On Apr 7, 2014, at 6:34 PM, Dan Charlesworth <[email protected]> wrote:

> Thanks, Guy.
> 
> I’m almost tempted to just ssl_bump none for 23.0.0.0/12, but I’m sure that 
> would lead to all sorts of annoyances for clients who are tracking users 
> download usage etc.
> 
> I’d appreciate if you could share your list of IP addresses, might be useful 
> for us.
> 

Some CIDRs of interest and the date I verified them. Akamai numbers are bound 
to vary based on logical and geographical location. Validate before use.

11/27/2013: Dropbox: 108.160.160.0/20

06/03/2013: WebEx: 64.68.96.0/19

05/03/2013: Mozilla: 63.245.208.0/20

11/20/2012: Akamai: 184.24.0.0/13

7/31/2012: swcdn.apple.com: 157.238.0.0/16

6/27/2012: Dropbox: 199.47.216.0/22

6/12/2012: Akamai 23.32.0.0/11, 207.108.0.0/15, 209.211.216.0/24, 
204.93.46.0/23, 216.243.192.0/19, 216.243.197.224/20

5/9/2012: supportdownload.apple.com: 67.135.105.0/24 (Akamai)

3/9/2012: Quicken: 206.108.40.0/21

Guy

> Dan
> 
> On 7 Apr 2014, at 11:23 pm, Guy Helmer <[email protected]> wrote:
> 
>> On Apr 6, 2014, at 11:58 PM, Dan Charlesworth <[email protected]> wrote:
>> 
>>> This somewhat vague error comes up with relative frequency from iOS apps 
>>> when browsing via our Squid 3.4.4 intercepting proxy which is performing 
>>> server-first SSL Bumping.
>>> 
>>> The requests in question don’t make it as far as the access log, but with 
>>> debug_options 28,3 26,3, the dst IP can be identified and allowed through 
>>> with ssl_bump none.
>>> 
>>> The device trusts Squid's CA, but apparently that’s not enough for the 
>>> Twitter iOS app and certain Akamai requests that App Store updates use.
>>> 
>>> Can anyone suggest how one might debug this further? Or just an idea of why 
>>> the client might be closing the SSL connection in certain cases?
>>> 
>>> Thanks!
>>> 
>>> 
>> 
>> I suspect that the Twitter app is using certificate pinning to prevent 
>> man-in-the-middle decryption: https://dev.twitter.com/docs/security/using-ssl
>> 
>> IIRC, I have had some difficulty tracking down or obtaining intermediate 
>> certs that Akamai uses. I ended up whitelisting many Akamai IP addresses 
>> from SSL interception on my test network.
>> 
>> Guy
> 

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