[TriLUG] RHEL ntp problem

Ron Kelley rkelleyrtp at gmail.com
Tue Jun 28 14:20:57 EDT 2011


* What is default route?

* What does /etc/resolv.conf have?

Thanks,

-----------------------------
Ron Kelley
rkelleyrtp at gmail.com



On Jun 28, 2011, at 12:40 PM, Heath Roberts wrote:

> I have a problem on a redhat server. NTP appears not to be working. ntpq -p
> takes ~15s to timeout and makes it appear that ntpd is only trying to get
> time from localhost and failing:
> 
> [root@<hostname> init.d]# ntpq -p
> localhost.localdomain: timed out, nothing received
> ***Request timed out
> 
> 
> ntpdate also fails, whether run from command line or the ntpd startup
> script:
> 
> [root@<hostname> init.d]# /etc/init.d/ntpd reload
> Shutting down ntpd:                                        [  OK  ]
> ntpd
> : Synchronizing with time server:                      [FAILED]
> Starting ntpd:                                             [  OK  ]
> [root@<hostname> init.d]# ntpdate -d            <----------- this is where
> it takes ~15s to timeout
> 28 Jun 12:28:17 ntpdate[23039]: ntpdate 4.2.2p1 at 1.1570-o Thu Nov 26 11:34:35
> UTC 2009 (1)
> 28 Jun 12:28:17 ntpdate[23039]: no servers can be used, exiting
> 
> 
> I have another machine on similar (theoretically identical) hardware that
> was built from the same repository at the same time that works. I've copied
> its ntp.conf to the problem machine, with no change.
> 
> Any ideas?
> 
> 
> 
> Other information that seems potentially relevant (sorry, I have to
> obfuscate hostnames and IP addresses):
> 
> 
> [root@<hostname>init.d]# uname -a
> Linux <hostname> 2.6.18-238.5.1.el5 #1 SMP Mon Feb 21 05:52:39 EST 2011
> x86_64 x86_64 x86_64 GNU/Linux
> 
> [root@<hostname> init.d]# ls -l /etc/ntp.conf
> -rw-r--r-- 1 root root 1368 Jun 28 12:11 /etc/ntp.conf
> [root@<hostname> init.d]# cat /etc/ntp.conf
> # The security options setup.
> # ignore        - Deny all packets and queries
> # kod            - Send Kiss-Of-Death packet on access violation
> # nomodify    - Deny ntpq / ntpdc queries that attempt to modify the server
> # notrap        - Deny control message trap service
> # noquery      - Deny all ntpq / ntpdc queries
> # noserve      - Deny all queries - except ntpq / ntpdc
> # notrust        - Deny access unless cryptographically authenticated
> # nopeer        - Deny all packets that attempt to establish a peer
> association
> 
> # do not fail on large time jumps - need for vmware
> tinker panic 0
> 
> # Prohibit general access to this service.
> restrict default ignore
> 
> # Permit all access over the loopback interface.
> restrict 127.0.0.1
> 
> driftfile /var/ntp/drift
> broadcastdelay  0.008
> 
> # time syncronization is critical on this server. don't screw with this
> # without talking to Heath Roberts in Network Services.
> 
> server w.x.y.z
> restrict w.x.y.z mask 255.255.255.255 nomodify notrap noquery
> server w.x.y.z
> restrict w.x.y.z mask 255.255.255.255 nomodify notrap noquery
> server w.x.y.z
> restrict w.x.y.z mask 255.255.255.255 nomodify notrap noquery
> server w.x.y.z
> restrict w.x.y.z mask 255.255.255.255 nomodify notrap noquery
> 
> 
> 
> [root@<HOSTNAME> etc]# tcpdump udp port 123
> tcpdump: WARNING: eth0: no IPv4 address assigned
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
> 12:15:48.777261 IP <source hostname>.31004 > <dest hostname 1>.ntp: NTPv2,
> Reserved, length 12
> 12:15:53.777112 IP <source hostname>.31004 > <dest hostname 1>.ntp: NTPv2,
