title: Authentication failed
body: <p>i got this error after setting a slave node, somebody please help~
  i can ssh on the slave node without problem, it only happens on jenkins.</p>
  
  <pre><code>[11/20/14 21:01:30] [SSH] Opening SSH connection to 10.105.5.34:22.
  [11/20/14 21:01:30] [SSH] Authentication failed.
  hudson.AbortException: Authentication failed.
      at hudson.plugins.sshslaves.SSHLauncher.openConnection(SSHLauncher.java:1178)
      at hudson.plugins.sshslaves.SSHLauncher$2.call(SSHLauncher.java:701)
      at hudson.plugins.sshslaves.SSHLauncher$2.call(SSHLauncher.java:696)
      at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
      at java.util.concurrent.FutureTask.run(FutureTask.java:166)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
      at java.lang.Thread.run(Thread.java:724)
  [11/20/14 21:01:30] Launch failed - cleaning up connection
  [11/20/14 21:01:30] [SSH] Connection closed.
  </code></pre>
  
  <p>jenkins version is the latest 1.59, ssh plugin also is the latest</p>