NTP users are strongly urged to take immediate action to ensure that their NTP daemons are not susceptible to being used in distributed denial-of-service (DDoS) attacks. Please also take this opportunity to defeat denial-of-service attacks by implementing Ingress and Egress filtering through BCP38. See ConfiguringUBloxAntarisRefclocksDev for discussion of this topic.
ntp-4.2.8p15 was released on 23 June 2020. It addresses 1 medium-severity security issue in ntpd, and provides 13 non-security bugfixes over 4.2.8p13.
Are you using Autokey in production? If so, please contact Harlan - he's got some questions for you.
6.1.18. Configuring u-blox Antaris Refclock
The GPS receiver from u-blox
is very nice for the use as a time source,
as the 1 PPS time pulse is routed to the DCD line of its serial ports,
just where the PPSAPI
will look for it. I use their
GPS Evaluation Kit
, as it
has got all the level shifting issues already solved for me.
By default the GPS module
toggles its timepulse on the clear edge,
and its duration is 100 ms, so if you see the time of your reference
clock being wrong by that amount, then the PPS signal on-time edge
configuration flag in your ntp.conf is configured in a wrong manner.
I use the NMEA driver
of the NTP server, which is hardcoded to run at 4800 baud, 8-bits, no parity.
So the GPS receiver may simply be configured to output just the NMEA RMC message
on the serial port connected to the PC. The receiver's default baudrate is different,
so this has to be reconfigured as well. The configuration of the receiver is done
using the u-center software accompanying the evaluation kit.
# NMEA GPS driver for u-blox receiver
server 127.127.20.0 prefer
fudge 127.127.20.0 time1 0.0 flag2 1 flag3 0
I got it running smoothly on a Debian/GNU Linux
system (sarge) and NTP server version 4.2.0a.
Both the kernel and the NTP server needed the
recompiling in order to make use of the PPS pulse.
The result I get looks like this:
remote refid st t when poll reach delay offset jitter
*GPS_NMEA(0) .GPS. 0 l 17 64 377 0.000 0.009 0.001
- 19 Jan 2006
Related Topics: UBloxAntarisRefclockUsers