Windows Azure supports federation and integration with Windows Server Active Directory. This information is not new. I observe that people tend to use services that don’t understand. The scope of this blog post is to explain how an end user login into Windows Azure Portal using federation mechanism.
Let’s assume that our company has already configured the integration of the private Active Directory with the federation mechanism. From our internal network a user wants to access the Windows Azure company portal (each company can define their own portal where users and subscriptions can be managed).
First thing that is done is made automatically when the user login into the computer and network with the credentials. In this moment the Active Directory server from our network is used to check the user credentials. There can be different ways of authentication from user/password to RSA SecureID, smartcard and so on. The company IT can configure different ways of authentication that will be recorded on the token (ticket) that is generated at this step.
When the user authenticate with success, the AD server will generate a token called Kerberos Ticket Granting Ticket (KTGT) that is valid for a specific time interval. The validation period is configurable by the company IT.
In the moment when a user wants to access the Windows Azure Portal of the company, the user will be redirected to the Windows Azure Active Directory where the company domain name will be added to the request. Based on the domain name, Windows Azure Active Directory will know what is the address of Active Directory Federation Service (ADFS) – from our on-premise network. This service needs to be exposed over internet through a public endpoint.
After this step, all the verification process will be on the client private network. The ADFS server will contact the client PC. In this step the KTGT ticket that was generated in the moment when user authenticates in the network is used to check the user. Based on this ticket the Ticket Granting Server (KDS) is contact to generate a Service Ticket (KST). The generated KST ticket is used by the client computer to authenticate to ADFS. During this last step the token is generated. This token is sight using Security Assertion Markup Language (SAML).
This is the last token that is generated and used. The user is redirected automatically to the Windows Azure Active Directory where the SAML token is attached. This is a POST request that contains all the information needed for the final steps (no credentials will be send from the client private network) to Windows Azure Active Directory. From this moment Windows Azure Active Directory will trust the user and will give access to the Windows Azure company portal.
Based on this token the Windows Azure Active Directory will be able to generate an identity token that is signed by Windows Azure Active Directory. This encrypted token contains the identity claims of the user. As in the previous step, this token is send through a POST to Windows Azure Portal.
With this encrypted token, Windows Azure Portal can extract the user identity and use to display all the related information and of course trust the user.
It is important to know, that IT team of the company can configure further authentications steps in the moment when KDS is generated. For example an authentication step that includes a RSA Security ID or a smart card can be requested.
And we are done. This is the authentication mechanism on Windows Azure Portal of a company that used the Federation. Implementing this mechanism is pretty simple and Windows Azure Portal can automatic generate the scripts required by IT to configure the system.
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