[WDMyCloud] ordinary users ssh recurringly breaks

Setup

Call me paranoid but I do not like Windoof file share even in my own home network, so I set up ssh. But it periodically breaks but I do not know why and have not got to investigate into it. I guess, however, that there is sort of system update.

Symptoms

Obviously, the connection fails. But, I get some messages too.

1. On the command line connection try I see
   @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
   @       WARNING: POSSIBLE DNS SPOOFING DETECTED!          @
   @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@   
2. After having worked around it, it is a permission denied.                                  
3. In MyCloud:/var/log/sshd.log I get
   User <your user> from debian.fritz.box not allowed because not listed in AllowUsers

Work-around

1. Use the command you get provided to remove the offending key:
   ssh-keygen -f "/home/<your user>/.ssh/known_hosts" -R <remote fqdn or ip address>
2. Add in /etc/ssh/sshd_config your user name to the list after AllowUsers. It is a space delimited list.
3. You need to reload the ssh config, e.g. with /etc/init.d/ssh reload

Update on firmware update

Installing a normal firmware update (why does WD it called like this since it is a patch of the Debian OS they use and not something in the eproms or what ever?) breaks it as well. Point its as far as I can tell they just replace the whole OS. Having that said it obviously removed my guerilla installation of subversion. I mere apt-get update && apt-get install subversion fixed this but file persimissions where left too untidy to leave key authentication working. Fix: chown thiemo /DataVolume/shares/Thiemo && chmod g-w /DataVolume/shares/Thiemo