NTP

Diese Anleitung ist für meine dcf-77 Funkuhr.

$ apt-get install ntp-refclock

Die Funkuhr hängt hier am ersten seriellen Port. Auf die Uhr wird über /dev/refclock-0 zugegriffen. Deshalb muss /dev/refclock-0 auf /dev/ttyS0 verweisen.
Verwendet man udev lässt sich das mittels folgendem Eintrag in z.B. /etc/udev/rules.d/10-myrules erreichen:

KERNEL=="ttyS0", NAME="%k", SYMLINK="refclock-%n", GROUP="tty"

Man kann den Link aber auch selbst erzeugen:

$ ln -s /dev/ttyS0 /dev/refclock-0

# /etc/ntp.conf, configuration for ntpd

# ntpd will use syslog() if logfile is not defined
logfile /var/log/ntpd
logconfig =all
driftfile /var/lib/ntp/ntp.drift
statsdir /var/log/ntpstats/

statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable

# You do need to talk to an NTP server or two (or three).
# meine dcf-77 Funkuhr
server 127.127.8.0 prefer mode 14

# pool.ntp.org maps to more than 100 low-stratum NTP servers.
# Your server will pick a different set every time it starts up.
#  *** Please consider joining the pool! ***
#  ***  http://www.pool.ntp.org/#join  ***
server pool.ntp.org
## uncomment for extra reliability

# ... and use the local system clock as a reference if all else fails
# NOTE: in a local network, set the local stratum of *one* stable server
# to 10; otherwise your clocks will drift apart if you lose connectivity.
#server 127.127.1.0
#fudge 127.127.1.0 stratum 13

# By default, exchange time with everybody, but don't allow configuration.
# See /usr/share/doc/ntp-doc/html/accopt.html for details.
#restrict default nomodify kod notrap nopeer noquery notrust noserve
restrict default ignore
restrict 127.127.8.0 nomodify

# Local users may interrogate the ntp server more closely.
restrict 127.0.0.1 nomodify

# Clients from this (example!) subnet have unlimited access,
# but only if cryptographically authenticated
#restrict 192.168.123.0  mask  255.255.255.0 notrust
restrict 192.168.57.0 mask 255.255.255.0 nomodify

# If you want to provide time to your local subnet, change the next line.
# (Again, the address is an example only.)
#broadcast 192.168.57.255

# If you want to listen to time broadcasts on your local subnet,
# de-comment the next lines. Please do this only if you trust everybody
# on the network!
#disable auth
#broadcastclient

Zur Erfolgskontrolle eignen sich folgende Befehle:

ntpq -c clocklist
ntpq -c peers

Aber auch ein Blick in /var/log/ntpd kann nicht schaden:

ntpd[869]: PARSE receiver #0: SYNCHRONIZED