[Dnsmasq-discuss] dnsmasq and RA

[Gene Czarcinski]

On 11/01/2012 10:12 AM, Simon Kelley wrote:
> 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?
>
Oops ... I had defined a IPv6 address so libvirt had radvd running. 
Reconfigured with IPv6 address and no radvd.  This does require that I 
add two ip6tables rules for port 547 and forwarding between guests.  It 
works.

Gene