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

[Simon Kelley]

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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