I have an entry from an OpenSSH
known_hosts file; I'd like to generate an SSHFP resource record for this. I can use
ssh-keygen to generate the fingerprint with no difficulty:
$ ssh-keygen -f foo_known_host -l 1040 09:a0:5c:5f:43:fb:e5:25:d8:0c:d8:dc:d7:7a:c4:62 foo.example.com. (RSA)
But it doesn't seem to like it for a DNS fingerprint record:
$ ssh-keygen -f foo_known_host -r foo failed to read v2 public key from foo_known_host.
So how do I do this?