Bug 1025841 - Unable to filter packets by VLAN tag
Summary: Unable to filter packets by VLAN tag
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: libpcap
Version: 6.4
Hardware: x86_64
OS: Linux
Target Milestone: rc
: ---
Assignee: Michal Sekletar
QA Contact: Tomas Dolezal
Depends On:
Blocks: 1070830 1159820
TreeView+ depends on / blocked
Reported: 2013-11-01 17:41 UTC by Norman Elton
Modified: 2015-07-22 06:17 UTC (History)
3 users (show)

Fixed In Version: libpcap-1.4.0-4.20130826git2dbcaa1.el6
Doc Type: Bug Fix
Doc Text:
Documentation for this issue is the same as for #1063328 Previously, running the "tcpdump" command with the filter expressioncontaining the keyword "vlan" produced unexpected output, as the filtergenerated by the libpcap Berkeley Packet Filter (BPF) compiler did notemploy BPF extensions. To fix this bug, libpcap has been amended and nowgenerates filters that use BPF extensions when appropriate. As a result,running "tcpdump" with filters containing "vlan" produces correct results.
Clone Of:
Last Closed: 2015-07-22 06:17:12 UTC
Target Upstream Version:

Attachments (Terms of Use)

System ID Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2015:1288 normal SHIPPED_LIVE libpcap bug fix update 2015-07-20 17:48:50 UTC

Description Norman Elton 2013-11-01 17:41:39 UTC
Tcpdump drops all packets when filtering by VLAN tag. Works fine when reading packets from a file, but not when reading from a NIC.

For example, this captures nothing:

tcpdump -i eth15 -nnte vlan

But this works as expected:

tcpdump -i eth15 -nnte -w - | tcpdump -r - vlan

Kernel information:

# uname -a
Linux blocto.safety.net.wm.edu 2.6.32-358.23.2.el6.x86_64 #1 SMP Sat Sep 14 05:32:37 EDT 2013 x86_64 x86_64 x86_64 GNU/Linux

Tcpdump information:

# rpm -q tcpdump

Driver information:

# ethtool -i eth15
driver: e1000e
version: 2.1.4-k
firmware-version: 5.10-2
bus-info: 0000:26:00.1
supports-statistics: yes
supports-test: yes
supports-eeprom-access: yes
supports-register-dump: yes
supports-priv-flags: no

Comment 2 Michal Sekletar 2013-11-08 09:10:07 UTC
This is not a bug in tcpdump itself but rather in libpcap. Reassigning there. Note that before doing something about this on libpcap side, some changes in kernel has to be introduced.

Comment 3 Michal Sekletar 2014-02-06 14:30:30 UTC
Just an quick update on the current status. Kernel part is done, now we can move to fixing libpcap.

Comment 4 Michal Sekletar 2014-11-04 12:36:51 UTC
Opened a pull request on github trying to address this.


Feel free to join the discussion on github and also testing would be much appreciated. Thanks.

Comment 9 errata-xmlrpc 2015-07-22 06:17:12 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.


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