How to Install a Free SSL Certificate on IIS With Win-ACME

What are IIS and Win-ACME?

IIS is the web server program that comes with Windows Server. It shows your websites to visitors. An SSL certificate is a file that puts a padlock on your site and scrambles the data.

Win-ACME is a free, third-party tool. It talks to Let's Encrypt, a service that gives free certificates. Win-ACME gets the certificate, installs it in IIS, and renews it for you. Ask Hostvento support whether you may use it on your plan.

Before you start

Your domain must point to your server.
Your site must be set up in IIS with a binding for your domain on port 80. A binding links a domain name to a site.
Port 80 must be open in the firewall, because Let's Encrypt checks your site over it.

Steps

Log in to the server with Remote Desktop.
Download the Win-ACME zip from the official Win-ACME site.
Right-click the zip and choose Extract All. Put it in a folder such as C:\win-acme.
Right-click wacs.exe and choose Run as administrator.
Press N to create a certificate with default settings.
Choose to pick from a list of IIS bindings. Press the key shown for that choice.
Select your site from the list.
Choose to create a certificate for all bindings, or only the one you pick.
Accept the terms of service when asked.
Enter your email address when asked. Let's Encrypt uses it for notices.
Wait for Win-ACME to finish. It checks your domain, gets the certificate and adds an https binding in IIS.
Open your site with https:// in a browser and check the padlock.

Renewals

Free certificates last a short time. Win-ACME makes a scheduled task in Windows that renews it for you. You can check it in Task Scheduler.

Tip: If it fails, check that your domain points to this server and that port 80 is open. Read the log files in the Win-ACME folder.

Quick recap

Win-ACME gets free certificates for IIS.
Run wacs.exe as administrator and follow the menu.
Your domain and port 80 must be reachable.
Renewal happens automatically through a scheduled task.