[RndTbl] strange IMAP / G3 problem

Trevor Cordes trevor at tecnopolis.ca
Mon Mar 7 16:33:07 CST 2016


On 2016-03-07 Theodore Baschak wrote:
> Not that I'd expect this to be the underlying cause, but have you
> tried with a valid cert? https://letsencrypt.org/ makes this free for
> those dabble in TLS without spending a fortune.

We thought at length about cert issues, but then again, why would the
4S be happy with the cert with one net connection and not with
another?  Does the iphone really have this?:

if ($3g and $selfsignedcert)
  barf()
else
  workfine()

For sure this is a stumper.

I setup a test account on another (almost identical) server that has a
legit Thawte SSL cert on it just now, out of curiosity, and we setup
his 4S to connect to it (same everything else) and it doesn't connect.
So same problem regardless of real or fake cert.  That actually makes
sense.

We did some tcpdumps at the same time and when connected with 3G *NO
TRAFFIC* shows up from the phone to the server!  Not a single TCP
packet.

Next we installed a telnet client on the 4S and telnetted to both
servers on port 993 and that did cause traffic to show in tcpdump
(yay!).

So the problem appears to be solely in the iOS default email
application!  It's like it really does have code in it like:

if ($3g and $ssl and $port993)
  barf()
else
  workfine()

We'll next be trying a different email app, just to see what happens
(my guess, it'll work fine, proving the 4S email app is complete
garbage -- still, what a weird bug!).


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