I keep getting an error on lines 200, 207: Error CS0246: Cannot find type 'NetworkStream'
Code:
Line 1: 
Line 2:   using System;

Line 3:   using System.Web.Services;
Line 4:   using System.Xml.Serialization;
Line 5: using System.Net;
Line 6: using System.Collections;
Line 7:   [WebService(Namespace="http://localhost/MyWebServices/")]
Line 8:   public class FirstService : WebService
Line 9:   {
Line 10:       [WebMethod]
Line 11:       public int Add(int a, int b)
Line 12:       {
Line 13:           return a + b;
Line 14:       }
Line 15: 
Line 16:       [WebMethod]
Line 17:       public String SayHello()
Line 18:       {
Line 19:     try
Line 20:     {
Line 21:         Smtp smtp = new Smtp();
Line 22:         smtp.server = "127.0.0.1";
Line 23:         smtp.from = "yyy@localhost (zzz)";
Line 24:         smtp.subject = "Hello World";
Line 25:         smtp.bodyHtml = "<HTML><BODY>Hello World</BODY></HTML>";
Line 26:         smtp.to.Add("root@localhost");
Line 27:         smtp.Send();
Line 28: 	return("success");
Line 29:     }
Line 30:     catch
Line 31:     {
Line 32: 	return("problem");
Line 33:     }
Line 34:       }
Line 35:   }
Line 36: public class SmtpException : System.Exception
Line 37: {
Line 38:     private string message;
Line 39:     public SmtpException( string str)
Line 40:     {
Line 41:         message = str;
Line 42:     }
Line 43:     public string What()
Line 44:     {
Line 45:         return message;
Line 46:     }
Line 47: };
Line 48: 
Line 49: public class Smtp : System.Net.Sockets.TcpClient
Line 50: {
Line 51:     public string from = null;
Line 52:     public ArrayList to;
Line 53:     public ArrayList cc;
Line 54:     public ArrayList bcc;
Line 55:     public string subject = null;
Line 56:     public string bodyText = null;
Line 57:     public string bodyHtml = null;
Line 58:     public string server = null;
Line 59: public Smtp()
Line 60: {
Line 61:     to = new ArrayList();
Line 62:     cc = new ArrayList();
Line 63:     bcc = new ArrayList();
Line 64: }
Line 65: public void Send()
Line 66: {
Line 67:     string message;
Line 68:     string response;
Line 69: 
Line 70:     Connect( server, 25);
Line 71:     response = Response();
Line 72:     if (response.Substring( 0, 3) != "220")
Line 73:     {
Line 74:         throw new SmtpException( response);
Line 75:     };
Line 76: 
Line 77:     message = "HELO me\r\n";
Line 78:     Write( message);
Line 79:     response = Response();
Line 80:     if (response.Substring( 0, 3) != "250")
Line 81:     {
Line 82:         throw new SmtpException( response);
Line 83:     }
Line 84: 
Line 85:     message = "MAIL FROM:<" + from + ">\r\n";
Line 86:     Write( message);
Line 87:     response = Response();
Line 88:     if (response.Substring( 0, 3) != "250")
Line 89:     {
Line 90:         throw new SmtpException( response);
Line 91:     }
Line 92: 
Line 93:     foreach ( string address in to )
Line 94:     {
Line 95:         try
Line 96:         {
Line 97:             message = "RCPT TO:<" + address + ">\r\n";
Line 98:             Write( message);
Line 99:             response = Response();
Line 100:             if (response.Substring( 0, 3) != "250")
Line 101:             {
Line 102:                 throw new SmtpException( response);
Line 103:             }
Line 104:         }
Line 105:         catch( SmtpException e)
Line 106:         {
Line 107:             System.Console.WriteLine("{ 0}", e.What());
Line 108:         }
Line 109:     }
Line 110: 
Line 111:     foreach ( string address in cc )
Line 112:     {
Line 113:         try
Line 114:         {
Line 115:             message = "RCPT TO:<" + address + ">\r\n";
Line 116:             Write( message);
Line 117:             response = Response();
Line 118:             if (response.Substring( 0, 3) != "250")
Line 119:             {
Line 120:                 throw new SmtpException( response);
Line 121:             }
Line 122:         }
Line 123:         catch( SmtpException e)
Line 124:         {
Line 125:             System.Console.WriteLine("{ 0}", e.What());
Line 126:         }
Line 127:     }
Line 128: 
Line 129:     foreach ( string address in bcc )
Line 130:     {
Line 131:         try
Line 132:         {
Line 133:             message = "RCPT TO:<" + address + ">\r\n";
Line 134:             Write( message);
Line 135:             response = Response();
Line 136:             if (response.Substring( 0, 3) != "250")
Line 137:             {
Line 138:                 throw new SmtpException( response);
Line 139:             }
Line 140:         }
Line 141:         catch( SmtpException e)
Line 142:         {
Line 143:             System.Console.WriteLine("{ 0}", e.What());
Line 144:         }
Line 145:     }
Line 146: 
Line 147:     message = "DATA\r\n";
Line 148:     Write( message);
Line 149:     response = Response();
Line 150:     if (response.Substring( 0, 3) != "354")
Line 151:     {
Line 152:         throw new SmtpException( response);
Line 153:     }
Line 154: 
Line 155:     message = "Subject: " + subject + "\r\n";
Line 156:     foreach ( string address in to )
Line 157:     {
Line 158:         message += "To: " + address + "\r\n";
Line 159:     }
Line 160:     foreach ( string address in cc )
Line 161:     {
Line 162:         message += "Cc: " + address + "\r\n";
Line 163:     }
Line 164: 
Line 165:     message += "From: " + from + "\r\n";
Line 166:     if (bodyHtml.Length > 0)
Line 167:     {
Line 168:         message += "MIME-Version: 1.0\r\n"
Line 169:             +" Content-Type: text/ html;\r\n"
Line 170:             +" charset=\" iso-8859-1\"\r\n";
Line 171:         message += "\r\n" + bodyHtml;
Line 172:     }
Line 173:     else
Line 174:     {
Line 175:         message += "\r\n" + bodyText;
Line 176:     };
Line 177:     message += "\r\n.\r\n";
Line 178:     Write( message);
Line 179:     response = Response();
Line 180:     if (response.Substring( 0, 3) != "250")
Line 181:     {
Line 182:         throw new SmtpException( response);
Line 183:     }
Line 184: 
Line 185:     message = "QUIT\r\n";
Line 186:     Write( message);
Line 187:     response = Response();
Line 188:     if (response.IndexOf(" 221") == -1)
Line 189:     {
Line 190:         throw new SmtpException( response);
Line 191:     }
Line 192: }
Line 193: public void Write( string message)
Line 194: {
Line 195:     System.Text.ASCIIEncoding en = new System.Text.ASCIIEncoding() ;
Line 196: 
Line 197:     byte[] WriteBuffer = new byte[ 1024] ;
Line 198:     WriteBuffer = en. GetBytes( message) ;
Line 199: 
Line 200:     NetworkStream stream = GetStream() ;
Line 201:     stream. Write( WriteBuffer, 0, WriteBuffer. Length);
Line 202: }
Line 203: public string Response()
Line 204: {
Line 205:     System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding();
Line 206:     byte[] serverbuff = new Byte[ 1024];
Line 207:     NetworkStream stream = GetStream();
Line 208:     int count = stream. Read( serverbuff, 0, 1024 );
Line 209:     if (count == 0)
Line 210:         return "";
Line 211: 
Line 212:     return enc. GetString( serverbuff, 0, count );
Line 213: }
Line 214: };