> Reserved, length 12
> 12:16:07.384655 IP <source hostname>.ntp > <dest hostname 2>.ntp: NTPv4,
> Client, length 48
> 12:16:07.477751 IP <dest hostname 2>.ntp > <source hostname>.ntp: NTPv4,
> Server, length 48
> 12:16:09.383854 IP <source hostname>.ntp > <dest hostname 3>.ntp: NTPv4,
> Client, length 48
> 12:16:09.395125 IP <dest hostname 3>.ntp > <source hostname>.ntp: NTPv4,
> Server, length 48
> 12:16:11.383959 IP <source hostname>.ntp > <dest hostname 1>.ntp: NTPv4,
> Client, length 48
> 12:16:11.384450 IP <dest hostname 1>.ntp > <source hostname>.ntp: NTPv4,
> Server, length 48
> 12:16:15.384436 IP <source hostname>.ntp > <dest hostname 4>.ntp: NTPv4,
> Client, length 48
> 12:16:15.468287 IP <dest hostname 4>.ntp > <source hostname>.ntp: NTPv4,
> Server, length 48
> 
> 10 packets captured
> 16 packets received by filter
> 0 packets dropped by kernel
> [root@<HOSTNAME> etc]# tcpdump -v udp port 123
> tcpdump: WARNING: eth0: no IPv4 address assigned
> tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 96
> bytes
> 12:17:12.383409 IP (tos 0x0, ttl  64, id 0, offset 0, flags [DF], proto: UDP
> (17), length: 76) <source hostname>.ntp > <dest hostname 3>.ntp: NTPv4,
> length 48
>        Client, Leap indicator:  (0), Stratum 2, poll 6s, precision -20
>        Root Delay: 0.000411, Root dispersion: 0.007751, Reference-ID: <dest
> hostname 1>
>          Reference Timestamp:  3518266571.384481638 (2011/06/28 12:16:11)
>          Originator Timestamp: 3518266569.389516592 (2011/06/28 12:16:09)
>          Receive Timestamp:    3518266569.395171970 (2011/06/28 12:16:09)
>          Transmit Timestamp:   3518266632.383346796 (2011/06/28 12:17:12)
>            Originator - Receive Timestamp:  +0.005655385
>            Originator - Transmit Timestamp: +62.993830204
> 12:17:12.394454 IP (tos 0x0, ttl  56, id 10462, offset 0, flags [DF], proto:
> UDP (17), length: 76) <dest hostname 3>.ntp > <source hostname>.ntp: NTPv4,
> length 48
>        Server, Leap indicator:  (0), Stratum 1, poll 6s, precision -20
>        Root Delay: 0.000000, Root dispersion: 0.000442, Reference-ID: GPS^@
>          Reference Timestamp:  3518266617.704929769 (2011/06/28 12:16:57)
>          Originator Timestamp: 3518266632.383346796 (2011/06/28 12:17:12)
>          Receive Timestamp:    3518266632.389916837 (2011/06/28 12:17:12)
>          Transmit Timestamp:   3518266632.390025585 (2011/06/28 12:17:12)
>            Originator - Receive Timestamp:  +0.006570036
>            Originator - Transmit Timestamp: +0.006678800
> 12:17:13.383469 IP (tos 0x0, ttl  64, id 0, offset 0, flags [DF], proto: UDP
> (17), length: 76) <source hostname>.ntp > <dest hostname 2>.ntp: NTPv4,
> length 48
>        Client, Leap indicator:  (0), Stratum 2, poll 6s, precision -20
>        Root Delay: 0.000411, Root dispersion: 0.007766, Reference-ID: <dest
> hostname 1>
>          Reference Timestamp:  3518266571.384481638 (2011/06/28 12:16:11)
>          Originator Timestamp: 3518266567.431153744 (2011/06/28 12:16:07)
>          Receive Timestamp:    3518266567.477801799 (2011/06/28 12:16:07)
>          Transmit Timestamp:   3518266633.383443862 (2011/06/28 12:17:13)
>            Originator - Receive Timestamp:  +0.046648047
>            Originator - Transmit Timestamp: +65.952290117
> 
> 
> 
> -- 
> Heath Roberts
> htroberts at gmail.com
> -- 
> This message was sent to: Ron Kelley <rkelleyrtp at gmail.com>
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