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Re: multiplexing -- don't do it

From: Amos Jeffries <squid3@treenet.co.nz>
Date: Tue, 03 Apr 2012 11:30:04 +1200
To: <ietf-http-wg@w3.org>
Message-ID: <c9c398c4ba4f66d46660d1c205f2dd16@treenet.co.nz>
On 03.04.2012 09:11, Mike Belshe wrote:
> On Mon, Apr 2, 2012 at 2:08 PM, Adrien W. de Croy <adrien@qbik.com> 
> wrote:
>> ------ Original Message ------
>> From: "Mike Belshe" <mike@belshe.com>
>> To: "Adrien W. de Croy" <adrien@qbik.com>
>> Cc: "Amos Jeffries" <squid3@treenet.co.nz>;"ietf-http-wg@w3.org" <
>> ietf-http-wg@w3.org>
>> Sent: 3/04/2012 8:52:22 a.m.
>> Subject: Re: multiplexing -- don't do it
>> On Mon, Apr 2, 2012 at 1:43 PM, Adrien W. de Croy < 
>> <adrien@qbik.com>
>> adrien@qbik.com> wrote:
>>> ------ Original Message ------
>>> From: "Mike Belshe" <mike@belshe.com>mike@belshe.com
>>> On Mon, Apr 2, 2012 at 6:57 AM, Amos Jeffries < 
>>> <squid3@treenet.co.nz><squid3@treenet.co.nz>
>>> squid3@treenet.co.nz> wrote:
>>>> On 1/04/2012 5:17 a.m., Adam Barth wrote:
>>>> On Sat, Mar 31, 2012 at 4:54 AM, Mark Nottingham wrote:
>>>>>> On 31/03/2012, at 1:11 PM, Mike Belshe wrote:
>>>>>> For the record - nobody wants to avoid using port 80 for new
>>>>>>> protocols.  I'd love to!  There is no religious reason that we 
>>>>>>> don't - its
>>>>>>> just that we know, for a fact, that we can't do it without 
>>>>>>> subjecting a
>>>>>>> non-trivial number of users to hangs, data corruption, and 
>>>>>>> other errors.
>>>>>>>  You might think its ok for someone else's browser to throw 
>>>>>>> reliability out
>>>>>>> the window, but nobody at Microsoft, Google, or Mozilla has 
>>>>>>> been willing to
>>>>>>> do that…
>>>>>> Mike -
>>>>>> I don't disagree on any specific point (as I think you know), 
>>>>>> but I
>>>>>> would observe that the errors you're talking about can 
>>>>>> themselves be viewed
>>>>>> as transient. I.e., just because they occur in experiments now, 
>>>>>> doesn't
>>>>>> necessarily mean that they won't be fixed in the infrastructure 
>>>>>> in the
>>>>>> future -- especially if they generate a lot of support calls, 
>>>>>> because they
>>>>>> break a lot MORE things than they do now.
>>>>>> Yes, there will be a period of pain, but I just wanted to 
>>>>>> highlight
>>>>>> one of the potential differences between deploying a standard 
>>>>>> and a
>>>>>> single-vendor effort.  It's true that we can't go too far here; 
>>>>>> if we
>>>>>> specify a protocol that breaks horribly 50% of the time, it 
>>>>>> won't get
>>>>>> traction. However, if we have a good base population and perhaps 
>>>>>> a good
>>>>>> fallback story, we *can* change things.
>>>>> That's not our experience as browser vendors.  If browsers offer 
>>>>> an
>>>>> HTTP/2.0 that has a bad user experience for 10% of users, then 
>>>>> major
>>>>> sites (e.g., Twitter) won't adopt it.  They don't want to punish 
>>>>> their
>>>>> users any more than we do.
>>>>> Worse, if they do adopt the new protocol, users who have trouble 
>>>>> will
>>>>> try another browser (e.g., one that doesn't support HTTP/2.0 such 
>>>>> as
>>>>> IE 9), observe that it works, and blame the first browser for 
>>>>> being
>>>>> buggy.  The net result is that we lose a user and no pressure is
>>>>> exerted on the intermediaries who are causing the problem in the 
>>>>> first
>>>>> place.
>>>>> These are powerful market force that can't really be ignored.
>>>> So the takeway there is pay attention to the intermediary people 
>>>> when
>>>> they say something cant be implemented (or won't scale 
>>>> reasonably).
>>> I agree we should pay attention to scalability - and we have.
>>> Please don't disregard that Google servers switched to SPDY with 
>>> zero
>>> additional hardware (the google servers are fully conformant 
>>> http/1.1
>>> proxies with a lot more DoS logic than the average site).  I know, 
>>> some
>>> people think Google is some magical place where scalability defies 
>>> physics
>>> and is not relevant, but this isn't true.  Google is just like 
>>> every other
>>> site, except much much bigger.   If we had a 10% increase in server 
>>> load
>>> with SPDY, Google never could have shipped it.  Seriously, who 
>>> would roll
>>> out thousands of new machines for an experimental protocol?  
