Linux.Desktop.Hacks [Electronic resources] نسخه متنی

Hack 92. Make an Internet Connection Using Bluetooth and a Mobile Phone

Linux now has good support for Bluetooth networking with mobile embedded
devices. This is useful for laptop and desktop users who want to use
a mobile phone for quick dialup access. But configuring the multitude
of Bluetooth options is still fairly cumbersome and unwieldy. This
quick and dirty hack uses simple shell scripts to establish a dialup
Internet connection, using Bluetooth as the link between a laptop and
mobile phone. Once it is set up, you can use the Bluetooth tools to
easily interface with a mobile phone's phone book
and provide SMS capability using a third-party utility, such as
gnokii (http://www.gnokii.org). It is also trivial to
replace the laptop used in this hack with a desktop PC equipped with
a low-cost USB Bluetooth dongle adapter device.

Bluetooth support in Linux is provided through the BlueZ software
stack (http://www.bluez.org).
This is a collection of utilities and drivers that configure the
underlying hardware, as well as provide the interface seen by
software applications. Each Bluetooth device contains a unique
identifiermuch like a network MAC addressthat is used
in communications to determine the source and destination of the data
being transmitted. Certain operations cannot be performed unless the
two communicating devices have been paired or
logically bound together using a password. In this way it is possible
to provide some level of safeguard against unauthorized use of a
mobile phone, while allowing those who have paired with it free reign
to make any calls they want. The script in this hack relies on such a
pairing to reduce the hassle of calling an ISP to a single click of a
desktop icon.

To begin, you must install the BlueZ protocol stack. The good news is
that BlueZ support is standard in most recent Linux distributions,
including those based on kernels 2.4 and 2.6. Linux supports most of
the inexpensive Bluetooth devices on the market (especially those
using the popular CSR chipset) because they are usually based on the
same generic parts, but with a different badge and label on the box.
Most distribution kernels are built with support for all the
currently supported Bluetooth hardware devices, but some older
systems must be updated for Bluetooth support. If the tools mentioned
here are not available on your system, first check to see if they are
included on the distribution installation discs or as downloads on
the BlueZ web site. Red Hat, SUSE, Mandrake, and Debian all ship with
Bluetooth support, but the Bluetooth tools might not have been
installed when you installed your distribution.

As a minimum, you should ensure that the
bluez-utils, bluez-pin, and
bluez-sdp packages are installed on your system.
These provide the tools and utilities required by Bluetooth, a GUI
application for pin entry, and a server program that can advertise
the system to other compatible Bluetooth devices. The
bluez-utils package also contains a range of
useful utilities, including hcitool and
rfcomm. You can use the former to enumerate
available Bluetooth devices, and the latter to establish a
connection. With the necessary packages installed, the following
command should tell you the Bluetooth address of the host Linux
laptop:

foo@bar:~$ hcitool dev
Devices:
hci0    00:09:DD:10:3F:8B

To communicate with a Bluetooth-enabled mobile phone, switch on its
Bluetooth function and ensure that it is set up to advertise its
presence to other devices (it needn't advertise
itself once the following steps have been completed, however). Look
for Bluetooth devices using the hcitool command
(this will take some time to complete):

foo@bar:~$ hcitool scan
Scanning ...
00:E0:03:3D:58:2E       bob

This shows that the Nokia 6230 mobile phone used in this example has
a hardware address of 00:E0:03:3D:58:2E and is
called bob. It is now possible to communicate with
that device and establish a connection to the modem device within it.
This will show up as an extra serial port (called
/dev/rfcomm0) that you can use to dial
connections to an ISP. Connect to the phone using a command similar
to the following:

foo@bar:~$ rfcomm bind 0 00:E0:03:3D:58:2E 1

You should ensure that you replace the hardware address
00:E0:03:3D:58:2E with the appropriate address
discovered previously on your own device, but leave the rest of the
command intact. Now you can use the phone's internal
modem via the /dev/rfcomm0 serial device. You
also can script these actions and store them in a file. This example
uses a file called
/usr/local/bin/bluetooth_call.sh with the
following contents:

#!/bin/sh
echo Configuring bluetooth...
rfcomm release 0
rfcomm bind 0 00:E0:03:3D:58:2E 1

Most Linux distributions provide an easy-to-use GUI tool for dialup
configuration. Locate the appropriate tool for your system and
configure a new connection using /dev/rfcomm0 in
place of /dev/modem, or whichever modem device
is selected by default on your system. In the case of