All right folks, time to fess up. What’s your count?
$ wc ~/.ssh/known_hosts -l 1470
Obviously there are some old machines in there – this file goes back at least five years. There are some duplicates as well as there is one line per host/port/user combination. It’s annoying that I can’t weed out old entries easily, as ssh now encrypts the entries in known_hosts by default. Of course that is a very sensible thing to do from a security perspective, but it’s a shame from a statistics point of view.
Mine is 534, but I removed all my machines from undergrad and graduate school, which was a lot. I am like you — of two minds about the encryption thing, because ssh machine name tab completion became unusable when they switched. I haven’t even investigated how the encryption is done. Seems if you have a live ssh agent, it should be able to decrypt the names on the fly for tab completion, etc. — bkuhn