Re: [RFC bluetooth-next 20/20] 6lowpan: bluetooth: add new implementation

Hi Johan,

On Wed, Jul 20, 2016 at 10:39 AM, Johan Hedberg [off-list ref] wrote:

Hi Alex,

On Tue, Jul 19, 2016, Alexander Aring wrote:

quoted

mhhh, I am not a bluetooth expert. What really means "periodically
change is RPA" and how is this done in the Linux bluetooth?

When "changing the RPA" happens, does that mean the all connections will
be lost (unregister interface). Then the previous connections will be
recreated (register interface) with a complete different MAC address?

Connections aren't lost when the random address is changed. That's why
we track the hci_conn->init_addr and hci_conn->resp_addr. The way this
is dealt with e.g. the Security Manager protocol is that the connection
creation address *is* the address for the remote device throughout the
entire connection, no matter what happens to the local and remote random
address during the connection. I would expect 6LoWPAN do do something
similar.

What was still unclear to me (maybe I missed it in the thread): does the
6LoWPAN for LE spec require using the connection creation address or the
identity address? If it would be the latter then that's something that
will never change and the whole interface recreation issue goes away.

For the MAC address I don't really know, but for the link-local IPv6
address I think the RPA shall be used:

   'The IPv6 link-local address configuration described in Section 3.2.2
   only reveals information about the 6LN to the 6LBR that the 6LBR
   already knows from the link-layer connection.  This means that a
   device using Bluetooth privacy features reveals the same information
   in its IPv6 link-local addresses as in its device addresses.
   Respectively, a device not using privacy at the Bluetooth level will
   not have privacy at the IPv6 link-local address either.'

-- 
Luiz Augusto von Dentz