Apache not parsing PHP files

I just had a confusing problem: instead of interpreting PHP-scripts in our webserver’s userdir apache serves them for download!

It’s caused by an upgrade from lenny to squeeze and I spend a lot of ours with fixing.

This is really a serious problem, these sites aren’t able to read for those people/search engines etc. that are browsing and, more fatal, if clients are able to access the PHP code of our students/staff they might explore security issues or passwords stored in these PHP files, so first of all I disabled the public access to the webserver.

So what was the problem? When I recognized that phpMyAdmin and other not userdir related stuff still works fine, I searched for issues that differ for userdirs. At long last I took a look into the libapache2-mod-php5 config file located in /etc/apache2/mods-available/php5.conf :

<IfModule mod_php5.c>
    <FilesMatch "\\.ph(p3?|tml)$">
        SetHandler application/x-httpd-php
    </FilesMatch>
    <FilesMatch "\\.phps$">
        SetHandler application/x-httpd-php-source
    </FilesMatch>
    # To re-enable php in user directories comment the following lines
    # (from <IfModule ...> to </IfModule>.) Do NOT set it to On as it
    # prevents .htaccess files from disabling it.
    <IfModule mod_userdir.c>
        <Directory /home/*/public_html>
            php_admin_value engine Off
        </Directory>
    </IfModule>
</IfModule>

As you can see, PHP is disabled if the userdir module was enabled… Disgusting! Commenting these lines out switched PHP for users on. Very annoying!