[ntp:questions] Information needed regarding the *struct interface*

Danny Mayer mayer at ntp.isc.org
Wed Mar 22 04:00:44 UTC 2006

Arul Kumar C wrote:
> Hi All,
> Could you please enlighten me on a basic doubt in the fundamental data
> structure of NTP, the *interface* structure.
>>From the NTPv4 code (ntp-4.2.0), we could see that NTP creates socket
> descriptor for each of the interface present on the node and stores in
> inter_list[].  Would not a single UDP socket per node would be
> sufficient through which all the NTP traffic could be sent or received.
>  Am I missing any basic understanding on this part of the code, could
> you please help me here.

Yes, you are missing some basic misunderstandings. I don't have the time
right now to get into a detailed discussion of this but I can say that
it provides the simplest way of handling multiple interfaces and
addresses. It is an absolute requirement that a server responds from the
same address as it received a packet on and that's hard to do with a
single interface especially when it has to work on as many platforms as
we do. Authentication requires it. There are serious obstacles with
doing this with a single interface.


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