicely unsorted btw, might want to clean that up.