Thank you for taking the time to report this bug and helping to make Ubuntu better. I appreciate the quality of this bug report and I'm sure it'll be helpful to others experiencing the same issue.
As I proved in my checks this is an upstream bug. OTOH while annoying it is not "very" fatal other than for convenience or certain automation (which could code workarounds I think). That said the best route to getting it fixed in Ubuntu in this case would be to file an upstream bug. It would be great if you're able to do that. Otherwise, I'm not sure what we can do directly in Ubuntu to fix the problem. If you do end up filing an upstream bug, please link to it from here so we get auto-notified once there is something we can merge or even backport depending on the complexity. Thanks! -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to openssh in Ubuntu. https://bugs.launchpad.net/bugs/1668093 Title: ssh-keygen -H corrupts already hashed entries Status in openssh package in Ubuntu: Confirmed Bug description: xenial @ 1:7.2p2-4ubuntu2.1 on amd64 has this bug. trusty @ 1:6.6p1-2ubuntu2.8 on amd64 does not have this bug. I have not tested any other ssh versions. The following should reproduce the issue: #ssh-keyscan XXXX > ~/.ssh/known_hosts # ssh root@XXXXX Permission denied (publickey). # ssh-keygen -H /root/.ssh/known_hosts updated. Original contents retained as /root/.ssh/known_hosts.old WARNING: /root/.ssh/known_hosts.old contains unhashed entries Delete this file to ensure privacy of hostnames # ssh root@XXXXXX Permission denied (publickey). # ssh-keygen -H /root/.ssh/known_hosts updated. Original contents retained as /root/.ssh/known_hosts.old WARNING: /root/.ssh/known_hosts.old contains unhashed entries Delete this file to ensure privacy of hostnames # ssh root@XXXXX The authenticity of host 'XXXXXX' can't be established. RSA key fingerprint is XXXXXX. Are you sure you want to continue connecting (yes/no)? # diff known_hosts.old known_hosts 1c1 < |1|BoAbRpUE3F5AzyprJcbjdepeDh8=|x/1AcaLxh45FlShmVQnlgx2qjxY= XXXXX --- > |1|nTPsoLxCugQyZi3pqOa2pc/cX64=|bUH5qwZlZPp8msMGHdLtslf3Huk= XXXXX To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1668093/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp