CODEWITHSUNDEEP
c#telnet
C.mac
C.mac

Reputation: 37

Telnet not sending data

I am trying to pass data to a telnet server. I get the initial prompt for login credentials but it won't take the username. I need to pass the username, wait for a password prompt and enter that. Then be able to send and receive data, keeping the socket open at all times.

my code looks like this(its rough as I am trying it in the console first)

try
            {
                client = new TcpClient("10.0.0.94",23);
                Console.WriteLine("Connected to server.");
            }
            catch (SocketException)
            {
                Console.WriteLine("Failed to connect to server");
                return;
            }

            //Assign networkstream
            NetworkStream networkStream = client.GetStream();


            byte[] data = new byte[1024];
            int size = networkStream.Read(data, 0, data.Length);
            recieved = Encoding.ASCII.GetString(data, 0, size);

            Console.WriteLine(recieved);


            if (recieved.Contains("login"))
            {

                string loginrx;
                string cmd = string.Format("{0}\r",user) ;

                byte[] writeBuffer = Encoding.ASCII.GetBytes(cmd);

                networkStream.Write(writeBuffer, 0, writeBuffer.Length);

                byte[] logindata = new byte[1024];
                int loginsize = networkStream.Read(logindata, 0, logindata.Length);
                loginrx = Encoding.ASCII.GetString(logindata, 0, loginsize);

                Console.WriteLine(loginrx);
                Console.ReadLine();

            }

I get the login prompt, but it all stops there.

any help would be great.

Upvotes: 0

Views: 769

Answers (2)

C.mac
C.mac

Reputation: 37

this worked like a charm

 while(Connected == false)
            {
                byte[] data = new byte[1024];
                int size = networkStream.Read(data, 0, data.Length);
                recieved = Encoding.ASCII.GetString(data, 0, size);
                Console.WriteLine(recieved);

                 if (recieved.Contains("login"))
                        {
                             login = string.Format("{0}\r\n",user);
                             Console.WriteLine("user request found:{0}", login);
                        }
                 else if (recieved.Contains("password"))
                 {
                     login = string.Format("{0}\r\n",pass);
                     Console.WriteLine("password request found:{0}", login);
                 }
                 else if (recieved.Contains("GNET"))
                 {
                     Console.WriteLine(recieved);
                     Connected = true;
                 }

                 byte[] loginBuffer = Encoding.ASCII.GetBytes(login);

                 networkStream.Write(loginBuffer, 0, loginBuffer.Length);
                 networkStream.Flush();


            }

Upvotes: 0

Scott Chamberlain
Scott Chamberlain

Reputation: 127543

One Send does not equal once receive. You need some way to tell that you are at the "end of a message" (likely a newline). See Message Framing for some learning materials.

You will need to consult the telnet protocol but likely you need to would need keep reading till you read in a newline before checking the text you got. You may want to use a var sr = new StreamReader(networkStream, Encoding.ASCII) with sr.ReadLine() to read in your strings instead of manually calling networkStream.Read and using Encoding.ASCII.GetString to decode.

Upvotes: 1

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