Wireshark: Facetime on Iphone 4: Vanilla unencrypted STUN and SIP | Hacker News Reader

Wireshark: Facetime on Iphone 4: Vanilla unencrypted STUN and SIP

blog.roychowdhury.org

54 pointspmikal17 comments

Hopefully once Apple "opens" up facetime, they will also enable calls outside the Facetime network. Otherwise the who's and what's of connecting to their registrar will probably be no better than the App Store situation today (eg, I'm sure gateways will be forbidden).

edit: Although the identifying info from those screenshots is scrubbed, the comments say the R-URI is basically user@ip:port. This is interesting: there's no SIP proxy in between. No wonder it only works over wifi.

Although the identifying info from those screenshots is scrubbed, the comments say the R-URI is basically user@ip:port. This is interesting: there's no SIP proxy in between.

Unfortunately I see "Bandwidth Limit Exceeded" when I go to that page but your comment makes me wonder whether they are doing SIP URI discovery via DNS-SD[1] given their penchant for DNS-SD.

[1] http://tools.ietf.org/html/draft-lee-sip-dns-sd-uri-03 (ignore the stuff about mDNS and substitute Wide-area Bonjour)

Its actually a little more complicated than that:

http://www.packetstan.com/2010/07/special-look-face-time-par...

Since Facetime is running SIP over WiFi, does AT&T still charge you minutes for a Facetime call or is that only for the non-facetime portion of the phonecall?

Apparently no:

“The voice call ends as soon as the FaceTime call connects... the FaceTime call is over Wi-Fi so does not use carrier minutes.”

http://news.cnet.com/8301-13579_3-20008289-37.html

This is cool. This, Google Voice and Sipdroid on my Desire (which lets you route all calls, automatically, to the SIP provider of you choice, either on Wi-Fi only or 3G as well) makes me feel good about the future of telephony.

Why is "unencrypted" considered a good thing? I find it kind of scary especially for a video conference app.

Your phone calls aren't point-to-point encrypted, either.

No, not end-to-end, but they are encrypted between your phone and the cell tower.

It's considerably more secure than an open wifi network.

GSM supports optional encryption, but there's no notification to the user whether a given call is encrypted.

Yes, but I'm pretty sure all US carriers use it all the time

(Though it's true that this opens you up to a potential MITM attack by a well equipped adversary, it's still a far cry from an open wifi network)

Remember all those scandals where politicians sent sexy texts to people they weren't supposed to? Video looks a lot better on the evening news.

Cue first FaceTime scandal in 3, 2...

I'm pretty sure those are usually leaked, not intercepted.

It's much easier to add encryption to an unencrypted channel than it is to interoperate with a fully encrypted one. As a user you might be more interested in encryption as soon as possible, but to the average HN reader an unencrypted standards-based stack is good news!

I may be missing something, but isn’t he saying that the FaceTime call, once initiated by a traditional phone call, is encrypted?

“Only the call part is Vanilla SIP. The procedure for registering a Facetime user into their servers etc. is all non-SIP, encrypted/ciphered.”

Does anyone think they're trying to figure out IPv6 to make this work over 3G?

What does one have to do with the other?

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