title: Udev rules are not working for libusb on Ubuntu 12.04
body: <p>I'm on Ubuntu 12.04.5 LTS, x86_64.</p>
  
  <p>I've a usb device that uses libusb to communicate with the computer.
  Once I plug it into the computer and run the communication program I get the following error:</p>
  
  <pre><code>libusb couldn't open USB device /dev/bus/usb/008/004: Permission denied.
  libusb requires write access to USB device nodes.
  libusb failed to find the Optotrak USB device.  Are you sure you have set the udev permissions correctly?
  </code></pre>
  
  <p>So if I chmod the /dev/bus/usb/008/004 as follows:</p>
  
  <pre><code>sudo chmod 777 /dev/bus/usb/008/004
  </code></pre>
  
  <p>and run the communication program again, then the device works perfectly.
  The problem is that every time I plug the device, the last number changes, so I should have to chmod every time the usb bus, but since not all users know the administrator password this is a problem.</p>
  
  <p>So the manufacturer suggest to edit the udev rules as follows. Create a 12-ndi-rules inside /etc/udev/rules.d :</p>
  
  <pre><code>BUS=="usb", SYSFS{idVendor}=="0403", SYSFS{idProduct}=="da77", GROUP="plugdev"
  </code></pre>
  
  <p>(I've checked with lsusb that SYSFS are correct)</p>
  
  <pre><code>lsusb 
  
  Bus 008 Device 004: ID 0403:da77 Future Technology Devices International, Ltd 
  </code></pre>
  
  <p>and then reload the rules:</p>
  
  <pre><code>sudo udevadm control --reload-rules
  </code></pre>
  
  <p>but still the permissions for bus 008/004 are not correctly set.</p>
  
  <p>How do I make these rules permament at every reboot? I would also like to get make them permanent also if I change the port of the usb device.</p>