manuals:servers:nginx [quietlife.nl wiki]

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===== nginx and Let's Encrypt with strong SSL ciphers =====

==== Let's Encrypt ====

> [[https://en.wikipedia.org/wiki/Let%27s_Encrypt|Let's Encrypt]] is a certificate authority that launched on April 12, 2016 that provides free X.509 certificates for Transport Layer Security (TLS) encryption via an automated process designed to eliminate the current complex process of manual creation, validation, signing, installation, and renewal of certificates for secure websites.

By default, certbot generates 2048 bit certificates, but 4096 bit should be preferred. This can be changed in the configuration:

<file bash /etc/letsencrypt/cli.ini>
# Use a 4096 bit RSA key instead of 2048
rsa-key-size = 4096
</file>

Then renew your certificate by requesting a new one for all your (sub)domains:

<code bash>
sudo certbot --nginx certonly -d quietlife.nl -d www.quietlife.nl -d wiki.quietlife.nl
</code>

And select ''2: Renew & replace the cert (limit ~5 per 7 days)''.
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=== SSL certificate renewal ===

Let's Encrypt certificates expire every three months, and certbot automatically renews them. After renewing the certificates, you have to reload nginx. This can be automated with a script you put in ''/etc/letsencrypt/renewal-hooks/post/'':

<code bash /etc/letsencrypt/renewal-hooks/post/nginx.sh>
#!/bin/sh
systemctl reload nginx.service
</code>

Make it executable:

<code bash>
sudo chmod +x /etc/letsencrypt/renewal-hooks/post/nginx.sh
</code>

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==== nginx ====
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=== Diffie-Hellman Ephemeral Parameters ===

> [[https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange|Diffie–Hellman key exchange]] (D–H) is a method of securely exchanging cryptographic keys over a public channel and was one of the first public-key protocols as originally conceptualized by Ralph Merkle and named after Whitfield Diffie and Martin Hellman.

Generate ''dhparams.pem'':

<code bash>
openssl dhparam -out dhparams.pem 4096
sudo mv dhparams.pem /etc/ssl/
sudo chown root:ssl-cert /etc/ssl/dhparams.pem
sudo chmod 640 /etc/ssl/dhparams.pem
</code>
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=== SSL cipher suite ===

Edit the global configuration file:

<file nginx /etc/nginx/nginx.conf>
##
# SSL Settings
##

ssl_protocols TLSv1.3 TLSv1.2;
ssl_prefer_server_ciphers on;
ssl_dhparam /etc/ssl/dhparams.pem;
ssl_ciphers EECDH+AESGCM:EDH+AESGCM;
ssl_ecdh_curve secp521r1:secp384r1;
ssl_session_timeout 10m;
ssl_session_cache shared:SSL:10m;
ssl_session_tickets off;
ssl_stapling on;
</file>


=== HTTP headers ===

Create a configuration file:

<file nginx /etc/nginx/conf.d/headers.conf>
add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload";
add_header X-Content-Type-Options nosniff;
add_header X-Frame-Options DENY;
</file>

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==== Restart nginx ====

<code bash>
sudo systemctl restart nginx.service
</code>

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