Final Update & Closing:
My settings:
LDAP base domain: cn=Users,dc=ads,dc=example,dc=local
LDAP username DN attribute: samAccountName
LDAP search filter: (&(memberOf=CN=InternetUsers,CN=Users,DC=ads,DC=example,DC=local)(sAMAccountName=%s))
AD structure:
Container: Users > squid, test, administrator
Other Containers (OU):
OU Main
–- OU1 --- User1
--- OU2 --- User2
All these users have been added to security group (global) named InternetUsers and this group resides in the "Users" container.
I am able to verify three users - test, squid, and administrator which are in Users container; but I am not able to authenticate User1 and User2 which are placed elsewhere in AD even though they are members of InternetUsers group.
I conclude that the search is limited to one level only. So either I have to find a way to provide multiple Base Domain values, or find a way to make the search query recursive. Both would perhaps require me to directly edit the .inc file. I am not planning to do it and will leave it at that. I would rather create local users in Squid and now focus on learning SquidGuard.
Thanks