ssh-agent

Problems with Key-based authentication
Key should be kept on disk protected by a passphrase.
Requires you type your passphrase each time to use it.
Seems little different than password-based login.
Annoys users.
Can't be called from automated processes like cron jobs.

Bad solution: Remove the passphrase
Hit 'enter' when setting the password when generating the key.
Change or remove a passphrase using the following
     ssh-keygen -p -f /path/to/password/protected/key
Unprotected keys can be stolen and used from any machine!

Better solution:  Use ssh-agent.