First of all, apologies for running a prehistoric version (2.5.6cvs), but that's what my Debian/Stable has (and it has its own patches too...). I tried to scan the bug reports to see if this had been fixed in a later version, but didn't find anything. Anyway, the problem is that I need to rsync from a machine that has no reverse mapping. I would expect it to be sufficient to specify the IP address in the hosts allow line, but no, the connection is rejected with (client side:) opening tcp connection to bagel.indexdata.dk port 873 @ERROR: access denied to fng from unknown (212.XXX.XXX.201) (server syslog) Sep 24 12:18:48 bagel rsyncd[5845]: rsync: name lookup failed for 212.XXX.XXX.201: Name or service not known Sep 24 12:18:48 bagel rsyncd[5845]: rsync denied on module fng from unknown (212.130.49.201) I can work around this by adding hosts allow unknown but that is not exactly what I want to do! Luckily I can get away with this by filtering at the firewall, but that isn't exactly proper. A random observation: When it works, the syslog says: rsync to fng/fngindex/ from fngindexdata@unknown (212.XXX.XXX.201) Maybe that tells you something about the host name being needed somewhere else in the auth process...
This worked fine for me using 2.5.7 as the server (the oldest version I had around) and also 2.6.3pre2. It may be that your "hosts allow" line has a problem. If not, try upgrading.