How to deploy a wild-card certificate? Steps and Precautions

in today's increasingly important website security protection, SSL certificates have become the standard for every website. However, when enterprises have multiple subdomains, applying and managing certificates one by one is not only time-consuming and labor-intensive, but also increases the risk of certificate expiration and omission. As a digital certificate that can protect the main domain name and all first-level subdomains at the same time, wild-card certificates are being favored by more and more enterprises and developers due to their convenience and cost-effectiveness. This article will explore the whole process of deployment of wild-card certificates in depth, from pre-preparation, specific application to installation and configuration, to follow-up precautions, to provide you with a clear and actionable implementation guide to help you easily implement HTTPS encryption on the whole site, and improve the security level and user trust of the website.

1. What preparation is required before deploying a wild-card certificate

Adequate preparation is key to ensuring a smooth process before officially deploying a wild-card certificate. First, you need to clarify the scope of the certificate, that is, confirm the list of domain names that need to be protected, usually including the primary domain name and all first-level subdomains that need to be encrypted. Second, it is crucial to choose a reputable certificate authority CA, which varies in verification process, price and compatibility. Finally, you also need to be prepared for domain management rights, as subsequent DNS verification or file verification depends on full control of the domain name.

1. Confirm the domain name and server environment

You need to list all the subdomains that need to be protected, and make sure that these domains all point to the same server or the same group of servers. At the same time, record the operating system of the server such as CentOS, Ubuntu and web server software such as Nginx, Apache, IIS, because the certificate configuration method of different environments is slightly different.

2, choose the appropriate authentication method

wild-card certificate usually supports DNS verification and HTTP file verification. DNS verification requires you to add a TXT record at the domain name resolution service provider, which is suitable for users without independent servers. HTTP verification requires placing an authentication file in the root directory of the website, which is suitable for users who have full control over the server. Choose the most convenient way according to your actual conditions.

2. What is the application and verification process for a wild-card certificate

After completing the preparation work, you can enter the application process for a wild-card certificate. The entire application process usually includes four steps: generating a CSR file, submitting the application, completing the verification and downloading the certificate. Among them, the CSR file contains your public key and domain name information, which is the core of the application. The verification process is a key step for the CA to confirm that you have control over the domain name. For a wild-card certificate, DNS verification is the most common way.

1, Generate a certificate signing request CSR

Use the OpenSSL tool to generate a private key and CSR file on the server. When generating a CSR, the generic name CN field must be filled in as an asterisk plus the main domain name, such as * .example.com, do not fill in the specific sub-domain name. Other fields such as organization name, city, etc. can be filled in according to the actual situation.

2, submit the application and complete the DNS verification

Copy the generated CSR content to the CA's application form and select the wild-card certificate type. After submission, the CA will provide a TXT record value for verification. You need to log in to the domain name management background and add a TXT record with the host record as _acme -challenge. The record value is the string provided by the CA. After waiting for the DNS to take effect, click the Verify button to complete the verification.

3. How to install the wild-card certificate on the server

After the verification is passed, the CA will issue the wild-card certificate file, usually including the certificate file, the private key file and the CA intermediate certificate. Upload these files to the server and modify the web server configuration file to complete the deployment. The core of the configuration lies in correctly specifying the path of the certificate and private key, and ensuring that all subdomain HTTPS requests can be responded correctly.

1, Nginx server configuration example

In the Nginx configuration, point the ssl_certificate instruction to the certificate file path, and the ssl_certificate_key instruction to the private key file path. At the same time, it is recommended to turn on the HTTP/2 protocol and HSTS header to improve access speed and security. After the configuration is completed, you need to overload the Nginx service to make the configuration take effect.

2, Apache server configuration points

For the Apache server, you need to use SSLCertificateFile and SSLCertificateKeyFile instructions in the virtual host configuration. In addition, you need to set SSLCertificateChainFile instructions to load CA intermediate certificates to avoid some browser errors. After modifying the configuration, you also need to restart the Apache service.

4. What are the precautions when deploying the wild-card certificate

Although the wild-card certificate is convenient, there are still some details that cannot be ignored in the process of deployment and use. First, the wild-card certificate can only protect the first-level subdomain, and cannot cover the second-level subdomain. For example, * .example.com cannot protect a.b.example.com. Second, the certificate private key must be properly kept. Once leaked, it needs to be revoked and re-issued immediately. Finally, the valid period of the certificate is usually one or two years. Be sure to set an expiration reminder to avoid the expiration of the certificate and make the website inaccessible.

1. Limitations on subdomain coverage

Be sure to make it clear that the coverage of the wild-card certificate is limited to the current level. If your business involves multiple subdomains, you need to consider using multiple certificates or adopting SAN certificates to meet your needs. The hierarchical relationship of all domain names should be sorted out at the early stage of planning.

2, Certificate Renewal and Automation Management

It is recommended to use the ACME protocol with automated tools such as Certbot to manage the application and renewal of wild-card certificates. Automatically add and delete TXT records through the DNS API, which can realize fully automatic renewal and completely eliminate the trouble of manual renewal. Regularly checking the valid period of the certificate and the private key permission is also a necessary operation and maintenance habit.

To sum up, the deployment of wild-card certificates is a system engineering involving preparation, application, configuration and operation and maintenance. With the step-by-step guide in this article, you can efficiently enable HTTPS encryption for all subdomains, and significantly improve the security and management efficiency of the website. The key is to sort out the domain name and environment in the early stage, complete the verification accurately when applying, pay attention to the details when configuring, and pay attention to the coverage limit and automatic renewal management of the certificate. By mastering these points, you can easily control the wild-card certificate and build a strong security line for the digital business of the enterprise.