[Dnsmasq-discuss] IPv6 - Router Advertisement

Simon Kelley simon at thekelleys.org.uk
Fri Nov 15 14:47:05 GMT 2013


On 15/11/13 12:10, Tsachi wrote:
> Thanks Simon,
> I will test it and let you know.
> Also what do you say regarding including "router lifetime=0" in the RA
> msg in this case ?

Sorry, I missed that. I just pushed a change to do this. If the ONLY 
prefixes being advertised have preferred lifetime of zero, then the 
router lifetime is now set to zero too.

Cheers,

Simon.


> Regards,
> Tsachi
>
> On Fri, Nov 15, 2013 at 1:27 PM, Simon Kelley<simon at thekelleys.org.uk>  wrote:
>> OK, I found the problem,
>>
>> http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commitdiff;h=dd9d9ce54c46b0e110f71f8cb19934bd2e8ae656
>>
>> or
>>
>> dnsmasq-2.68test2 should fix it. The patch will apply to 2.67, if you'd
>> rather do that.
>>
>>
>> Thanks for the report.
>>
>>
>> Cheers,
>>
>> Simon.
>>
>>
>>
>> On 14/11/13 17:38, Tsachi wrote:
>>>
>>> Hi,
>>> I have a question regarding dnsmasq behavior regarding IPv6 RA message
>>> while using the "constructor" config option.
>>> Version details: Kernel 2.6.35, Dnsmasq ver 2.67
>>>
>>> I am working on a small Linux router device which obtains a single
>>> dynamic global \64 prefix from a network (the prefix is changing every
>>> time the device connects to the network).
>>>
>>> This prefix is published (RA) on the device LAN interface (eth0) for
>>> the purpose of hosts Global address generation (using SLAAC).
>>>
>>> The following dnsmasq ipv6 configurations are set:
>>> dhcp-range=::,constructor:eth0, ra-only,64,60
>>> log-dhcp
>>> dhcp-option=option6:23,[::]
>>> ra-param=eth0,20
>>>
>>>
>>> The LAN interface (eth0) starts with link local address.
>>>
>>> After the device connects to the network, a new ipv6 global address is
>>> manually assigned to the eth0 interface ( \64 constructed from the
>>> prefix that the device received).
>>>
>>> ip addr add 2002::21a:2bff:fe3c:4d5e/64 dev eth0
>>>
>>> As expected, this triggers periodic unsolicited RA messages (and RA
>>> responses to RS).
>>> Log shows the following RA messages - "RTR-ADVERT(eth0) 2002::"
>>>
>>> After some time the device disconnects from the network and then the
>>> eth0 IPv6 address is removed:
>>>
>>> ip addr del 2002::21a:2bff:fe3c:4d5e/64 dev eth0
>>>
>>> The log shows the following RA messages " router advertisement on
>>> 2002::, old prefix for eth0"
>>>
>>> But the log doesn't show – "RTR-ADVERT" messages (nor the device sends
>>> any RA after, and will not response to RS requests).
>>>
>>> I was hoping to see an unsolicited RA massage (RTR-ADVERT) announcing
>>> this prefix with preferred-time=0 and maybe also "router lifetime=0",
>>> so hosts are aware of the disconnection.
>>>
>>> What do you think regarding unsolicited RA massage when the interface
>>> global ip address is deleted?
>>>
>>>
>>> By the way, In a different scenario, if I delete the interface ipv6
>>> address and add a new one, the log shows:
>>>
>>> router advertisement on 2012::, old prefix for eth0
>>> router advertisement on 2055::, constructed for eth0
>>> RTR-ADVERT(eth0) 2055::
>>> RTR-ADVERT(eth0) 2012:: old prefix
>>>
>>>
>>> The second prefix is sent with "preferred-time=0", as expected.
>>> Thanks,
>>> Tsachi
>>>
>>> _______________________________________________
>>> Dnsmasq-discuss mailing list
>>> Dnsmasq-discuss at lists.thekelleys.org.uk
>>> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
>>>
>>
>>
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