diff --git a/lib/cookieless.php b/lib/cookieless.php
new file mode 100644
index 00000000000..8c96c1227ef
--- /dev/null
+++ b/lib/cookieless.php
@@ -0,0 +1,130 @@
+<?php
+/**
+* Enable cookieless sessions by including $CFG->usesid=true;
+* in config.php.
+* Based on code from php manual by Richard at postamble.co.uk
+* Attempts to use cookies if cookies not present then uses session ids attached to all urls and forms to pass session id from page to page.
+* If site is open to google, google is given guest access as usual and there are no sessions. No session ids will be attached to urls for googlebot.
+* This doesn't require trans_sid to be turned on but this is recommended for better performance
+* you should put :
+* session.use_trans_sid = 1 
+* in your php.ini file and make sure that you don't have a line like this in your php.ini
+* session.use_only_cookies = 1
+* @author Richard at postamble.co.uk and Jamie Pratt
+* @license http://www.gnu.org/copyleft/gpl.html GNU Public License
+*/
+/**
+* You won't call this function directly. This function is used to process 
+* text buffered by php in an output buffer. All output is run through this function 
+* before it is ouput.
+* @param string $buffer is the output sent from php
+* @return string the output sent to the browser
+*/
+function sid_ob_rewrite($buffer){
+    $replacements = array(
+        '/(<\s*(a|link|script|frame|area)\s[^>]*(href|src)\s*=\s*")([^"]*)(")/i',
+        '/(<\s*(a|link|script|frame|area)\s[^>]*(href|src)\s*=\s*\')([^\']*)(\')/i');
+ 
+    $buffer = preg_replace_callback($replacements, "sid_rewrite_link_tag", $buffer);
+    $buffer = preg_replace('/<form\s[^>]*>/i',
+        '\0<input type="hidden" name="' . session_name() . '" value="' . session_id() . '"/>', $buffer);
+    
+      return $buffer;
+}
+/**
+* You won't call this function directly. This function is used to process 
+* text buffered by php in an output buffer. All output is run through this function 
+* before it is ouput.
+* This function only processes absolute urls, it is used when we decide that 
+* php is processing other urls itself but needs some help with internal absolute urls still.
+* @param string $buffer is the output sent from php
+* @return string the output sent to the browser
+*/
+function sid_ob_rewrite_absolute($buffer){
+    $replacements = array(
+        '/(<\s*(a|link|script|frame|area)\s[^>]*(href|src)\s*=\s*")((?:http|https)[^"]*)(")/i',
+        '/(<\s*(a|link|script|frame|area)\s[^>]*(href|src)\s*=\s*\')((?:http|https)[^\']*)(\')/i');
+ 
+    $buffer = preg_replace_callback($replacements, "sid_rewrite_link_tag", $buffer);
+    $buffer = preg_replace('/<form\s[^>]*>/i',
+        '\0<input type="hidden" name="' . session_name() . '" value="' . session_id() . '"/>', $buffer);
+    return $buffer;
+}
+/**
+* A function to process link, a and script tags found 
+* by preg_replace_callback in {@link sid_ob_rewrite($buffer)}.
+*/
+function sid_rewrite_link_tag($matches){
+    $url = $matches[4];
+    $url=sid_process_url($url);
+    return $matches[1]. $url.$matches[5];
+}
+/**
+* You can call this function directly. This function is used to process 
+* urls to add a moodle session id to the url for internal links.
+* @param string $url is a url
+* @return string the processed url
+*/
+function sid_process_url($url) {
+    global $CFG;
+    if ((preg_match('/^(http|https):/i', $url)) // absolute url
+        &&  ((stripos($url, $CFG->wwwroot)!==0) && stripos($url, $CFG->httpswwwroot)!==0)) { // and not local one
+        return $url; //don't attach sessid to non local urls
+    }
+    if ($url[0]=='#' ) {
+        return $url; //don't attach sessid to anchors
+    }
+    if (strpos($url, session_name())!==FALSE)
+    {
+        return $url; //don't attach sessid to url that already has one sessid
+    }
+    if (strpos($url, "?")===FALSE){
+        $append="?".strip_tags(session_name() . '=' . session_id() );
+    }    else {
+        $append="&amp;".strip_tags(session_name() . '=' . session_id() );
+    }
+    //put sessid before any anchor
+    $p = strpos($url, "#");
+    if($p!==FALSE){
+        $anch = substr($url, $p);
+        $url = substr($url, 0, $p).$append.$anch ;
+    } else  {
+        $url .= $append ;
+    }
+    return $url;    
+}
+
+
+/**
+* Call this function before there has been any output to the browser to
+* buffer output and add session ids to all internal links.
+*/
+function sid_start_ob(){
+    global $CFG;
+    //don't attach sess id for google
+    if (!empty($CFG->opentogoogle)) {
+        if (empty($_SESSION['USER'])) {
+            if (!empty($_SERVER['HTTP_USER_AGENT'])) {
+                if (strpos($_SERVER['HTTP_USER_AGENT'], 'Googlebot') !== false ) {
+                    $CFG->usesid=false;
+                    return;
+                }
+                if (strpos($_SERVER['HTTP_USER_AGENT'], 'google.com') !== false ) {
+                    $CFG->usesid=false;
+                    return;
+                }
+            }
+        }
+    }
+    ini_set("session.use_trans_sid", "true"); // try and turn on trans_sid
+    if (ini_get("session.use_trans_sid")!=0 ){ 
+        // use trans sid as its available
+        ini_set("url_rewriter.tags", "a=href,area=href,script=src,link=href," 
+            . "frame=src,form=fakeentry");
+        ob_start('sid_ob_rewrite_absolute');
+    }else{
+        //rewrite all links ourselves
+        ob_start('sid_ob_rewrite');
+    }
+}
+?>
\ No newline at end of file
diff --git a/lib/setup.php b/lib/setup.php
index 7deed07c7cc..71619ad04bc 100644
--- a/lib/setup.php
+++ b/lib/setup.php
@@ -330,10 +330,12 @@ $CFG->httpswwwroot = $CFG->wwwroot;
 
