[Dovecot] force ciphers order for clients

[Reindl Harald]

Am 14.08.2013 18:54, schrieb Robert Schetterer:
> http://www.kuketz-blog.de/perfect-forward-secrecy-mit-apple-mail/
> 
> it looks like DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA can be forced in use
> with apple mail
> 
> 
> ( if no ECDHE is possible ,by missing openssl 1.x etc,
> seems that apple mail tries ECDHE first if fails its going to use
> RSA-AES128-SHA )
> 
> force soltution as tried
> 
> ssl_cipher_list =
> DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!CBC:!PSK:!SRP:!DSS:!SSLv2:!RC4
> 
> so far so good , it worked nice with recent thunderbird too
> but it fails with outlook 2003 pop3s / win7
> 
> so i thought about using an order like this
> 
> ssl_cipher_list =
> DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA:ALL:!LOW:!SSLv2:!EXP:!aNULL

ssl_cipher_list =
EECDH+AES:EDH+AES:-SHA1:EECDH+RC4:EDH+RC4:RC4-SHA:EECDH+AES256:EDH+AES256:AES256-SHA:HIGH:!aNULL:!eNULL:!EXP:!MD5:!LOW:!SSLv2

is what is *higly* recommended after testing webservers by https://www.ssllabs.com/ssltest/ and
works with Outlook 2003/2007/2010 as well as Thunderbird, iOS, Apple Mail, currently
there exists even no way to force web-browsers to FS without open BEAST-attack and
i doubt in context mail it does not look much better

however, make sure you are using *the latest* dovecot version and at least openssl 1.0.1e
thunderbird: TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)

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