The key distinction between libapache2-mod-php5 (traditional mod_php) and libapache2-mod-php5filter lies in their processing architecture:

# Traditional mod_php configuration
LoadModule php5_module /usr/lib/apache2/modules/libphp5.so
AddHandler application/x-httpd-php .php

# Filter module configuration
LoadModule php5_module /usr/lib/apache2/modules/libphp5filter.so
AddOutputFilter PHP .php
SetOutputFilter PHP

mod_php (libapache2-mod-php5):

• Best for traditional LAMP stacks where PHP is primary content
• Embeds PHP interpreter directly in Apache
• Higher memory usage but faster execution
• Recommended for: WordPress, Drupal, Magento

php5filter (libapache2-mod-php5filter):

• Works as output filter in Apache pipeline
• Better for mixed content applications
• Allows other filters to process before PHP
• Recommended for: XML/XSLT processing, complex filtering chains

Benchmark results in typical environments:

Advanced configuration for mod_php:

    php_value max_execution_time 30
    php_value memory_limit 128M
    php_admin_flag safe_mode off

Filter-specific configuration:

    SetOutputFilter PHP
    SetInputFilter PHP
    php_flag display_errors on

For filter module not executing PHP:

# Check if filter is properly loaded
apache2ctl -M | grep php5filter

# Verify handler registration
grep -r "AddOutputFilter" /etc/apache2

When configuring PHP with Apache2, you'll encounter two primary integration methods:

# Traditional module (mod_php)
sudo apt-get install libapache2-mod-php5

# Filter module
sudo apt-get install libapache2-mod-php5filter

The traditional mod_php embeds PHP directly into Apache:

• PHP runs as part of the Apache process
• Higher memory usage per Apache child process
• .php files are processed automatically

# Typical mod_php configuration
<FilesMatch \.php$>
    SetHandler application/x-httpd-php
</FilesMatch>

The php5filter operates differently:

# Filter module configuration example
<FilesMatch \.php$>
    SetHandler php5-fcgi
    Action php5-fcgi /php5-fcgi
</FilesMatch>

Benchmark tests show:

Choose mod_php when:

• Running dedicated PHP servers
• Need maximum PHP performance
• Server has sufficient RAM

Choose php5filter when:

• Running mixed content servers
• Memory is constrained
• Need to chain content filters

For filter module with FastCGI:

# In apache2.conf
LoadModule fcgid_module modules/mod_fcgid.so
<IfModule mod_fcgid.c>
    AddHandler fcgid-script .php
    FCGIWrapper /usr/bin/php-cgi .php
</IfModule>