[Dnsmasq-discuss] RA support in dnsmasq

[Gene Czarcinski]

On 11/28/2012 03:31 PM, Simon Kelley wrote:
> On 25/11/12 18:39, Gene Czarcinski wrote:
>> On 11/25/2012 01:10 PM, Vladislav Grishenko wrote:
>>> Hi Gene,
>>> Instead of deprecating/turning-off logging by facility, it would be
>>> better
>>> to have ability to tune loglevel for each sysbsystem.
>>> Like following: where 0 means
>>> log-level=dhcp,dhcpv6,6,dns,7,ra,-1
>>>
>>> Best Regards, Vladislav Grishenko
>> Yes, that is indeed a good idea,
>>
>> I have no intention of deprecating logging but I also do not want a
>> large amount of information-less clutter in the syslog which may hide
>> something that is important. The "RTR-ADVERT" messages being issued
>> every 3 to 5 seconds with separate messages for each virtual interface
>> that is started is a bit much.
>
> But they're only that frequent for the first minute. After that 
> they're every 10 minutes, I think.
Something is definitely not working correctly.  I do not know if you 
have a qemu/kvm setup so duplicating the conditions that way will not work.

Attached is a piece of syslog (before I patched things to suppress the 
messages).  BTW, I also have no idea why anything is being done with 
"p33p1" ... that is the real NIC on that system.  I have also attached 
the dnsmasq conf file for that interface.

I am willing to try any testing.  Unless I can get things to work as 
they are suppose to, user reception of using dnsmasq to handle RA will 
get support somewhere between zero and none :-)
>>
>> I have taken a look at the code and (I hope) I just do not understand
>> how things are really working.
>>
>> If log-dhcp is specified (command line or conf-file), OPT_LOG_OPTS is
>> set. A little grepping resulted in rfc3315.c and rfc2131.c as issuing
>> messages with log6_packet() and log_packet() respectively. Sounds good,
>> the test can be done in a central place. But, looking more closely, the
>> only thing OPT_LOG_OPTS does is determine the form of the syslog message
>> ... not if it is being issued. And, of course, there are other calls to
>> my_syslog() scattered throughout.
>>
>> BTW, warning or at least error message should always be issued. It is
>> all the info massages that are becoming overwhelming.
>>
>> Certainly there should be a lot of messages to support debugging and the
>> code should always be compiled in. But, when things are working well it
>> is better to have most of those messages inhibited so that some warning
>> or error message will be seen.
>
>
> I see the RTR_ADVERT messages as being equivalent to the logs of DHCP 
> request and replies - they are at a minimum level which allows 
> tracking of the history of interaction with a client. The DHCP logs, 
> at least have equivalents in most DHCP servers.
>
> It's important to know which prefixes are being advertised, since 
> that's a function of quite a lot of configuration: not just dnsmasq 
> config, but kernel-level interface configuration too.
>
> Cheers,
>
> Simon.
>
>
>
>
>>>>>
>>>>> 3. Similar to radvd, should there be some dnsmasq parameters which 
>>>>> are
>>>>> used to specify how often RAs will be issued?
>
> There could be, but only if it makes sense to tune that for network 
> performance, not just prettifying the logs. The philosophy in dnsmasq 
> has always been to hide useless tuning settings and try and let people 
> configure what they want to do, not control every field of every 
> packet. I be no-one uses that option in radvd
>
>
>
>
>
>
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>

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# dnsmasq conf file created by libvirt
strict-order
domain-needed
domain=net6
expand-hosts
local=/net6/
pid-file=/var/run/libvirt/network/net6.pid
bind-dynamic
interface=virbr11
dhcp-range=192.168.6.128,192.168.6.254
dhcp-no-override
dhcp-leasefile=/var/lib/libvirt/dnsmasq/net6.leases
dhcp-lease-max=127
dhcp-hostsfile=/var/lib/libvirt/dnsmasq/net6.hostsfile
addn-hosts=/var/lib/libvirt/dnsmasq/net6.addnhosts
dhcp-range=fd00:beef:10:6::1,ra-only
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