Configure Apache with SSL/TLS Certificates on CentOS 8

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Follow through this guide to learn how to configure Apache with SSL/TLS Certificates on CentOS 8.

Are you using Nginx instead? Check our guide on setting up Nginx with SSL/TLS certificates by following the link below;

Configure Nginx with SSL/TLS certificates on CentOS 8

Configure Apache with SSL/TLS Certificates on CentOS 8

Run System Update

Update your system package by executing;

dnf update

Install Apache and SSL/TLS module on CentOS 8

Apache HTTP server is provided by the httpd package while mod_ssl packages provides the Apache SSL/TLS module. Both packages can be installed by running;

dnf install httpd mod_ssl

Running Apache

Start and enable Apache to run on system boot.

systemctl enable --now httpd

Allow HTTPS on Firewall

To allow external access to Apache over HTTPS, open 443 (HTTPS) depending on the traffic to server.

In this guide, since we configuring Nginx to the TLS certificates, we are opening port 443/tcp.

firewall-cmd --add-port=443/tcp --permanent

If you are looking at redirecting the HTTP traffic to HTTPS, open port 80 too.

firewall-cmd --add-port=80/tcp --permanent
firewall-cmd --reload

Generate SSL/TLS Certificates

There are multiple options to choose from when you want to secure Apache with SSL/TLS certificates.

  • You can use self-signed certificates for test purposes.
  • You can order for a commercially trusted server certificate from your preferred CA
  • You can use the freeautomated, and open CA, Let’s Encrypt.

Well, in this guide, we are using the first option of self-signed SSL/TLS certificates for demonstration purposes.

So how do you generate the self-signed SSL/TLS certificates on CentOS 8? Openssl command is used to generate the SSL/TLS certificates as shown below;

openssl req -newkey rsa:4096 -nodes -keyout /etc/pki/tls/private/kifarunix-demo.key -x509 -days 365 -out /etc/pki/tls/certs/kifarunix-demo.crt

So what are the openssl command line options used above?

  • req: It is used to create CSR as well as the self signed certificates.
  • -newkey rsa:4096: This option creates a new certificate request and a 4096 bits RSA key at the same time.
  • -nodes: When this option is specified then if a private key is created it will not be encrypted.
  • -keyout /etc/pki/tls/private/kifarunix-demo.key: Writes the newly created private key to the specified filename. Replace the filename accordingly.
  • -x509: This option outputs a self signed certificate instead of a certificate request.
  • -days 365: Used to specify the validity period for the self signed certificate generated. This therefore is valid for 365 days.
  • -out /etc/pki/tls/certs/kifarunix-demo.crt: Specifies the output filename to write the self signed certificate to.

When the command runs, you are prompted to provide certificate identification details such the Country Name of your organization, the State, the Locality, the name of Organization, the Organization Unit, the Common Name (This is the most important detail), optional email.

You can as well be able to provide these details on the command line using the -subj option of the openssl-req command as shown below;

-subj "/C=CN/ST=STATE/L=CITY/O=ORG NAME/OU=Department/CN=DOMAIN_NAME/emailAddress=name@domain"

For example to generate a self-signed SSL/TLS certificate for the domain, and all its sub-domains (Common name will be written as *, you can openssl-req command as;

(Replace the domain names accordingly)

openssl req -newkey rsa:4096 -nodes -keyout /etc/pki/tls/private/kifarunix-demo.key -x509 -days 365 -out /etc/pki/tls/certs/kifarunix-demo.crt \
-subj "/C=US/ST=Oregon/L=Springfield/O=kifarunix-demo/OU=IT/CN=*[email protected]"

Well, there you go. Your private key has been written to /etc/pki/tls/private/kifarunix-demo.key while your certificate has been written to /etc/pki/tls/certs/kifarunix-demo.crt.

Well, want to use commercially signed certificates? Generate the CSR and submit it to your favourite CA to order for trusted certificates.