     class object {};
 
-    unset(${'MoodleSession'.$CFG->sessioncookie});
-    unset($_GET['MoodleSession'.$CFG->sessioncookie]);
-    unset($_POST['MoodleSession'.$CFG->sessioncookie]);
-
+    if (empty($CFG->usesid) && !empty($_COOKIE['MoodleSession'.$CFG->sessioncookie])  )
+    {
+        unset(${'MoodleSession'.$CFG->sessioncookie});
+        unset($_GET['MoodleSession'.$CFG->sessioncookie]);
+        unset($_POST['MoodleSession'.$CFG->sessioncookie]);
+    }
     //compatibility hack for Moodle Cron, cookies not deleted, but set to "deleted"
     if (!empty($_COOKIE['MoodleSession'.$CFG->sessioncookie]) && $_COOKIE['MoodleSession'.$CFG->sessioncookie] == "deleted") {
         unset($_COOKIE['MoodleSession'.$CFG->sessioncookie]);
@@ -341,6 +343,11 @@ $CFG->httpswwwroot = $CFG->wwwroot;
     if (!empty($_COOKIE['MoodleSessionTest'.$CFG->sessioncookie]) && $_COOKIE['MoodleSessionTest'.$CFG->sessioncookie] == "deleted") {
         unset($_COOKIE['MoodleSessionTest'.$CFG->sessioncookie]);
     }
+    if (!empty($CFG->usesid) && empty($_COOKIE['MoodleSessionTest'.$CFG->sessioncookie]))
+    {
+        require_once("$CFG->dirroot/lib/cookieless.php");
+        sid_start_ob();
+    }
 
     if (!isset($nomoodlecookie)) {
         session_name('MoodleSession'.$CFG->sessioncookie);
@@ -404,10 +411,13 @@ $CFG->httpswwwroot = $CFG->wwwroot;
 
