[ntp:questions] Simple ntp setup, but network issue

Jeff Boyce jboyce at meridianenv.com
Tue Aug 29 19:54:20 UTC 2006


Greetings -

I am still working (when I have spare time) on diagnosing my problem 
communicating with an ntp server.  As people helpfully pointed out to me 
last week, from my ntpq results (see below) it appears that I have a network 
communication problem and I should do some type of network trace to see what 
is occurring.

[root at Bison root]# ntpq -p
     remote           refid      st t when poll reach   delay   offset
jitter
==============================================================================
 rainforest.neor 0.0.0.0         16 u    - 1024    0    0.000    0.000
4000.00
*LOCAL(0)        LOCAL(0)        10 l   21   64  377    0.000    0.000
0.008

A partial listing of the tcpdump showing three pings and starting the ntp 
service is below.  I don't know how to interpret all of this, but am 
assuming that the two lines I have marked indicate my problem.  I am not 
sure exactly what this tells me or how to fix it, so I am hoping to get some 
experienced guidance from the list here.  The address 192.168.112.10 is my 
dsl modem which serves as my network gateway, bison is my linux server.

Partial output of tcpdump
Sent 3 Pings to rainforest.neorack.com
11:31:41.839155 bison > rainforest.neorack.com: icmp: echo request (DF)
11:31:41.840913 jeff.1651 > bison.ssh: P 208:260(52) ack 221 win 65179 (DF)
11:31:41.880647 bison.ssh > jeff.1651: . ack 260 win 8576 (DF) [tos 0x10]
*** 11:31:42.150646 arp who-has 192.168.112.10 tell bison
*** 11:31:42.150939 arp reply 192.168.112.10 is-at 0:15:5:4f:ec:6f
11:31:42.850665 bison > rainforest.neorack.com: icmp: echo request (DF)
11:31:43.163271 0.00:40:8c:55:57:34.4000 > 
0.ff:ff:ff:ff:ff:ff.452:ipx-sap-req 4
11:31:43.850660 bison > rainforest.neorack.com: icmp: echo request (DF)
11:31:44.162307 0.00:40:8c:55:57:34.4000 > 
0.ff:ff:ff:ff:ff:ff.452:ipx-sap-req 4
11:31:45.162242 0.00:40:8c:55:57:34.4000 > 
0.ff:ff:ff:ff:ff:ff.452:ipx-sap-req 4

Started ntp service
11:32:02.030685 bison.ntp > rainforest.neorack.com.ntp: v4 client strat 0 
poll 4 prec -6 (DF)
11:32:02.102846 jeff.1661 > bison.10000: . ack 9983 win 65497 (DF)
11:32:03.030690 bison.ntp > rainforest.neorack.com.ntp: v4 client strat 0 
poll 4 prec -6 (DF)
11:32:04.030667 bison.ntp > rainforest.neorack.com.ntp: v4 client strat 0 
poll 4 prec -6 (DF)
11:32:05.030668 bison.ntp > rainforest.neorack.com.ntp: v4 client strat 0 
poll 4 prec -6 (DF)
11:32:06.030670 bison.ntp > rainforest.neorack.com.ntp: v4 client strat 0 
poll 4 prec -6 (DF)
11:32:07.030662 bison.ntp > rainforest.neorack.com.ntp: v4 client strat 0 
poll 4 prec -6 (DF)
11:32:08.030670 bison.ntp > rainforest.neorack.com.ntp: v4 client strat 0 
poll 4 prec -6 (DF)
11:32:09.030669 bison.ntp > rainforest.neorack.com.ntp: v4 client strat 0 
poll 4 prec -6 (DF)

I don't know if I need to make a configuration change in my linux server or 
in my gateway dsl box (an ActionTec appliance from Qwest).  Below is the 
routing table and the hosts file for my server, if that helps.  I also have 
the option of setting up Static Routes or Port Forwarding on the software in 
the dsl appliance, but I don't know what needs to be changed or the most 
appropriate place to change the configuration if there are options.  Advice 
on this issue would be most appreciated, especially if I can learn something 
new that prevents me from running into similar problems in the future.  I am 
a novice linux administrator so please give me the basics with some 
explanation.  Thanks.

[jeffb at Bison jeffb]$ netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt 
Iface
192.168.112.0   0.0.0.0         255.255.255.0   U         0 0          0 
eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 
eth0
0.0.0.0         192.168.112.10  0.0.0.0         UG        0 0          0 
eth0

 /etc/hosts
127.0.0.1 bison localhost.localdomain localhost
192.168.112.1 bison
192.168.112.105 jeff
192.168.112.100 pamk


Jeff Boyce
www.meridianenv.com 




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