Bluetooth

Red Hat Linux now provides Bluetooth support for both serial connections and BlueZ protocol–supported devices. Bluetooth is a wireless connection method for locally connected devices such as keyboards, mice, printers, and even PDAs and Bluetooth capable cell phones. You can think of it as a small local network dedicated to your peripheral devices, eliminating the needs for wires. Bluetooth devices can be directly connected through your serial ports or through specialized Bluetooth cards connected to USB ports or inserted in a PCI slot. BlueZ is the official Linux Bluetooth protocol and has been integrated into the Linux kernel since version 2.4.6. The BlueZ protocol was developed originally by Qualcomm and is now an open source project, located at bluez.sourceforge.net. It is included with Red Hat in the bluez-utils and bluez-libs packages, among others. Check the BlueZ site for a complete list of supported hardware, including adapters, PCMCIA cards, and serial connectors.

Both GNOME and KDE provide Bluetooth configuration and management tools. GNOME provides the GNOME Bluetooth subsystem, which features a device manager, a plugin for Nautilus to let the GNOME file browser access Bluetooth devices, and a file server. For KDE, the KDE Bluetooth Utilities is currently under development, providing similar tools for accessing Bluetooth devices. To connect mobile phones to a system using Bluetooth you can use the GNOME Phone manager or KDE's K68 tool. Red Hat also includes the Bluetooth File Sharing applet for receiving Bluetooth files.

Note

The Affix Frontend Environment (AFE), an alternative to BlueZ, provides an easy-to-use method for accessing Bluetooth devices (affix.sourceforge.net).

Bluetooth Configuration

Configuration information is located in the /etc/bluetooth directory, along with the /etc/pcmcia directory for notebooks. Use the hciconfig command to configure Bluetooth devices, hcitool to configure Bluetooth connections. Use hciattach to attach serial devices to a serial port such as /dev/ttyS1, and rfcomm to configure and attach RFCOMM devices. The HCI information is saved in /etc/bluetooth/hcid.conf, and RFCOMM configuration information is in /etc/bluetooth/rfcomm.conf. With l2ping, you can detect a Bluetooth device.

You can start and stop the Bluetooth service using the service command and the Bluetooth service script, /etc/rc.d/init.d/bluetooth.

service bluetooth start

This script will start up the Bluetooth daemon for HCI devices, hcid, and run any detection and configuration tools, including sdpd for the Service Discovery Protocol, and rfcomm. It will also activate any serial Bluetooth devices, using hciattach to detect them.

BlueZ includes several modules and drivers, including the core Bluetooth protocols for HCI (Host Controller Interface) devices, HCI USB, UART, PCMCIA, and virtual HCI drivers, along with modules to support protocols for L2CAP (Logical Link Control and Adaptation Protocol), serial port emulation (RFCOMM), Ethernet emulation (BNEP), SCO (Synchronous Connection-Oriented links for real-time voice), and the Service Discovery Protocol (SDP), which automatically detects services available for an application. In addition, extended services are supported, such as PAN (personal area networking) and LAN (LAN access over PPP).

Personal Area Networks: PAN

PAN allows you to use Bluetooth to implement a personal area network supporting IP protocols, much like a wireless LAN for a small number of computers and devices. Bluetooth supports a much smaller bandwidth (1 to 2 megabits) than that used for a standard LAN, but it is sufficient for connecting and transferring data from handheld devices such as Palm Pilots. Several devices and computers can be configured as PAN users, connecting through a central Group Network (GN) computer. Alternatively, the PAN users could connect to a gateway system operating as a network access point connecting the Bluetooth personal network to a large LAN network. The PAN nodes run their own service daemon, pand. PAN user clients will also load the bnep.o module implementing a Bluetooth network device. The PAN server then needs to instructs its pand daemon to listen for the address for that device (alternatively, you could use SDP). On both the server and user systems, a virtual network device is created called bnep0, which can be configured using local IP protocol addresses. On Red Hat, you can create a ifcfg-bnep0 file and have it configured to use either static or dynamic (DHCP) addressing ( /etc/sysconfig/network-scripts/ ). Check the HOWTO-PAN file on the BlueZ site for more details (currently, there is no Red Hat Bluetooth networking tool).

Note

Bluetooth support in the Linux kernel needs to be enabled first before you can use it. You can add support in the form of a kernel module, as described in Chapters 32 and 33. Be sure to configure the kernel to include Bluetooth support along with any Bluetooth protocols you may need like RFCOMM and SCO. By enabling support as modules you will not a have to recompile the entire kernel.

Note

Currently under development, the Gnome Bluetooth subsystem provides a gnome interface for administering and accessing your Bluetooth devices (gnome-bluetooth-admin). Check the gnome-bluetooth RPM package.