 /// now do a session test to prevent random user switching
     if ($SESSION != NULL) {
-        if (empty($_COOKIE['MoodleSessionTest'.$CFG->sessioncookie])) {
-            report_session_error();
-        } else if (isset($SESSION->session_test) && $_COOKIE['MoodleSessionTest'.$CFG->sessioncookie] != $SESSION->session_test) {
-            report_session_error();
+        //only do test if MoodleSessionTest cookie is set and usesid is on, or when usesid is off
+        if ((!empty($_COOKIE['MoodleSessionTest'.$CFG->sessioncookie]) && !empty($CFG->usesid))||empty($CFG->usesid) ) {
+            if (empty($_COOKIE['MoodleSessionTest'.$CFG->sessioncookie])) {
+                report_session_error();
+            } else if (isset($SESSION->session_test) && $_COOKIE['MoodleSessionTest'.$CFG->sessioncookie] != $SESSION->session_test) {
+                report_session_error();
+            }
         }
     }
 
diff --git a/lib/weblib.php b/lib/weblib.php
index c1e5d272cab..b4034825353 100644
--- a/lib/weblib.php
+++ b/lib/weblib.php
@@ -844,7 +844,14 @@ function popup_form($common, $options, $formname, $selected='', $nothing='choose
             continue;
 
         } else {
-            $optstr = '   <option value="' . $common . $value . '"';
+           if (!empty($CFG->usesid) && !isset($_COOKIE[session_name()]))
+            {
+                $url=sid_process_url( $common . $value );
+            } else
+            {
+                $url=$common . $value;
+            }
+            $optstr = '   <option value="' . $url . '"';
 
             if ($value == $selected) {
                 $optstr .= ' selected="selected"';
@@ -3947,7 +3954,13 @@ function notice_yesno ($message, $linkyes, $linkno) {
  */
 function redirect($url, $message='', $delay='0') {
 
+    global $CFG;
     //$url     = clean_text($url);
+   if (!empty($CFG->usesid) && !isset($_COOKIE[session_name()]))
+    {
+       $url=sid_process_url($url);
+    }
+
     $message = clean_text($message);
 
     $url = html_entity_decode($url); // for php < 4.3.0 this is defined in moodlelib.php
diff --git a/login/index.php b/login/index.php
index c19bbb91c12..913b38f0d5e 100644
--- a/login/index.php
+++ b/login/index.php
@@ -91,11 +91,11 @@
 
 /// Check if the user has actually submitted login data to us
 
-    if ($frm and (get_moodle_cookie() == '') and ($frm->username!='guest') and !$user and empty($CFG->alternateloginurl)) {    // Login without cookie
+    if (empty($CFG->usesid) and $frm and (get_moodle_cookie() == '') and ($frm->username!='guest') and !$user and empty($CFG->alternateloginurl)) {    // Login without cookie
 
         $errormsg = get_string("cookiesnotenabled");
 
-    } else if ($frm) {                             // Login WITH cookies
+    } else  if ($frm) {                             // Login WITH cookies
 
         $frm->username = trim(moodle_strtolower($frm->username));
 
diff --git a/login/index_form.html b/login/index_form.html
index 98a6ff09402..d68bdb29b14 100644
--- a/login/index_form.html
+++ b/login/index_form.html
@@ -11,9 +11,16 @@
 <?php } ?>
   <tr>
     <td width="50%" align="center" valign="top" class="content left">
-      <p><?php print_string("loginusing") ?>:<br />
-        (<?php print_string("cookiesenabled");?>) 
-         <?php helpbutton("cookies", get_string("cookiesenabled"))?><br /><?php formerr($errormsg) ?>
+      <p><?php print_string("loginusing") ?>:
+        <?php
+        if (empty($CFG->usesid))
+        {
+            echo "<br />(";
+            print_string("cookiesenabled");
+            echo ")";
+            helpbutton("cookies", get_string("cookiesenabled"));
+        }
+        ?><br /><?php formerr($errormsg) ?>
       </p>
       <form action="index.php" method="post" name="login" id="login">
         <table border="0" align="center">