title: Terminal plugin for Jenkins shows error 403
body: <p>i try to install terminal plugin on Jenkins and have a problem with it. I download latest version of plugin from </p>
  
  <pre><code>https://wiki.jenkins.io/display/JENKINS/Terminal+Plugin
  </code></pre>
  
  <p>and after i installed it i reboot server and then i run command in terminal(no matter any) i get an error : [JENKINS TERMINAL] ERROR: 403
  Here screenshot: 
  <a href="https://i.stack.imgur.com/KNcmV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KNcmV.png" alt="enter image description here"></a>
  Maybe whom know issue ? how can i fix it ? Thanks for suggest.</p>