mailinabox/conf/nginx-ssl.conf

# from https://gist.github.com/konklone/6532544 and https://mozilla.github.io/server-side-tls/ssl-config-generator/
###################################################################################################################

# Basically the nginx configuration I use at konklone.com. 
# I check it using https://www.ssllabs.com/ssltest/analyze.html?d=konklone.com
#
# To provide feedback, please tweet at @konklone or email eric@konklone.com.
# Comments on gists don't notify the author. 
# 
# Thanks to WubTheCaptain (https://wubthecaptain.eu) for his help and ciphersuites.
# Thanks to Ilya Grigorik (https://www.igvita.com) for constant inspiration.

# Path to certificate and private key.
# The .crt may omit the root CA cert, if it's a standard CA that ships with clients.
#ssl_certificate /path/to/unified.crt;
#ssl_certificate_key /path/to/my-private-decrypted.key;

# Tell browsers to require SSL (warning: difficult to change your mind)
# Handled by the management daemon because we can toggle this version or a
# preload version.
#add_header Strict-Transport-Security max-age=31536000;

# Prefer certain ciphersuites, to enforce Forward Secrecy and avoid known vulnerabilities.
# 
# Forces forward secrecy in all browsers and clients that can use TLS,
# but with a small exception (DES-CBC3-SHA) for IE8/XP users.
# 
# Reference client: https://www.ssllabs.com/ssltest/analyze.html
ssl_prefer_server_ciphers on;
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';

# Cut out (the old, broken) SSLv3 entirely. 
# This **excludes IE6 users** and (apparently) Yandexbot.
# Just comment out if you need to support IE6, bless your soul.
ssl_protocols TLSv1.2 TLSv1.1 TLSv1;

# Turn on session resumption, using a cache shared across nginx processes,
# as recommended by http://nginx.org/en/docs/http/configuring_https_servers.html
ssl_session_cache shared:SSL:50m;
ssl_session_timeout 1d;
#keepalive_timeout   70; # in Ubuntu 14.04/nginx 1.4.6 the default is 65, so plenty good

# Buffer size of 1400 bytes fits in one MTU.
# nginx 1.5.9+ ONLY
#ssl_buffer_size 1400; 

# SPDY header compression (0 for none, 9 for slow/heavy compression). Preferred is 6. 
# 
# BUT: header compression is flawed and vulnerable in SPDY versions 1 - 3.
# Disable with 0, until using a version of nginx with SPDY 4.
spdy_headers_comp 0;

# Now let's really get fancy, and pre-generate a 2048 bit random parameter
# for DH elliptic curves. If not created and specified, default is only 1024 bits. 
#
# Generated by OpenSSL with the following command:
#   openssl dhparam -outform pem -out dhparam2048.pem 2048
# 
# Note: raising the bits to 2048 excludes Java 6 clients. Comment out if a problem.
ssl_dhparam STORAGE_ROOT/ssl/dh2048.pem;


# OCSP stapling - means nginx will poll the CA for signed OCSP responses, 
# and send them to clients so clients don't make their own OCSP calls.
# http://en.wikipedia.org/wiki/OCSP_stapling
# 
# while the ssl_certificate above may omit the root cert if the CA is trusted,
# ssl_trusted_certificate below must point to a chain of **all** certs
# in the trust path - (your cert, intermediary certs, root cert)
#
# 8.8.8.8 and 8.8.4.4 below are Google's public IPv4 DNS servers. 
# nginx will use them to talk to the CA.
ssl_stapling on;
ssl_stapling_verify on;
resolver 127.0.0.1 valid=86400;
resolver_timeout 10;