MyServiceAuthorizationManager.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ServiceModel;
using MPRBSL.Helpers;
using WebMatrix.WebData;

namespace MPRBSL.WebServices
{
    public class MyServiceAuthorizationManager : ServiceAuthorizationManager
    {
        protected override bool CheckAccessCore(OperationContext operationContext)
        {
            return WebSecurity.Initialized && WebSecurity.IsAuthenticated && WebSecurity.CurrentUserName == (HttpContext.Current.Session["UserName"] as string);
        }
    }
}