diff --git a/htdocs/index.php b/htdocs/index.php
index 71f8aed2..840aa92c 100644
--- a/htdocs/index.php
+++ b/htdocs/index.php
@@ -72,6 +72,15 @@ if ($n && $p[0] == SALT_ADMIN)
             $page = require("admin/certificate.php");
           break;
 
+          case "chrono":
+          case "chrono/":
+          case "chrono/init":
+          case "chrono/init/":
+          case "chrono/start":
+          case "chrono/start/":
+            $page = require("admin/chrono.php");
+          break;
+
           case "exercices/import":
           case "exercices/import/":
             $page = require("admin/import_exercices.php");
diff --git a/htdocs/js/countdown.js b/htdocs/js/countdown.js
index 3ae82d6a..fee573f2 100644
--- a/htdocs/js/countdown.js
+++ b/htdocs/js/countdown.js
@@ -1,6 +1,10 @@
 function update_end()
 {
-  var left = (end_challenge - new Date())/1000;
+  var left;
+  if (typeof end_challenge === 'undefined')
+    left = 14400;
+  else
+    left = (end_challenge - new Date())/1000;
 
   if (left < 0) left = 0;
 
diff --git a/onyx/include/admin/chrono.php b/onyx/include/admin/chrono.php
new file mode 100644
index 00000000..954684c0
--- /dev/null
+++ b/onyx/include/admin/chrono.php
@@ -0,0 +1,22 @@
+<?php
+
+if(!defined('ONYX')) exit;
+
+$p = $out[0];
+
+if (count($p) > 2)
+{
+  switch($p[2])
+  {
+  case "start":
+    file_put_contents($VAR["misc_dir"]."/challenge_started", time());
+    break;
+
+  case "init":
+    unlink($VAR["misc_dir"]."/challenge_started");
+    break;
+  }
+}
+
+header("Location: /".SALT_ADMIN."/");
+exit();
\ No newline at end of file
diff --git a/onyx/include/common.php b/onyx/include/common.php
index 5d7b7b22..f21a6236 100644
--- a/onyx/include/common.php
+++ b/onyx/include/common.php
@@ -14,7 +14,13 @@ require_once("common/Theme.class.php");
 $template = new Template();
 
 $template->assign("ERRmessage", false);
-$template->assign("END", $VAR['end_challenge']);
+
+if (is_file($VAR["misc_dir"]."/challenge_started"))
+{
+  $VAR["start_challenge"] = intval(file_get_contents($VAR["misc_dir"]."/challenge_started"));
+  $VAR["end_challenge"] = $VAR["start_challenge"] + 14400;
+  $template->assign("END", $VAR['end_challenge']);
+}
 
 if (!empty($LANG))
   $template->assign("LANG", $LANG);
diff --git a/onyx/tpl/bootstrap/admin/home.tpl b/onyx/tpl/bootstrap/admin/home.tpl
index 33a7366d..25101ae8 100644
--- a/onyx/tpl/bootstrap/admin/home.tpl
+++ b/onyx/tpl/bootstrap/admin/home.tpl
@@ -25,4 +25,14 @@
   {/if}
   </div>
 </div>
+
+<div class="panel panel-default">
+  <div class="panel-heading">
+    <h3 class="panel-title">Chrono</h3>
+  </div>
+  <div class="panel-body">
+    <a href="/{$SALT_ADMIN}/chrono/start" class="btn btn-success">Start</a>
+    <a href="/{$SALT_ADMIN}/chrono/init" class="btn btn-danger">R&eacute;initialiser</a>
+  </div>
+</div>
 {/block}
diff --git a/onyx/tpl/bootstrap/admin/layout.tpl b/onyx/tpl/bootstrap/admin/layout.tpl
index bc3b77c9..05e0b339 100644
--- a/onyx/tpl/bootstrap/admin/layout.tpl
+++ b/onyx/tpl/bootstrap/admin/layout.tpl
@@ -11,7 +11,9 @@
 {block name=end}
   <script src="/js/countdown.js"></script>
   <script type="text/javascript">
+  {if isset($END)}
     var end_challenge = new Date({$END * 1000});
+  {/if}
     update_end();
   </script>
 {/block}
diff --git a/onyx/tpl/bootstrap/public/layout.tpl b/onyx/tpl/bootstrap/public/layout.tpl
index 44b1a683..6056acc6 100644
--- a/onyx/tpl/bootstrap/public/layout.tpl
+++ b/onyx/tpl/bootstrap/public/layout.tpl
@@ -42,17 +42,9 @@
 {block name=end}
 <script src="/js/countdown.js"></script>
 <script type="text/javascript">
-   var end_challenge = new Date({$END * 1000});
-{literal}
-$(document).ready(function() {
-   update_end();
-   $('#carousel-team').carousel({
-     interval: 10000 });
-
-   setInterval( function() {
-     update_end();
-     }, 1000);
-});
-{/literal}
+{if isset($END)}
+  var end_challenge = new Date({$END * 1000});
+{/if}
+  update_end();
 </script>
 {/block}
diff --git a/onyx/tpl/bootstrap/teams/layout.tpl b/onyx/tpl/bootstrap/teams/layout.tpl
index 481a7527..c0002f59 100644
--- a/onyx/tpl/bootstrap/teams/layout.tpl
+++ b/onyx/tpl/bootstrap/teams/layout.tpl
@@ -8,18 +8,10 @@
 {block name=end}
 <script src="/js/countdown.js"></script>
 <script type="text/javascript">
-   var end_challenge = new Date({$END * 1000});
-{literal}
-$(document).ready(function() {
-   update_end();
-   $('#carousel-team').carousel({
-     interval: 2000 });
-
-   setInterval( function() {
-     update_end();
-     }, 1000);
-});
-{/literal}
+{if isset($END)}
+  var end_challenge = new Date({$END * 1000});
+{/if}
+  update_end();
 </script>
 {/block}