Simplicity is a form of art...

Matching MD5 SSH fingerprint

Today I was attempting to update a local repository, when SSH complained about a changed fingerprint, something like the following:

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:p4ZGs+YjsBAw26tn2a+HPkga1dPWWAWX+NEm4Cv4I9s.
Please contact your system administrator.
Add correct host key in /home/user/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /home/user/.ssh/known_hosts:9
ECDSA host key for 192.168.56.101 has changed and you have requested strict checking.
Host key verification failed.

Using multiple OpenSSH daemons

I administer a couple of systems which provide interactive access by end users, and for this interactive access I position OpenSSH. However, I also use this for administrative access to the system, and I tend to have harder security requirements for OpenSSH than most users do.

For instance, on one system, end users with a userid + password use the sFTP server for publishing static websites. Other access is prohibited, so I really like this OpenSSH configuration to use chrooted users, internal sftp support, whereas a different OpenSSH is used for administrative access (which is only accessible by myself and some trusted parties).

Switching OpenSSH to ed25519 keys

With Mike's news item on OpenSSH's deprecation of the DSA algorithm for the public key authentication, I started switching the few keys I still had using DSA to the suggested ED25519 algorithm. Of course, I wouldn't be a security-interested party if I did not do some additional investigation into the DSA versus Ed25519 discussion.