Setting up SSRS server with alternative to anonymous authentication

I am trying to set up a VM with SSRS report server. The SSRS reports on the report server has to be accessible from an iframe on another web site / server.

When I'm accessing the report server URL on an external computer browser I have to enter credentials for the VM user. On the following link it says that anonymous authentication is unsupported: https://technet.microsoft.com/en-us/library/cc281310(v=sql.105).aspx

The only solution I have at the moment is to enter the credentials in the URL like "http:userLogin:userPassword@myDomain.com/ReportServer". However this solution exposes my VM user in the iframe code.

How do I set up my SSRS server so I can access the SSRS reports from any computer's browser without having to enter VM credentials? Is there an alternate solution to anonymous authentication in this scenario?

Thanks in advance

You can provide a custom auth extension for SSRS that handles security. And while these are a bit complex, a custom auth extension that enables anonoymous access is trivial.

See https://learn.microsoft.com/en-us/sql/reporting-services/security/authentication-with-the-report-server

and the SSRS 2016 sample here: https://github.com/Microsoft/Reporting-Services/tree/master/CustomSecuritySample2016

You can also proxy traffic to SSRS using your own HTTP handlers or perhaps IIS ARR. If doing by hand you would configure SSRS to use HTTP Basic auth and add the basic auth header when you make the HTTP request from your application.