letsencrypt.conf

location ^~ /.well-known/acme-challenge {
        root /var/www/letsencrypt;
        default_type "text/plain";
}

ssl.conf

ssl_dhparam /etc/ssl/certs/dhparam.pem;

ssl_session_cache   shared:SSL:10m;
ssl_session_timeout 10m;
keepalive_timeout   70;
ssl_session_tickets off;

ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers 'kEECDH+ECDSA+AES128 kEECDH+ECDSA+AES256 kEECDH+AES128 kEECDH+AES256 +SHA !aNULL !eNULL !LOW !MD5 !EXP !DSS !PSK !SRP !kECDH !CAMELLIA !RC4 !SEED';
ssl_ecdh_curve secp384r1;
ssl_prefer_server_ciphers on;

ssl_stapling on;
ssl_stapling_verify on;

resolver 8.8.8.8 8.8.4.4 valid=300s;
resolver_timeout 5s;

add_header Strict-Transport-Security "max-age=15768000; includeSubdomains; preload";
add_header X-Frame-Options DENY;
add_header X-Content-Type-Options nosniff;