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Implement windows authentication and
security in WCF Service
This is continuation with previous post on “Security in WCF -I”.
Here I’ll explain how we can implement windows authentication with transport level security in
intranet environment.
Windows authentication
In intranet environment, client and service are .Net application.Windows authentication is most
suitable authentication type in intranet where client credentials stored in windows accounts &
groups. Intranet environment address a wide range of business applications. Developers have
more controlled in this environment.
For Intranet, you can use netTcpBinding,NetNamedPipeBinding and NetMsmqBinding for
secure and fast communication.
Windows credential is default credential type and transport security is default security mode for
these bindings.
Protection Level
You can set Transport Security protection level through WCF:
 None: WCF doesn’t protect message transfer from client to service.
 Signed: WCF ensures that message have come only from authenticated caller. WCF
checks validity of message by checking Checksum at service side. It provides
authenticity of message.
 Encrypted & Signed: Message is signed as well as encrypted. It provides integrity,
privacy and authenticity of message.
Configuration in WCF Service for Windows Authentication
Service is hosted on netTcpBinding with credential type windows and protection level as
EncryptedAndSigned.
var tcpbinding = new NetTcpBinding(SecurityMode.Transport);
//Client credential will be used of windows user
tcpbinding.Security.Transport.ClientCredentialType =
TcpClientCredentialType.Windows;
// When configured for EncryptAndSign protection level, WCF both signs
the message and encrypts
//its content. The Encrypted and Signed protection level provides
integrity,
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//privacy, and authenticity.
tcpbinding.Security.Transport.ProtectionLevel =
System.Net.Security.ProtectionLevel.EncryptAndSign;
Client credential type can be set by TcpClientCredentialType enum.
public enum TcpClientCredentialType
{
None,
Windows,
Certificate
}
Protection level can be set by ProtectionLevel enum.
// Summary:
// Indicates the security services requested for an authenticated
stream.
public enum ProtectionLevel
{
// Summary:
// Authentication only.
None = 0,
//
// Summary:
// Sign data to help ensure the integrity of transmitted data.
Sign = 1,
//
// Summary:
// Encrypt and sign data to help ensure the confidentiality and
integrity of
// transmitted data.
EncryptAndSign = 2,
}
WCF Service Code
Service Host
class Program
{
static void Main(string[] args)
{
Uri baseAddress = new Uri("http://localhost:8045/MarketService");
using (var productHost = new ServiceHost(typeof(MarketDataProvider)))
{
var tcpbinding = new NetTcpBinding(SecurityMode.Transport);
//Client credential will be used of windows user
tcpbinding.Security.Transport.ClientCredentialType =
TcpClientCredentialType.Windows;
// When configured for EncryptAndSign protection level, WCF both signs the
message and encrypts
//its content. The Encrypted and Signed protection level provides integrity,
//privacy, and authenticity.
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tcpbinding.Security.Transport.ProtectionLevel =
System.Net.Security.ProtectionLevel.EncryptAndSign;
ServiceEndpoint productEndpoint = productHost.
AddServiceEndpoint(typeof(IMarketDataProvider), tcpbinding,
"net.tcp://localhost:8000/MarketService");
ServiceEndpoint producthttpEndpoint = productHost.AddServiceEndpoint(
typeof(IMarketDataProvider), new BasicHttpBinding(),
"http://localhost:8045/MarketService");
productHost.Open();
Console.WriteLine("The Market service is running and is listening on:");
Console.WriteLine("{0} ({1})",
productEndpoint.Address.ToString(),
productEndpoint.Binding.Name);
Console.WriteLine("{0} ({1})",
producthttpEndpoint.Address.ToString(),
producthttpEndpoint.Binding.Name);
Console.WriteLine("nPress any key to stop the service.");
Console.ReadKey();
}
}
}
Alternatively, you can configure the binding using a config file:
<bindings>
<netTcpBinding>
<binding name = "TCPWindowsSecurity">
<security mode = "Transport">
<transport
clientCredentialType = "Windows"
protectionLevel = "EncryptAndSign"
/>
</security>
</binding>
</netTcpBinding>
</bindings>
Run WCF Service
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Client Application
static void Main(string[] args)
{
try
{
Console.WriteLine("Connecting to Service..");
var proxy = new ServiceClient(new NetTcpBinding(),
new EndpointAddress("net.tcp://localhost:8000/MarketService"));
Console.WriteLine("MSFT Price:{0}", proxy.GetMarketPrice("MSFT.NSE"));
Console.WriteLine("Getting price for Google");
double price = proxy.GetMarketPrice("GOOG.NASDAQ");
}
catch (FaultException ex)
{
Console.WriteLine("Service Error:" + ex.Detail.ValidationError);
}
catch (Exception ex)
{
Console.WriteLine("Service Error:" + ex.Message);
}
Console.ReadLine();
}
ServiceClient is custom class which inherits ClientBase<T> class in System.ServiceModel
namespace to create channels and communication with service on endpoints.
public class ServiceClient : ClientBase, IMarketDataProvider
{
public ServiceClient() { }
public ServiceClient(string endpointConfigurationName) :
base(endpointConfigurationName) { }
public ServiceClient(string endpointConfigurationName, string
remoteAddress) :
base(endpointConfigurationName, remoteAddress) { }
public ServiceClient(string endpointConfigurationName,
System.ServiceModel.EndpointAddress remoteAddress) :
base(endpointConfigurationName, remoteAddress)
{ }
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public ServiceClient(System.ServiceModel.Channels.Binding binding,
System.ServiceModel.EndpointAddress remoteAddress) :
base(binding, remoteAddress)
{}
///
/// IMarketDataProvider method
///
///
///
public double GetMarketPrice(string symbol)
{
return base.Channel.GetMarketPrice(symbol);
}
}
Verify User credentials in Service
You can see caller information in WCF service by ServiceSecurityContext class. Every operation
on a secured WCF service has a security call context. The security call context is represented by
the class ServiceSecurityContext.The main use for the security call context is for custom security
mechanisms, as well as analysis and auditing.
ServiceSecurityContext.Current in Quickwatch window.
Send Alternate Windows credentials to Service
WCF also give option to send alternate windows credential from client. By default it send logged
in user credential. You can send alternate credential like below
proxy.ClientCredentials.Windows.ClientCredential.Domain = "mydomain";
proxy.ClientCredentials.Windows.ClientCredential.UserName = "ABC";
proxy.ClientCredentials.Windows.ClientCredential.Password = "pwd";
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Now If I run client application with changed credentials, if credentials are of valid windows user,
service will authenticate caller else it will reject caller request. In my case I deliberately gives
wrong credential to produce reject exception.
Service sends “System.Security.Authentication.InvalidCredentialException with message "The
server has rejected the client credentials.”
I hope you understood windows authentication concept here. If you have any question please feel
free to send me comments.
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