"A" Grade SSL/TLS with Nginx and StartSSL
piotr at cloudflare.com
Tue Oct 15 04:39:42 UTC 2013
> I spent some time hacking on my SSL conf recently. Nothing new, but I
> figured I'd share it with the group:
> Feel free to comment here.
> a few pointers for configuring state-of-the-art TLS on Nginx.
Far from it, from the top:
You should be using:
instead of compiling OpenSSL yourself and playing with CFLAGS & LDFLAGS.
> listen 443;
> ssl on;
That's deprecated syntax, you should be using:
listen 443 ssl;
> ssl_dhparam /path/to/dhparam.pem;
While there is nothing wrong with it per se, DH params are only used
by DHE, which is simply too slow to be used.
> ssl_session_timeout 5m;
Not only doesn't it change anything (5m is the default value), but
it's way too low value to be used.
Few examples from the real world:
Google : 28h
Facebook : 24h
Twitter : 4h
> ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
SSLv3 is still out there, so you shouldn't be dropping support for it
unless you know the consequences very well... This definitely
shouldn't be a general recommendation.
> ssl_ciphers 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:ECDHE-RSA-RC4-SHA:ECDHE-ECDSA-RC4-SHA:RC4-SHA:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK';
Why would you put ECDSA cipher suites here when you're using RSA certificate?
You should also disable:
- DHE cipher suites, because they're too slow compared to the alternative,
- CAMELLIA cipher suites (if you're using AES-NI), because they're too
slow compared to the alternative.
Overall, that's far from the state-of-the-art SSL configuration for
nginx. The only good thing about it is that it's using OCSP and
achieves "A" grade on ssllabs.com, which can tell you a lot about the
quality of the tests they're running.
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