>>> Nobody.  How
>>> would we have convinced the executive team "this will be faster", 
>>> if they
>>> were faced with some huge cap-ex bill?  Doesn't sound very 
>>> convincing, does
>>> it?  In my mind, we have already proven clearly that SPDY scales 
>>> just fine.
>>> But I'm open to other data.  So if you have a SPDY implementation 
>>> and
>>> want to comment on the effects on your server, lets hear it!   And 
>>> I'm not
>>> saying SPDY is free.  But, when you weigh costs (like compression 
>>> and
>>> framing) against benefits (like 6x fewer connections),  there is no
>>> problem.  And could we make improvements still?  Of course.  But 
>>> don't
>>> pretend that these are the critical parts of SPDY.  These are the 
>>> mice nuts.
>>> For a forward proxy, there are several main reasons to even exist:
>>> a) implement and enforce access control policy
>>> b) audit usage
>>> c) cache
>>> you block any of these by bypassing everything with TLS, you have a
>>> non-starter for corporate environments.  Even if currently admins 
>>> kinda
>>> turn a blind eye (because they have to) and allow port 443 through, 
>>> as more
>>> and more traffic moves over to 443, more pressure will come down 
>>> from
>>> management to control it.
>>> Best we don't get left with the only option being MITM.
>> In my talk at the IETF, I proposed a solution to this.
>> Browsers need to implement SSL to trusted proxies, which can do all 
>> of the
>> a/b/c that you suggested above.  This solution is better because the 
>> proxy
>> becomes explicit rather than implicit.  This means that the user 
>> knows of
>> it, and it IT guys knows of it.  If there are problems, it can be
>> configured out of the system.  Implicit proxies are only known the 
>> the IT
>> guy (maybe), and can't be configured out from a client.  The browser 
>> can be
>> made to honor HSTS so that end-to-end encryption is always enforced
>> appropriately.
>> Further, proxies today already need this solution, even without 
>> SPDY.
>>  Traffic is moving to SSL already, albeit slowly, and corporate 
>> firewalls
>> can't see it today.  Corporate firewall admins are forced to do 
>> things like
>> block facebook entirely to prevent data leakage.  But, with this 
>> solution,
>> they could allow facebook access and still protect their IP.  (Or 
>> they
>> could block it if they wanted to, of course).
>> Anyway, I do agree with you that we need better solutions so that we 
>> don't
>> incur more SSL MITM.  Many corporations are already looking for 
>> expensive
>> SSL MITM solutions (very complex to rollout due to key management) 
>> because
>> of the reasons I mention above, and its a technically inferior 
>> solution.
>> So lets do it!
>> I basically agree with all the above, however there is the ISP
>> intercepting proxy to think about.
>> Many ISPs here in NZ have them, it's just a fact of life when you're 
>> 150ms
>> from the US and restricted bandwidth.  Pretty much all the big ISPs 
>> have
>> intercepting caching proxies.
>> There's just no way to make these work... period...
>> unless the ISP is to
>> a) try and support all their customers to use an explicit proxy, or
>> b) get all their customers to install a root cert so they can do 
>> MITM.
>> Maybe we need a better way to force a client to use a proxy, and 
>> take the
>> pain out of it for administration.  And do it securely (just 
>> remembering
>> why 305 was deprecated).
> Do proxy pacs or dhcp work for this?
> Note that we also need the browsers to honor HSTS end-to-end, even if 
> we
> turn on "GET https://".
> Mike

For browsers, when WPAD is setup in the network and the browser 
shipping with default auto-configuration. Yes. For all other situations, 
not so much.

Unfortunately several major browsers still ship with "no proxy" as 
their default, meaning the WPAD does not work for 10-20% of users. On 
top of that WPAD is still a non-standard mess not supported by 
non-browser agents, and admin are understandably very reluctant to do 
the little bit of extra work without a great deal of need. Admin who do 
make the jump toward auto-conf simplicity are forced to add MITM 
underneath anyway.

Received on Monday, 2 April 2012 23:30:30 UTC

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