[OpenWrt-Devel] IPv6 firewall and Port Control Protocol (Was: Barrier Breaker 14.07-rc1)

David Lang david at lang.hm
Thu Jul 17 20:03:55 EDT 2014

I know that IPv6 designers pine for the "good old days" of the Internet when no 
security was needed.

But the reality is that hackers and worms have shown that leaving systems 
exposed to the Internet is just a Bad Idea.

As such, the idea that IPv6 would "restore" the "everyone can connect to 
everyone on any port" of the early '80s was wishful thinking at best.

link-local addressing isn't a good idea, because the average home will have 
three separate links (wired plus two bands of wireless), these can get bridged 
together, but that causes problems as well.

There is no answer here that will satisfy everyone.

But do you really want to see the news stories about how anyone running openwrt 
is vulnerable to $lastest_windows_exploit but people running stock firmware 

Yes, it would be ideal if every host was locked down so that it was safe for 
them to be exposed.

But that's not the world we live in.

David Lang

On Wed, 16 Jul 2014, Lyme Marionette wrote:

> ----- Original Message -----
> On Wednesday, July 16, 2014 2:10:53 PM "Gui Iribarren" <gui at altermundi.net> wrote:
>> Benjamin is giving some great examples of real-world scenarios where
>> an
>> default-open firewall simplifies administration,
>> and where a default-closed firewall would be not only unnecessary
>> (provides no benefits), but would indeed complicate setting up
>> things.
> There have been many good arguments posted on this subject and to throw my opinion in, it a question of effort and expectations.
> I think everyone can agree that:
> -It takes equal effort to turn a firewall on, as it does to turn one off.
> -It takes equal effort to create a specific block list, as it does to create a specific allow list.
> -UPnP is not included by default for either the ipv4 or ipv6 stacks.
> I would also go further to suggest that:
> -Consistency is good, even if it consistent for superficial reasons.
> We know that, for NAT reasons, that the ipv4 stack by default blocks incoming connections:
> -Because it doesn't know by default where to route them.
> -ipv4 end-points have been traditionally insecure.
> The two ways to get around this (for gaming, etc):
> -Through setting firewall rules to route the traffic to an end-point.
> -Through the use of UPnP (which is used by most games to host, and gaming consoles).
> With the adoption of ipv6 there is the opportunity to change this behaviour such that instead of incoming traffic being restricted for technical reasons, that incoming traffic is routed to the correct end-point.
> However, that begs the questions:
> A) Is that consistent with what people would expect?
> B) Are ipv6 end-points secure by design?
> In regards to A, from the mindset of a non-technical user, would wager that the answer is 'no'. Even though there is a change in technology with ipv6, the ipv6 technology fulfills the same role as ipv4 and this could be seen as opposing direction between the two. This would likely catch many end-users by surprize unless they read the small print regarding this.
> As for B, given my view of software development, applications, networks, etc (I've been in the IT business for over 25 years now) I would wager that 80% of applications are secure, and that the 0ther 20% make the potential change in policy very risky.
> IMO, which others may disagree with, would be to include UPnP by default which would/should resolve most of the hosting issues.
> Thanks.
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