Re: Telnet, <CR><LF>, etc.

Mark Crispin (MRC%PANDA.COM@SUMEX-AIM.Stanford.EDU)
Sat, 1 Aug 87 12:23:39 PDT

Greg Minshall -

     The last time I used a hardwired terminal connected to a Unix
system, I found that the RETURN key on the terminal's keyboard
would cause the Unix system to believe that it had received a
newline. While it is possible that the terminal had been modified
so that the RETURN key sent a linefeed, there was a separate LINE
FEED key. I forget whether or not I tried using the LINE FEED key
as an alternative newline.

     What your Telnet implement has, in effect, done is eliminate
transparency. Most implementors of Telnet programs across the
network have been very careful to make sure that transparency is
preserved, since the ARPANET was traditionally a heterogenous
network. Now, it may be true that today's Internet is a mostly
homogenous Unix network, but there are still some non-Unix boxes
out there.

     I cannot help but get the impression from the tone of your
message that you have no real justification for your implementation's
behavior other than a possible interpretation of admittedly ambiguous
standards. You haven't offered any operational explanation as to
why your implementation must behave in the way it does. Is there
something particularly special about 4.3 that demands this behavior
that other versions of Unix did not have?

     Please don't get me wrong; I have been a frequent critic of
the explanations in the Telnet standards as they are presently
reflected in the RFC's. I have periodically pontificated about
various finer operational details that are glossed over in the
standards or are inadequately explained; during a recent TCP/IP
conference I had a presentation on these details (I'm also
supposed to write an article about this for Connexions...).

     We're not out to criticize you or make your life difficult.
Your mistake is only one of many that have come up in various
Telnet implementations over the years. Please accept our
judgement not as a criticism of your basically fine work, but
rather as a source of information on what you must do to get
your implementation interoperating correctly with the rest of
the network. We all have a shared interest in maximizing
interoperability, and the folklore we have developed over the
years is based on long, hard experience and much compromise.
Thank you.

-- Mark --

This archive was generated by hypermail 2.0b3 on Thu Mar 09 2000 - 14:38:48 GMT