Re: [v6ops] Status of CLAT implementation on iPhone? (IPv4 apps on IPv6-only PDP type)

Gert Doering <> Mon, 23 February 2015 18:20 UTC

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Date: Mon, 23 Feb 2015 19:20:05 +0100
From: Gert Doering <>
To: Tore Anderson <>
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Subject: Re: [v6ops] Status of CLAT implementation on iPhone? (IPv4 apps on IPv6-only PDP type)
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On Mon, Feb 23, 2015 at 07:09:28PM +0100, Tore Anderson wrote:
> > [CLAT as an app]
> Assuming it's possible to write such an app for iOs in the first place,
> couldn't you pre-load it on the handsets you sell and have it start up
> automatically? If so, the user wouldn't be required to care. As I
> understand it, it's common carrier practise to pre-load the handsets
> with other kinds of "value add" apps anyway, right?

>From what I understand, it would be possible to write such an app,
using the VPN API.  The problem with that API is that you need NDA'ed
documentation from Apple, and the resulting app needs to be specially
signed by Apple to be permitted to access it (which makes sense, given
that such an app is effectively able to steal other app's traffic) - so
you need fairly deep involvement from Apple, and if they are interested
enough to do that, they could write the CLAT themselves right away...

Auto-starting a VPN app is also possible (VPN on demand), but I'm not 
sure this can be tied to "only on 3G, and only if no IPv4 is there", so 
that aspect could be a bit tricky.

> For the record, I'm not disagreeing that having it in iOS proper would
> be the optimal solution. It just seems to me there's another viable way
> forward that does not depend on Apple being the ones to implement the
> CLAT. But I'm probably missing something?

Access restrictions to the VPN API...

Gert Doering
        -- NetMaster
have you enabled IPv6 on something today...?

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