[EMAIL PROTECTED] writes: > On Fri, Aug 20, 2004 at 10:26:08AM +0400, 3APA3A ([EMAIL PROTECTED]) wrote: > [...] > > you state: > > > > If there is a host with reliable time on the network (that is host > > synchronized with some hardware source, like radio clocks, cesium > > clocks, GPS clocks, etc) - whole network will be finally, after some > > time, synchronized with this host. > > > > Depending upon the criticality of the time sensitive applications on > > the network, you might want to reconsider the use of "radio clocks" > > and especially "GPS clocks". These time sources are also subject to > > attacks. Any free air broadcast is subject to jamming. This is > > essentially a DoS. Spoofing to provide incorrect time signal is also > > possible with free air broadcast, but less easy to do. > [...] > > For a fixed installation detecting if someone is dinking the gps signal > is trivial. The unit starts thinking it is not in Kansas anymore. > -- > Chief Gadgeteer > Elegant Innovations >
That's fine as long as your time receiver actually interprets locations also. I have seen GPS time signal receivers that only extract the time, not the locaation. These receivers do not know or care where they are; they just want to know what time it is. Also, what about a GPS time receiver on a moving vehicle, such as a ship at sea? They would not necessarily know that the location information was wrong, unles they also had other means of determining location. Besides, it might only be *SLIGHTLY* wrong, but wrong enough to cause the time signal to be off enough to cause the application to produce erroneous results. It all depends on the application. -- -------- "And there came a writing to him from Elijah" [2Ch 21:12] -------- R. J. Brown III [EMAIL PROTECTED] http://www.elilabs.com/~rj voice 859 567-7311 Elijah Laboratories Inc. P. O. Box 166, Warsaw KY 41095 fax 859 567-7311 ----- M o d e l i n g t h e M e t h o d s o f t h e M i n d ------ _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
