References listed in #871373:

 * Bug 871373 - Broken configuration for httpd 2.4
   https://bugzilla.redhat.com/show_bug.cgi?id=871373
   
   http 2.4 use the Require directive for all access control
   see: http://httpd.apache.org/docs/2.4/mod/mod_authz_core.html#require

   http 2.2 use the allow/deny/order which are emulated by the mod_acces_compat
   see: httpd.apache.org/docs/2.4/mod/mod_access_compat.html

(In reply to comment #1)
...
>    http 2.4 use the Require directive for all access control
>    see: http://httpd.apache.org/docs/2.4/mod/mod_authz_core.html#require

-----------
...
Require all

The all provider mimics the functionality the was previously provided by the 'Allow from all' and 'Deny from all' directives. This provider can take one of two arguments which are 'granted' or 'denied'. The following examples will grant or deny access to all requests.

    * Require all granted
    * Require all denied

...
-----------


For host specific Require directive:
see http://httpd.apache.org/docs/2.4/mod/mod_authz_host.html

-----------
...
Require local

The local provider allows access to the server if any of the following conditions is true:

    the client address matches 127.0.0.0/8
    the client address is ::1
    both the client and the server address of the connection are the same

This allows a convenient way to match connections that originate from the local host:

    * Require local

...
-----------

* Authorization Containers

The authorization container directives <RequireAll>, <RequireAny> and <RequireNone> may be combined with each other and with the Require directive to express complex authorization logic.

...

When multiple Require directives are used in a single configuration section and are not contained in another authorization directive like <RequireAll>, they are implicitly contained within a <RequireAny> directive. Thus the first one to authorize a user authorizes the entire request, and subsequent Require directives are ignored.

...


Apache 2.4 configuration
 
<RequireAll>
   Require all granted
   # Require local
   Require valid-user
</RequireAll>

nagios-3.4.3-3.fc18 has been submitted as an update for Fedora 18.
https://admin.fedoraproject.org/updates/nagios-3.4.3-3.fc18

Package nagios-3.4.3-3.fc18:
* should fix your issue,
* was pushed to the Fedora 18 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing nagios-3.4.3-3.fc18'
as soon as you are able to.
Please go to the following url:
https://admin.fedoraproject.org/updates/FEDORA-2012-19786/nagios-3.4.3-3.fc18
then log in and leave karma (feedback).

nagios-3.4.3-3.fc18 has been pushed to the Fedora 18 stable repository.  If problems still persist, please make note of it in this bug report.