[Dnsmasq-discuss] dnsmasq and RA

Simon Kelley simon at thekelleys.org.uk
Thu Nov 1 14:12:44 GMT 2012


On 01/11/12 13:48, Gene Czarcinski wrote:
> On 11/01/2012 08:59 AM, Gene Czarcinski wrote:
>> On 10/31/2012 04:41 PM, Gene Czarcinski wrote:
>>> Instead of running both radvd and dnsmasq, I would like to run only
>>> dnsmasq and have it do what is now being done by radvd.
>>>
>>> This is for libvirt so there are some specifics which could help.
>>>
>>> 1. There will be one and only one interface for an instance of dnsmasq.
>>>
>>> 2. Currently (at least with some patches I have created) run one ipv4
>>> dhcp subnetwork or one ipv6 dhcp supnetwork or both one ipv4 network
>>> and one ipv6 network.
>>>
>>> 3.  If a dhcp-range is specified for the ipv6 subnetwork then I need
>>> the AdvManagedFlag on which (I believe) is done with the additional
>>> dsnmasq parameter "enable-ra".
>>>
>>> 4.  But, I may have an IPv6 subnetwork but dhcp-range has not been
>>> specified.  In this case I want the AdvManagedFlag off. This one is
>>> the situation that I am not clear on.
>>>
>>> 5.  None of the other dnsmasq capabilities with respect to RA will be
>>> used.
>>>
>>> Comments/suggestions?
>>>
>>> If this requires a little enhancement patch, I am willing.
>>>
>>>
>> OK, I believe I have answered my own question but I would still like
>> confirmation.
>>
>> I ran a test with no radvd running ... only dnsmasq.  With enable-ra
>> and dhcp-range specified for ipv6 addresses, the client side gets a
>> dhcp6 address and RA default route.  With enable-ra and NO dhcp-range
>> specified, the client gets a SLAAC address and RA default route.
>>
>> With enable-ra and dhcp-range,I do notice a lot of RTR-ADVERT messages
>> ... like one every couple of seconds.  Is there a way to suppress this
>> message and/or increase the time between the events or at least the
>> messages [that is without disabling dhcp logging] ?
>>
>> Maybe it would be useful is this message was only sent to the syslog
>> once every ten or twenty events.
>>
> One additional question  With enable-ra and dhcp-range, then dnsmasq
> supplies the RDNS info in the RA packet but it does not if dchpv6 is not
> specified.  It seems like this should be reversed.

It will always supply the RDNS info if it can find a dhcp-option to get
the info from. I wonder if you have another RA daemon on the net which
is providing advertisements ahich are being used when you don't have
them correctly configured in dnsmasq?


Cheers,

Simon.

> 
> Gene
> 
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