PPP-over-minicom mini-HOWTO Winfried Tr�mper <winni@xpilot.org>
--------------------------- v0.0 09 December 1996
You want a menu-driven tool for dealing with PPP? An easy but powerful
database with telephone numbers of your ISP? Want to see what happens
when logging in? Then this mini-HOWTO is for you!
1. Introduction
PPP has become the standard network protocol for hooking up
to the internet via dial-in connections. The associated
daemon "pppd" ships with a very primitive tool for dialing
which handles only very simple setups well.
I will describe an alternate solution on the basis of "minicom".
This document is a short version of the German "Internetanbindung
mit PPP" ("http://www.uni-koeln.de/themen/linux/ppp/")
1.1. The terminal program "minicom"
"minicom" is a very sophisticated tool for dialing into
other computers (ISPs or BBSs). It has a fancy colored menu,
a telephone database and a powerful scripting language. Thus
it is ideally suited for use in conjunction with "pppd".
BTW, if you run "/sbin/mgetty /dev/modem" everyone with a
valid account on your machine can dial in (e.g. using
"minicom"). But thats another story. Please see the docs of
"mgetty" for details.
1.2. Feedback
I'm only interested in feedback that improves this mini-HOWTO.
I won't answer general questions about Linux, PPP, SLIP or
networking.
1.3. Known bugs
At the time of writing, there seem to be some bugs in
"minicom", "runscript" and the method described below:
- "runscript" does not wait for external programs to
finish
print "blah"
! sleep 10
print "blup"
This script exits immediatly (but not when straced
...)
- "pppd" takes the serial device away from minicom
(when not fed via stdin)
It seems that Miquel van Smoorenburg (the author of minicom)
is too busy to get his fingers on the above. So volunteers
are welcome.
2.0. Dialing with minicom
Many guides on PPP recommend to leave minicom after it's been
used for dialing. But there is really no need to leave this
comfortable program ...
2.1. Configure minicom
Execute "minicom -s" and choose the menu item "Serial port
setup". The first entry should be "Serial Device" this is
the most important setting: the serial device your
modem is attached to. (Any volunteers to mess up minicom to
handle several serial devices at once?)
Press <return> to confirm and <esc> to exit to the initial
setup menu. Choose "Exit to minicom" and type "atdt99999".
Your modem should start to dial immediatly and you should
hear a click when the modem hooks up to the line. Of course
"99999" is no valid telephone number.
2.2. Starting PPP manually
Maybe you've already tried to dial the telephone number of
your ISP instead of "99999". Did you see funny characters
on the screen after login in (if not, type "ppp")? They
result from the "pppd" (or equivalent) started at the other
end of the line. If so you can try to start the
"pppd"-daemon on your side and evaluate the log-files
afterwards.
To start "pppd" inside minicom, you can define a new
upload method (figure out yourself) or re-define the
setting "kermit programm" from the configuration menu
"Filename and paths":
A - Download directory :
B - Upload directory :
C - Script directory :
D - Script program : /usr/bin/runscript
E - Kermit program : /usr/sbin/pppd file /etc/ppp/mini_options
Now if you see those funny characters next time you dial
to your ISP you can press <Alt-K> to start "pppd".
The rest of this mini-HOWTO deals with automating the task
of logging in and starting "pppd".
2.3. Evaluating logfiles
Although I do not want to explain how PPP is to be configured,
I give a short tip how to read the log-file. To extract the
essential information from the logfile "/var/log/debug" (or
alternative "/var/log/daemon.log") execute the commands
tail -n 40 /var/log/debug |\
grep -E " pppd\[[0-9]*\]:" |\
sed -e "s/^.*pppd\[/[/"
You should see messages like
sent [LCP ConfReq id=0x1 <mru 296>]
rcvd [LCP ConfRej id=0x1 <mru 296>]
which indicate that we sent a config-request to set the maximum
recieve unit (mru) to 296. The other side refects this setting
("configuration rejected"). In this case I just removed the
option "mru" from "/etc/ppp/options" (see below).
2.4. Configure a telephone number
If the above was successful you may want to store a telephone
number in minicoms database. Press <Alt-D> to pop up the
dialing menu and use the cursor keys to select "Edit":
A - Name : Xeno
B - Number : 022039697303
C - Dial string # : 1
D - Local echo : No
E - Script : /etc/ppp/login.script
F - Username : ppp-382
G - Password : top-secret
H - Terminal Emulation : VT102
I - Backspace key sends : Delete
J - Linewrap : Off
K - Line Settings : Curr 8N1
This is a sample entry to dial to one of my ISPs. The script
"/etc/ppp/login.script" is shown below. Two special variables
are passed to this script: $(LOGIN) and $(PASS) which are
set to the values submitted as username (F) and password (G).
This feature makes minicom somewhat flexible because you
need only one script to automate your login to several ISPs.
2.5. A login script
"minicom" starts the login-script after it recieves the string
"CONNECT". To be precise, "minicom" does not execute the script
itself but calls the utility "runscript" as a sub-process for that.
Below is a example I use for my ISPs.
# v1.0, 20.08.96 Winfried Tr�mper <winni@xpilot.org>
print ""
print "Automatic login via /etc/ppp/login.script"
## uncomment if you need to press enter to get the prompt
#send ""
expect {
"ogin:"
"ogin>"
"sername:"
"sername>"
"NO CARRIER" exit 1
}
send "$(LOGIN)"
expect {
"assword:"
"assword>"
timeout 20
}
send "$(PASS)"
expect {
"port" send "ppp"
"Start your PPP now"
"}!}!}"
timeout 10
}
print ""
print "Now switching into ppp-mode ..."
print ""
! /usr/sbin/pppd file /etc/ppp/mini_options
print ""
print "the command killall -TERM pppd terminates pppd"
The ability of "runscript" to call external programs is used
to start "pppd". Copy your original options-file for ppp
to "/etc/ppp/options.ttyS1" (where you have to replace "ttyS1"
with the device your modem is attached to) and delete all
lines from /etc/ppp/options that are specific to your modem
(like "connect", "crtscts" or "modem").
Put the options that should be specific to the ppp-connection
via minicom in "/etc/ppp/mini_options". One of these options
should be
disconnect "chat '' '\d\d+++\d\dATH\r\c'"
This is a must because "pppd" is fed via stdin and can't hang
up the modem via "crtscts".
2.6. Automated dialing on startup
Use the option "-d" to dial a certain telephone number on
startup of minicom.
You may also try
open -sl -- minicom -d 1
To throw minicom at another console (see the Consoles-Many
mini-HOWTO for details).
2.7. Future extensions
Because "pppd" is a daemon it is not designed for
user-interaction or observation. Thats ok. After all, we're
using a unix-like os ...
The canonical solution is a backend. Any volunteers to hack
up minicom?
Fancy extensions would be:
- automatic generation of the login-script by watching
the user dialing in manually
- automatic evalutaion of the log-files with
correction of options
- extraction of messages like shown in 2.3.
End of the PPP-via-minicom mini-HOWTO