title: How to solve ADB device unauthorized in Android ADB host device?
body: <p>When I'm using a rooted Android device as ADB host to send adb command "adb devices" to Samsung S4, I received device unauthorized error message. However when I tried adb to Samsung Galaxy Nexus, it is working fine. Can anyone advise how to solve my Samsung S4 problem?</p>
  
  <pre class="lang-none prettyprint-override"><code>=========================================
  # adb devices
  List of devices attached
  4d00f9169907301b        unauthorized
  =========================================
  </code></pre>
  
  <p>Thanks in advance.</p>
  
  <p><strong>Edit:</strong>
  Found that this problem only happened to Android 4.2.2 and above. The following link explained that Google has implemented some new security features for using adb.</p>
  
  <p><a href="http://nelenkov.blogspot.com/2013/02/secure-usb-debugging-in-android-422.html">http://nelenkov.blogspot.com/2013/02/secure-usb-debugging-in-android-422.html</a></p>
  
  <p>Appreciate if anyone can help on this.</p>