[ntp:questions] Leap-second flag not forwarded to NTP clients
Santi Saez
santi at woop.es
Tue Aug 14 10:34:10 UTC 2012
Hello,
I'm making some tests with "leapfile" feature on ntpd to send fake
leap-seconds and ensure our Linux platform is resilient to the bug :)
Lab is quite simple: a "master" server with local clock running ntpd
with leapfile feature, and a "client" system also running ntpd that
connects to the "master".
I have just found that leap-second flag is forwarded from the "master"
to the "client" without problems on CentOS-6 boxes (running 4.2.4p8-2),
but with the same configuration it doesn't work on Debian Squeeze
(4.2.6.p2+dfsg-1+b1). If I query ntpd it returns "leap_add_sec" and
"leap=01" flags, and running a tcpdump I also see those flags, but the
"client" system seems that it's ignoring the flags, as I say: this only
happens on Debian running 4.2.6.p2 from upstream.
This is the config on CentOS systems = works OK
* master
driftfile /var/lib/ntp/drift
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery
restrict 127.0.0.1
restrict -6 ::1
server 127.127.1.0 iburst
fudge 127.127.1.0 stratum 10
includefile /etc/ntp/crypto/pw
keys /etc/ntp/keys
keysdir /etc/ntp
crypto pw password
* client
driftfile /var/lib/ntp/drift
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery
restrict 127.0.0.1
restrict -6 ::1
server 172.16.2.1 iburst
includefile /etc/ntp/crypto/pw
keys /etc/ntp/keys
This is the config on Debian systems = leap-second not forwarded from
"master" to the "client"
* master
leapfile "/etc/leap-seconds.list"
driftfile /var/lib/ntp/drift
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery
restrict 127.0.0.1
restrict -6 ::1
server 127.127.1.1 iburst
fudge 127.127.1.1 stratum 10
includefile /etc/ntp/crypto/pw
keys /etc/ntp/keys
* client
driftfile /var/lib/ntp/drift
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery
restrict 127.0.0.1
restrict -6 ::1
server 10.204.3.2 iburst
includefile /etc/ntp/crypto/pw
keys /etc/ntp/keys
The unique difference is the way leap-second is configured, it depends
on ntpd version [1], the remaining conf is the same on both master and
client servers.
What can be the reason that blocks leap-second being forwarded on
Debian/4.2.6.p2 systems? Thanks!
[1] http://support.ntp.org/bin/view/Support/ConfiguringNTP#Section_6.14.1.
Santi Saez
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