From ab7bfdda5bb451e5a5d1c33cf3bc3dad8ed24faa Mon Sep 17 00:00:00 2001 From: Simon Tatham Date: Sat, 17 Apr 2021 13:23:57 +0100 Subject: [PATCH] Docs: historical (ish) text about Telnet and Rlogin. SUPDUP came, at my insistence, with a history section in the docs for people who hadn't heard of it. It seems only fair that the other obsolete network protocols (or, at least, the ones we *wish* were obsolete :-) should have the same kind of treatment. --- doc/config.but | 4 ++++ doc/using.but | 38 ++++++++++++++++++++++++++++++++++---- 2 files changed, 38 insertions(+), 4 deletions(-) diff --git a/doc/config.but b/doc/config.but index c7da25eb..7256f817 100644 --- a/doc/config.but +++ b/doc/config.but @@ -37,6 +37,10 @@ Rlogin, and SUPDUP. \b See \k{using-rawprot} for an explanation of \q{raw} connections. +\b See \k{using-telnet} for a little information about Telnet. + +\b See \k{using-rlogin} for information about using Rlogin. + \b See \k{using-supdup} for information about using SUPDUP. \b The \q{Bare ssh-connection} option in the \q{Connection type} box diff --git a/doc/using.but b/doc/using.but index 763616e1..9c86b196 100644 --- a/doc/using.but +++ b/doc/using.but @@ -582,12 +582,42 @@ protocol}\q{Raw}, from the \q{Protocol} buttons in the \q{Session} configuration panel. (See \k{config-hostname}.) You can then enter a host name and a port number, and make the connection. +\H{using-telnet} Connecting using the \i{Telnet} protocol + +PuTTY can use the Telnet protocol to connect to a server. + +Telnet was perhaps the most popular remote login protocol before SSH +was introduced. It was general enough to be used by multiple server +operating systems (Unix and VMS in particular), and supported many +optional protocol extensions providing extra support for particular +server features. + +Unlike SSH, Telnet runs over an unsecured network connection, so it is +a very bad idea to use it over the hostile Internet (though it is +still used to some extent as of 2020). + +\H{using-rlogin} Connecting using the \i{Rlogin} protocol + +PuTTY can use the Rlogin protocol to connect to a server. + +Rlogin was similar to Telnet in concept, but more focused on +connections between Unix machines. It supported a feature for +passwordless login, based on use of \q{privileged ports} (ports with +numbers below 1024, which Unix traditionally does not allow users +other than \cw{root} to allocate). Ultimately, based on the server +trusting that the client's IP address was owned by the Unix machine it +claimed to be, and that that machine would guard its privileged ports +appropriately. + +Like Telnet, Rlogin runs over an unsecured network connection. + \H{using-supdup} Connecting using the \i{SUPDUP} protocol -PuTTY can use the SUPDUP protocol to connect to a server. SUPDUP is a -login protocol used mainly by PDP-10 and Lisp machines during the -period 1975-1990. Like Telnet and Rlogin, it is unsecured, so modern -systems almost never support it. +PuTTY can use the SUPDUP protocol to connect to a server. + +SUPDUP is a login protocol used mainly by PDP-10 and Lisp machines +during the period 1975-1990. Like Telnet and Rlogin, it is unsecured, +so modern systems almost never support it. To make a connection of this type, select \q{SUPDUP} from the \q{Connection type} radio buttons on the \q{Session} panel (see