[ 30 July 1997
  The Linux PPP-over-ISDN mini-HOWTO is not being maintained by 
  the author any more.  If you are interested in maintaining the 
  PPP-over-ISDN mini-HOWTO, please get in touch with me at 
  <tjbynum@metalab.unc.edu>. ]

Date: Sat, 13 Apr 1996 20:15:17 -0700 (PDT)
From: Nobody <rmarc@netcom.com>
Subject: Serial ISDN using MLPPP

R Marc Phillips | Need and be abandoned.
rmarc@netcom.com| Hope and be denied.
Semi-Psychotic  | Love and be destroyed.
Mostly Confused | -me

This is a basic guide to using ppp over an external ISDN device.  As of
yet there are no drivers that I know of for ISDN cards readily available
in the USA.  This is a guide to ISDN over a serial port.

The first thing you'll need is PPP compiled on your linux system.  With 
most releases of Linux Slackware, it is an option on recompiling and 
sometimes installing.  If you don't have it you can get the latest BETA from:

ftp.funet.fi:/pub/Linux/BETA/ppp/ppp-2.2

Note that this is for later kernels (1.3.8x and above) for earlier kernels
you may want to look for ppp2.2.0d or e.  A search on www.yahoo.com for ppp
should yield something.

Once you have that installed and functional (you can usual see if it's 
functional, if you're not sure, by just typing pppd at a prompt. You'll 
then see a bunch of garbage start scrolling across your screen.  This 
means you have it installed.  It'll time out in a minute or two or you 
can go to another virtual terminal and kill the process.).

Now you'll want to make a pap-secrets file.  This is a file that simply 
contains you username and password.  PAP stands for Password 
Authentication Protocol which is a function of PPP and a required 
component of MultilinkPPP as defined in the RFC documentation on 
Multilink protocols:

http://www.cis.ohio-state.edu/htbin/rfc/rfc1356.html

I'd advise that you put this file in /etc/ppp and call it something like 
pap or pap-secrets.  What you name it really doesn't matter.  The file 
should have two lines in it.  The first line containing your username 
and the second containing your password.

Once you've done that, you can try out a PPP connection.  The easiest way 
would be to make a file called "pppfix" or something (again, it can be 
called whatever you want).  Here is an example:

#!/bin/sh
pppd modem crtscts defaultroute +ua [path to pap file] connect 'chat \
ABORT BUSY ABORT ERROR "" AT[init string] OK ATD[ISP's Phone #] CONNECT' \
[your comm port] 115200

There are two parts to this, the pppd component and the chat component.

I've put anything that you need to decide upon in square brackets.  You 
need to replace those with the appropriate information.  Say you made a 
file in your /etc/ppp directory called "pap" that contains your username 
and password.  You'd put in /etc/ppp/pap replacing "[path to pap file]."
For "[init string]" you'll want to put in the appropriate string for 
MultilinkPPP (this will work equally as well for a modem, so if you want 
to use your modem put in a string for it).  You can look in your manual 
to find the appropriate string.  I'll give a few:

For a 3com impact put in: s71=1s80=1&d2
For a Bitsurfer put in: %a2=92@b0=2&d2
For a Bitsurfer Pro: %a2=92@b0=2@m2=p&d2
For an Adtran ISU express: s54=12&d2

Add whatever else you would normally for your box, but these are what is 
necessary for MultilinkPPP plus the &d2 which will insure that your box 
will hang up when you disconnect.  Some TA's have a hard time hanging up
without that &d2 (especially the Bitsurfer and Bitsurfer pro)

After the ATD you put in your ISP's ISDN phone number in replace of 
"[ISP's Phone #]." (note that with the Bitsurfer and Bitsurfer pro it is 
necessary to tell the TA to dial the same number twice seperated by an "&."
It is not necessary to put in an escape character).

Where you see "[your comm port]" you'll need to replace that with the 
appropriate comm port. In most cases that will be /dev/cuaX where the X 
is a number between 0 and 3.  0 being comm1 and 3 being comm4.

Now make the file executable by typing "chmod 755 <filename>" or 
whatever you'd like the permissions to be (700 if you only want root to 
have rights to it).  You'll want to also make sure that your pap file 
is readible to whomever is running the pppd process so that it'll log in. To 
run it you'd simply type the name of the file.

When you run this it should connect and then you can type "ifconfig" at 
your prompt.  You should see that you have an "inet addr"  under "Link 
encap: Point-Point Protocol" like so:

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Bcast:127.255.255.255  Mask:255.0.0.0
          UP BROADCAST LOOPBACK RUNNING  MTU:2000  Metric:1
          RX packets:132 errors:0 dropped:0 overruns:0
          TX packets:132 errors:0 dropped:0 overruns:0

ppp0      Link encap:Point-Point Protocol  
          inet addr:204.31.114.199  P-t-P:163.179.20.26  Mask:255.255.255.0
          UP POINTOPOINT RUNNING  MTU:1500  Metric:1
          RX packets:47 errors:0 dropped:0 overruns:0
          TX packets:62 errors:0 dropped:0 overruns:0

To hang up, kill the process.  If you don't know how to do that type "man 
ps" and then "man kill" and read.

Here's an example:

kill `ps -x | grep pppd | head -1 | cut -c2-5`

You should then write scripts to manage your ppp connections.

This is only one way to do it, there are others.  You can download some 
scripts for this from the following ftp site:

ftp.netcom.com/ftp/pub/rm/rmarc/lnxstuff.zip

There's a readme file with it.  I didn't write these scripts and they are 
not the ones I use.  They are nice for a beginner and do not use PAP so 
you'll have to modify them if you want to do MultilinkPPP.


Have fun.

