[ntp:questions] Source address in response always the same as target address in request?

David L. Mills mills at udel.edu
Wed Dec 5 03:30:41 UTC 2007


Guys,

In both the NTPv4 specification and reference implementation the 
destination address used by the client when mobilizeing the association 
and sending the request must match the source address when receiving the 
response. This is a property of all RPC protocols known to me that use 
addresses to match requests with responses. This is so obvious a 
requirement that maybe the specification doesn't make it clear enough.

Dave

Brian Utterback wrote:
> guuwwe at hotmail.com wrote:
> 
>> Are there any clear requirements in NTP/SNTP RFC docs about the UDP
>> source address in
>> all responses the same as the UDP target address in the original
>> requests?
>> I doubt it would be a UDP requirement because this is domain of upper
>> protocols.
> 
> 
> 
> Yes and no. The basic protocol does not require it. The reference
> implementation does require it. The Autokey crypto authentication
> scheme currently requires it, but there has been some discussion
> recently about the nature of that requirement and whether it could
> be relaxed, but I don't see that discussion going anywhere in this
> regard.
> 
> Brian Utterback




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