[ntp:questions] Re: "Listen on" semantics

Danny Mayer mayer at ntp.isc.org
Sun Sep 24 03:34:27 UTC 2006

Maarten Wiltink wrote:
> At this point, people will shriek 'that's an SNTP server! Not NTP!' But
> is it? What's the difference? The current definition seems to be that
> to be an NTP server, you have to implement the client functionality (the
> math) yourself. I think it's more important _that_ the math is being
> done. _Where_ is not that important.

No, that's not true. The receiving end MUST be the one doing the math.
There is no way for the server to know what the delays are in getting a
packet to the client. Only the client has a chance to know that.

> [...]
>> OpenBSD's OpenNTP was, as I recall (and IMO), originally a malignantly
>> broken SNTP implementation.
> Malignantly, no less? Come off it. Sure, they made mistakes, but that
> wasn't the intent. The intent was to build something with no exploits.
> If the question is what comes first, working right or not getting rooted,
> well, they _are_ OpenBSD.

Which means absolutely nothing. People don't set up to create buggy or
exploitable code. I don't assume that just because they've given
themselves a label that they have an automatic level of trust in their
software. On top of that even if the code is not exploitable it doesn't
mean that it's correct.

> (Wouldn't a client-mode real NTP, combined with an OpenSNTP server, be
> the ideal configuration?)



> Groetjes,
> Maarten Wiltink

More information about the questions mailing list