On Aug 21, 2010, at 12:20 AM, Christopher Morrow wrote:

>  o routers are required to be able to send redirect messages
>  o routers should NOT do this by default

I concur with this position from an opsec standpoint; at the same time, I don't 
know that *mandating* a default configuration setting for a legal (if largely 
iatrogenic) mode of operation is something that the IETF should be doing.

Here's an alternate formulation which gets the point across, but doesn't stray 
into the area of :

1.      Routers are required to be able to send redirect messages.

2.      It is recommended that routers should NOT do this by default.

As was mentioned somewhere in the 6man thread, the root of the problem has to 
do with the ugliness of IPv6 in general, and the whole v6 ICMP/ND mess in 
particular.  Unfortunately, those ships have long since sailed; while it's 
tempting to try and retrofit fixes for poor design decisions in the fundamental 
protocol specifications by mandating sane implementation defaults in 
conformance documents, a recommendation rather than a mandate seems more 
situationally-appropriate in this context.  

The 'right way', impractical though it may be, is in fact to fix this problem 
is to go back and fix the protocol specifications; since that isn't going to 
happen, making recommendations gets the point across without being overbearing.

YMMV, of course.

-----------------------------------------------------------------------
Roland Dobbins <[email protected]> // <http://www.arbornetworks.com>

    Injustice is relatively easy to bear; what stings is justice.

                        -- H.L. Mencken




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