Question

I made this program for a school, and it involves a telnet server. When I run it, it returnes strange characters such as ÿûÿû. Here is the output:

Client connected with the IP /127.0.0.1
Client /127.0.0.1 has entered the username ÿûÿû ÿûÿû'ÿýÿûÿýdcole.

My code:

Socket client = serv.accept();

InetAddress clientip = client.getInetAddress();

out("Client connected with the IP " + clientip);

InputStream clientinput = client.getInputStream();
OutputStream clientoutput = client.getOutputStream();

Scanner in = new Scanner(clientinput);
clientoutput.write("Please enter your username: ".getBytes());

String username = in.nextLine();
out("Client " + clientip + " has entered the username " + username + ".");

String pass = "Please enter the password for " + username + ": ";
clientoutput.write(pass.getBytes());

String password = in.nextLine();

if (username.equals("dcole") && password.equals("test")) {
    clientoutput.write("\r\nCorrect password!".getBytes());
} else {
    clientoutput.write("\r\nIncorrect password!".getBytes());
}

Answer 1

Maybe there is some dirty information in your InputStream from when you created the Socket. Are you able to clean out the data before you ask for the username, such as calling in.nextLine(); and discarding the data, or by calling clientinput.skip(clientinput.available()); Try doing this before asking for the username – ie immediately after creating the Scanner.

As a follow-on, as you are talking to a Telnet server, I would definately encourage you to follow the advise of @StephenC – you should be implementing the correct handshaking and data transmission properties of the Telnet specification rather than simply sending Strings through the Socket.