[ntp:questions] Re: Public servers?

David L. Mills mills at udel.edu
Thu Jul 31 23:32:41 UTC 2003


Let me introduce you to SNTP (RFC-2030, as amended in process). SNTP, 
meet Tim. If I have unfairly accused you, my apologies.

That's an interesting idea to wiretap NTP on the way past a router and 
flip back a reply. Very trusting, but most of us would consider that a 
middleman attack unless validated by NTPv4 Autokey.


Tim Hogard wrote:
> NTP was built to solve a complex time problem that simply does not
> exist for 99.99+% of the users on the net however because NTP is a
> solution to a problem they have, NTP server operators get nailed.
> For most time applications, round trip time is meaningless.  A
> "set the clock" operation is one UDP packet to a nearby router
> which sends back the time.
> I would propose that a field be set up so say protocol 5 (is that
> next consider it VerySimpleNTP), simply sends a packet back with
> the current time with the assumption that none of the other issues
> need to be considered.  That means a VSNTP overhead on a typical
> NTP server is a syscal to get the time and one to send it in the
> packet.  It would also make sense to put in the RFC that any router
> that responds to public NTP packets is assumed to give concent for
> its use only to thouse users who's packets would normally flow
> through that router.  With those two things and Cisco IOS, its
> faster to send back the current time than it is to forward the
> packet.

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