How to Generate a Self-Signed SSL Certificate in CentOS

OpenSSL is a popular open-source library used for SSL encryption and certificate management. If it’s not already installed on your server, you can install it using the following command:

yum install openssl

A certificate authority (CA) is a trusted entity that issues digital certificates. To create a self-signed certificate, we first need to create our own CA.

To create a CA, create a new directory to store the certificate and private key:
mkdir ~/myCA
cd ~/myCA

Next, create a private key for the CA:

openssl genpkey -algorithm RSA -out private/myCA.key

With the private key generated, we can now create a CA certificate:

openssl req -key private/myCA.key -new -x509 -out myCA.crt

When prompted, fill out the required information to generate the certificate. The most important fields are the “Common Name” field, which should be the domain name or IP address of your server, and the “Organization” field, which should contain the name of your organization.

With the CA created, we can now create a server certificate for our website.

First, create a directory for the server certificate and private key:

mkdir ~/myServer
cd ~/myServer

Next, create a private key for the server:

openssl genpkey -algorithm RSA -out private/myServer.key

With the private key generated, we can now create a certificate signing request (CSR):

openssl req -key private/myServer.key -new -out myServer.csr

When prompted, fill out the required information. The “Common Name” field should be the domain name or IP address of your server.

With the CSR generated, we can now sign the server certificate using our CA:

openssl x509 -req -in myServer.csr -CA ~/myCA/myCA.crt -CAkey ~/myCA/private/myCA.key -CAcreateserial -out myServer.crt

With the SSL certificate and private key generated, the final step is to configure your web server to use the certificate. The exact steps will vary depending on the web server you are using, but in general, you’ll need to specify the path to the SSL certificate and private key in the server configuration file.

For example, if you’re using Apache, you can add the following lines to your httpd.conf file or a virtual host configuration file:

SSLEngine on
SSLCertificateFile /root/myServer/myServer.crt
SSLCertificateKeyFile /root/myServer/private/myServer.key

Don’t forget to restart the web server after making these changes.