[ipv6-wg] [v6ops] Extension Headers / Impact on Security Devices

> > Taking into account that stateless ACLs of all router vendors we
> > tested (results tb published soon) can be avoided/evaded by adding ~5
> > extension headers to datagrams I fully understand any operator who
> > does not want SSH on its devices to be reachable from the Internet
> > (over v6 with extension headers) and hence acts in a way similar to
> > the one Steinar described.
> 
> There is a big difference between an operator dropping all packets with
> EHs that are destined for *his own devices/routers* (I have no problem
> with that - your devices, your rules), and an operator that drops
> *transit* traffic destined for his customers because his routers cannot
> understand/parse/filter its L4/EH payload.

I certainly appreciate this distinction. However, problems arise in
practice when customers *ask* for various types of protection - which
are most sensibly implemented on border routers.

Just to be clear - we don't drop IPsec traffic today (neither IPv6
nor IPv4). 

> In my opinion, an ISP/IP transit network shouldn't even attempt to
> parse the L4/EH payload in customer traffic (except if the customer
> asks for it of course), it should just deliver the packets.

The problem is - the customer *does* ask for it, in many cases.

> > I doubt Steinar loses many customers (due to "application breakage")
> > by taking that path. In contrary I expect many of his customers
> > valueing the increased level of device & network availability gained
> > by eliminating an entire class of attacks.
> 
> The first operator I mentioned above won't lose any customers because
> his filtering activities doesn't impact customer traffic. The second
> operator would lose my business, at least. And probably others' too, as
> business customers might want their site2site IPSEC tunnels to work,
> residental customers might want their Xbox One online gaming to work,
> and so on.

I agree - IPSEC tunnels and Xbox One online gaming need to work. That
doesn't mean *all* extension header combinations should be expected
to work - and it appears that they often don't.

I expect we'll see much more of these discussions in the coming years,
as IPv6 traffic grows. And I certainly also expect significant size
IPv6 DDoS attacks - at least some of which will probably be based on
extension header manipulation.

Steinar Haug, AS 2116