In article <[EMAIL PROTECTED]>, Richard B. Gilbert <[EMAIL PROTECTED]> wrote: > Alexandre Carrausse wrote:
> > I agree but the link between the GPS antenna and the secure area will be > > coper, not fiber. No. The copper would terminate on the GPS receiver, which would be outside the secure area. The fibre would carry the baseband NMEA signal. > If you are allowed to have a fiber optic link but not a copper link you > could run NTP over the fiber link! I'm not aware of any refclock that There are two likely reasons for restricting to fibre: one is EMP protection, the other is security. If security is the case, and you operate a bidirectional protocol like NTP, the electronics at the remote end of the link would almost certainly also be considered part of the secure area and subject to the same restrictions as the main area, unless the data was encrypted and they were not the final end point of the transmission. (Google "covert channels" for more.) He might be allowed to operate a link that was uni-directional, which would allow him to have the complete receiver in an insecure area, and transmit the data optically (phototdiodes aren't very good light sources, so there is little risk of information leaking the other way). I don't believe that ntpd needs to be able to talk to NMEA time sources, although it may try to configure them. _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
