Generate CSR via CLI when Subject Alternative Name field is long (FortiOS 5.0)
In FortiOS 5, Certificate Signing Requests (CSRs) can include multiple Subject Alternative Names.
In the GUI, the Subject Alternative Name (SAN) text field does allows multiple items to be entered(comma delimited), the text field itself has a 60 character limit.
Considering that each SAN entered also needs an Identifier, this limit can be easily hit in just a name or two.
This article explains how to generate a CSR in the FortiGate CLI instead in order to overcome this limit.
Solution
To get around this limitation when needed, you can use the 'execute vpn certificate [store] generate [...]' CLI command. This command is run from Global when VDOMs are in use.
Command Syntax
execute vpn certificate [store] generate [cert_name] [key_size] [CN] [Country] [State/Province] [City] [OU] [email] [SANs - optional]
Command Options
store: ca, crl, local, remote
cert_name: Name for Certificate, purely meant as an identifier
key_Size: Key Encyrption Size, Options are 1024, 1536, and 2048
CN: Common Name, the name the certificate is signed for
Country: Country name or Country Code
State/Province: State or Province Name
City: City Name
OU: Organizational Unit, similar to Directories in a Directory Service
email: Email address for IT Contact
SANS: Other accepted names, should include CN if CN is to be accepted
SAN Syntax
Email: email:admin@companyname.com
IP Address: IP:1.1.1.1
URL: URI:http://companyname.com
DNS Name: DNS:www.companyname.com
Example
execute vpn certificate local generate test_cert 2048 companyname.com CA Ontario Ottawa IT,Certificates admin@companyname.com DNS:companyname.com,DNS:www.companyname.com,DNS:vpn.companyname.com
Certificate Name: test_cert
Key Size: 2048
CN: companyname.com
Country: CA (Canada)
State/Province: Ontario
City: Ottawa
OU: [root] > IT > Certificates
Email: jason@jason.com
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Technical Note: FortiGate - Generate CSR via CLI when Subject Alternative Name field is long