[ntp:questions] Problems configuring an NTP subnet

SimoTerradillos, Carlos Joaquin carlos.simo at eess.madrid.cepsa.es
Tue May 23 19:01:16 UTC 2006


Hello:

I`m trying to set up a NTP subnet over a LAN. This subnet has following structure:

1.-NTP Server
This server also is a client from another "central server" outside my LAN..
My /etc/ntp.conf file is like this:

server EESS_NTPSRV_1
server 127.127.1.0
fudge 127.127.1.0 stratum 5
restrict 172.19.250.0 mask 255.255.255.224 notrust nomodify notrap
broadcast 172.19.250.31
authentication no
driftfile /etc/ntp/drift
tinker dispersion 1.000
statsdir /var/log/ntp/
filegen peerstats file peerstat.log enable


EESS_NTPSRV_1 is the server outside my LAN "172.19.250.0". I want use my NTP server as broadcast server.

2.-NTP clients
In this case, /etc/ntp.conf is like this:

driftfile /etc/ntp/drift
broadcastclient
authenticate no
statsdir /var/log/ntp/
filegen peerstats file peerstat.log enable



My NTP Server seems synchronize OK with EESS_NTPSRV_1, as shows an `ntpq -p` :
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 LOCAL(0)        LOCAL(0)         5 l    3   64  377    0.000    0.000   0.008
 172.19.250.31   0.0.0.0         16 -    -   64    0    0.000    0.000 4000.00
*EESS_NTPSRV_1   172.31.61.173    2 u   48   64  377   52.855  -495811   0.008

An `ntpq -c rv` over my NTP Server shows:

status=06a4 leap_none, sync_ntp, 10 events, event_peer/strat_chg,
version="ntpd 4.1.1 at 1.786 Tue Jan 28 15:20:29 CET 2003 (1)",
processor="i686", system="Linux2.4.20-28.7", leap=00,
stratum=3, precision=-17, rootdelay=60.590, rootdispersion=705358.888,
peer=42678, refid=ces_ssh,
reftime=c81ddb99.b86a7ef9  Tue, May 23 2006 21:06:01.720, poll=6,
clock=c81ddbb8.0e33df2a  Tue, May 23 2006 21:06:32.055, state=3,
offset=-494949.280, frequency=-500.000, jitter=0.011,
stability=16134.000




My NTP Client seems doing anything; when execute ntpq -p shows the following:

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================

nothing else.

If I execute `ntpq -c rv` over my NTP Client shows:

status=c011 sync_alarm, sync_unspec, 1 event, event_restart,
version="ntpd 4.1.0 Wed Sep  5 06:54:30 EDT 2001 (1)", processor="i686",
system="Linux2.4.7-10", leap=11, stratum=16,
precision=-15, rootdelay=0.000, rootdispersion=0.945, peer=0,
refid=0.0.0.0, reftime=00000000.00000000  Thu, Feb  7 2036  7:28:16.000,
poll=4, clock=c81ddb94.a4db7ae5  Tue, May 23 2006 21:05:56.643, state=1,
offset=0.000, frequency=0.000, jitter=0.031, stability=0.000


Also, I`ve used tcpdump to check if my server sends broadcast packets. When I execute `tcpdump -n -i eth0 port 123` from my client:

19:24:41.241764 172.19.250.3.ntp > 172.19.250.2.ntp:  v4 client strat 0 poll 6 p
rec -16 (DF) [tos 0x10] 
19:24:41.241764 172.19.250.2.ntp > 172.19.250.3.ntp:  v4 server strat 3 poll 6 p
rec -17 (DF) [tos 0x10] 
19:24:45.611764 172.19.250.2.ntp > 172.19.250.31.ntp:  v4 bcast strat 3 poll 6 p
rec -17 (DF) [tos 0x10] 
19:24:58.241764 172.19.250.3.ntp > 172.19.250.2.ntp:  v4 client strat 0 poll 6 p
rec -16 (DF) [tos 0x10] 
19:24:58.241764 172.19.250.2.ntp > 172.19.250.3.ntp:  v4 server strat 3 poll 6 p
rec -17 (DF) [tos 0x10] 
19:25:16.241764 172.19.250.3.ntp > 172.19.250.2.ntp:  v4 client strat 0 poll 6 p
rec -16 (DF) [tos 0x10] 
19:25:16.241764 172.19.250.2.ntp > 172.19.250.3.ntp:  v4 server strat 3 poll 6 p
rec -17 (DF) [tos 0x10] 
19:25:34.241764 172.19.250.3.ntp > 172.19.250.2.ntp:  v4 client strat 0 poll 6 p
rec -16 (DF) [tos 0x10] 
19:25:34.241764 172.19.250.2.ntp > 172.19.250.3.ntp:  v4 server strat 3 poll 6 p
rec -17 (DF) [tos 0x10] 
19:25:48.601764 172.19.250.2.ntp > 172.19.250.31.ntp:  v4 bcast strat 3 poll 6 p
rec -17 (DF) [tos 0x10] 
19:25:52.241764 172.19.250.3.ntp > 172.19.250.2.ntp:  v4 client strat 0 poll 6 p
rec -16 (DF) [tos 0x10] 
19:25:52.241764 172.19.250.2.ntp > 172.19.250.3.ntp:  v4 server strat 3 poll 6 p
rec -17 (DF) [tos 0x10] 

172.19.250.2 is  NTP Server address
172.19.250.3 is NTP Client address
172.19.250.31 is LAN broadcast address 

It seems that my client is receving NTP broadcast packets...but it doesn´t work.



Can anyone helps me?


Thanks,
Carlos.  
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