misunderstanding scale

Owen DeLong owen at delong.com
Tue Mar 25 06:02:16 UTC 2014


On Mar 24, 2014, at 8:52 PM, George Herbert <george.herbert at gmail.com> wrote:

> 
> 
> 
> On Mon, Mar 24, 2014 at 8:02 PM, Owen DeLong <owen at delong.com> wrote:
> 
> On Mar 24, 2014, at 9:21 AM, William Herrin <bill at herrin.us> wrote:
> 
> > On Sun, Mar 23, 2014 at 11:07 PM, Naslund, Steve <SNaslund at medline.com> wrote:
> >> I am not sure I agree with the basic premise here.   NAT or Private addressing does not equal security.
> >
> > Hi Steve,
> >
> > It is your privilege to believe this and to practice it in the
> > networks you operate.
> >
> > Many of the folks you would have deploy IPv6 do not agree. They take
> > comfort in the mathematical impossibility of addressing an internal
> > host from an outside packet that is not part of an ongoing session.
> > These folks find that address-overloaded NAT provides a valuable
> > additional layer of security.
> 
> Which impossibility has been disproven multiple times.
> 
> > Some folks WANT to segregate their networks from the Internet via a
> > general-protocol transparent proxy. They've had this capability with
> > IPv4 for 20 years. IPv6 poorly addresses their requirement.
> 
> Actually, there are multiple implementations of transparent proxies available
> for IPv6. NAT isn’t the same thing at all.
> 
> If you want to make your life difficult in IPv6, you can. Nobody prevents you from
> doing so. It is discouraged and non-sensical, but quite possible at this point.
> 
> Owen
> 
> 
> 
> Right.  fc00::/7 exists.  If you want to emulate your internal use of 10.0.0.0/8 plus NAT (or, proxies or load balancers or whatever) in your IPv6 implementation go ahead.  Putting in some robust filtering that if the fc00::/7 ever appears outside the internal gateway the traffic goes poof should be as easy as the equivalents for 10, 172.16, 192.168 …

More accurately fd00::/8. fc00::/8 was reserved for ULA coordinated which failed to gain consensus. While IETF did set aside the /7, only fd00::/8 has a legitimate documented purpose.

Owen



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