What IP Addresses Will the Let’s Encrypt Servers Use to Validate My Web Server?


Scott Campbell

What IP Addresses Will the Let’s Encrypt Servers Use to Validate My Web Server?

If you are using Let’s Encrypt for your website’s SSL certificate, you may wonder what IP addresses the Let’s Encrypt servers will use to validate your web server. This information is important if you have firewall rules or other security measures in place that restrict incoming traffic based on IP addresses.

Understanding Let’s Encrypt Validation

Before we dive into the IP addresses used by Let’s Encrypt for validation, let’s briefly understand how the validation process works. When you request an SSL certificate from Let’s Encrypt, they need to verify that you have control over the domain(s) for which you are requesting the certificate.

To achieve this, Let’s Encrypt uses a domain validation method called ACME (Automated Certificate Management Environment). ACME requires you to prove ownership of the domain by responding to a specific challenge provided by the Let’s Encrypt server.

The IP Addresses Used by Let’s Encrypt Servers

Let’s Encrypt uses multiple validation servers distributed globally to ensure quick and reliable verification. The IP addresses used by these servers can change over time as Let’s Encrypt continues to scale their infrastructure and add more servers.

To obtain an up-to-date list of IP addresses used for validation, you can refer to the official documentation provided by Let’s Encrypt.

Best Practices for Firewall Rules

If you need to allow incoming traffic from Let’s Encrypt servers for domain validation purposes, it is recommended to use DNS-based firewall rules instead of relying solely on specific IP addresses. This approach ensures that your firewall rules are always up-to-date, even if Let’s Encrypt changes their validation server IP addresses.

However, if you prefer to use IP-based firewall rules, it’s crucial to regularly check the official Let’s Encrypt documentation for any changes in the IP address ranges used for validation.

Additional Considerations

It’s worth noting that Let’s Encrypt may also perform validation through outbound connections from their servers to your web server. This means that your web server should allow incoming traffic on port 80 (HTTP) or port 443 (HTTPS) from any IP address. Restricting access to specific IP addresses may result in failed domain validation.

In Summary

Let’s Encrypt uses multiple validation servers with dynamically changing IP addresses. To ensure a smooth domain validation process, it is recommended to use DNS-based firewall rules or regularly update your IP-based firewall rules according to the information provided by Let’s Encrypt. Additionally, allowing inbound traffic on ports 80 and 443 from any IP address is essential for successful domain validation.

Keep in mind that staying informed about updates and following best practices will help you maintain a secure and reliable SSL certificate setup with Let’s Encrypt.

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