fix #235

shadowsocks-csharp/Model/Configuration.cs

@@ -121,6 +121,11 @@ namespace Shadowsocks.Model
             {
                 throw new ArgumentException(I18N.GetString("Port out of range"));
             }
+        }
+
+        public static void CheckLocalPort(int port)
+        {
+            CheckPort(port);
             if (port == 8123)
             {
                 throw new ArgumentException(I18N.GetString("Port can't be 8123"));

shadowsocks-csharp/View/ConfigForm.cs

@@ -84,7 +84,7 @@ namespace Shadowsocks.View
                 };
                 int localPort = int.Parse(ProxyPortTextBox.Text);
                 Configuration.CheckServer(server);
-                Configuration.CheckPort(localPort);
+                Configuration.CheckLocalPort(localPort);
                 _modifiedConfiguration.configs[_oldSelectedIndex] = server;
                 _modifiedConfiguration.localPort = localPort;