[SR-Users] Evil SBC/B2BUA, was Re: uac_replace_from recovery with modified header

[Daniel-Constantin Mierla]

Hello,

I expected from the previous email that the conversation makes no sense, 
because it is somehow a clear misunderstanding. In the initial topic of 
updating some headers you come up with the idea that (quoted):

"So that's for example a very good scenario where it pays off to have an 
SBC in your system"

It was not my case in the past 12 years, really, not for such thing, no 
matter how you want to put it, not even as possible scenario, not at all 
as a very good one.

And if you suggest that is 'the solution' for fraud preventions, then I 
am SIP blind, not short sighted. Terminology like saves a*ses, plain FUD 
or short sighted does not have anything to do with technical arguments, 
its for throwing in a no-arguments discussion. I guess sems guys are 
happy coding already...

You divert easily to different use cases of kamailio, which don't have 
anything to do anymore with "a SBC for updating headers" or "SBC as 
b2bua". Suddenly is also about gateways between protocols and breaking 
out, what SBC have to do with these specific elements? Can't there be 
fraud between two pure IP RTC providers?!?! I know also a sbc can run on 
separate box with linux, that can provide ssh tunneling if needed, or 
other value added features such as a web server, which can be a must in 
a specific operator business plan.

But I said that I refer to proper SIP SBC as the function, not to a 
specific application/system as a whole which can do something else, ivr, 
voicemail, etc... or what so ever system that does port forwarding. Now, 
you come to say that one can interpolate or do derivatives to the 
application and could get a space shuttle, but it is no more a SBC.

I am really more than happy sems gets what you need and how you wanted, 
is a cool application, I never said something else. You can ask for 
license fee refund if you got kamailio for a sbc function and is not :-)

Besides SIP blindness, I am getting also speechless - "any b2bua-like 
element in general is bad because it limits innovation as a whole is 
just wrong" - maybe one can explain me how an UA can use any 
functionality that is not supported in the b2bua, when is in a session 
with the 1/2 of the b2bua.

No sense for more, back to testing 4.0.0...

Cheers,
Daniel


On 1/25/13 12:54 PM, Andreas Granig wrote:
> Hi,
>
> On 01/24/2013 11:52 PM, Daniel-Constantin Mierla wrote:
>>> Since you claim that your cool stuff gets broken, I'd appreciate you
>>> to come forward with an example, otherwise it's plain FUD.
>>
>> I think you could really come up with a better demand in this
>> discussion, otherwise is clear misunderstanding of the topic and makes
>> no sense for further debate.
>>
>> Anyhow, for the peace of your soul, alice and bob have a shared password
>> and want to exchange a private token/data carried with each request in a
>> custom header xyz. The body of this header is set as base64 of the value
>> resulted from encryption of the token with a specific encryption
>> algorithm known only by alice and bob, using the shared password, own
>> via branch parameter value, contact uri, call id and from tag. Let me
>> know how a sbc/b2bua will make that work. I let you disclose it to sems
>> guys so they can be happy fixing this extension to work through sems
>> sbc. Or maybe the FUD is coming from the other direction ...
>
> Your reasoning goes like this: A proxy allows to pass through any kind 
> of method and any kind of headers and bodies, and is therefore open 
> and good. An sbc blocks unknown methods and headers and bodies and 
> messes with the messages, and is therefore bad.
>
> This is simply not true. Just because the default kamailio config 
> allows this openness doesn't mean that's how all kamailio configs are 
> deployed. It's straight forward to limit message types and to filter 
> messages, and in fact lots of people do this. Now does this make 
> kamailio suddenly bad? At the same time, it's easy to let an sbc pass 
> through unknown message types and not filter the messages, and thus in 
> no way limit the end-to-end communication. Is it then still bad?
>
> In the end, it's the use case that matters. If you're bashing 
> telco-style operators because they're providing PSTN break-outs and 
> bear the risk of getting victims of fraud and therefore are protecting 
> this line of signalling, then this seems a bit short-sighted.
>
>>> Future RTC platforms from real IP companies will (and already do)
>>> provide web APIs, where you can build fancy applications using
>>> HTML5/JS on top. There is even no need for SIP at all to do so, as
>>> long as you stay in your walled garden, so there is also no need for a
>>> SIP proxy. Just saying.
>>
>> If you speak about the webrtc, it will have a role on online
>> interactions. But I don't see replacing the telephony system. Nobody
>> will stay with the browser open to be reachable (even less open to
>> several providers). So walled gardens rtc will be as an addition feature
>> to existing walled gardens.
>>
>>>
>>> However, if you care about interoperability, you'll also in the future
>>> use SIP or XMPP.
>>
>> At some point (I hope) it will end up in a email-servers-like grid. And
>> I won't care about what is the protocol behind that much...
>
> Fully agree. But compared to email, you've different networks in RTC, 
> like SIP, XMPP, SS7, ISDN etc. As long as it stays all-IP and nobody 
> holds up his hands to collect money for such transits or terminations, 
> it's all good, and you as an operator don't have to care about someone 
> abusing your service (it's an annoyance which you better stop at some 
> point, but it doesn't cost you thousands of dollars per 
> hour/day/whatever). However, these business models charging for such 
> communications won't go away any time soon, and I as an end-user 
> actually appreciate to be able to call also mobile numbers, even 
> though the feature set is limited to what we had for the last 100 
> years. The whole world is going through a transition period from 
> circuit switched networks to packet switched networks, and during this 
> period, you as an operator better protect your assets as long as you 
> get charged for it from up-stream.
>
> But again, this is just ONE use case of an sbc, and it doesn't mean 
> your end-to-end communication gets stripped down to the bare basics by 
> definiton.
>
>>> From a functional perspective, it makes perfect sense to split call
>>> legs in certain scenarios with a b2bua (which is essentially what sbcs
>>> are), because it allows to actively engage in established dialogs,
>>> which in turn is what you want or need for server-side voice
>>> applications. And this is why proxies and sbcs (or b2buas, or however
>>> you want to call them) can perfectly work together in a SIP system.
>>
>> Do you mean, me, as user paying for the RTC service (so we practically
>> talk here about location service, because all is IP), I want the
>> provider to actively engage in my 3d naked hologram call with my doctor?
>> For? Putting pills advertising banners in the middle?
>
> Methods for secure end-to-end communication do exist, it's a matter of 
> providing endpoints which properly implement them and let the users 
> know if the operators tinkered with their communication channel.
>
> This is not specific to sbcs though, as you can engage in a dialog 
> with kamailio as well (like dialog/uac for example). It's a matter of 
> how far you want to push your proxy to do certain tasks. And for some 
> tasks, a b2bua element is better suited than a proxy by design. This 
> doesn't mean you can't do things both ways.
>
> As an operator, it comes down to knowing your scenarios and choosing 
> the right tools for the right job. Saying that an sbc or any 
> b2bua-like element in general is bad because it limits innovation as a 
> whole is just wrong.
>
>> At the end, I haven't heard that telephony operators are major players
>> in RTC innovation, but maybe they didn't deployed enough SBCs ... and
>> the baby brother ALGs ...
>
> The big telco operators have a much different agenda than small and 
> innovating startups. Just because the big telcos use sbcs doesn't mean 
> that sbcs prevent innovation. It's their mind and business plan which 
> does, you can't blame it on technology.
>
> Andreas
>
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-- 
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio World Conference, April 16-17, 2013, Berlin
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