diff --git a/install/install.php b/install/install.php
index a8431b2248a43b0b73ed939ac03d2490eadb32cc..3061d34a7391344b02e6e034d5560b8525fab617 100644
--- a/install/install.php
+++ b/install/install.php
@@ -145,6 +145,46 @@ if(is_file('dist/lib/'.$dist['baseid'].'.lib.php')) include_once 'dist/lib/'.$di
 include_once 'dist/lib/'.$dist['id'].'.lib.php';
 include_once 'dist/conf/'.$dist['confid'].'.conf.php';
 
+//** Include addon lib config files
+if(is_dir('dist/lib.d')) {
+	// scheme is: <addon-name>.<distconfid>.conf.php
+	if(($dir = opendir('dist/lib.d'))) {
+		while(false !== ($cur = readdir($dir))) {
+			$curpath = 'dist/lib.d/' . $cur;
+			if(strpos($curpath, '..') !== false
+					|| !is_file($curpath)
+					|| !preg_match('/\.(?:' . preg_quote($dist['id'], '/') . '|' . preg_quote($dist['baseid'], '/') . ')\.lib\.php$/', $cur)) {
+				
+				// invalid entry or entry not for current distribution
+				continue;
+			}
+			// valid file name and either generic or for current distribution
+			include_once $curpath;
+		}
+		closedir($dir);
+	}
+}
+
+//** Include addon dist config files
+if(is_dir('dist/conf.d')) {
+	// scheme is: <addon-name>.<distconfid>.conf.php
+	if(($dir = opendir('dist/conf.d'))) {
+		while(false !== ($cur = readdir($dir))) {
+			$curpath = 'dist/conf.d/' . $cur;
+			if(strpos($curpath, '..') !== false
+					|| !is_file($curpath)
+					|| !preg_match('/\.' . preg_quote($dist['confid'], '/') . '\.conf\.php$/', $cur)) {
+				
+				// invalid entry or entry not for current distribution
+				continue;
+			}
+			// valid file name and either generic or for current distribution
+			include_once $curpath;
+		}
+		closedir($dir);
+	}
+}
+
 //****************************************************************************************************
 //** Installer Interface
 //****************************************************************************************************
@@ -171,7 +211,9 @@ if(is_dir('/usr/local/ispconfig')) {
 }
 
 //** Detect the installed applications
+$this->call_hook('find_installed_apps', false);
 $inst->find_installed_apps();
+$this->call_hook('find_installed_apps', true);
 
 //** Select the language and set default timezone
 $conf['language'] = $inst->simple_query('Select language', array('en', 'de'), 'en','language');
@@ -183,6 +225,7 @@ $conf['language_file_import_enabled'] = true;
 
 //** Select installation mode
 $install_mode = $inst->simple_query('Installation mode', array('standard', 'expert'), 'standard','install_mode');
+$inst->set_install_mode($install_mode);
 
 //** tRNG dependencies
 $conf['tRNG']='';
@@ -456,6 +499,8 @@ if($install_mode == 'standard' || strtolower($inst->simple_query('Configure Web
 	}
 }
 
+$inst->call_hook('configure_webserver_selection', true);
+
 if($install_mode == 'standard' || strtolower($inst->simple_query('Configure Firewall Server', array('y', 'n'), 'y','configure_firewall')) == 'y') {
 	//* Check for Firewall
 	if(!$conf['ufw']['installed'] && !$conf['firewall']['installed']) {
@@ -547,7 +592,9 @@ if($install_mode == 'standard' || strtolower($inst->simple_query('Install ISPCon
 	$inst->install_ispconfig_interface = false;
 }
 
+$inst->call_hook('install_ispconfig', false);
 $inst->install_ispconfig();
+$inst->call_hook('install_ispconfig', true);
 
 //* Configure DBServer
 swriteln('Configuring DBServer');
diff --git a/install/lib/installer_base.lib.php b/install/lib/installer_base.lib.php
index 3a8338bfc3d7d51e8b562964156488fdaf066b21..d3167b859030b883013c8c333fe71b666a4dc458 100644
--- a/install/lib/installer_base.lib.php
+++ b/install/lib/installer_base.lib.php
@@ -37,7 +37,9 @@ class installer_base {
 	public $install_ispconfig_interface = true;
 	public $is_update = false; // true if it is an update, falsi if it is a new install
 	public $min_php = '5.3.3'; // minimal php-version for update / install
-
+	private $addon_classes = null;
+	private $install_mode = '';
+	
 	public function __construct() {
 		global $conf; //TODO: maybe $conf  should be passed to constructor
 		//$this->conf = $conf;
@@ -56,6 +58,14 @@ class installer_base {
 		echo 'WARNING: '.$msg."\n";
 	}
 
