How do I send telnet option codes?

Question

I've written a socket listener in Java that just sends some data to the client.

If I connect to the server using telnet, I want the server to send some telnet option codes. Do I just send these like normal messages?

Like, if I wanted the client to print "hello", I would do this:

PrintWriter out = new PrintWriter(clientSocket.getOutputStream());
out.print("hello");
out.flush();

But when I try to send option codes, the client just prints them. Eg, the IAC char (0xff) just gets printed as a strange y character when I do this:

PrintWriter out = new PrintWriter(clientSocket.getOutputStream());
out.print((char)0xff);
out.flush();

score 2 · Accepted Answer · answered Dec 26 '10 at 17:16

2

If you use the default character encoding I would expect 0xff to be turned into two characters.

I suggest you use the plain OutputStream without a PrintWriter. That way the bytes will be sent without translation.

answered Dec 26 '10 at 17:16

Peter Lawrey

score 2 · Answer 2 · edited May 23 '17 at 09:58

2

edited May 23 '17 at 09:58

Community

answered Dec 26 '10 at 17:22

eater

2 Answers2