jacobian/openstack.compute — pull request #14 by rizumu (2012-02-28 22:25:17+00:00)
Title: The use of authorized_keys2 for protocol 2 has been deprecated and is no longer supported by some distros

Rackspace recently upgraded Arch Linux to a newer image which no longer supports the deprecated, since 2001, authorized_keys2. openstack.compute was uploading my public key to ~/.ssh/authorized_keys2 instead of ~/.ssh/authorized_key. I discovered this because I began receiving a password prompt each and every login and took a look at Arch's default /etc/ssh/sshd_config.

See the discussion here:
http://serverfault.com/questions/116177/whats-the-difference-between-authorized-keys-and-authorized-keys2