Nginx SSL/TLS configuration for "A+" Qualys SSL Labs rating

nginx-tls.conf

#
# Name: nginx-tls.conf
# Auth: Gavin Lloyd <gavinhungry@gmail.com>
# Desc: Nginx SSL/TLS configuration for "A+" Qualys SSL Labs rating
#
# Enables HTTP/2, PFS, HSTS and OCSP stapling. Configuration options not related
# to SSL/TLS are not included here.
#
# Additional tips:
#
#   * Enable CAA DNS record: https://sslmate.com/caa
#
# Example: https://www.ssllabs.com/ssltest/analyze.html?d=gavinhungry.com
#

server {
  listen [::]:80;
  listen      80;
  server_name domain.tld www.domain.tld;

  # Redirect all non-https requests
  rewrite ^ https://$host$request_uri? permanent;
}

server {
  listen [::]:443 ssl http2 default_server;
  listen      443 ssl http2 default_server;

  server_name domain.tld www.domain.tld;

  # Certificate(s) and private key
  ssl_certificate /etc/ssl/domain.crt;
  ssl_certificate_key /etc/ssl/domain.key;

  # RFC-7919 recommended: https://wiki.mozilla.org/Security/Server_Side_TLS#ffdhe4096
  ssl_dhparam /etc/ssl/ffdhe4096.pem;

  # Or, generate random dhparam
  # openssl dhparam 4096 -out /etc/ssl/dhparam.pem
  # ssl_dhparam /etc/ssl/dhparam.pem;

  ssl_protocols TLSv1.3 TLSv1.2;
  ssl_prefer_server_ciphers on;
  ssl_ecdh_curve secp521r1:secp384r1;
  ssl_ciphers EECDH+AESGCM:EECDH+AES256;

  ssl_session_cache shared:TLS:2m;
  ssl_buffer_size 4k;

  # OCSP stapling
  ssl_stapling on;
  ssl_stapling_verify on;
  resolver 1.1.1.1 1.0.0.1 [2606:4700:4700::1111] [2606:4700:4700::1001]; # Cloudflare

  # Set HSTS to 365 days
  add_header Strict-Transport-Security 'max-age=31536000; includeSubDomains; preload' always;
}

Hi Gavin, Hi all,

This works for me with nginx 1.21.3 and openssl 1.1.1l - it is in the server block.

server {
...
# Some cybersecurity tools use TLSv1.2 otherwise I would have used only TLSv1.3
ssl_protocols TLSv1.3 TLSv1.2;

    # The TLS 1.2 ciphers below will not work with very old browsers and Android phones.
    # Please do not ignore the +AES256 as otherwise you will get AES128.
    ssl_ciphers ECDH+CHACHA20:ECDH+AESGCM+AES256;

    # The TLS 1.3 ciphers below are fewer than those in the RFC. But they work.
    ssl_conf_command Ciphersuites TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384;

    # The commands below directly affect how Openssl will behave.
    ssl_conf_command Options ServerPreference,PrioritizeChaCha,NoRenegotiation,NoResumptionOnRenegotiation;

    # My server is not heavy loaded so I am okay to use secp384r1. Saw no effect on website speed.
    ssl_ecdh_curve secp521r1:secp384r1;

    # Do not use 2048 (see SSLTEST rating guide)
    ssl_dhparam /etc/ssl/dsa4096.pem;

...
}

Beautiful, it worked

Do you need to add the header "Content-Security-Policy" for extra security measures?

No need for ssl_dhparam at all

Thanks @Mageek627 . You are right. No need for ssl_dhparam. Here is my latest configuration on nginx 1.21.6

ssl_prefer_server_ciphers on;
ssl_ciphers "TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384";
ssl_conf_command Ciphersuites TLS_CHACHA20_POLY1305_SHA256;
ssl_conf_command Options ServerPreference,PrioritizeChaCha,NoRenegotiation,NoResumptionOnRenegotiation;
ssl_ecdh_curve secp521r1:secp384r1;

Here is one from the NSA/defense.gov, ref https://media.defense.gov/2021/Jan/05/2002560140/-1/-1/0/ELIMINATING_OBSOLETE_TLS_UOO197443-20.PDF & https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-52r2.pdf

ssl_protocols TLSv1.3 TLSv1.2;
ssl_ciphers ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384:AES256-GCM-SHA384;
ssl_ecdh_curve secp384r1;	
ssl_prefer_server_ciphers on;
  
ssl_session_tickets off;

https://github.com/nsacyber/Mitigating-Obsolete-TLS/blob/master/webserver/nginx-tls.txt