校园网自动出校软件---校园网登入器

Question

校园网每次出校访问外网都要在login填写表单，包括用户名和密码。设计软件能够自动出校。应该有人做过类似的，请介绍下基本原理，并附上核心代码。谢谢。
网上有段代码，请帮忙分析下，谢谢：
  WebRequest webRequest = WebRequest.Create(@"http://10.188.0.43/a01.htm");
                try
                {
                    if (((args.Length == 0 && username == "" && password == "")||i!="2")&&args.Length!=3)
                    {
                        Console.WriteLine("请输入校园网用户名，并按回车");
                        username = Console.ReadLine();
                        Console.WriteLine("请输入校园网密码，并按回车");
                        password = Console.ReadLine();
                    }
                    else if (username == "" && password == "")
                    {
                        username = args[0];
                        password = args[1];
                    }
                    
                }
                catch (Exception e)
                {
                    Console.WriteLine("用户名密码获取出错");
                    //ch = Console.Read();
                }
                Stream os = null;
                try
                {
                    Console.WriteLine("开始连接");
                    //webRequest = WebRequest.Create(@"http://10.188.0.43/a01.htm");
                    webRequest.ContentType = "application/x-www-form-urlencoded";
                    webRequest.Method = "POST";
                    byte[] bytes = Encoding.ASCII.GetBytes("DDDDD=" + username + "&upass=" + password + "&0MKKey=%B5%C7%C2%BC+Login");
                    webRequest.ContentLength = bytes.Length;   //Count bytes to send
                    os = webRequest.GetRequestStream();
                    os.Write(bytes, 0, bytes.Length);    //Send it
                    Console.WriteLine("正在连接...");
                }
                catch (Exception e2)
                {
                    Console.WriteLine(e2.Message);
                    //ch = Console.Read();
                }
                finally
                {
                    if (os != null)
                    {
                        os.Close();
                    }
                }
                try
                { // get the response
                    WebResponse webResponse = webRequest.GetResponse();
                    if (webResponse == null)
                    {
                        Console.WriteLine("服务器没有返回信息");
                    }
                    else
                    {
                        StreamReader sr = new StreamReader(webResponse.GetResponseStream(), Encoding.Default);
                        string response = sr.ReadToEnd();