Description of problem:
No users, including local users, including root, can log in to the system if it
has been configured by authconfig to use ldap and the ldap server becomes
unavailable.

Version-Release number of selected component (if applicable):
RH9 

Steps to Reproduce:
1. Use authconfig to set up a system to use ldap authentication (not just user
info), but give it a bogus ldap server
2. Attempt to log in as root (or anyone else)
3. Hope that you remembered to keep an already logged-in session open. =:)
    
Additional info:
Bug has shown up under a number of other components, ex: bug #77575.

Proposed solution:
The solution to this problem was found by one of my students. Authconfig adds
the following line to /etc/pam.d/system-auth:

account [default=bad success=ok user_unknown=ignore service_err=ignore
system_err=ignore] /lib/security/$ISA/pam_ldap.so

That line should read: 

account [default=bad success=ok user_unknown=ignore service_err=ignore
system_err=ignore authinfo_unavail=ignore] /lib/security/$ISA/pam_ldap.so

The addition of 'authinfo_unavail=ignore' to the line will cause pam_ldap.so to
return an 'ignore' value instead of the default 'bad' when it cannot contact the
server.