a.there is also a setting in /etc/ldap.conf called pam_groupdn. This
lets you define an LDAP object with multiple membe attributes to
control who can login. I find it easy to use
b. SSH can be told to only accept logins from a posix group (same deal
just handled at a different part of the stack)
One other question came to mind, and that was users with ssh keys.
How will migrating to LDAP-only authentication affect them? Is there
a way to continue allowing these users to use their keys for login?