+	public function set_install_mode($mode) {
+		$this->install_mode = $mode;
+	}
+	
+	public function get_install_mode() {
+		return $this->install_mode;
+	}
+	
 	public function simple_query($query, $answers, $default, $name = '') {
 		global $autoinstall, $autoupdate;
 		$finished = false;
@@ -150,7 +160,8 @@ class installer_base {
 	//** Detect installed applications
 	public function find_installed_apps() {
 		global $conf;
-
+	
+		$this->call_hook('find_installed_apps', false);
 		if(is_installed('mysql') || is_installed('mysqld')) $conf['mysql']['installed'] = true;
 		if(is_installed('postfix')) $conf['postfix']['installed'] = true;
 		if(is_installed('postgrey')) $conf['postgrey']['installed'] = true;
@@ -180,6 +191,8 @@ class installer_base {
 		if(is_installed('cron') || is_installed('anacron')) $conf['cron']['installed'] = true;
 
 		if (($conf['apache']['installed'] && is_file($conf['apache']["vhost_conf_enabled_dir"]."/000-ispconfig.vhost")) || ($conf['nginx']['installed'] && is_file($conf['nginx']["vhost_conf_enabled_dir"]."/000-ispconfig.vhost"))) $this->ispconfig_interface_installed = true;
+		
+		$this->call_hook('find_installed_apps', true);
 	}
 
 	public function force_configure_app($service, $enable_force=true) {
@@ -2816,6 +2829,40 @@ class installer_base {
 
 		return $tContents;
 	}
+	
+	public function call_hook($hook_name, $after = true) {
+		if(is_null($this->addon_classes)) {
+			// load addon libs
+			$this->addon_classes = array();
+			$libpath = realpath(dirname(__FILE__).'/..') . '/lib.d';
+			if(($dir = opendir($libpath))) {
+				while(false !== ($cur = readdir($dir))) {
+					if(strpos($cur, '..') !== false || !is_file($libpath . '/' . $cur) || substr($cur, -8) !== '.lib.php') {
+						continue;
+					}
+					$class_name = substr($cur, 0, -8) . '_addon_installer';
+					include_once $libpath . '/' . $cur;
+					if(!class_exists($class_name)) {
+						continue;
+					}
+					
+					$this->addon_classes[] = new $class_name;
+				}
+				closedir($dir);
+			}
+		}
+		
+		$call_method = 'onBefore';
+		if($after === true) {
+			$call_method = 'onAfter';
+		}
+		reset($this->addon_classes);
+		foreach($this->addon_classes as $cl) {
+			if(method_exists($cl, $call_method)) {
+				call_user_func(array($cl, $call_method), $hook_name);
+			}
+		}
+	}
 
 }
 
diff --git a/install/update.php b/install/update.php
index 633db3b9c7d447b352a59a4953069e28a3fcdca7..6bca0687590c862493cf28bcbca9b3aaadadca89 100644
--- a/install/update.php
+++ b/install/update.php
@@ -142,11 +142,52 @@ if(isset($cmd_opt['autoinstall']) && is_file($cmd_opt['autoinstall'])) {
 	define('AUTOINSTALL', false);
 }
 
+
 //** Include the distribution-specific installer class library and configuration
 if(is_file('dist/lib/'.$dist['baseid'].'.lib.php')) include_once 'dist/lib/'.$dist['baseid'].'.lib.php';
 include_once 'dist/lib/'.$dist['id'].'.lib.php';
 include_once 'dist/conf/'.$dist['confid'].'.conf.php';
 
+//** Include addon lib config files
+if(is_dir('dist/lib.d')) {
+	// scheme is: <addon-name>.<distconfid>.conf.php
+	if(($dir = opendir('dist/lib.d'))) {
+		while(false !== ($cur = readdir($dir))) {
+			$curpath = 'dist/lib.d/' . $cur;
+			if(strpos($curpath, '..') !== false
+					|| !is_file($curpath)
+					|| !preg_match('/\.(?:' . preg_quote($dist['id'], '/') . '|' . preg_quote($dist['baseid'], '/') . ')\.lib\.php$/', $cur)) {
+				
+				// invalid entry or entry not for current distribution
+				continue;
+			}
+			// valid file name and either generic or for current distribution
+			include_once $curpath;
+		}
+		closedir($dir);
+	}
+}
+
+//** Include addon dist config files
+if(is_dir('dist/conf.d')) {
+	// scheme is: <addon-name>.<distconfid>.conf.php
+	if(($dir = opendir('dist/conf.d'))) {
+		while(false !== ($cur = readdir($dir))) {
+			$curpath = 'dist/conf.d/' . $cur;
+			if(strpos($curpath, '..') !== false
+					|| !is_file($curpath)
+					|| !preg_match('/\.' . preg_quote($dist['confid'], '/') . '\.conf\.php$/', $cur)) {
+				
+				// invalid entry or entry not for current distribution
+				continue;
+			}
+			// valid file name and either generic or for current distribution
+			include_once $curpath;
+		}
+		closedir($dir);
+	}
+}
+
 //** tRNG dependencies
 $conf['tRNG']='';
 
@@ -299,7 +340,9 @@ checkDbHealth();
 /*
  *  dump the new Database and reconfigure the server.ini
  */
+$inst->call_hook('updateDbAndIni', false);
 updateDbAndIni();
+$inst->call_hook('updateDbAndIni', true);
 
 //** read server config from db into $conf['server_config']
 $tmp = $inst->db->queryOneRecord("SELECT config FROM ?? WHERE server_id = ?", $conf["mysql"]["database"] . '.server', $conf['server_id']);
@@ -321,7 +364,9 @@ if($reconfigure_master_database_rights_answer == 'yes') {
 //}
 
 //** Detect the installed applications
+$this->call_hook('find_installed_apps', false);
 $inst->find_installed_apps();
+$this->call_hook('find_installed_apps', true);
 
 //** Check for current service config state and compare to our results
 if ($conf['mysql']['master_slave_setup'] == 'y') $current_svc_config = $inst->dbmaster->queryOneRecord("SELECT mail_server,web_server,dns_server,firewall_server,db_server FROM ?? WHERE server_id=?", $conf['mysql']['master_database'] . '.server', $conf['server_id']);