SAML configuration for Internet site with multiple hostnames

When you configure a SAML for an internet site shared by multiple sites, the SAML authentication leads to a redirect to the first server in the configuration as the response url is always pointing to that server.

We tried to set it up with AAD. The config was the following:

Domino:

• Internet site (+associated rules)

  • mapped to:

    • webapp1.example.com

    • webapp2.example.com

• IdPcat config:

  • mapped host:

    • webapp1.example.com

    • webapp2.example.com

• AzureAD Enterprise app:

  • Entity ID:

    • https://webapp1.example.com

    • https://webapp2.example.com

  • Reply URL:

    • https://webapp1.example.com/names.nsf?SAMLLogin

    • https://webapp2.example.com/names.nsf?SAMLLogin

(servers are clustered, certificates shared,SAML is working).

Everything is working OK, except for the fact that when webapp2.example.com is accessed and the user is authenticated, he is being redirected to webapp1.example.com , because the reply url in the SAML request is computed, probably, based on service provider id or the first host name.

I see potential solutions:

1. Compute the reply url based on the current host name (preferred)

2. Allow mapping of multiple IdP config to a internet site

   1. now, when the first match is done, it's used for all requests, so even if I separate IdP configs for webapp1 and webapp2, only webapp1 is loaded, so I must separate the internet sites too

   2. this would mean that for federationmetadata.xml update, multiple documents would have to be updated even if the file is the same

I had a case opened CS0391137, but we did not find a solution.