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.
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.
See ConfiguringWWVRefclocksDev for discussion of this topic.
6.1.19. Configuring WWV Refclocks
These notes concern getting the WWV refclock driver working on Linux.
Redhat linux 9.0 did not work with ntp-4.2.0 due to some unsupported ioctls.
Redhat Fedora Core 2.0 works with ntp-4.2.0, but with the current ntp-4.2.0 release it will be necessary to apply the a patch (shown below, courtesy of Tim Shoppa who discovered the correct ioctl call) otherwise you will end up with very poor (i.e. hundreds of msecs) offset and jitter. This patch is just for the ntp-4.2.0-7 fedora core RPM version, but you could hand-apply it to the non-redhat version.
With the $50 ramsey HFRC1 WWV receiver kit and some wire tacked to the ceiling serving as an antenna, I am currently getting performance which is on-par with various Internet stratum-1 servers
remote refid st t when poll reach delay offset disp
==============================================================================
*scrappy.margrav .WV15. 1 u 127 128 377 2.06 3.248 0.95
+time-nw.nist.go .ACTS. 1 u 6 128 377 80.86 8.965 0.93
+time-a.nist.gov .ACTS. 1 u 28 128 377 118.10 4.062 1.25
the relevant section of my ntp.conf is as follows
server 127.127.36.0
fudge 127.127.36.0 time1 0.005200 time2 0.014657 flag2 1 flag3 1 flag4 1
statistics clockstats loopstats peerstats
statsdir /var/log/ntp/
filegen clockstats file clockstats type day enable
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
Edit time1 and time2 for the propagation time for WWV and WWVH for your own location, using the locations of WWV and WWVH which can be found on the web, along with a great circle calculator (also found on the web). I simply divided by the speed of light (3.0e8 m/sec) but if you want you can use various propagation calculation programs to account for other factors like ionosphering bouncing, etc.
The following patch has been applied to
ntp-dev
as of September 7, 2004.
--- ntp-4.2.0/libntp/audio.c.ioctl 2004-06-27 20:41:31.600401280 -0700
+++ ntp-4.2.0/libntp/audio.c 2004-06-27 20:41:35.704747259 -0700
@@ -284,6 +284,8 @@
printf("audio_init: set: play_size %d, rec_size %d\n",
s_size.play_size, s_size.rec_size);
# endif /* HAVE_STRUCT_SND_SIZE */
+ int tmp = (16<<16)+6; /* 16 fragments, each fragment is 2^6 bytes */
+ ioctl(fd,SNDCTL_DSP_SETFRAGMENT, &tmp);
# ifdef AIOGFMT
if (ioctl(fd, AIOGFMT, &s_c_p) == -1)
Related Topics: WWVRefclockUsers
--
DavidMargrave - 28 Jun 2004
I've put up a couple of pages with summary statistics from my WWV refclock implementation.
Clockstats data
Loopstats data
--
DavidAndersen - 28 Oct 2009