diff --git a/shadowsocks-csharp/Config.cs b/shadowsocks-csharp/Config.cs
new file mode 100755
index 00000000..3800e832
--- /dev/null
+++ b/shadowsocks-csharp/Config.cs
@@ -0,0 +1,56 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.Serialization.Json;
+using System.Text;
+using System.IO;
+
+namespace shadowsocks_csharp
+{
+    [Serializable]
+    public class Config
+    {
+        public string server;
+        public int server_port;
+        public int local_port;
+        public string password;
+
+        public static Config Load()
+        {
+            DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(Config));
+            try
+            {
+                using (FileStream fs = File.OpenRead(@"config.json"))
+                {
+                    Config config = ser.ReadObject(fs) as Config;
+                    return config;
+                }
+            }
+            catch (IOException e)
+            {
+                return new Config
+                {
+                    server = "127.0.0.1",
+                    server_port = 8388,
+                    local_port = 1080,
+                    password = "foobar!"
+                };
+            }
+        }
+
+        public static void Save(Config config)
+        {
+            DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(Config));
+            try
+            {
+                using (FileStream fs = File.Open(@"config.json",FileMode.Create))
+                {
+                    ser.WriteObject(fs, config);
+                }
+            }
+            catch (IOException e)
+            {
+                Console.Error.WriteLine(e);
+            }
+        }
+    }
+}
diff --git a/shadowsocks-csharp/Encryptor.cs b/shadowsocks-csharp/Encryptor.cs
index c40d9212..d998cda8 100755
--- a/shadowsocks-csharp/Encryptor.cs
+++ b/shadowsocks-csharp/Encryptor.cs
@@ -10,11 +10,12 @@ namespace shadowsocks_csharp
         public byte[] encryptTable = new byte[256];
         public byte[] decryptTable = new byte[256];
 
-        private Int64 compare(byte x, byte y, UInt64 a, int i) {
-            return (Int64)(a % (UInt64)(x + i)) - (Int64)(a % (UInt64)(y + i));
+        private long compare(byte x, byte y, ulong a, int i)
+        {
+            return (long)(a % (ulong)(x + i)) - (long)(a % (ulong)(y + i));
         }
 
-        private byte[] mergeSort(byte[] array, UInt64 a, int j)
+        private byte[] mergeSort(byte[] array, ulong a, int j)
         {
             if (array.Length == 1)
                 return array;
diff --git a/shadowsocks-csharp/Local.cs b/shadowsocks-csharp/Local.cs
index cfe95ae9..66ad8184 100755
--- a/shadowsocks-csharp/Local.cs
+++ b/shadowsocks-csharp/Local.cs
@@ -13,6 +13,7 @@ namespace shadowsocks_csharp
     {
         private int port;
         private Encryptor encryptor;
+        Socket listener;
         public Local(int port)
         {
             this.port = port;
@@ -23,7 +24,7 @@ namespace shadowsocks_csharp
         {
 
             // Create a TCP/IP socket.
-            Socket listener = new Socket(AddressFamily.InterNetwork,
+            listener = new Socket(AddressFamily.InterNetwork,
                 SocketType.Stream, ProtocolType.Tcp);
             IPEndPoint localEndPoint = new IPEndPoint(0, port);
 
@@ -40,6 +41,11 @@ namespace shadowsocks_csharp
 
         }
 
+        public void Stop()
+        {
+            listener.Close();
+        }
+
 
         public void AcceptCallback(IAsyncResult ar)
         {
diff --git a/shadowsocks-csharp/Program.cs b/shadowsocks-csharp/Program.cs
index c3f34158..417442a6 100755
--- a/shadowsocks-csharp/Program.cs
+++ b/shadowsocks-csharp/Program.cs
@@ -12,10 +12,12 @@ namespace shadowsocks_csharp
         [STAThread]
         static void Main()
         {
-            new Local(1081).Start();
+            Local local = new Local(1081);
+            local.Start();
             Application.EnableVisualStyles();
             Application.SetCompatibleTextRenderingDefault(false);
             Application.Run(new Form1());
+            local.Stop();
         }
     }
 }
diff --git a/shadowsocks-csharp/shadowsocks-csharp.csproj b/shadowsocks-csharp/shadowsocks-csharp.csproj
index e20d1ebf..349a69cb 100755
--- a/shadowsocks-csharp/shadowsocks-csharp.csproj
+++ b/shadowsocks-csharp/shadowsocks-csharp.csproj
@@ -10,7 +10,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>shadowsocks_csharp</RootNamespace>
     <AssemblyName>shadowsocks-csharp</AssemblyName>
-    <TargetFrameworkVersion>v2.0</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v3.5</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <StartupObject>
     </StartupObject>
@@ -35,13 +35,23 @@
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
+    <Reference Include="System.Core">
+      <RequiredTargetFramework>3.5</RequiredTargetFramework>
+    </Reference>
     <Reference Include="System.Data" />
     <Reference Include="System.Deployment" />
     <Reference Include="System.Drawing" />
+    <Reference Include="System.Runtime.Serialization">
+      <RequiredTargetFramework>3.0</RequiredTargetFramework>
+    </Reference>
+    <Reference Include="System.ServiceModel.Web">
+      <RequiredTargetFramework>3.5</RequiredTargetFramework>
+    </Reference>
     <Reference Include="System.Windows.Forms" />
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Config.cs" />
     <Compile Include="Encryptor.cs" />
     <Compile Include="Form1.cs">
       <SubType>Form</SubType>
@@ -54,6 +64,7 @@
     <Compile Include="Properties\AssemblyInfo.cs" />
     <EmbeddedResource Include="Form1.resx">
       <DependentUpon>Form1.cs</DependentUpon>
+      <SubType>Designer</SubType>
     </EmbeddedResource>
     <EmbeddedResource Include="Properties\Resources.resx">
       <Generator>ResXFileCodeGenerator</Generator>