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I'm configuring nginx and am trying to find a cipher list that gives an A standard over at SSLlabs while also allowing common browsers to access the website.

I am not an expert and am asking this question here because I've been unable to achieve the goals above using various default/recommended values.

I'm using Debian 9, currently sporting nginx 1.10.3 and openssl 1.1.0f.

  • nginx's default value did not get an "A" from SSL labs.

  • https://cipherli.st/ list got an "A" but Chromium 65 / Chrome 66 fails to connect.

    ECDHE-RSA-AES256-GCM-SHA512:DHE-RSA-AES256-GCM-SHA512:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-SHA384;
    
  • https://github.com/ssllabs/research/wiki/SSL-and-TLS-Deployment-Best-Practices gets an "A" but chromium cannot connect.

    ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA:ECDHE-ECDSA-AES128-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA256;
    
  • https://mozilla.github.io/server-side-tls/ssl-config-generator/ (which doesn't seem to be up to date with my version of openssl) 'modern' option does not work with Chrome/Chromium.

    ssl_ciphers 'ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256';
    
  • https://mozilla.github.io/server-side-tls/ssl-config-generator/ 'intermeriate' option does not get an A.

    ssl_ciphers 'ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS';                           
    

In all cases of scoring "B", the SSL Labs report says: "This server does not support Forward Secrecy with the reference browsers. Grade capped to B." and the further explanation says:

You need to support and prefer ECDHE suites in order to enable forward secrecy with modern web browsers.

...but it looks like I am listing ECDHE ones first.

The other SSL options I have set are

ssl_session_cache shared:SSL:30m;
ssl_session_timeout 1d;
ssl_prefer_server_ciphers on;
ssl_protocols TLSv1 TLSv1.1 TLSv1.2
ssl_dhparam /etc/nginx/dh_param.pem
ssl_ecdh_curve secp521r1;
ssl_stapling on;
ssl_stapling_verify on;

I'm well out of my depth, so apologies in advance if this question is something I'm doing wrong.

  • 1
    The ciphers are not the problem. You are using an unsupported curve. – Steffen Ullrich May 1 '18 at 10:48
  • @SteffenUllrich thank you. using secp384r1 seems to work. – artfulrobot May 1 '18 at 11:00
  • Actually, things seem to work without specifying a curve at all. (I note that mozilla's config generator does not specify a curve.) – artfulrobot May 1 '18 at 11:04