How to detect if ASP.NET is enabled in IIS 7

Question

The challenge is to determine whether ASP.NET is enabled within IIS7 in a reliable and correct way.

Enabling/Disabling is done in this case by going into:

Server Manager -> 
    Roles -> 
        Web Server (IIS) -> 
            Remove Role Services -> 
                Remove ASP.NET

The natural place to determine this should be within the applicationHost.config file. However, with ASP.NET enabled or disabled, we still have the "ManagedEngine" module available, and we still have the isapi filter record in the tag.

The best I can find at the moment is to check if the <isapiCgiRestriction> tag includes the aspnet_isapi.dll, or that the ASPNET trace provider is available.

However these aren't detecting the presence of the ASP.NET config directly, just a side effect that could conceivably be reconfigured by the user.

I'd rather do this by examining the IIS configuration/setup rather than the OS itself, if possible, although enumerating the Roles & Services on the server might be acceptable if we can guarantee that this technique will always work whenever IIS7 is used.

Update

Thanks for the responses. Clarifying exactly what I want to do, I'm pulling settings from a variety of places in the server's configuration into a single (readonly) view to show what the user needs to have configured to allow the software to work.

One of the settings I need to bring in is this one:

The one highlighted in red.

I don't need to manipulate the setting, just reproduce it. I want to see whether the user checked the ASP.NET box when they added the IIS role to the server, as in this example they clearly didn't.

I'd like to do this by looking at something reliable in IIS rather than enumerating the role services because I don't want to add any platform specific dependencies on the check that I don't need. I don't know if it will ever be possible to install IIS7 on a server that doesn't have the Roles/Services infrastructure, but in preference, I'd rather not worry about it. I also have a load of libraries for scrubbing around IIS already.

However, I'm also having trouble finding out how to enumerate the Roles/Services at all, so if there's a solution that involves doing that, it would certainly be useful, and much better than checking the side effect of having the ASPNET trace provider lying around.

Unfortunately, if you don't check the ASP.NET button, you can still get the ManagedEngine module in the IIS applicationHost.config file, so it's not a reliable check. You can also have ASP.NET mapped as an isapi filter, so checking them isn't enough. These things are especially problematic in the case where ASP.NET was installed but has been removed.

It looks like the best solution would be to examine the Role Services. However, API information on this is looking pretty rare, hence the cry for help.

Answer 1

The absolute way to know if they checked that or not is to search the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\InetStp\Components

In there you should see two values set to 1, ASPNET and NetFxEnvironment and NetFxExtensibility. This registry key is the IIS Setup key that contains all the components that have been enabled in IIS.

Answer 2

Determining if asp.net is even an installed feature (prerequisite for enabling it) can be done through PowerShell, which implies there is .net api out there for it if you dig hard enough. The PowerShell methods:

Import-Module servermanager
Get-WindowsFeature web-asp-net

Which will return an object of type Microsoft.Windows.ServerManager.Commands.Feature. The installed property is boolean and indicates whether or not the feature is installed.