I have a headless server with (until recently) working SSH and public key auth. I deactivated passwords and had a problem resembling the one in this thread, ie. upon SSH-ing into my server I get:
Permission denied (publickey).
Ratnakar Pawar helpfully suggested:
$chmod go-w ~/ $chmod 700 ~/.ssh $chmod 600 ~/.ssh/authorized_keys
Which solved both priyaudupi's issue and - for a time - mine. However now this issue seems to automatically reset on a 24-48 hour basis, I have changed the authorisation correctly twice (plugging in my keyboard and very carefully blind typing commands. This gives me normal passwordless, public auth ssh from the single authorised computer... then fails again within 48 hours.
What might be causing this, I can't think of anything that would be able to automatically change permissions on my folders either... any suggestions?
Update 2nd May 2014
I have checked
crontab -l for both the root and user, I have nothing on my user. The only cron task on root is one that updates my DNS server. It does so more regularly than the problem re-occurs and does not use chmod or chown...