update nginx SSL options, fixes #61

conf/nginx-ssl.conf

-# https://gist.github.com/konklone/6532544
-##########################################
+# from: https://gist.github.com/konklone/6532544
+###################################################################################
 
-# required: path to certificate and private key
-# the .crt may omit the root CA cert, if it's a standard CA that ships with clients.
+# 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;
 
-# optional: tell browsers to require SSL (warning: difficult to change your mind)
+# Tell browsers to require SSL (warning: difficult to change your mind)
 add_header Strict-Transport-Security max-age=31536000;
 
-# optional: prefer certain ciphersuites, to enforce Perfect Forward Secrecy and avoid known vulnerabilities.
-# done in consultation with:
-#   http://ggramaize.wordpress.com/2013/08/02/tls-perfect-forward-secrecy-support-with-apache/
-#   https://www.ssllabs.com/ssltest/analyze.html
+# 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-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-RC4-SHA:ECDHE-RSA-AES256-SHA:RC4-SHA:AES256-GCM-SHA384:AES256-SHA256:CAMELLIA256-SHA:ECDHE-RSA-AES128-SHA:AES128-GCM-SHA256:AES128-SHA256:AES128-SHA:CAMELLIA128-SHA;
+ssl_ciphers 'kEECDH+ECDSA+AES128 kEECDH+ECDSA+AES256 kEECDH+AES128 kEECDH+AES256 kEDH+AES128 kEDH+AES256 DES-CBC3-SHA +SHA !aNULL !eNULL !LOW !MD5 !EXP !DSS !PSK !SRP !kECDH !CAMELLIA !RC4 !SEED';
+
+# 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;
 
-# optional: turn on session resumption, using a 10 min cache shared across nginx processes
+# Turn on session resumption, using a 10 min cache shared across nginx processes,
 # as recommended by http://nginx.org/en/docs/http/configuring_https_servers.html
 ssl_session_cache   shared:SSL:10m;
 ssl_session_timeout 10m;
 keepalive_timeout   70;
 
+# Buffer size of 1400 bytes fits in one MTU.
 # nginx 1.5.9+ ONLY
-#ssl_buffer_size 1400; # 1400 bytes to fit in one MTU
+#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 /path/to/dhparam2048.pem;
 
-# SPDY header compression (0 for none, 1 for fast/less compression, 9 for slow/heavy compression)
-spdy_headers_comp 6;
 
 # 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
+# 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 below is Google's public DNS server. nginx will use it to talk to the CA.
-#
-# If the issuer certificate is not found (e.g. the certificate is self-signed),
-# nginx will skip this with the warning: '"ssl_stapling" ignored, issuer certificate not found'.
+# 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 8.8.8.8;
+resolver 8.8.8.8 8.8.4.4 valid=86400;
+resolver_timeout 10;
 #ssl_trusted_certificate /path/to/all-certs-in-chain.crt;