NTP's ntp.conf

pxumsgdxpcvjm · 08-30-2007, 08:46 PM

For something as basic as time, I would think that this file would be a little easier to understand.

I'm running Slackware 12.0 and it comes with an pre-configured /etc/ntp.conf file.

Code:

# Sample /etc/ntp.conf:  Configuration file for ntpd.
#
# Undisciplined Local Clock. This is a fake driver intended for backup
# and when no outside source of synchronized time is available. The
# default stratum is usually 3, but in this case we elect to use stratum
# 0. Since the server line does not have the prefer keyword, this driver
# is never used for synchronization, unless no other other
# synchronization source is available. In case the local host is
# controlled by some external source, such as an external oscillator or
# another protocol, the prefer keyword would cause the local host to
# disregard all other synchronization sources, unless the kernel
# modifications are in use and declare an unsynchronized condition.
#
server	127.127.1.0	# local clock
fudge	127.127.1.0 stratum 10	
server  pool.ntp.org

#
# Drift file.  Put this in a directory which the daemon can write to.
# No symbolic links allowed, either, since the daemon updates the file
# by creating a temporary in the same directory and then rename()'ing
# it to the file.
#
driftfile /etc/ntp/drift
multicastclient			# listen on default 224.0.1.1
broadcastdelay	0.008

#
# Keys file.  If you want to diddle your server at run time, make a
# keys file (mode 600 for sure) and define the key number to be
# used for making requests.
# PLEASE DO NOT USE THE DEFAULT VALUES HERE. Pick your own, or remote
# systems might be able to reset your clock at will.
#
#keys		/etc/ntp/keys
#trustedkey	65535
#requestkey	65535
#controlkey	65535

# Don't serve time or stats to anyone else by default (more secure)
restrict default noquery nomodify
# Trust ourselves.  :-)
restrict 127.0.0.1

I've done a little searching and found what certain statements mean but there is still a few things I don't understand. The documentation of NTP is just as complex as this configuration file. "stratum", "broadcastdelay", "fudge", etc. Huh? I'm one that likes to know exactly what each line in a configuration file means.

All I'm trying to do is get this computer syncing with a number of servers and allow other computers on my LAN (running Windows XP) syncing with this box.

What do I need to do this? (I don't expect anyone to write the file for me, just a point in the right direction.)

Thanks to any replies.

Okie · 08-30-2007, 09:24 PM

add this to your /etc/ntp.conf

Code:

server 0.us.pool.ntp.org
server 1.us.pool.ntp.org
server 2.us.pool.ntp.org

this is all mine has, none of the other stuff the default has...

as far as syncing XP on your lan goes i have no clue...

FragInHell · 08-30-2007, 09:34 PM

Hi,

I'm no expert in NTP, but here goes:

Code:

server	127.127.1.0	# local clock
fudge	127.127.1.0 stratum 10

This is the local system time and I think the fudge it to give it a stratum. This is in case you lose your internet connection, ntp will use the internal system clock.
A stratum is the accuracy of the source clock. Stratum 1 clocks are the most accurate, and are driven by a GPS clock, or an atomic clock.
There are a few public stratum one clocks about but not many. a Stratum 2 clock is not as accurate, but might have its source as a stratum 1 clock.
Therefore the lower the stratum number the more accurate the clock is.
There is a list of publicly available clocks on the ntp site some where.
I think therefore if you create a ntp server on you internal network and its sources are stratum 2 your server would then be a stratum 3 source.(not 100% sure about this)
You can point your ntp config at as many as you like.
Some public clocks like you to subscribe to there mail list etc so they can keep track of the number of users.

Code:

broadcastdelay

I'm sorry not sure about this one.

One thing you can try once you have your ntp setup is run ntpq
then type peers. This will show you which clocks you are syncing from, accuracy etc.