Quick OpenLDAP tip boys & girls…
When using syncrepl to replicate from a master LDAP server to a slave LDAP server, always remember to configure the ACLs on the master LDAP server to allow the “sync dn” to read everything.
I know it sounds entirely obvious but today I realized that the order in which I had defined the ACLs on the master LDAP server was preventing the sync dn from reading the “userPassword” attribute and thus also preventing it from syncing it to the slave. The consequence of which was that users would not be able to authenticate against the slave server! Shit!
Of course, since everything else was syncing properly, all the NSS (lookup) stuff worked fine but anything authentication related like PAM wouldn’t work because the user bind would fail with “Invalid credentials” in /var/log/secure. It had a been some time since I tested authentication so I must never have actually tested authentication against the slave (whoops!) and thus didn’t notice until now. I know I tested lookups but testing authentication must have slipped by somehow. Grrr, testing.
Good thing I caught the problem early and it never escalated into a problem, that really could have sucked down the line.
Don’t make the same mistake I did.