From: Patrick McHardy <kaber@trash.net>
To: Stig <stig@ubnt.com>
Cc: netfilter-devel@vger.kernel.org
Subject: Re: ULOG and vlans
Date: Thu, 28 Jul 2011 13:15:38 +0200 [thread overview]
Message-ID: <4E3144DA.7060009@trash.net> (raw)
In-Reply-To: <CAL-yc8_nbzJu8FxAVBycdeXtciz=FGYxXzQtT88xYQ3wX60hBQ@mail.gmail.com>
On 27.07.2011 20:59, Stig wrote:
> I'm using ULOG iptables target to capture packets for pmacct (a
> netflow exporter). I noticed when ulog gets a packet from a vlan
> interface that the ulog header shows a mac_len of 18 bytes, but it
> appears that the vlan tag has already been stripped from the packet
> header:
>
> (gdb) p/x *ulog_pkt
> $7 = {
> mark = 0x0,
> timestamp_sec = 0x4e2f6077,
> timestamp_usec = 0x222f3,
> hook = 0x0,
> indev_name = {0x65, 0x74, 0x68, 0x31, 0x2e, 0x31, 0x30, 0x30, 0x0, 0x0, 0x0,
> 0x0, 0x0, 0x0, 0x0, 0x0},
> outdev_name = {0x0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x5, 0xf, 0x0,
> 0x0, 0x5, 0xf, 0x0, 0x0},
> data_len = 0x40,
> prefix = {0x0, 0x0, 0x2, 0x0, 0x72, 0x60, 0x2f, 0x4e, 0xed, 0x6, 0x0, 0x0,
> 0xa, 0x40, 0x80, 0xfd, 0x2, 0x0, 0x0, 0x0, 0x14, 0x0, 0x1, 0x0, 0xfe,
> 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0},
> mac_len = 0x12,
> mac = {0x0, 0xd, 0xb9, 0x15, 0x6d, 0x1, 0x0, 0xf, 0x30, 0x4, 0x35, 0x4f,
> 0x8, 0x0, 0x45, 0x0, 0x0, 0x54, 0xff, 0x21, 0x12, 0x0, 0x0, 0x21, 0x12,
> 0x0, 0x0, 0x40, 0x0, 0x0, 0x0, 0x14, 0x0, 0x2, 0x0, 0x72, 0x60, 0x2f,
> 0x4e, 0xed, 0x6, 0x0, 0x0, 0xa, 0x40, 0x80, 0xfd, 0x3, 0x0, 0x0, 0x0,
> 0x14, 0x0, 0x1, 0x0, 0xfe, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2, 0xd,
> 0xb9, 0xff, 0xfe, 0x15, 0x6d, 0x1, 0x14, 0x0, 0x6, 0x0, 0xff, 0xff, 0xff,
> 0xff, 0xff},
> payload = 0x941cc35
> }
>
>
> If the vlan has been remove, shouldn't the mac_len be reduced to 14?
Yes. How is your vlan device configured (ip -s link show vlanX)?
>
> This causes parsing problems of the ip header for pmacct because it
> does the following:
>
> if (ulog_pkt->mac_len) {
> memcpy(jumbo_container, ulog_pkt->mac, ulog_pkt->mac_len);
> memcpy(jumbo_container+ulog_pkt->mac_len, ulog_pkt->payload, hdr.caplen);
> hdr.caplen += ulog_pkt->mac_len;
> hdr.len += ulog_pkt->mac_len;
>
>
> Obviously I can work around it, but I'm wondering if this is the
> expected behavior for ulog with vlans?
No, if the tag is stripped, the length should reflect that.
next prev parent reply other threads:[~2011-07-28 11:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-27 18:59 ULOG and vlans Stig
2011-07-28 11:15 ` Patrick McHardy [this message]
2011-07-28 17:00 ` Stig
2011-07-29 14:23 ` Patrick McHardy
2011-07-29 18:59 ` Stig
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