Let's encrypt provide free and easy SSL certificates. Nevertheless it need to verify that you own the machine. In order to do that we usually use HTTP verification with the .well-known directory.

But sometime our servers are not reachable from the internet. Therefore the HTTP validation is not possible. Hopefully there is another way the acme challenge can be validated: DNS validation.

In this post we will see how we can generate Let's encrypt SSL certificate for offline machine with DNS validation for domains hosts by OVH.