07 Oct 07 SSHD configuration public key only.

In order to set up ssh to only accept login by public key and not interactive login, the following changes are needed to sshd_config

PermitRootLogin without-password

Change:

#PubkeyAuthentication yes

to

PubkeyAuthentication yes

You must restart the sshd daemon next to implement:
hp-ux(HP may change this with no notice):
/sbin/init.d/secsh stop
/sbin/init.d/secsh start

Linux(RH distros):
service sshd restart

Make sure you have placed a public key file from a system you want to login and tested it first or your access will be console, hands on the keyboard only. That can be a big problem on remote systems.
For more on public key configuration and exchange, click here