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Prerequisites for Using an Arbitrary Mechanism on the Web Server 
To be able to use an arbitrary authentication mechanism that sets the user information in HTTP header variables, your system must meet the following requirements:

Because the user authentication takes places on the Web server, we also recommend using SNC for the connection between the WGate and the AGate if the ITS installation is a dual host installation.
We also recommend using SNC for the connections to systems that accept logon tickets.
Each Web server has pre-defined HTTP header variables that it uses for various purposes. For example, the Microsoft Internet Information Server (IIS) and the Apache Web server use the header variable