And the behavior is clearly against what the manpage says: -H Hash a known_hosts file. This replaces all hostnames and addresses with hashed representations within the specified file; the original content is moved to a file with a .old suffix. These hashes may be used normally by ssh and sshd, but they do not reveal identifying information should the file's contents be disclosed. This option will not modify existing hashed hostnames and is therefore safe to use on files that mix hashed and non-hashed names.
-- 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
