Re: [IPv6] [v6ops] Why folks are blocking IPv6 extension headers? (Episode 1000 and counting) (Linux DoS)

[Fernando Gont <[e-mail]>]

Hi, Brian,

On 21/5/23 22:28, Brian E Carpenter wrote:
[...]
>>> I'm not sure how that's a no brainer, who decides "the ones you really
>>> need"?
>>
>> Typically. whoever runs the destination AS or network. Or the transit
>> AS, if the packets will affect the transit AS.
> 
> And there's the problem. The operator of a large network cannot possibly
> know which extension headers every host on the network needs. It's
> called permissionless innovation, and is supposed to be one of the main
> success factors for the Internet.
> 
>>> If everyone independently makes that decision then we wind up
>>> with an Internet that can't evolve and is perpetually stuck in the
>>> status quo.
>>
>> Well, yes, there's no big brother making decisions about mine or your
>> networks' policies.... hence everyone makes decisions independently.

FWIW, I was referring to filtering at the destination AS or network.



>  From the point of view of hosts, there is an anonymous Big Brother, the
> moment that any upstream operator blocks a wanted extension header.

Well, that depends on the type of network. If we-re referring to an 
enterprise user, yes, by definition there's a Big Brother (security team).

If we're reerring to e.g. a home user (ISP client), then I agree with 
you. But then, there's RFC9098 -- where the ISP is not trying to protect 
their user, but their own infrastructure.



>> (IN a way that's why QUIC runs on top of UDP ... although in the case of
>> QUIC, I bet it has more to do with NATs thatn with explicit firewalling)
> 
> It's to do with *any* barrier to IP layer transparency. This is a very
> basic tussle in the architecture.

That depends on what one means by "IP layer transparency". If you mean 
the existence of e.g. filtering at layer 4+, well, that's probably long 
gone (at least for r.g. enterprise and home networks).

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
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