*BSD News Article 96536


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From: guy@netapp.com (Guy Harris)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Difference between rlogin and telnet
Date: 30 May 1997 12:24:57 -0700
Organization: Network Appliance
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References: <864993028.196308@reef.island.net.au> <5mmvkd$8kq@ui-gate.utell.co.uk> <5mn8in$dve@netaxs.com>
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Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:41895

A. Karl Heller <heller@cdnow.com> wrote:
>  I believe rlogin also passes some terminal information that telnet does
>not.

"telnet" is a class of programs, not a program; Telnet is a protocol,
but an extensible one.

I.e., Telnet allows one to pass the terminal type over the wire with the
terminal-type option (RFC 1091), and the terminal speed over the wire
with the terminal speed option (RFC 1079), but not all Telnet clients
necessarily use this option if available and not all Telnet servers
necessarily make this option available.

The same applies to the Telnet window size option (RFC 1073).

(Now, there *is* the issue of what you send over the wire with the
terminal-type option; the RFC says you should use one of the terminal
types from the "Assigned Numbers" RFC, but the BSD Telnets have, at
least in the past, ignored that and just sent the value of $TERM.  I
suppose that allows one to handle terminals not in the terminal type
list, but it could cause problems if one of the systems involved doesn't
happen to use the same terminal-type names that UNIX "termcap" and
"terminfo" databases use....)