Installing Certbot for TLS on CentOS 8

Updated by Linode Written by Rajakavitha Kodhandapani

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What is Certbot?

Certbot is a tool that automates the process of getting a signed certificate via Let’s Encrypt to use with TLS.

For most operating system and web server configurations, Certbot creates signed certificates, manages the web server to accept secure connections, and can automatically renew certificates it has created. In most cases, Certbot can seamlessly enable HTTPS without causing server downtime.

Before You Begin

Make sure you have registered a Fully Qualified Domain Name (FQDN) and set up A and AAAA DNS records that point to your Linode’s public IPv4 and IPv6 addresses. Consult our DNS Records: An Introduction and DNS Manager guides for help with setting up a domain.

Note
If you’re using Apache, change each instance of nginx to apache in the following sections.
  1. Enable the EPEL repository:

    sudo yum install epel-release
    sudo yum update
    
  2. Download and install the Certbot and web server-specific packages:

    sudo curl -O https://dl.eff.org/certbot-auto
    sudo mv certbot-auto /usr/local/bin/certbot-auto
    chmod 0755 /usr/local/bin/certbot-auto
    
  3. Run Certbot:

    sudo /usr/local/bin/certbot-auto --nginx
    
  4. Certbot will ask for information about the site. The responses will be saved as part of the certificate:

      
    # sudo /usr/local/bin/certbot-auto --nginx
    Saving debug log to /var/log/letsencrypt/letsencrypt.log
    Plugins selected: Authenticator nginx, Installer nginx
    No names were found in your configuration files. Please enter in your domain
    name(s) (comma and/or space separated)  (Enter 'c' to cancel): www.example.com
    Obtaining a new certificate
    Performing the following challenges:
    http-01 challenge for www.example.com
    Waiting for verification...
    Cleaning up challenges
    Deploying Certificate to VirtualHost /etc/nginx/nginx.conf
    
    Please choose whether or not to redirect HTTP traffic to HTTPS, removing HTTP access.
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    1: No redirect - Make no further changes to the webserver configuration.
    2: Redirect - Make all requests redirect to secure HTTPS access. Choose this for
    new sites, or if you're confident your site works on HTTPS. You can undo this
    change by editing your web server's configuration.
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 2
    Redirecting all traffic on port 80 to ssl in /etc/nginx/nginx.conf
    
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    
    
    
  5. Certbot will also ask if you would like to automatically redirect HTTP traffic to HTTPS traffic. It is recommended that you select this option.

  6. When the tool completes, Certbot will store all generated keys and issued certificates in the /etc/letsencrypt/live/$domain directory, where $domain is the name of the domain entered during the Certbot certificate generation step.

    Note
    Certbot recommends pointing your web server configuration to the default certificates directory or creating symlinks. Keys and certificates should not be moved to a different directory.

    Finally, Certbot will update your web server configuration so that it uses the new certificate, and also redirects HTTP traffic to HTTPS if you chose that option.

  7. If you have a firewall configured on your Linode, you may need to add a firewall rule to allow incoming and outgoing connections to the HTTPS service. On CentOS 8, firewalld is the default tool for managing firewall rules. Configure firewalld for HTTP and HTTPS traffic:

    sudo firewall-cmd --zone=public --permanent --add-service=http
    sudo firewall-cmd --zone=public --permanent --add-service=https
    sudo firewall-cmd --reload
    

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This guide is published under a CC BY-ND 4.0 license.