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

Hi, On 01/24/2013 11:52 PM, Daniel-Constantin Mierla wrote: 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. 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. 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. 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 _______________________________________________ SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users(a)lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users