Installing a GoDaddy certificate on your Fortigate is fairly straight forward. Perform the following steps:
1) Log into the Forgitate. On the main dashboard, under ‘Features’, be sure to enable the ‘Certificates’ option. It will then display in the left sidebar.
2) Go to System > Certificates > Local Certificates.
3) Click Generate. Fill in the fields:
Certificate Name: vpn.domain.com
ID Type: Domain Name
Domain Name: vpn.domain.com
Key Type: RSA
Key Size: 2048
Enrollment Method: File Based
4) Click OK.
5) Highlight the newly created entry in Local Certificates and download it. Open with notepad to grab the CSR. Use this CSR to request your certificate with GoDaddy.
6) Once GoDaddy has issued the certificates, download the IIS package from GoDaddy. Return to the Local Certificates section of the Fortigate, and select ‘Import’, selecting the newly downloaded GoDaddy certificate.