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Tasklist

FS#38052 - [libpcap] 1.5.1-1 broken tpacket v3 support

Attached to Project: Arch Linux
Opened by Plex (plexor) - Saturday, 07 December 2013, 18:24 GMT
Last edited by Andreas Radke (AndyRTR) - Wednesday, 29 January 2014, 11:27 GMT
Task Type Bug Report
Category Packages: Core
Status Closed
Assigned To Thomas Bächler (brain0)
Architecture All
Severity High
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No

Details

Description:
The new tpacket v3 support in libpcap 1.5.1 is broken for programs, such as knockd, that set the read timeout to 0.

Additional info:
When udp 'knock' packets are sent to the knockd server, the packets are not registered (haven't tested tcp).
Rebuilding libpcap 1.5.1 with tpacket v3 support disabled, or downgrading to the previous (1.4.0) package works around the issue.

The patch that works for me:
disable_tpacketv3.diff: http://gbpaste.org/Ugabh

Related package versions:
libpcap 1.5.1-1
linux 3.12.3-1
glibc 2.18-10
libnl 3.2.23-1
libusbx 1.0.17-1
knockd 0.6-2 (AUR)

Steps to reproduce:
1. Install and configure knockd on host A to have some udp packet knock sequence.
2. Start knockd on host A (knockd -Dv)
3. On host B, install knockd to install the 'knock' client.
4. On host B, knock host A with the knock sequence used above. (e.g. knock -u 1111 2222 3333)
5. Host A should register the knocks, but it doesn't.
6. After downgrading to libpcap 1.4.0 (or using the above patch) and repeating the above, the knock sequence will register.
This task depends upon

Closed by  Andreas Radke (AndyRTR)
Wednesday, 29 January 2014, 11:27 GMT
Reason for closing:  Fixed
Comment by Gaetan Bisson (vesath) - Saturday, 07 December 2013, 18:55 GMT
Could you report this issue at: https://github.com/the-tcpdump-group/libpcap/issues
Comment by Thomas Bächler (brain0) - Sunday, 08 December 2013, 11:20 GMT
Agreeing with Gaetan. I'd rather have an official fix from the developers than disabling a feature.
Comment by Plex (plexor) - Sunday, 08 December 2013, 16:26 GMT
I totally agree, but since tpacket v3 support is broken in 1.5.1, should at least disable it to fallback to the working v2 until the problem is resolved.
Comment by Andreas Radke (AndyRTR) - Monday, 27 January 2014, 14:47 GMT
Should be fixed in 1.5.3 currently in testing.

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