[Dnsmasq-discuss] bug: trunk DHCP offer/replies being ignored by some devices

Pedro MG Palmeiro mgondium at gmail.com
Sat Apr 8 00:55:42 BST 2017

The latest firmware for the printer is from 2015. This is one of those
shared Epson/Fuji/Xerox models which I believe is entering EOL, since there
is already another printer
called M200 (Ecotank). Anyway, I'll report it.

Should the the implementation be correct in dnsmasq, then there will be
more reports of this behavior from gateways implementing it, and that may
move Epson into action.

Adding a mac exclude switch to dnsmasq is just marginally better than
setting the printer IP manually, since both require intervention per device.

A switch disabling the whole implementation, or making it optional, thus
reverting to the old behavior would be better if feasible, but I don't
agree with removing it completely.

If nothing can be done, or be deemed unfeasible to be done, my opinion is
that not much harm is done, since there is a way of getting things working
(manual IP).

So, for me (3) it is.


On Fri, Apr 7, 2017 at 11:00 PM, Simon Kelley <simon at thekelleys.org.uk>

> On 06/04/17 14:01, Pedro MG Palmeiro wrote:
> > Dnsmasq trunk replies are being ignored by some devices, in my case, two
> > epson printers (AL-M200).
> > Dnsmasq 2.76 works fine.
> >
> > This could be related with
> > http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;
> > =88a77a78ad27adc3ed87b7ee603643d26cb896ee
> >
> > Please refer to
> > https://bugs.lede-project.org/index.php?do=details&task_id=673
> > for tcpdumps.
> >
> But RFC 6842 assures us that no clients are broken by this change :)
> The options here, as I see it are
> 1) revert the change and don't support 6842
> 2) provide a way to disable the client-id reply for broken clients.
> 3) provide a flag to disable the client-id for all clients.
> 4) make the new behaviour optional, and provide a flag to enable it.
> 5) declare it No Our Problem and get the broken clients fixed.
> 5) is possible - have you talked to Epson? the AL-M200 looks like a
> current product, and likely has field-upgradable firmware.
> 1) is not attractive.
> 2) may be possible. There is already a config option to tell dnsmasq to
> ignore _incoming_ client-ids for a particular client, that could be
> extended to apply to _outgoing_ cones too.
> Specifically, you'd need to add something like
> dhcp-host=<MAC address of printer>,id:*
> to turn off this for just those machines.
> 4) is not attractive.
> I'm interested in peoples opinions; a flag to kill the new client-uid
> behaviour globally, or just for particular MAC/IP addresses, or based on
> a tag?
> A pity, the original patch was so simple.......
> Cheers,
> Simon.
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