Generate Let’s Encrypt Wildcard SSL Certificate

STEP 1. Install Let’s Encrypt Certbot Tool

Before you can create free wildcard certificates, you need certbot installed. I’m using an CentOS Server here. To install it, run the following commands:

sudo yum update
sudo yum -y install letsencrypt

STEP 2. Generate Let’s Encrypt Wildcard SSL Certificate

After installing Certbot, you can now start creating certificates.

For wildcard certificates Let’s Encrypt requires verification via DNS. This ensures that you are really authorized to create a certificate for this domain.

So, to create a wildcard certificate for the *.strcpy.com domain, we run the following commands:

sudo certbot certonly --manual --preferred-challenges=dns --email webmaster@avanet.com --server https://acme-v02.api.letsencrypt.org/directory --agree-tos -d strcpy.com -d *.strcpy.com

After completing the above command, it is still necessary to verify the ownership of the domain. For this purpose, it is necessary to create a TXT record on the DNS servers.

After verification, the certificates are generated and can be downloaded from the following path:

/etc/letsencrypt/live/strcpy.com/

Later we need the files cert.pem and privkey.pem. The last one must be renamed from privkey.pem to privkey.key.