Skip site navigation (1)Skip section navigation (2)
Date:      Fri, 2 Jul 2004 19:11:55 -0500 (CDT)
From:      Mike Silbersack <silby@silby.com>
To:        David Malone <dwmalone@maths.tcd.ie>
Cc:        freebsd-net@freebsd.org
Subject:   Re: RANDOM_IP_ID sysctl?
Message-ID:  <20040702190516.Q65076@odysseus.silby.com>
In-Reply-To: <200406291413.ab33924@salmon.maths.tcd.ie>
References:  <200406291413.ab33924@salmon.maths.tcd.ie>

next in thread | previous in thread | raw e-mail | index | archive | help

On Tue, 29 Jun 2004, David Malone wrote:

> It seems to me that RANDOM_IP_ID might be better as a sysctl rather
> than a kernel option. Would anyone mind if I changed this?
>
> 	David.

I'd rather see a sysctl that switched between incremental frag IDs and 
arc4random() based IDs, followed by the removal of RANDOM_IP_ID.

For more info, see:

http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/netinet/ip_id.c

(I think we're still using the old code that's collision prone.)

Given that we're in a 16-bit space anyway, it's simpler to just use 
arc4random and stop pretending that we can avoid collisions.

Remember:  An IP ID collision is equivalent to a packet being lost; this 
is not a big deal.

Mike "Silby" Silbersack



Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20040702190516.Q65076>