Linux Netfilter discussions
 help / color / mirror / Atom feed
From: "Peter Reckmann" <preckmann@online.de>
To: netfilter@vger.kernel.org
Subject: Need tech explanation for NFLog TLV type 16 (0x10) - hardware link layer header
Date: Wed, 27 Jan 2016 14:00:40 +0100	[thread overview]
Message-ID: <5335FB9FCD34414CBC32917DA4973A03@computer1> (raw)

TLV type 16 (0x10) is "hardware link layer header".  Normally, the data for 
this field has a length of 14 bytes.  6 for the destination MAC, 6 for the 
source MAC, and 2 for the Ethernet type (08 00) which is IP.  This seems to 
be the Ethernet Header for the packet.  But, about 20% of the packets I am 
seeing have a length of 30 bytes.  So in addition to sMac, dMac, type, I am 
seeing an extra 12 bytes.  What is this?  Here is an example:

45:00:00:3C:2B:6A:00:00:80:11:8D:B9

I have seen this in a regular iptables log before.  Here is an example:

owblk_udp_drop IN=eth0 OUT=eth1 
MAC=b8:27:eb:c2:bd:37:00:1b:77:d2:88:62:08:00:45:00:00:3f:06:5a:00:00:7f:11:ab:c5 
SRC=192.168.0.61 DST=192.168.8.1 LEN=63 TOS=0x00 PREC=0x00 TTL=127 ID=1626 
PROTO=UDP SPT=1242 DPT=53 LEN=43.

So MAC= comes back with DesMac, SrcMac, and type again and then there are 
these additional bytes: 45:00:00:3f:06:5a:00:00:7f:11:ab:c5

Again 12 bytes.  They always start with 45:00:00 What are these?  What do 
they represent?

Thanks in advance! 


             reply	other threads:[~2016-01-27 13:00 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-27 13:00 Peter Reckmann [this message]
  -- strict thread matches above, loose matches on Subject: below --
2016-02-12 16:39 Need tech explanation for NFLog TLV type 16 (0x10) - hardware link layer header Peter Reckmann

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=5335FB9FCD34414CBC32917DA4973A03@computer1 \
    --to=preckmann@online.de \
    --cc=netfilter@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox