I have the following code snippet to test a plain-text username/password against the AD,

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Asked: May 27, 20262026-05-27T12:26:49+00:00 2026-05-27T12:26:49+00:00

I have the following code snippet to test a plain-text username/password against the AD,

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I have the following code snippet to test a plain-text username/password against the AD, which works fine if I hit F5 in visual studio and try it via the WCFTestClient, but once I deploy to IIS and try the same function, it will never return true for ValidCredentials; is there something security wise that needs to be set for the Identity that the Application Pool runs under?

I tried setting the App Pool identity to my own account (domain admin) just to test if this was the problem, but that didn’t help either, so I’m a bit lost as to how to fix this.

The site (Custom API) has anonymous access set up.

try
{
    // create a "principal context" - e.g. your domain (could be machine, too) 
    using (PrincipalContext pc = new PrincipalContext(ContextType.Domain, DomainName))
    {
        // validate the credentials
        if (pc.ValidateCredentials(UserName, Password))
        {
            IsValid = true;
            break;
        }
    }
}
catch (Exception)
{
    LoggingControler.LogWarning(null, "Unreachable Domain: " + Domain);
}

I’ve gone over things again, and it’s all due to Rights in Windows. Network Service somehow doesn’t have enough rights to execute PrincipalContext.ValidateCredentials. If I change the Application Pool Identity to the identity of a Domain Administrator, the code works.

If someone can tell me how to set up a Limited User account with the proper rights to execute PrincipalContext.ValidateCredentials, I can finish this.