diff --git a/include/config_default.inc.php b/include/config_default.inc.php
index 3818cfd57..19b110da1 100644
--- a/include/config_default.inc.php
+++ b/include/config_default.inc.php
@@ -638,6 +638,12 @@ $conf['picture_url_style'] = 'id';
 // tags is not unique, all tags with the same url representation will be shown
 $conf['tag_url_style'] = 'id-tag';
 
+// force an explicit port in the url (like ":80" or ":443")
+// * 'none' : do not add any port, whatever protocol is detected
+// * 'auto' : tries to smartly add a port based on $_SERVER variables
+// * 123 : adds ":123" next to url host
+$conf['url_port'] = 'none';
+
 // +-----------------------------------------------------------------------+
 // |                                 tags                                  |
 // +-----------------------------------------------------------------------+
diff --git a/include/functions_url.inc.php b/include/functions_url.inc.php
index 1e66d527c..d6cbc3227 100644
--- a/include/functions_url.inc.php
+++ b/include/functions_url.inc.php
@@ -32,6 +32,7 @@ function get_root_url()
  */
 function get_absolute_root_url($with_scheme=true)
 {
+  global $conf;
   // TODO - add HERE the possibility to call PWG functions from external scripts
 
   // Support X-Forwarded-Proto header for HTTPS detection in PHP
@@ -61,15 +62,30 @@ function get_absolute_root_url($with_scheme=true)
     else
     {
       $url .= $_SERVER['HTTP_HOST'];
-      if ( (!$is_https && $_SERVER['SERVER_PORT'] != 80)
-            ||($is_https && $_SERVER['SERVER_PORT'] != 443))
+
+      $url_port = null;
+
+      if ('none' == $conf['url_port'])
       {
-        $url_port = ':'.$_SERVER['SERVER_PORT'];
-        if (strrchr($url, ':') != $url_port)
+        // do nothing
+      }
+      elseif ('auto' == $conf['url_port'])
+      {
+        if ((!$is_https && $_SERVER['SERVER_PORT'] != 80) || ($is_https && $_SERVER['SERVER_PORT'] != 443))
         {
-          $url .= $url_port;
+          $url_port = ':'.$_SERVER['SERVER_PORT'];
         }
       }
+      else
+      {
+        // we have a custom port
+        $url_port = ':'.$conf['url_port'];
+      }
+
+      if (!empty($url_port) and strrchr($url, ':') != $url_port)
+      {
+        $url .= $url_port;
+      }
     }
   }
   $url .= cookie_path();