ssh authentication only via Radius

Greetings everyone, We have few of linux servers which we are trying to get authenticated only via radius. I found out I'm able to authenticate using radius password or using local (system) password. I am trying to configure it in such a way that as long as radius server is up and responding user should only able to logon via ssh with his radius password (no login with local password or even other local user and password ) And in case of radius is unavailable/not responding, user should able to logon locally with local pass My question to all experts is 1) can it be done 2) what changes and where needs to be done (/etc/pam.d/sshd or system-auth-ac) Thanks Shri