How to configure Nginx with Let’s Encrypt on CentOS 7

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How do I secure my Nginx web server with Let’s Encrypt free ssl certificate on my CentOS 7 or RHEL 7 server? How to configure Nginx with Let’s Encrypt on CentOS 7 server?

Let’s Encrypt is a free, automated, and open certificate authority for your website or any other projects. This page shows how to use Let’s Encrypt to install a free SSL certificate for Nginx web server. You will learn how to properly deploy Diffie-Hellman on your server to get SSL labs A+ score on a CentOS/RHEL 7.
Tutorial requirements
Operating system/appCentOS 7 + Apache with mod_ssl
Root privileges requiredYes
DifficultyIntermediate (rss)
Estimated completion time20m
Table of contents

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How to secure Nginx with Let’s Encrypt on CentOS 7

Our sample setup is as follows:
How to secure configure Nginx with Let's Encrypt on CentOS RHEL 7

How to secure Nginx with Let’s Encrypt on CentOS 7

The procedure is as follows to obtaining an SSL certificate:

  1. Get acme.sh software:
    git clone https://github.com/Neilpang/acme.sh.git
  2. Create /.well-known/acme-challenge/ directory:
    mkdir -p /var/www/html/.well-known/acme-challenge/
  3. Obtaining an SSL certificate your domain:
    acme.sh --issue -w /DocumentRootPath/ -d your-domain
  4. Configure TLS/SSL on Nginx:
    vi /etc/nginx/sites-available/default
  5. Setup cron job setup for auto renewal
  6. Open port 443 (HTTPS):
    sudo firewall-cmd --add-service=https

Let us see how to install acme.sh client and use it on a CentOS/RHEL 7 to get an SSL certificate from Let’s Encrypt.

Step 1 – Install the required software

Install the git, wget, curl and bc packages with the yum command:
$ sudo yum install git bc wget curl

Step 2 – Install acme.sh Let’s Encrypt client

Clone the repo:
$ cd /tmp/
$ git clone https://github.com/Neilpang/acme.sh.git

clone acme.sh git
Install acme.sh client on to your system, run:
$ cd acme.sh/
$ sudo -i
# ./acme.sh --install

install acme.sh client on centos 7 or rhel 7
After install, you must close current terminal and reopen again to make the alias take effect. Or simply type the following source command:
$ sudo source ~/.bashrc

Step 3 – Create acme-challenge directory

Type the following mkdir command. Make sure you set D to actual DocumentRoot path as per your needs:
# D=/usr/share/nginx/html
# mkdir -vp ${D}/.well-known/acme-challenge/
###---[ NOTE: Adjust permission as per your setup ]---###
# chown -R nginx:nginx ${D}/.well-known/acme-challenge/
# chmod -R 0555 ${D}/.well-known/acme-challenge/

Also create directory to store SSL certificate:
# mkdir -p /etc/nginx/ssl/cyberciti.biz/

Step 4 – Create dhparams.pem file

Run openssl command:
# cd /etc/nginx/ssl/cyberciti.biz/
# openssl dhparam -out dhparams.pem -dsaparam 4096

Step 5 – Obtain a certificate for domain

Issue a certificate for your domain:
acme.sh --issue -w /path/to/www/htmlRoot/ -d example.com -k 2048
sudo acme.sh --issue -w /usr/local/nginx/html -d server2.cyberciti.biz -k 2048

CentOS Obtain Let's Encrypt certificate for domain

Step 6 – Configure Nginx

You just successfully requested an SSL Certificate from Let’s Encrypt for your CentOS 7 or RHEL 7 server. It is time to configure it. Edit default.ssl.conf:
$ sudo vi /etc/nginx/conf.d/default.ssl.conf
Append the following config:

## START: SSL/HTTPS server2.cyberciti.biz ###
server {
    #------- Start SSL config with http2 support ----#
    listen 10.21.136.134:443 http2;
    server_name server2.cyberciti.biz;
    ssl on;
    ssl_certificate /etc/nginx/ssl/cyberciti.biz/server2.cyberciti.biz.cer;
    ssl_certificate_key /etc/nginx/ssl/cyberciti.biz/server2.cyberciti.biz.key;
    ssl_session_timeout 30m;
    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
    ssl_ciphers ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS;
    ssl_session_cache shared:SSL:10m;
    ssl_dhparam /etc/nginx/ssl/cyberciti.biz/dhparams.pem;
    ssl_prefer_server_ciphers on;
 
    ## Improves TTFB by using a smaller SSL buffer than the nginx default
    ssl_buffer_size 8k;
 
    ## Enables OCSP stapling
    ssl_stapling on;
    resolver 8.8.8.8;
    ssl_stapling_verify on;
 
    ## Send header to tell the browser to prefer https to http traffic
    add_header Strict-Transport-Security max-age=31536000;
 
    ## SSL logs ##
    access_log /var/log/nginx/ssl_access.log;
    error_log /var/log/nginx/ssl_error.log;
    #-------- END SSL config -------##
    # Add rest of your config below like document root, php and more ##
    location / {
        root   /usr/share/nginx/html;
        index  index.html index.htm;
    }
    # Allow php apps
    location ~ \.php$ {
        root /usr/share/nginx/html;
        fastcgi_pass   127.0.0.1:9000;
        fastcgi_index  index.php;
        include        fastcgi_params;
        fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
    }
}
## END SSL server2.cyberciti.biz ######

Save and close the file in vi/vim text editor.

Step 7 – Install certificate

Install the issued cert to nginx server:
# acme.sh --installcert -d server2.cyberciti.biz \
--keypath /etc/nginx/ssl/cyberciti.biz/server2.cyberciti.biz.key \
--fullchainpath /etc/nginx/ssl/cyberciti.biz/server2.cyberciti.biz.cer \
--reloadcmd 'systemctl reload nginx'

install let us encrupt certifcate in rhel 7
Make sure port os open with the ss command or netstat command:
# ss -tulpn

Step 8 – Firewall configuration

You need to open port 443 (HTTPS) on your server so that clients can connect it. Update the rules as follows:
$ sudo firewall-cmd --add-service=https
$ sudo firewall-cmd --runtime-to-permanent

Step 9 – Test it

Fire a web browser and type your domain such as:
https://server2.cyberciti.biz
Test it with SSLlabs test site:
https://www.ssllabs.com/ssltest/analyze.html?d=server2.cyberciti.biz
RHEL CentOS 7 Nginx SSL Labs A+ Test result for Nginx with Lets Encrypt Certificate

Step 10 – acme.sh commands

List all certificates:
# acme.sh --list
Renew a cert for domain named server2.cyberciti.biz
# acme.sh --renew -d server2.cyberciti.biz
Please note that a cron job will try to do renewal a certificate for you too. This is installed by default as follows (no action required on your part). To see job run:
# crontab -l
Sample outputs:

8 0 * * * "/root/.acme.sh"/acme.sh --cron --home "/root/.acme.sh" > /dev/null

Upgrade acme.sh client:
# acme.sh --upgrade
Getting help:
# acme.sh --help | more

Conclusion

You learned how to install and set up Let’s Encrypt TLS/SSL certificate on your CentOS Linux 7 server. See acme.sh project home page here for more information.

This entry is 3 of 3 in the Linux, Nginx, MySQL, PHP (LEMP) Stack for CentOS/RHEL 7 Tutorial series. Keep reading the rest of the series:
  1. How to install and use Nginx on CentOS 7 / RHEL 7
  2. How to install PHP 7.2 on CentOS 7/RHEL 7
  3. How to configure Nginx with Let's Encrypt on CentOS 7

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.


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