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cpe simple security and the opportunity cost of stateful packet filters



On Jul 24, 2007, at 15:43, Kurt Erik Lindqvist wrote:
On 24 jul 2007, at 21.08, Roland Bless wrote:
[at some point, somebody wrote:]
It will be really nice to make sure that we can progress with more
parameters available in the RA.
Yes, but host implementations must also be enable to make use
of such features...
It would be even better if there was even content I could access  
with or without those features...
"If you don't like the news, go out and make some of your own."  -- 
Wes "scoop" Nisker
One of the concerns behind my original initiative to leave the  
*stateful* part of the IPv6 packet filter turned off by default in  
the AirPort Extreme 802.11n base station was my [apparently mistaken]  
judgment that the measurable benefits for network security it  
provided were heavily outweighed by the opportunity cost it posed by  
hindering the deployment of ad-hoc peer-to-peer applications where  
the vast majority of peers are expected to be at the end of the last  
mile in a residential deployment.
P2P applications already very difficult for average Internet users to  
participate effectively in such networks due to the stateful  
filtering in IPv4/NAT gateways, and services like UPnP IGD and NAT- 
PMP don't repair all the damage.  If these packet filters are allowed  
to become ubiquitous in IPv6, then my fear is that the most likely  
applications that would otherwise be able to deliver that content  
you'd like to access, with or without any whizzy new router  
advertisement parameters, will never be developed for IPv6 where they  
might be simple enough for average users to operate.  All the user  
complexity created by IPv4/NAT stateful filters will have been  
duplicated in the IPv6 stateful filters.
If we are not careful, IPv6 may be saddled with all the b0rkenneff  
that IPv4/NAT plagues us with today, without any measurable benefit  
beyond merely addressing the burdensomely high and rapidly increasing  
cost of public IP addresses.  We are setting up a vicious circle.
+ Nobody will want to use IPv6 because there isn't any content worth  
accessing, while...
+ Nobody will develop content worth accessing because IPv6 is more  
difficult to use than IPv4, and in fact, is also broken fundamentally  
in ways that IPv4/NAT isn't, while...
+ Nobody will have any incentive to make IPv6 any easier to use  
because users aren't interested in any of the content available  
exclusively via IPv6, while... [lather, rinse, repeat]
If this happens, mark my words: IPv6 will wither and die-- and it  
will not be an honorable death, as IPv4/NAT will be wielding the  
sword that cuts it down.  Those among us who really, really despise  
NAT might do well to bear in mind all the ways we could be  
undermining our own objectives by failing to consider how we might be  
preventing IPv6 from being usable by new applications in ways that  
IPv4/NAT will never be able to match.
Still working on polishing my philosophy essay.  Sigh.


--
james woodyatt <jhw@apple.com>
member of technical staff, communications engineering