Re: [homenet] I-D Action: draft-haddad-homenet-multihomed-00

Op 23 okt. 2012, om 19:19 heeft mike het volgende geschreven:

> On 10/23/12 9:56 AM, Teco Boot wrote:
>> Op 23 okt. 2012, om 17:20 heeft Michael Thomas het volgende geschreven:
>> 
>>> On 10/22/2012 08:35 PM, Lorenzo Colitti wrote:
>>>> On Tue, Oct 23, 2012 at 4:18 AM, Michael Thomas <mike@mtcc.com <mailto:mike@mtcc.com>> wrote:
>>>> 
>>>>    No, sorry. Corporate VPN's using v6 and the lack of a coherent source address selection mechanism causes breakage in bizarre and unpredictable ways. You are not going to get the results you hope for if your mac uses an ISP prefix to get back inside the corpro firewall, uRPF if nothing else. SLAAC changes a lot of things over v4.
>>>> 
>>>> 
>>>> VPN clients already modify the routing table to ensure traffic going through the VPN goes through the VPN, to enforce policies around split tunneling, and so on. Mine even monitors the routing table for changes so it can act on them.
>>> Routing is irrelevant.
>>> 
>>>> Can you explain why this behaviour, combined with the "prefer matching interface" rule in RFC 3484, is not sufficient? If not, then there is no problem to solve here.
>>> Your ISP gives you 2001:xxxx:: via SLAAC. Your employer gives you 2000::,
>>> but also has 2001:yyyy::. You connect to a server on 2001:yyyy::. Your
>>> 3484 v6 stack picks 2001:xxxx for the source address. Hilarity ensues:
>>> 
>>> 1) the packet gets rejected via uRPF
>>> 2) the return packet splats against the inside firewall since it's not allowed outside
>>> 3) the packet makes it outside unarmored with sad faces from the security team
>> Employer should also provide 2001:yyyy::. Or make server accessible via Internet.
>> BRDP will handle this scenario nicely, also for existing hosts.
>> 
> Presumably, the reason it's behind the corpro firewall is because they don't
> want it accessible to the internet at large.
OK.

> I'm not sure if giving each host a
> prefix in 2001:yyyy's address space is scalable either for the hosts, the SLAAC
> announcements, or just carving up 2001:yyyy's addresses, especially if you have
> a large VPN population. I've done that myself, and I have doubts that it's the
> right approach.
I can't get why employer doesn't assign a 2000:: address to the server, other 
than test uRPF filters and get protocol designers crazy :-)

Teco

> 
> Mike
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