Bug 249001
Summary: | traceroute incorrectly reports MPLS information in ICMP unreachable as icmp checksum wrong | ||||||||
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Product: | Red Hat Enterprise Linux 4 | Reporter: | Ralph Angenendt <ralph+rh-bugzilla> | ||||||
Component: | traceroute | Assignee: | Jiri Skala <jskala> | ||||||
Status: | CLOSED ERRATA | QA Contact: | |||||||
Severity: | low | Docs Contact: | |||||||
Priority: | medium | ||||||||
Version: | 4.5 | CC: | aglotov, jplans, kajtzu, mmalik, mnagy, skywalk2, syeghiay, tao, vincew | ||||||
Target Milestone: | rc | ||||||||
Target Release: | --- | ||||||||
Hardware: | All | ||||||||
OS: | Linux | ||||||||
Whiteboard: | |||||||||
Fixed In Version: | Doc Type: | Bug Fix | |||||||
Doc Text: | Story Points: | --- | |||||||
Clone Of: | Environment: | ||||||||
Last Closed: | 2008-09-10 08:39:55 UTC | Type: | --- | ||||||
Regression: | --- | Mount Type: | --- | ||||||
Documentation: | --- | CRM: | |||||||
Verified Versions: | Category: | --- | |||||||
oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||||
Cloudforms Team: | --- | Target Upstream Version: | |||||||
Embargoed: | |||||||||
Attachments: |
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Description
Ralph Angenendt
2007-07-20 09:17:20 UTC
At my site I found that specifying a packet size of 72 or larger (99 is convenient) seems to avoid the bug. This may serve as a temporary work-around pending install of another version. I can reproduce this. Martin, It related to the previous epoch of the traceroute (1.4a). All mine are >= 2.0.x :) Try is it reproducable under RHEL5 or Fedora. (In reply to comment #3) > Martin, > > It related to the previous epoch of the traceroute (1.4a). > > All mine are >= 2.0.x :) > > Try is it reproducable under RHEL5 or Fedora. That doesn't help for RHEL4 at all. And it worked before ... true, and I can reproduce it as well... very annoying :( I have now downgraded to the package on original RHEL4 and working fine again so it must be a bug on traceroute. Created attachment 308811 [details]
traceroute-1.4a12-icmp_cksum.patch
This bugzilla has Keywords: Regression. Since no regressions are allowed between releases, it is also being proposed as a blocker for this release. Please resolve ASAP. backing out patch #18 makes mpls info work Created attachment 314534 [details]
The patch ensures the MPLS data are not included to the chk_sum function.
The MPLS data are added to the packets for routing purpose on the entry point of label switched network. This label should be taken away when the packet leaves this kind of network. Unfortunately the ICMP packets contain this label.
The patch detects real length of ICMP packet and didn't include MPLS to check sum calculation. This fixes the bug.
The MPLS stuff is supposed to be attached to the packet, please refer to RFC 4950 You are right. Thank you for your notice. There is an implementation of this RFC in the sources but it works after packet size definition on the command line: traceroute google.com 140 (140 is necessary minimum for rel. 24) This means that current traceroute-1.4a12-24.EL4.1.i386 works fine with this extra parameter: - no "Icmp checksum is wrong" message - MPLS packets are indicated in accordance to RFC 4950 This bug (#249001) will be fixed in next release increasing minimum packet size. This bug fix will fix also RFC 4950 compliance as a "side effect". Jiri, How about fixing the buffer patch which broke this in the first place? Thanks :) That would be bug #164466 which is restricted to us mere mortals ;-) Hi, my fix is an extension of mentioned buffer patch. I increased the minimal buffer size to allow receiving MPLS information. An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHBA-2008-0883.html |