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New HOWTO: Modem-HOWTO - page 14

Table of Contents

  • April 12, 2001
  13.  Uugetty for Dial-In (from the old Serial-HOWTO)

  Be aware that you could use mgetty as a (better?) alternative to
  uugetty.  mgetty is newer and more popular than uugetty.  See
  ``Getty'' for a brief comparison of these 2 gettys.


  13.1.  Installing getty_ps

  Since uugetty is part of getty_ps you'll first have to install
  getty_ps.  If you don't have it, get the latest version from
  metalab.unc.edu:/pub/Linux/system/serial.  In particular, if you want
  to use high speeds (57600 and 115200 bps), you must get version 2.0.7j
  or later.  You must also have libc 5.x or greater.


  By default, getty_ps will be configured to be Linux FSSTND (File
  System Standard) compliant, which means that the binaries will be in
  /sbin, and the config files will be named /etc/conf.{uu}getty.ttySN.
  This is not apparent from the documentation!  It will also expect lock
  files to go in /var/lock.  Make sure you have the /var/lock directory.

  If you don't want FSSTND compliance, binaries will go in /etc, config
  files will go in /etc/default/{uu}getty.ttySN, and lock files will go
  in /usr/spool/uucp.  I recommend doing things this way if you are
  using UUCP, because UUCP will have problems if you move the lock files
  to where it isn't looking for them.

  getty_ps can also use syslogd to log messages.  See the man pages for
  syslogd(1) and syslog.conf(5) for setting up syslogd, if you don't
  have it running already.  Messages are logged with priority LOG_AUTH,
  errors use LOG_ERR, and debugging uses LOG_DEBUG.  If you don't want
  to use syslogd you can edit tune.h in the getty_ps source files to use
  a log file for messages instead, namely /var/adm/getty.log by default.

  Decide on if you want FSSTND compliance and syslog capability.  You
  can also choose a combination of the two.  Edit the Makefile, tune.h
  and config.h to reflect your decisions.  Then compile and install
  according to the instructions included with the package.


  13.2.  Setting up uugetty


  With uugetty you may dial out with your modem while uugetty is
  watching the port for logins.  uugetty does important lock file
  checking.  Update /etc/gettydefs to include an entry for your modem.
  For help with the meaning of the entries that you put into
  /etc/gettydefs, see the "serial_suite" collected by Vern Hoxie.  How
  to get it is in section See``About getty_em''.  When you are done
  editing /etc/gettydefs, you can verify that the syntax is correct by
  doing:



       linux# getty -c /etc/gettydefs



  13.2.1.  Modern Modems

  If you have a 9600 bps or faster modem with data compression, you can
  lock your serial port to one speed.  For example:


       # 115200 fixed speed
       F115200# B115200 CS8 # B115200 SANE -ISTRIP HUPCL #@S @L @B login: #F115200

  If you have your modem set up to do RTS/CTS hardware flow control, you
  can add CRTSCTS to the entries:


       # 115200 fixed speed with hardware flow control
       F115200# B115200 CS8 CRTSCTS # B115200 SANE -ISTRIP HUPCL CRTSCTS #@S @L @B login: #F115200



  13.2.2.  Old slow modems

  If you have a slow modem (under 9600 bps) Then, instead of one line
  for a single speed, your need several lines to try a number of speeds.
  Note the these lines are linked to each other by the last "word" in
  the line such as #4800.  Blank lines are needed between each entry.
  Are the higher modem-to-serial_port speeds in this example really
  needed for a slow modem ??  The uugetty documentation shows them so
  I'm not yet deleting them.



       # Modem entries
       115200# B115200 CS8 # B115200 SANE -ISTRIP HUPCL #@S @L @B login: #57600

       57600# B57600 CS8 # B57600 SANE -ISTRIP HUPCL #@S @L @B login: #38400

       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: #4800

       4800# B4800 CS8 # B4800 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: #115200



  13.2.3.  Login Banner

  If you want, you can make uugetty print interesting things in the
  login banner.  In Greg's  examples, he has 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 uugetty 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 '@@'.



  13.3.  Customizing uugetty

  There are lots of parameters you can tweak for each port you have.
  These are implemented in separate 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
  uugetty (older than 2.0.7e), or aren't using FSSTND, then the default
  file will be /etc/default/uugetty.ttySN.  Greg's
  /etc/conf.uugetty.ttyS3 looked like this:


       # sample uugetty configuration file for a Hayes compatible modem to allow
       # incoming modem connections
       #
       # line to initialize
       INITLINE=ttyS3
       # timeout to disconnect if idle...
       TIMEOUT=60
       # modem initialization string...
       # format:   ... (chat sequence)
       INIT="" 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 - run-levels (2345 or 345, etc.)  config file location,
  port, speed, and default terminal type:



       S3:2345:respawn:/sbin/uugetty -d /etc/default/uugetty.ttyS3 ttyS3 F115200 vt100



  Restart init:


       linux# init q



  For the speed parameter in your /etc/inittab, you want to use the
  highest bps rate that your modem supports.

  Now Linux will be watching your serial port for connections.  Dial in
  from another machine and login to you Linux system.


  uugetty has a lot more options, see the man page for uugetty) (often
  just called getty) for a full description.  Among other things there
  is a scheduling feature, and a ringback feature.
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