Prevent Copy Paste Url In Asp.net

-------Write Code in Master Page-----------

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

public partial class Admin : System.Web.UI.MasterPage

{

    protected void Page_Load(object sender, EventArgs e)

    {

        if (!Request.FilePath.Contains("Default"))

        {

            string strPreviousPage = "";

            if (Request.UrlReferrer != null)

            {

                strPreviousPage = Request.UrlReferrer.Segments[Request.UrlReferrer.Segments.Length - 1];

            }

            if (strPreviousPage == "")

            {

                Response.Redirect("Default.aspx");

            }

        }

    }

}