Get your modem to dial out correctly. If you haven't read section How do I dial out with my modem go read it now.
For dialin and dialout use, you have to set up your modem
a certain way (again, using the AT command on your modem):
E1 command echo ON
Q0 result codes are reported
V1 verbose ON
S0=0 never answer (uugetty handles this with the WAITFOR option)
If you don't set these correctly, your INIT string in
your config file may fail, hosing the whole process. But, more
on config files below...
&C1 DCD is on after connect only
&S0 DSR is always on
DTR on/off resets modem (depends on manufacturer - RTFM)
These affect what your modem does when calls start and end.
If your modem does not support a stored profile, you can set these
through the INIT string in your config file. See below. Some
modems come with DIP switches that affect register settings. Be sure
these are set correctly, too.
I have started a collection of modem setups for different types of modems. So far, I only have a few of them, if you would like to send me your working configuration, please do so! If you would like me to send you one of the configurations, just mail me and ask. I'm not listing them here due to space concerns. I have setups for Telebit T1600, USR Courier, and Zoom 14.4/28.8 modems.
uugetty For dialing into, and out from your modem, we want to use uugetty.
uugetty does important lock file checking.
Replace the stock getty with getty_ps as described in
section
What is getty_ps
.
Update /etc/gettydefs to include entries for
modems (note that the entries point to each other, these are not for
fixed speed):
# Modem entries
38400# B38400 CS8 # B38400 SANE -ISTRIP HUPCL #@S @L @B login: #19200
19200# B19200 CS8 # B19200 SANE -ISTRIP HUPCL #@S @L @B login: #9600
9600# B9600 CS8 # B9600 SANE -ISTRIP HUPCL #@S @L @B login: #2400
2400# B2400 CS8 # B2400 SANE -ISTRIP HUPCL #@S @L @B login: #1200
1200# B1200 CS8 # B1200 SANE -ISTRIP HUPCL #@S @L @B login: #300
300# B300 CS8 # B300 SANE -ISTRIP HUPCL #@S @L @B login: #38400
If you have a 9600 bps or faster modem, you can lock
your serial port speed and let the modem handle the transition to
other bps rates. Then, instead of the step down series of lines listed
above, /etc/gettydefs only needs to contain one line for the
modem:
# 38400 fixed speed
F38400# B38400 CS8 # B38400 SANE -ISTRIP HUPCL #@S @L @B login: #F38400
# 19200 fixed speed
F19200# B19200 CS8 # B19200 SANE -ISTRIP HUPCL #@S @L @B login: #F19200
# 9600 fixed speed
F9600# B9600 CS8 # B9600 SANE -ISTRIP HUPCL #@S @L @B login: #F9600
If you have your modem set up to do RTS/CTS hardware flow control, you can add CRTSCTS to the entries:
# 38400 fixed speed with hardware flow control
F38400# B38400 CS8 CRTSCTS # B38400 SANE -ISTRIP HUPCL CRTSCTS #@S @L @B login: #F38400
# 19200 fixed speed with hardware flow control
F19200# B19200 CS8 CRTSCTS # B19200 SANE -ISTRIP HUPCL CRTSCTS #@S @L @B login: #F19200
# 9600 fixed speed with hardware flow control
F9600# B9600 CS8 CRTSCTS # B9600 SANE -ISTRIP HUPCL CRTSCTS #@S @L @B login: #F9600
If you want, you can make uugetty print interesting things in the
login banner. In my examples, I have the system name, the serial
line, and the current bps rate. You can add other things:
@B The current (evaluated at the time the @B is seen) bps rate.
@D The current date, in MM/DD/YY.
@L The serial line to which getty is attached.
@S The system name.
@T The current time, in HH:MM:SS (24-hour).
@U The number of currently signed-on users. This is a
count of the number of entries in the /etc/utmp file
that have a non-null ut_name field.
@V The value of VERSION, as given in the defaults file.
To display a single '@' character, use either '\@' or '@@'.
Next, make sure that you have an outgoing and incoming device for the
serial port
your modem is on. If you have your modem on ttyS3 you will
need the /dev/cua3, and /dev/ttyS3 devices. If you
don't have the correct devices, see section
Creating devices in /dev
on how to create
devices, and create the devices.
uugetty There are lots of parameters you can tweak for each port you have.
These are implemented in seperate config files for each port.
The file /etc/conf.uugetty will be used by all
instances of uugetty, and /etc/conf.uugetty.ttySN
will only be used by that one port. Sample default config files can
be found with the getty_ps source files, which come with most
Linux distributions. Due to space concerns,
they are not listed here. Note that if you are using older versions
of getty (older than 2.0.7e), or aren't using FSSTND, then the
default files will be in
/etc/default/uugetty.ttySN. My
/etc/conf.uugetty.ttyS3 looks like this:
# sample uugetty configuration file for a Hayes compatible modem to allow
# incoming modem connections
# alternate lock file to check... if this lock file exists, then uugetty is
# restarted so that the modem is re-initialized
ALTLOCK=cua3
ALTLINE=cua3
# line to initialize
INITLINE=cua3
# timeout to disconnect if idle...
TIMEOUT=60
# modem initialization string...
#
# format: <expect> <send> ... (chat sequence)
INIT="" \d+++\dAT\r OK\r\n ATH0\r OK\r\n AT\r OK\r\n
WAITFOR=RING
CONNECT="" ATA\r CONNECT\s\A
# this line sets the time to delay before sending the login banner
DELAY=1
#DEBUG=010
Add the following line to your /etc/inittab, so that
uugetty is run on your serial port (substituting in the
correct information for your environment - port, speed, and
terminal type):
S3:456:respawn:/sbin/uugetty ttyS3 F38400 vt100
Restart init:
linux# init q
For the speed parameter in your inittab, you will want to use the
highest bps rate
that your modem supports. Since there is no speed named 57600 or
115200, you must use the setserial program to set your serial
port to a higher speed. See section
How do I set up my serial ports for higher speeds?
for
doing this. Then, use 38400 bps in your inittab.
Now Linux will be watching your serial port for connections. Dial in from another site and login to you Linux system. Rejoice.
getty and uugetty have a lot more options, see the man
page for getty(1m) for a full description. Among other things
there is a scheduling feature, and a ringback feature. RTFM :-).
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