Path: utzoo!attcan!uunet!lll-winken!lll-tis!mordor!joyce!ames!pasteur!ucbvax!opus.CRAY.COM!dab
From: dab@opus.CRAY.COM (Dave Borman)
Newsgroups: comp.protocols.tcp-ip
Subject: Re:  TCP/IP terminalservers and BREAK(/^C)
Message-ID: <8810272051.AA06701@oliver.cray.com>
Date: 27 Oct 88 20:51:29 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 19


To fix a telnet client so that you can flush output when you type ^C
is really not very hard, and can be done without modifying the telnet
server.  When the client sends the IAC IP (sent when the user types ^C,
or whatever the interrupt character is (What? your telnet doesn't send
IAC IP? Well, since you're changing it anyway, add a user option to say
what character should be translated to IAC IP)), also send a IAC DO
TIMING-MARK.  You then proceed to throw away all data until you see a
IAC WILL/WONT TIMING-MARK, at which point you resume output.  All telnet
servers should respond to the DO TIMING-MARK, regardless if they support
it or not (if they don't, then you have a real brain-dead telnetd
implementation, even 4.2 responds).

The only problem with this fix is that depending on how long the pipe
is, you may sit there for several seconds while the output is being
discarded, but at least it won't scroll off the screen.  A good telnet
implementation should allow you to do both TIMING-MARK and SYNC, so
that you can choose whatever works best.

			-Dave Borman, Cray Research, Inc.