FreeBSD ntpd PPS setup (PPS slave) / 2006-05-01

I set up a new ntp server at work, and it is coupled to the meinberg gps timestandard. The meinberg is a very reliable time source but I don't want to invite the entire Internet to come over and bash it.

So an 'old' (2001) Dell PowerEdge 2550 got repurposed as FreeBSD ntp server. A lot nicer than it's previous role: windows domain controller.

The kernel:

FreeBSD metronoom 5.4-RELEASE-p13 FreeBSD 5.4-RELEASE-p13 #2: Fri Apr 21 16:09:21 UTC 2006 root@metronoom:/usr/obj/usr/src/sys/METRONOOM i386

The special bit in the kernel config is

options         PPS_SYNC                # for ntpd

in devfs.conf I link cuaa0 (first serial port) to pps0, so ntpd can open /dev/pps0 which is for clockdriver 22:

link cuaa0 pps0

And ntp.conf:

# get time from stardate

server stardate.cs.uu.nl prefer iburst

driftfile /var/ntp/ntp.drift

# fudge a local clock at stratum 10

server  127.127.1.0
fudge   127.127.1.0 stratum 10

# talk pps

enable pps kernel auth

server 127.127.22.0
#  minpoll 4 maxpoll 4 version 4
fudge  127.127.22.0 flag3 1
fudge  127.127.22.0 refid PPS

# access restrictions . localhost and staff can check everything. rest can
# get the time

restrict 127.0.0.1 
restrict 131.211.80.0 mask 255.255.254.0
restrict default kod notrap nopeer noquery

keys /etc/ntp.keys
trustedkey 3

# moeltiepaas!

broadcast 224.0.1.1 ttl 2 key 3

# announce policy

setvar access_policy="experimental server not suitable for production" default