[Dnsmasq-discuss] dnsmasq 2.61 no periodic RA's and sendto errors

Simon Kelley simon at thekelleys.org.uk
Sun May 13 21:00:13 BST 2012

On 13/05/12 17:29, Jim Bos wrote:
> On 05/12/2012 04:34 PM, Simon Kelley wrote:
>> On 11/05/12 15:16, Vladislav Grishenko wrote:
>>> Hi Simon,
>>> dnsmasq 2.61 has couple of issues:
>>> 1. No Router Advertisement and corresponding syslog sendto error when
>>> replying on Router Solicitation from Windows XP and possible other OSes
>>> It's caused by absence of source IPv6 address in RS packet, what is
>>> allowed
>>> by RFC if host's interface doesn't acquired valid link-local yet
>>> In this case RA should be sent to all nodes multicast address (sources
>>> has
>>> ALL_HOSTS define, which has a bit different meaning)
>>> 2. For non-slaac modes periodic RA doesn't work because next RA event
>>> could
>>> be reset by empty next slaac event
>>> Actually it could work only for the first time, if additional random
>>> delay
>>> is 0.
>>> Patches attached.
>>> Best Regards, Vladislav Grishenko
>> Many thanks. That solves the mystery of the sometime-missing periodic
>> RAs. I was aware that could sometime happen, but hadn't reproduced the
>> problem.
>> I've put out 2.62test1 with these fixes in place. This probably needs
>> another release, but I'll leave it a week or two in case any other
>> regressions come to light in 2.61.
>> Jim, I'm pretty sure this is the fix for you problem.
>> Cheers,
>> Simon.
> I tried the patches already but unfortunately still don't get RA's. But
> note I'm using SLAAC-only and the patch seem to be for non-slaac cases.
>   I'll see if I can try an almost empty config file on another PC to
> exclude any specific problem on my router.

Based on the config you sent me, the patch is relevant: if all the 
existing DHCPv4 clients have replied to pings to their SLAAC addresses, 
then periodic RAs may  stop. This includes the case where there are no 
DHCPv4 leases in existance.

When you do the testing, check the system logs: dnsmasq logs each time 
it send an RA, so looking for those is good to discriminate between RAs 
not sent, and RA lost in transit.



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