WCF - Preventing Unauthorized Clients

Question

Hello,

I have a WCF service that I only want my applications to have access to. My applications consist of a traditional web interface that uses JQuery and a Silverlight interface. Neither of these interfaces require the user to login.

Is there a way that I can tell a WCF service to only allow clients that originated from my domain? If so, how?

Thank you!

Answer 1

You could add a security restriction in IIS to only allow calls from the domain to the webservice.

Answer 2

Unless you consider windows auth (since requests are coming from your domain), the preferred way to do this would be at a different level, via firewalls. At that level, you can restrict incoming traffic to a known set of IP addresses. This will only go so far, since IPs can be spoofed, but this is an open service, so there you go. A better alternative would be both firewalls and windows auth.

Alternatively, you could check client IP addresses in WCF by querying OperationContext.Current.IncomingMessageProperties.

Answer 3

Yes, of course you can - just require Windows credentials (i.e. an Active Directory account in your domain) from your callers.

Anyone not authenticated against your domain will be rejected.

You can do this by specifying either netTcpBinding with transport security (if everything is behind a corporate firewall), or wsHttpBinding with message security:

<bindings>
   <netTcpBinding>
      <binding name="DomainUsersOnly">
         <security mode="Transport">
            <transport clientCredentialType="Windows" />
         </security>
      </binding>
   </netTcpBinding>
   <wsHttpBinding>
      <binding name="HttpDomainUsersOnly">
         <security mode="Message">
            <message clientCredentialType="Windows" />
         </security>
      </binding>
   </wsHttpBinding>
</bindings>

Now, all you need to do is reference one of those binding configurations in your endpoints:

<endpoint name="whatever"
          address="......"
          binding="netTcpBinding"
          bindingConfiguration="DomainUsersOnly"
          contract="IYourservice" />

and you should be good to go.

Answer 4

If all of your legitimate users are supposed to be on your internal corporate LAN (on the same subnet), then you could lock it down by IP address using an approach like this. You could also clamp it down to several specific IP masks that way if you wanted to.

But if you want to allow legitimate users to hit it from anywhere, then this is not a good approach. Authentication would be better in that case.