[plug] Linux replacing terminal server

[Bernd Felsche]

On Wed, Apr 02, 2003 at 08:07:34PM +0800, Craig Ringer wrote:
> >Connecting a dumb terminal to a terminal server requires the
> >terminal server to establish an IP connection to some host that'll
> >talk to a character-based widget. In the past, the terminal server
> >established a "telnet" connection to a pre-configured host when the
> >user press the "any" key. The host sends a login prompt to the
> >terminal server which the terminal server dutifully causes to be
> >pumped out to the serial port corresponding to the dumb terminal on
> >which the key was pressed.

> OK, there was the source of confusion - I've only ever heard of
> wyse terminal setups where the terms were connected directly to
> the machine hosting the users' sessions. "classic" terminal server
> means about zilch to me.

> Oh well - sorry for wasting your time. The only useful thing I can
> tell you is that I've never heard of any such configuration
> involving a linux box, for what it means.

Not wasting my time at all. Re-thinking a process occasionally
delivers alternative solutions. Too often in computing do people
rush to implement the first "solution" that comes to mind.

> You may well have better luck whipping up a simple application in 
> something like perl or python as the serial<->remote interface rather 
> than trying to assemble a house of cards from misc programs and shell 
> scripts. It'd be especially easy if the remote host expects raw 
> character data from the tty, but shouldn't be too bad even if the remote 
> host wants a "real" telnet protocol connection.

The telnet connection would be a minimum. Input is "cooked"
(half-baked into characters with the possibility of local
flow-control) on the terminal server... it has to be to packetise
for telnet - else all the bits arrive in a stream and the receiving
host cannot tell which are stop bits, etc. The timing would be lost.
Of course, one could invent a whole new protocol, but frankly; I'm
too old for that.

A perl program could be written to do just about all of the hard
work... though netcat does most of the IP stuff without it having to
be reinvented. A perl "wrapper" that execs a no-privilege netcat,
having set local line parameters, might be a good option.

Meanwhile, I'm trying to figure out why I get
	~ # su nobody date
	date: date: Permission denied
and
	~ # su nobody /bin/date
	/bin/date: /bin/date: cannot execute binary file
yet
	~ # su nobody
	nobody:/root> date
	Wed Apr  2 23:44:31 WST 2003
works...

Scratches head and wonders how much sleep'll be lost over that one.

-- 
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