[Dnsmasq-discuss] Tag requests for a DHCP address from devices using a Locally Administered MAC address

[themiron.ru at gmail.com]

Hi,

LAA stands for locally-administrated address itself, so from my opinion "laa-address" is a bit tautologic.
Let's use just "laa", also it ~fits already used one word tags:
	"bootp"
	"cpewan-id"
	"dhcpv6"
	"known"
	"known-othernet"
	<interface>
--
Best Regards, Vladislav Grishenko

-----Original Message-----
From: Dnsmasq-discuss <dnsmasq-discuss-bounces at lists.thekelleys.org.uk> On Behalf Of Pali Rohar
Sent: Sunday, July 26, 2020 7:20 PM
To: dnsmasq-discuss at lists.thekelleys.org.uk
Subject: Re: [Dnsmasq-discuss] Tag requests for a DHCP address from devices using a Locally Administered MAC address

On Sunday 26 July 2020 15:35:24 Geert Stappers wrote:
> On Sun, Jul 26, 2020 at 06:07:52AM -0700, dev at lutean.com wrote:
> > > > iOS 14
> > > 
> > > CISCO provides an IOS, https://en.wikipedia.org/wiki/Cisco_IOS
> > > My second guess on IOS is an Apple Computer Inc product.
> > > 
> > > 
> > > > will by default use randomized, private MAC addresses.
> > > 
> > > Yeah right, let's sell a depleted MAC address pool as a privacy 
> > > improvement ...
> > > 
> > 
> > It is an upcoming feature of Apple products that will be on by 
> > default: https://support.apple.com/en-ca/HT211227

Ah :-( So Apple devices would be broken on lot of networks. Another reason why to not buy them. I heard from lot of people that they are not supporting Apple devices on networks anymore and I now I'm seeing reasons for such decisions. Maintaining such crap must be really pain.

> > It is already available through the public beta.
> > 
> > So Apple devices as of October or sooner will be changing their MAC 
> > addresses by default
> > 
> > > 
> > > > In my testing these devices use a MAC address with the LAA bit 
> > > > set (2nd least significant bit of the first byte of the MAC). It 
> > > > restricts this to host addresses (least significant bit is set to 0).
> > > 
> > > Speaks about two bits
> > > 
> > > 
> > > > This patch detects MAC addresses with this bit set and tags the 
> > > > request with the tag "laa-address". This would allow other rules 
> > > > to decide what to do with these requests (such as ignoring them).
> > > 
> > > Speaks about one bit
> > > 
> > > 
> > > 
> > > Speaking about bits, see
> > https://en.wikipedia.org/wiki/MAC_address#/media/File:MAC-48_Address
> > .svg
> > > for the "exploded view"
> > > 
> > 
> > https://en.wikipedia.org/wiki/MAC_address#Unicast_vs._multicast
> > 
> > The reason two bits are tested is because:
> > - one bit is the UAA / LAA bit
> > - one bit is the unicast / multicast bit
> > 
> > so this patch wouldn't tag LAA multicast MAC addresses should those 
> > happen to be in use somewhere.
> > 
> > So specifically a device with an LAA unicast MAC address would get a 
> > tag. This requires testing two bits.
> > 
> 
> OK, thanks for elaborating

I think that big misunderstanding comes from commit message which says that one bit (LAA) is tested, but in patch itself are tested two bits.

I guess that fixing commit message to properly describe that testing both bits (and which) are needed should be enough.

Anyway, I'm not sure if 'laa-address' is correct name if it is not set for every laa-address, but only for unicast laa-address.

--
Pali Rohár
pali.rohar at gmail.com

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