Manual browser: sdpd(8)

SDPD(8) System Manager's Manual SDPD(8)


sdpdBluetooth Service Discovery Protocol daemon


sdpd [-dh] [-c path] [-G group] [-g group] [-u user]


The sdpd daemon keeps a database of Bluetooth Service Records registered on the host and responds to Service Discovery inquiries from remote Bluetooth devices.

In order to discover services, remote Bluetooth devices send Service Search and Service Attribute or Service Search Attribute requests over Bluetooth L2CAP connections on the SDP PSM (0x0001). The sdpd daemon will try to find matching Service Records in its Service Database and will return the requested record extracts for the remote device to interpret. The remote device will then make a separate connection in order to access the service.

Bluetooth applications, running on the host, are able to insert, remove and update Service Records with the sdpd daemon via the control socket. It is possible to query entire contents of the Service Database locally with sdpquery(1) using the -l option.

The command line options are as follows:

-c path
Specify path to the control socket. The default path is /var/run/sdp.
Do not detach from the controlling terminal.
-G group
Grant permission to members of the group to modify the sdpd Service Database.
-g group
Specifies the group the sdpd should run as after it initializes. The value specified may be either a group name or a numeric group ID. This only works if sdpd was started as root. The default group name is “_sdpd”.
Display usage message and exit.
-u user
Specifies the user the sdpd should run as after it initializes. The value specified may be either a user name or a numeric user ID. This only works if sdpd was started as root. The default user name is “_sdpd”.




sdpquery(1), sdp(3)

The “Service Discovery Protocol” section of the Bluetooth Core specifications, available at


The original sdpd daemon first appeared in FreeBSD 5.3 and was imported into NetBSD 4.0 by Iain Hibbert under the sponsorship of Itronix, Inc. This version was rewritten by Iain Hibbert for NetBSD 6.0 in order to allow Bluetooth applications to fully specify service records.


Maksim Yevmenkin <> Iain Hibbert


The sdpd daemon will listen for incoming L2CAP connections on a wildcard BD_ADDR.

In case of multiple Bluetooth controllers connected to the same host it is possible to limit visibility of Service Records according to the controller the connection is made through.

Requests to insert, remove or update service records can only be made via the control socket. The sdpd daemon will check the peer's credentials and will only accept the request when the peer is the superuser, of if the peer is a member of the group specified with the -G option.

The sdpd daemon does not check for duplicated Service Records and only performs minimal validation of the record data sent in the Insert/Update Record requests. It is assumed that application must obtain all required resources such as RFCOMM channels etc., before registering the service.


sdpd only ever generates 16-bit sequence headers, so if a response was to grow over UINT16_MAX, the sequence header will be wrong.

There is no way for clients to discover the maximum packet size that sdpd will accept on the local socket. Currently this is SDP_LOCAL_MTU as defined in <bluetooth/sdp.h>.

May 7, 2009 NetBSD 7.0