[ntp:questions] Re: NTS multicast response on IPv6

David L. Mills mills at udel.edu
Fri Jan 20 01:07:21 UTC 2006


Mauricio,

I think what you intend is called NTP Manycast, not multicast. See the 
authentication options page in the documentation.

Dave

Mauricio Schramm wrote:

> Thanks Danny,
> 
> I think I was not totally clear in my question, what I need is to make my
> NTP client to discover by multicast a NTP server on my IPv6 network. I can
> do it using IPv4 broadcast, but I'm unable to do the same with IPv6
> multicast. Do you have any suggestion to solve this problem?
> 
> In the environment I'm working the NTP clients request the time periodically
> to the server, the server is not multicasting/broadcasting anything to the
> clients, do you think the authentication issue you talked about may be the
> cause of the problem? I will double check that, but I don't think I am
> facing any authentication problem since direct queries (IPv6 or IPv4) to the
> server are working just fine.
> 
> Thanks again,
> Mauricio
> 
> 
> On 1/18/06, Danny Mayer <mayer at ntp.isc.org> wrote:
> 
>>Mauricio Schramm wrote:
>>
>>>Hi,
>>>
>>>    I'm trying to set up an NTP server that answers multicast requests
>>
>>from
>>
>>>IPv6 clients without any success.
>>
>>Please understand that is not how multicast works. The clients are
>>passive and only receive multicast packets from the server (modulo the
>>authentication keydance).
>>
>>
>>>I just don't know if the problem is with
>>>the client or with the server and I don't have a reliable test tool to
>>
>>make
>>
>>>sure if any of them is correctly set. Does someone already tried this
>>
>>with
>>
>>>success? I tried it with up to date Red Hat Linux and Free BSD and Open
>>
>>BSD
>>
>>>servers and it never worked. Does someone know if I can use tools like
>>
>>ntpq
>>
>>>to do my tests?
>>>
>>
>>IPv4 and IPv6 multicast work in the latest ntp-dev release. Please note
>>however that you must set up authentication on both the client and the
>>server unless you explicitly disable authentication on the client.
>>
>>
>>>Do you know if something like that is supposed to work:
>>>    ntpq -n -c rv ff05::101
>>>or
>>>    ntpq -n -c rv ff01::101
>>>
>>
>>This is wrong. ntpq can only request information about a specific host.
>>
>>Danny
>>
>>
>>>Thanks,
>>>Mauricio
>>
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