netdev - Re: Linux, tcpdump and vlan

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <m3ps2l5ugw.fsf@maximus.localdomain>
Date:	Sat, 21 Jul 2007 23:15:43 +0200
From:	Krzysztof Halasa <khc@...waw.pl>
To:	Ben Greear <greearb@...delatech.com>
Cc:	andrei radulescu-banu <iubica2@...oo.com>,
	Stephen Hemminger <shemminger@...ux-foundation.org>,
	Patrick McHardy <kaber@...sh.net>,
	linux-kernel@...r.kernel.org,
	Linux Netdev List <netdev@...r.kernel.org>
Subject: Re: Linux, tcpdump and vlan

Ben Greear <greearb@...delatech.com> writes:

>> IOW: I think all Ethernet interfaces should always be VLAN-aware,
>> stripping the tag (only one) early on RX and adding it late on TX.
>> That means tcpdump would see packets with exactly one tag removed
>> (unless there was no tag), in both RX and TX.
>>
>> Tcpdump would need other means to get VLAN id...
>>
> What benefit will this add?  It will certainly decrease performance to
> copy around
> the header for every VLAN packet, so there would have to be a good reason to
> add this logic...

I'd have to do some tests... Hopefully in this decade, forget it for
now.

The primary reason - consistency with hw VLAN cards -> simpler
code.

The performance is already decreased (not sure if it's noticeable)
most of the time, i.e., when not transparently bridging VLAN
trunks. Bridging VLAN trunks is, of course, theoretically possible,
but it's rather not a common operation when using .1Q.
That is, with header reordering, of course.

Anyway, -ENOPATCH from me for now.
-- 
Krzysztof Halasa
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html