Here’s how you can create your own SSL certificates right from your Linux terminal.
What Is an SSL Certificate?
SSL stands for Secure Socket Layer. An SSL certificate verifies the identity of a website and enables an encrypted (secure) connection between the website and your browser.
A secure connection will encrypt all data sent back and forth between your web browser and the server you are communicating with. This prevents any person or computer in the middle from intercepting and reading the data being transferred.
Can I Use a Self-Signed SSL Certificate on My Website?
You can install and use your own self-signed SSL certificate on your website and to enable encrypted connections. However, since a trusted certificate authority hasn’t signed the certificate, visitors’ web browsers will show a warning saying so, and state that the site can not be positively identified because of this.
For this reason, self-signed certificates are generally best used for development and testing purposes, or for applications such as a company or home intranet where users are coming from an internal network and not connecting via the internet.
Again, it’s important to note that although a self-signed SSL certificate may cause warnings in your web browser, it will still enable a secure connection that works in exactly the same way as any certificate created by one of the trusted authorities.
If you want to generate an SSL certificate for a public website but be sure that users don’t receive any confusing warnings, you might want to look into how you can set up a free SSL certificate from a trusted certificate authority.
Installing OpenSSL on Linux
To generate a self-signed SSL certificate on Linux, you’ll first need to make sure that you have OpenSSL installed. To do so, open a terminal and enter the appropriate commands corresponding to the distro you’re using.
If you are using a Debian-based system such as Ubuntu or Linux Mint:
If you are using an RPM-based distro like Fedora or CentOS:
To install OpenSSL on Arch Linux:
It should take a few moments for your system to download and install the openssl package.
Creating Your Self-Signed SSL Certificate
Once you’ve made sure that you have OpenSSL installed, you can create your SSL certificate by entering a single command. OpenSSL will create the certificate and corresponding encryption key in the current directory. So, make sure you’re in the directory where you want your certificate and key saved before you enter any other commands.
To create your self-signed SSL certificate, enter the following command at the prompt, replacing the two instances of myserver with the filenames that you would like to use.
The command will generate a certificate and a private key used to sign the certificate. You can name the files according to your will. The aforementioned command will generate a self-signed certificate using 4096-bit encryption which is valid for 365 days.
To complete the process, the system will ask several questions about the organization the certificate is intended for. If you are just planning to use the certificate for personal development or testing purposes, you can fill in any values you like except for the Common Name field. In this field, you should enter the domain name of the website where you plan to install the certificate.
Your SSL Certificate Is Now Ready to Use
That’s all there is to it. You should now have an SSL certificate (CRT file) and the encryption key (KEY file) used to sign it. Just follow the instructions on the platform where you’d like to install your certificate and you will be able to connect to your website using encrypted HTTPS connections.
Not many Linux users know this but you can also use OpenSSL to encrypt files, entire disk directories, and more.
