[ntp:questions] Security when using non windows sntp client with Windows SNTP server

Danny Mayer mayer at ntp.isc.org
Sun May 7 02:00:03 UTC 2006

sandy wrote:
> Hi all,
> My requirement is to use SNTP. I am trying to synchronize time between
> a linux based system as sntp client and  windows 2000 SNTP server. I
> notice that time is getting synchronized. I am not sure whether the
> packets are secured. Can anybody please tell me whethere the packets
> are secure by default ? If not, how to add security for these packets ?
>  Could you please guide me ? 
> Regards,
> Sandy

Windows SNTP server has no concept of security. It receives an NTP
request and returns an NTP packet. That's it.

It is not clear what you mean by secure. Are you asking if they are
encrypted, authenticated, or something else?

Please note the NTP does not support encryption. What you get with the
reference implementation NTP as opposed to SNTP is authentication of the
*server*, but that requires several round trips to set up the
validation. SNTP is not really meant for that. What you can do is
install NTPd on the Server and then use NTPd on the clients. You would
need to generated keys that you would need to distribute to each client
you want to have authenticate against the server.


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