[RADIATOR] Certificate Not Trusted - InCommon?

Heikki Vatiainen hvn at open.com.au
Wed Jun 2 16:26:36 UTC 2021

On 2.6.2021 18.42, Ullfig, Roberto Alfredo wrote:

> Also this document:
> https://docs.microsoft.com/en-us/troubleshoot/windows-server/networking/certificate-requirements-eap-tls-peap 
> "For wireless clients, the Subject Alternative Name (SubjectAltName) 
> extension contains the server's fully qualified domain name (FQDN)."
> What is this referring to? Does the SAN for our cert need to match 
> anything, like the server radiator is running on, etc....

When profiles are provisioned AD policies or other tools, they set the 
WLAN name, expected CA certificates and the expected name in the RADIUS 
server's certificate (and possible other information). It seems the name 
in a profile is expected to be in SAN when TLS based EAP authentication 
is done.

With HTTPS the browser knows from the URL the expected name of the web 
server and the certificate name validation is based on that. With, for 
example PEAP, the name is part of the profile settings, or manual 
configuration. The client knows from its configuration settings this 
configuration and that's what the SAN of your cert needs to match.

There's no need for the SAN to match the name of the server Radiator 
runs on. If you have multiple Radius servers for redundancy purposes, 
the can use the same certificate or different certificates. In the 
latter case, the profile or other configuration must know about the both 
names or otherwise the client devices will start prompting about uknown 
or untrusted certificate.

Getting back to Trust-On-First-Use (TOFU), if you have a profile, then 
there should be no TOFU triggered prompts because the trust settings are 
already defined.


Heikki Vatiainen <hvn at open.com.au>

Radiator: the most portable, flexible and configurable RADIUS server
anywhere. SQL, proxy, DBM, files, LDAP, TACACS+, PAM, Active Directory,
DIAMETER etc. Full source on Unix, Windows, MacOSX, Solaris, VMS, etc.

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