Ubuntu
traceroute package

traceroute --mtu doesn't work on recent kernels

Bug #1354704 reported by Graham Inggs
8
This bug affects 1 person
Affects Status Importance Assigned to Milestone
traceroute (Debian)
Fix Released
Unknown
traceroute (Ubuntu)
Fix Released
Undecided
Unassigned
Trusty
Fix Released
Undecided
Unassigned

Bug Description

[SRU] The debdiff attached to comment #4 backports traceroute 1:2.0.20-2 from Utopic to Trusty and fixes the following bugs present in 1:2.0.19-3 in Trusty:
 - Fix segfault with --mtu (LP: #1330558)
 - Fix --mtu on recent kernels (LP: #1354704)

[IMPACT]
Users of traceroute in Trusty are unable to make use of the --mtu option to discover the MTU along the path being traced. This works fine in Precise.

[Test Case]
Run traceroute with the --mtu option, e.g.:
traceroute --mtu 8.8.8.8

Expected behaviour: a regular traceroute of the path to the host is printed, including F=<NUM> at the hops where the MTU is reached.

Actual behaviour (in Trusty): segmentation fault.

[Regression Potential]
Minimal: traceroute is recommended by netperfmeter, subnetcalc and xorp, and depended on by libnet-traceroute-perl and zentyal-network.

-----------------------------------------------------------------------------

Running traceroute with the --mtu option gives strange output on recent kernels:

$ traceroute --mtu 8.8.8.8
traceroute to 8.8.8.8 (8.8.8.8), 30 hops max, 65000 byte packets
1 * 0.015 ms * 0.007 ms * 0.006 ms
2 * 0.006 ms * 0.007 ms * 0.006 ms
3 * 0.006 ms * 0.006 ms * 0.006 ms
4 * 0.006 ms * 0.008 ms * 0.007 ms
5 * 0.007 ms * 0.006 ms * 0.006 ms

I see similar numbers up to hop 30 and they appear almost instantly.
In Sid, Ubuntu Utopic and Ubuntu Trusty, traceroute 2.0.20 produces
output as above but 2.0.19 and 2.0.18 all segfault (as in #750759)
with the --mtu option.

In Ubuntu Precise (kernel 3.2), traceroute 2.0.18, 2.0.19 and 2.0.20
all work correctly with the --mtu option.

See original description
Revision history for this message
Graham Inggs (ginggs) wrote :

See also LP: #1330558

Bug Watch Updater (bug-watch-updater)
Changed in traceroute (Debian):
status: Unknown → New
Bug Watch Updater (bug-watch-updater)
Changed in traceroute (Debian):
status: New → Fix Released
Revision history for this message
Graham Inggs (ginggs) wrote :

Fix released in traceroute 1:2.0.20-2 in utopic.

Changed in traceroute (Ubuntu):
status: New → Fix Released
Revision history for this message
Graham Inggs (ginggs) wrote :

The attached debdiff backports 1:2.0.20-2 to Trusty as an SRU.

Upstream 2.0.20 changelog indicates only bugfixes:

2014-06-14 Dmitry Butskoy <email address hidden> - 2.0.20
 * Describe all complementary long options in the man page (Jan Synacek)
 * Use correct service name for AS lookups (Frederic Mangano)
 * Avoid some rare case null dereference (<email address hidden>)
 * Improve expiration check for simultaneous probes

Graham Inggs (ginggs)
description: updated
Revision history for this message
Graham Inggs (ginggs) wrote :

The fact that the fix for LP: #1354704 relies on the fix for LP: #1330558 from 2.0.20, and that the other changes in 2.0.20 are very small and introduce no new features, makes me think it is worth uploading the complete new version rather than cherry-picking the fix for the --mtu option alone.

Revision history for this message
Chris J Arges (arges) wrote : Please test proposed package

Hello Graham, or anyone else affected,

Accepted traceroute into trusty-proposed. The package will build now and be available at http://launchpad.net/ubuntu/+source/traceroute/1:2.0.20-0ubuntu0.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

Changed in traceroute (Ubuntu Trusty):
status: New → Fix Committed
tags: added: verification-needed
Revision history for this message
Andreas Hasenack (ahasenack) wrote :

Works with 1:2.0.20-0ubuntu0.1 on trusty:

root@nsn7:~# ifconfig wlan0 mtu 1400
root@nsn7:~# traceroute --mtu 8.8.8.8
traceroute to 8.8.8.8 (8.8.8.8), 30 hops max, 65000 byte packets
 1 192.168.48.1 (192.168.48.1) 2.714 ms F=1400 1.041 ms 1.268 ms
 2 213.253.214.217 (213.253.214.217) 4.515 ms 1.314 ms 4.647 ms
 3 82.141.188.13 (82.141.188.13) 6.941 ms 3.253 ms 4.873 ms
(...)

root@nsn7:~# ifconfig wlan0 mtu 1389
root@nsn7:~# traceroute --mtu 8.8.8.8
traceroute to 8.8.8.8 (8.8.8.8), 30 hops max, 65000 byte packets
 1 192.168.48.1 (192.168.48.1) 1.272 ms F=1389 1.120 ms 9.785 ms
 2 213.253.214.217 (213.253.214.217) 1.311 ms 2.442 ms 2.640 ms
 3 82.141.188.13 (82.141.188.13) 5.924 ms 1.838 ms 4.321 ms
(...)

Graham Inggs (ginggs)
tags: added: verification-done
removed: verification-needed
Revision history for this message
Chris J Arges (arges) wrote : Update Released

The verification of the Stable Release Update for traceroute has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package traceroute - 1:2.0.20-0ubuntu0.1

---------------
traceroute (1:2.0.20-0ubuntu0.1) trusty; urgency=medium

  * Backport 1:2.0.20-2 to Trusty as an SRU
    - Fix segfault with --mtu (LP: #1330558)
    - Fix --mtu on recent kernels (LP: #1354704)
 -- Graham Inggs <email address hidden> Mon, 11 Aug 2014 12:07:54 +0200

Changed in traceroute (Ubuntu Trusty):
status: Fix Committed → Fix Released
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