BlueZ
 
Official Linux Bluetooth protocol stack

kernel code
The kernel modules of BlueZ are included in the Linux 2.4 and 2.6 kernel series. It is always a good idea to use the latest stable kernel. For some older ones the Bluetooth subsystem can be updated through patches. 

libraries and tools
To use the latest Bluetooth kernel modules is one important thing, but without support from the userspace these modules are useless. For the minimal functionality the bluez-libs and bluez-utils are needed. But it is safe to install all other packages as well. 


bluez-libs-2.22.tar.gz 
bluez-utils-2.22.tar.gz 
bluez-pin-0.26.tar.gz 
bluez-firmware-1.1.tar.gz 

bluez-hcidump-1.27.tar.gz 
bluez-hciemu-1.2.tar.gz 
For some Linux distributions pre-compiled binary packages exists. Other distributions picked up BlueZ and provide their own packages, so it is always a good idea to check the package lists of the distributions.