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

Danny Mayer mayer at ntp.isc.org
Mon Dec 10 04:09:05 UTC 2007


Brian Utterback wrote:
> Perhaps proper, but ill-advised. Look at the trouble we have
> had trying to satisfy that requirement. I am sitting at a
> system that currently has over 300 UDP ports in use. Exactly
> one of those UDP ports is bound on each interface, namely 123.
> Interestingly, it is also bound twice on the wildcard address
> as well.
> 
> Until recently, it wasn't possible in a portable manner, for
> a process to listen on a UDP port, receive a request and
> then issue a reply with the reply's source address guaranteed
> to be the same as the request's destination address. And
> virtually all UDP protocols had a way to deal with it, except
> NTP.
> 

Not true. NTP had a number of bugs in it that needed to get fixed.
Getting through all of the use cases took a long time to get right.
That's a bug not an architectural flaw.

Danny



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