[Bug 674701] Re: NTP client packets always have bad checksum

[Mike Holper]

Is there any particular value that you want me to set snaplen to with
the -s option?

Thanks,

Mike


On Mon, Nov 15, 2010 at 4:29 AM, Chuck Short <chuck.short at canonical.com> wrote:
> Please try using the -s swtich with tcpdump and see if you can
> reproduce.
>
> thanks
> chuck
>
> ** Changed in: ntp (Ubuntu)
>   Importance: Undecided => Low
>
> ** Changed in: ntp (Ubuntu)
>       Status: New => Incomplete
>
> --
> NTP client packets always have bad checksum
> https://bugs.launchpad.net/bugs/674701
> You received this bug notification because you are a direct subscriber
> of the bug.
>
> Status in “ntp” package in Ubuntu: Incomplete
>
> Bug description:
> Binary package hint: ntp
>
> UDP packets from my Ubuntu 10.10 NTP client (.143.2) to my NTP server (.143.13) appear to always have a bad checksum, as reflected here in this tcpdump capture: (started as "sudo tcpdump -nvv udp port 123")
> -----------------------------
> 11:12:46.871451 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 76)
>    192.168.143.2.123 > 192.168.143.13.123: [bad udp cksum 1cf6!] NTPv4, length 48
>        Client, Leap indicator:  (0), Stratum 4 (secondary reference), poll 10s, precision -20
>        Root Delay: 0.367874, Root dispersion: 0.486328, Reference-ID: 192.168.143.13
>          Reference Timestamp:  3498584143.872812747 (2010/11/12 10:55:43)
>          Originator Timestamp: 3498584143.811634063 (2010/11/12 10:55:43)
>          Receive Timestamp:    3498584143.872812747 (2010/11/12 10:55:43)
>          Transmit Timestamp:   3498585166.871437788 (2010/11/12 11:12:46)
>            Originator - Receive Timestamp:  +0.061178639
>            Originator - Transmit Timestamp: +1023.059803709
> 11:12:46.873147 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 76)
>    192.168.143.13.123 > 192.168.143.2.123: [udp sum ok] NTPv4, length 48
>        Server, Leap indicator:  (0), Stratum 3 (secondary reference), poll 10s, precision -14
>        Root Delay: 0.367065, Root dispersion: 0.405197, Reference-ID: 149.20.54.20
>          Reference Timestamp:  3498580747.587430417 (2010/11/12 09:59:07)
>          Originator Timestamp: 3498585166.871437788 (2010/11/12 11:12:46)
>          Receive Timestamp:    3498585166.812102258 (2010/11/12 11:12:46)
>          Transmit Timestamp:   3498585166.812599122 (2010/11/12 11:12:46)
>            Originator - Receive Timestamp:  -0.059335514
>            Originator - Transmit Timestamp: -0.058838650
> -----------------------------
> This is my first bug report, so hopefully I've included everything that is needed. If not, please let me know what else is needed and I'll do my best to get it.
>
> Thanks!
>
> ProblemType: Bug
> DistroRelease: Ubuntu 10.10
> Package: ntp 1:4.2.4p8+dfsg-1ubuntu6
> ProcVersionSignature: Ubuntu 2.6.35-22.35-generic 2.6.35.4
> Uname: Linux 2.6.35-22-generic x86_64
> NonfreeKernelModules: nvidia
> Architecture: amd64
> Date: Fri Nov 12 11:11:46 2010
> EcryptfsInUse: Yes
> ExecutablePath: /usr/sbin/ntpd
> InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
> NtpStatus:
>  remote           refid      st t when poll reach   delay   offset  jitter
>  ==============================================================================
>  *nematode.local  149.20.54.20     3 u  964 1024  377    0.816  -60.770   5.488
> ProcAttrCurrent: /usr/sbin/ntpd (enforce)
> ProcEnviron:
>
> SourcePackage: ntp
> mtime.conffile..etc.ntp.conf: 2010-11-10T10:30:46.779535
>
> To unsubscribe from this bug, go to:
> https://bugs.launchpad.net/ubuntu/+source/ntp/+bug/674701/+subscribe
>

-- 
NTP client packets always have bad checksum
https://bugs.launchpad.net/bugs/674701
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