[Dnsmasq-discuss] Need help configuring dhcp stateful IPv6

Andre Coetzee andre_4you at yahoo.co.uk
Sat May 19 10:19:31 BST 2012

--- On Fri, 18/5/12, Simon Kelley <simon at thekelleys.org.uk> wrote:
>From: Simon Kelley <simon at thekelleys.org.uk>
>Subject: Re: [Dnsmasq-discuss] Need help configuring dhcp stateful IPv6
>To: dnsmasq-discuss at lists.thekelleys.org.uk
>Date: Friday, 18 May, 2012, 12:10
>On 18/05/12 09:59, Andre Coetzee wrote:
>> When I set my dhcp-range option in dnsmasq.conf with a prefix-length of
>> 123, I get an "inconsistent DHCPv6 range" error. setting this value to
>> 125 or greater seems to work, also setting it to 120 or less seems to be
>> acceptable to dnsmasq.


>> When I enable networking on a client machine (linux), I see
>> "RTR-SOLICIT(eth0)" messages in the logs, but no responses or
>> advertisements coming from the dnsmasq machine.
>OK, first thing, your post took me straight to an embarrassing bug: it's
>all broken if the prefix length is NOT divisible by 8 - all bets are off
>in that case.
>How is the relevant interface configured? The
>prefix length there must  match that configured into dnsmasq.

Thank you Simon for this valuable information. Changing the prefix in the conf file 
to /120 and also changing the subnet mask on the interface to match (and restarting dnsmasq)
now results in router advertisements and dhcp addresses being issued.

May I suggest that the "prefix must be divisible by 8" caveat be documented in the man page
either in the section where the dhcp-range IPv6 prefix length option is discussed,
or under a new section "BUGS/KNOWN ISSUES"?

Many thanks

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