Connecting pppd to a serial port and passwords

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From - Mon Apr 12 06:10:33 1999
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From: Kevin Lentin <kevinl@cs.monash.edu.au>
Newsgroups: comp.unix.sco.misc
Subject: Re: Manual dial-up PPP
Date: 11 Apr 1999 08:59:01 GMT
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Evan Hunt <evanh@sco.COM> wrote:

> I didn't say pppd couldn't do it, just that I didn't understand
> why you wanted it to.  It's designed to bring the link up silently
> when you request IP connectivity;

Sounds like a dangerous design goal to me. Useful feature yes, but as the
only mode of operation, very limited. I can see my employer being quite
pissed to discover that their system automatically dials into a PPP server
that charges them by the hour when any user types in a bad hostname.

> I regard that as a good, useful
> design.  Wanting to manually dial the phone and type your password
> every time seems like a hassle, a feature few people would desire.

On a personal machine maybe. On a machine owned by a client where a
consultant wishes to dial into base when on-site and not leave their
password on said machine? I can't believe it.

> The fact that you're the first person to ask for this feature in the
> three years I've been responsible for MSTPPP on SCO platforms, suggests
> that I may have been correct in that evaluation. :)

I'm amazed. Even Windows has the ability to forget a password. I tend to be
like this. My natural way of using computers is completely contrary to the
way large OS companies think. I spend my life battling against computers.
And so do all the people I went through university with. Except for those
that use them purely as applicaiton platforms where occasionally one person
gets through a day without a complaint. Maybe I'm obtuse, maybe I'm a
one-in-a-million kinda guy, a revolutionary ahead of my time, a complete
idiot? Who knows? I just find it hard to believe that something as simple
as this is impossible from two completely separate PPP implementations.
Time to grab the source for the PPP I'm running on this Linux box and take
it to work. That amazes me. 

> I can think of two ways to do this.  Here's the simpler one:  Set
> up your modem so it doesn't hang up when it gets an EOF.  I forget
> how to do that, but there's an AT command sequence that allows it--
> perhaps someone else could help out here?

&D0&C0. Possible. But the standard SCO locking, getty setup will manually
hang up the modem as soon as the dialer/getty discovers nobody is using the
link.

> Create a script called "startppp" on the remote side that runs pppd
> for you with all the necessary options.  Configure MSTPPP on the local
> side with no phone number, the specific name of the serial port you'll
> be using, and a chat script that just calls "startppp"--something like
> this:

>     1.2.3.4 Any tty1A 115200 N/A "" "" "" startppp

> When you want to start up a PPP link, you use kermit to connect to
> your modem and dial the phone.  Without logging out or entering
> "ATH", quit from kermit.  The modem should remain connected.  Run
> pppd with either the "dedicated" or "auto up" option, on that same
> serial port.  PPP should treat the modem as if it were a fixed serial
> link--connect, run "startppp", negotiate with the remote PPP daemon,
> and establish a link, without bothering to dial.

I would have though that possible. But I've tried and failed. I have
another PPP link working on the machine over an actual dedicated serial
link and I would have imagined that starting the remote pppd, suspending
kermit and then somehow kicking the pppd would be enough. All it needs to
do is, as you say, pretend that tty1A is a fixed port. But it just won't. I
don't know why. I just get that gethostent errot in syslog and nothing
else.

> I've never tested this, but I can't think why it wouldn't work.

Me neither, which is why I asked here :-)

> Here's the more complicated way:  Write a dialer program, based on
> atdialer.c in /usr/lib/uucp, which dials the modem for you.  When it
> connects, your program should pop up a terminal window so that you can
> log in.  AFter you've done so, you can close the window, and then your
> dialer program would pass control of the terminal back to the calling
> process, just as atdialer already does.

Or, of course, the dialer could just exit without doing ANYTHING if the
kermit connection is already up. Good idea.

-- 
[======================================================================]
[     Kevin Lentin               Email: K.Lentin@cs.monash.edu.au      ]
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