Device::USB::FAQ(3pm)					User Contributed Perl Documentation				     Device::USB::FAQ(3pm)

NAME

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

SYNOPSIS

       perldoc Device::USB::FAQ

DESCRIPTION

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

QUESTIONS

   Which platforms does Device::USB support?
       "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.

   Do I have to use Device::USB as root?
       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.)

   How do I enable use of Device::USB as a non-root user?
       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.

SEE ALSO

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

AUTHOR

       G. Wade Johnson (wade at anomaly dot org) Paul Archer (paul at paularcher dot org)

       Houston Perl Mongers Group

ACKNOWLEDGEMENTS

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

COPYRIGHT &; LICENSE
       Copyright 2006 Houston Perl Mongers

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

perl v5.14.2							    2006-09-03						     Device::USB::FAQ(3pm)