Re: I-D ACTION:draft-jabley-ipv6-rh0-is-evil-00.txt

[gnn at neville-neil.com]

At Thu, 10 May 2007 17:09:31 -0400,
Joe Abley wrote:
> 
> 
> The above sentences far more closely resemble what I meant to write,  
> compared to the text that actually appeared in the draft :-)
> 
> I note that KAME's response to this is similar, but it's not clear
> to me that it's precisely identical: a patched KAME implementation
> treats the type 0 routing header as an unknown routing header
> (according to <http://www.kame.net/newsletter/20070502/>). This
> suggests to me that a patched KAME implementation will process a
> datagram containing RH0, but that RH0 header(s) in the datagram will
> not be acted upon. I would welcome corrections to my feeble
> assumptions in this area (I have done no tests, nor read any source
> code to confirm).
> 
> A packet containing RH0 presumably is intended not to be processed
> on the system identified by the destination address field; if it
> was, no RH0 would be present. This suggests to me that "MUST drop"
> is the right thing, rather than "process as if RH0 was not there";
> in addition, if we assume that today any packet with RH0 is likely
> to be malicious, any processing of a packet containing RH0 which has
> the potential to result in backscatter seems like it should properly
> be avoided.

The Kame folks can comment on the current state of their change, they
made a couple of them.  In FreeBSD 6 an 5 (the stable branches) we
have a sysctl to turn processing on and off.  In 7 (aka HEAD or
CURRENT) we treat the RH0 as unknown.  Code diffs can be seen here:

HEAD:

http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/netinet6/route6.c.diff?r1=1.12;r2=1.13;f=h

STABLE:

http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/netinet6/route6.c.diff?r1=1.11.2.1;r2=1.11.2.2;f=h

Best,
George

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