New changes in the [Nagios](http://www.apache.org/>Apache 2.2's authentication have made some things a with respect to LDAP integration a little different.
For example, the new module that handles ldap authentication is called mod_authnz_ldap. This is a little unique in terms of the other authentication and authorization plugins, with separate the these two aspects. mod_authnz_ldap combines the 'n' and 'z' parts. After the upgrade from Apache 2.0 to 2.2 I started experiencing issues with a proxied This was the case for my Nagios environment after the upgrade, which I verified using a generic printenv script.I modified the configurations for ldap authentication and most of the sites using LDAP worked fine with the exception of Nagios, where the lack of the "REMOTE_USER" environment variable resulted in a very ugly server errors.
The Apache documentation suggests that the "AuthLDAPRemoteUserAttribute" is necessary and should default to uid, which is how my LDAP system is configured. Well, sure, but it's not working ....
Some more digging also revealed that the "AuthType" (in my case Basic) also introduces another option: "AuthBasicProvider". This seems to default to file. Once I set this to 'ldap' nagios started working again.
To make a long story short, ldap authentication and authorization still works, but things have been more modularized, which requires some modification to the Apache configs. The modules that seem to interact and are required to some extent are: mod_authnz_ldap, mod_auth_basic, mod_auth_user, mod_auth_digest. Of course there are some more like mod_auth_host for host based authentication ....
Oh, and if you are doing some fancy authentication against multiple requirements, like host and user and you are using LDAP, then you probably want to look at "AuthzLDAPAuthoritative" as well. It defaults to 'on' but i've had to switch it to 'off' for several sites.
\\@matthias