The command below can get you a CSR. Make due substitution.

openssl req -new -newkey rsa:4096 -nodes -keyout domain.key -out domain.csr \
-subj "/C=CN/ST=STATE/L=CITY/O=ORG NAME/OU=Department/CN=DOMAIN_NAME/emailAddress=name@domain"

Be sure to keep the key safe as you will need when installing the certificates.

Configure Apache to Use SSL/TLS Certificates

Now that you have your SSL/TLS private key and certificate (sel-signed in this case), proceed to configure Apache to use them.

Open Apache SSL configuration file for editing.

vim /etc/httpd/conf.d/ssl.conf

Apart from installing the SSL/TLS certificates, there are some ciphers provided by that aims to provide Strong SSL Security for all modern browsers. We will also add these ciphers to Apache SSL configuration.

In this guide, we are making changes to the default SSL virtual host configuration.

## Redirect HTTP Traffic to HTTPS
<VirtualHost *:80>
    DocumentRoot /var/www/html
    RewriteEngine On
    RewriteCond %{HTTPS} off
    RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

## Begin SSL configuration

Listen 443 https
SSLPassPhraseDialog exec:/usr/libexec/httpd-ssl-pass-dialog
SSLSessionCache         shmcb:/run/httpd/sslcache(512000)
SSLSessionCacheTimeout  300
SSLCryptoDevice builtin

<VirtualHost _default_:443>
ErrorLog logs/ssl_error_log
TransferLog logs/ssl_access_log
LogLevel warn
SSLEngine on
SSLProtocol -all +TLSv1.3 +TLSv1.2
SSLOpenSSLConfCmd Curves X25519:secp521r1:secp384r1:prime256v1
SSLHonorCipherOrder on
SSLCertificateFile /etc/pki/tls/certs/kifarunix-demo.crt
SSLCertificateKeyFile /etc/pki/tls/private/kifarunix-demo.key
<FilesMatch "\.(cgi|shtml|phtml|php)$">
    SSLOptions +StdEnvVars
<Directory "/var/www/cgi-bin">
    SSLOptions +StdEnvVars
BrowserMatch "MSIE [2-5]" \
         nokeepalive ssl-unclean-shutdown \
         downgrade-1.0 force-response-1.0
CustomLog logs/ssl_request_log \
          "%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x \"%r\" %b"
Header always set Strict-Transport-Security "max-age=63072000; includeSubDomains; preload"
Header always set X-Frame-Options DENY
Header always set X-Content-Type-Options nosniff
SSLCompression off
#SSLUseStapling on
#SSLStaplingCache "shmcb:logs/stapling-cache(150000)"
SSLSessionTickets Off

The Online Certificate Status Protocol (OCSP) stapling is disabled since we are using self-signed certificates.

Save the configuration file and check for any configuration syntax.

apachectl configtest


httpd -t
Syntax OK

Create sample Apache test page on the default root directory;

vim /var/www/html/index.html
<!DOCTYPE html>
<p>Configuring Apache to use SSL/TLS certificates on CentOS 8</p>

Running Apache with SSL/TLS enabled

You can now restart Apache to effect the changes.

systemctl restart httpd

Testing Apache SSL/TLS configuration

It is now time to test whether Apache is able to server HTTPS requests as well as redirect HTTP traffic to HTTPS traffic. Access it using the server’s IP address of hostname, https://server-IP-or-Hostname.

Configure Apache with SSL/TLS Certificates on CentOS 8

Even if you try with http://server-IP-or-Hostname, it will be redirected to HTTPS.

And that marks our POC. You have learnt how to configure Apache with SSL/TLS Certificates on CentOS 8.

Related Tutorials

Install Redmine with Apache and MariaDB on CentOS 8

Install Apache with Self-signed Certificate on FreeBSD 12

Install phpMyAdmin with Apache on Fedora 30

Remove Apache Test Page on Fedora 30/29


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1 thought on “Configure Apache with SSL/TLS Certificates on CentOS 8”

  1. apachectl configtest

    AH00526: Syntax error on line 41 of /etc/httpd/conf.d/ssl.conf:
    Invalid command ‘%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x “%r” %b’, perhaps misspelled or defined by a module not included in the server configuration

    Please how to resolve this error


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