Device::USB::FAQ - Frequently Asked Questions for Device::USB

       Thanks go to various users who submitted questions and answers for the list. In  particular,  Anthony  L.
       Awtrey who contributed the first FAQ answer.

       G. Wade Johnson (gwadej at cpan dot org) Paul Archer (paul at paularcher dot org)

       Houston Perl Mongers Group

       Copyright 2006-2013 Houston Perl Mongers

       This  document  is  free  software; you can redistribute it and/or modify it under the same terms as Perl
       itself.

perl v5.40.0                                       2024-10-20                              Device::USB::FAQ(3pm)

       This is an attempt to answer some of the frequently asked questions about the Device::USB module

       Device::USB::FAQ - Frequently Asked Questions for Device::USB

WhichplatformsdoesDevice::USBsupport?
       "Device:USB" supports any platform that "libusb" supports. This list currently includes Linux, FreeBSD,
       NetBSD, OpenBSD, Darwin, and MacOS X.

       There is a port of the "libusb" library to the Windows environment called "LibUsb-Win32". Because I don't
       have a development environment for testing this library, "Device::USB" does not yet support this library.

   DoIhavetouseDevice::USBasroot?
       By default, access to the USB devices on a Unix-based system appear to be limited to the root account.
       This usually causes access to most of the "libusb" features to fail with a permission error.

       Using the "Device::USB" module as root avoids this feature, but is not very satisfying from a security
       standpoint. (See the next question for more options.)

   HowdoIenableuseofDevice::USBasanon-rootuser?
       Some of the attributes of USB devices are available to non-root users, but accessing many of the more
       interesting features require special privileges.  According to the libusb source, the open() function
       requires either device nodes to be present or the usbfs file system to be mounted in specific locations.
       Those places in order are:

       1)  /dev/bus/usb  - pre-2.6.11: via devfs / post-2.6.11: via udev

       2)  /proc/bus/usb - usbfs

       Look in both locations on your system for which of these two methods your libusb will use.

       No  matter  which  method  your system uses, you will probably want to create a separate group to control
       access. Run this command to add a system group:

         addgroup --system usb

       or

         groupadd --system usb

       You can then add users to that group to allow access to your usb devices.

       DEVFS/HOTPLUG

       TODO

       UDEV

       If you use Debian/Ubuntu, look in the /etc/udev/permissions.rules file.  If  you  want  to  allow  global
       access to all usb devices, make this change:

       Change this:
         SUBSYSTEM=="usb_device", MODE="0664"

       To this:
         SUBSYSTEM=="usb_device", MODE="0664", GROUP="usb"

       After you reboot, all usb devices will inherit the mode and group specified.

       If  you  want to only change permissions for certain devices, you can add this on one line and adjust the
       product and vendor IDs:

         SUBSYSTEM=="usb_device", GROUP="usb", \
           SYSFS{idVendor}=="1234", SYSFS{idProduct}=="1234"

       USBFS

       The usbfs defaults to root as the user and group. This can be changed in the  /etc/fstab  by  adding  the
       following on one line:

         none /proc/bus/usb usbfs noauto,\
             listuid=0,listgid=118,listmode=0664,\
             busuid=0,busgid=118,busmode=0775,\
             devuid=0,devgid=118,devmode=0664\
             0 0

       The  value  118  in the above should be replaced with the group id of your usb group (created above). The
       list* values are to allow listing devices, the bus* is to control access to the bus directories  and  the
       dev*  values  control  access  to  the  device  files.  This approach does not allow the kind of granular
       permission that the udev approach gives,  so  it  is  all  or  nothing  unless  permissions  are  changed
       programmatically.

       If  your  /etc/fstab file already has a line for /proc/bus/usb, add the options above to the line that is
       already there rather than adding the new line. For example, you would change

         usbfs   /proc/bus/usb   usbfs   noauto  0 0

       to

         usbfs   /proc/bus/usb   usbfs  noauto,\
             listuid=0,listgid=118,listmode=0664,\
             busuid=0,busgid=118,busmode=0775,\
             devuid=0,devgid=118,devmode=0664\
             0 0

       Once again, this needs to be all on one line with the "\" characters removed.

       Device::USB and the "libusb" library site at <http://libusb.sourceforge.net/>.

       perldoc Device::USB::FAQ