DHCP release on poweroff if MACaddr is local scope

[Robert Moskowitz]

I am working in the IEEE 802 Privacy Recommendations Study Group:

http://www.ieee802.org/PrivRecsg/

There will be matching work on this in the IETF, but the WorkGroup has 
not been chartered (will be after the November IETF meeting).

Minimally we will be developing a Recommended Practice for using 
Randomized Local MAC Addresses to enhance device privacy.  IEEE 802.1 
may recommend segmenting the local scope address space to separate items 
like Virtual Machines, from ephemeral privacy addresses.  The SDN 
community has already asked to get a part of the local address space 
carved out for them.

But there is considerable ripple effects when a device,  based on some 
policy TBD, keeps changing its MAC Address.  The most obvious one is 
DHCP address leases.  Using tools like MACspoof:

https://github.com/feross/SpoofMAC

You can begin to see what happens. Much of the smarts for the client for 
WiFi will go into the WPA Supplicant and Jouni Malinen is already 
working on this.  But I am also working on it for wired connections and 
can see a general advantage where at poweroff (or reboot) a device 
includes sending a DHCP Release.

Yes, this only helps in a limited set of cases (not where you unplug 
from the wired cafe), but every case where we can 'make things better' 
seems wise.

In the IETF there will probably be recommendations on Lease times for 
local scope addresses.

I welcome any comments on this.