Subject: Celeste's Guide to Terminals & Modems under Solaris 2.x

From: [email-masked] (Celeste Stokely)
Date: Tue, 22 Feb 1994 15:42:22 GMT

Celeste's Guide to Terminals & Modems under Solaris 2.x
          =======================================================
                           Revision 2/2/94

                                 INDEX
                                 -----
  Section    Description                                            Page
  ----------------------------------------------------------------------
   A.........Setting up a terminal on Solaris 2.x......................2
                 BEFORE YOU BEGIN: SET UP THE TERMINAL.................2
                 ENABLING SOLARIS FOR A TERMINAL.......................2
                 add_terminal script...................................3

   B.........Setting Up a Bidirectional Modem on Solaris 2.x...........4
                 BEFORE YOU BEGIN: SETTING UP THE MODEM................4
                 ENABLING SOLARIS FOR A BIDIRECTIONAL MODEM............4
                 add_modem script......................................6

   C.........Setting up a Modem for dial-out only......................7
                 BEFORE YOU BEGIN: SETTING UP THE MODEM................7
                 ENABLING SOLARIS FOR A DIAL-OUT-ONLY MODEM............7

   D.........Tip and /etc/remote ......................................8
                 /etc/remote example...................................9

   E.........Setting other serial port modes..........................10
                 /etc/ttydefs examples................................11

   F.........Random notes of various uses of serial ports.............12
                 Parity in UUCP.......................................12
                 Flow control with UUCP...............................13

   This document uses a "cook book" approach to setting up modems and
   terminals under Sun's Solaris 2.x. It is not a tutorial and does not
   cover all variations of serial port usage. But, between the explanations
   and the scripts, you should be able to get common asynchronous modems
   and terminals working fairly quickly.

   You must execute the commands as root and you will probably have to
   reboot the machine. So, plan the system's downtime accordingly.

   You may distribute this information to anyone who wants it, as long as
   you never attempt to copyright it in any way. If you find errors in it,
   or have suggestions for changes in future revisions, please let me know
   via email.

   Go for it--you can do it!

   ..Celeste Stokely
   Unix System Administration Consultant, Stokely Consulting
   EMAIL:          [email-masked]
   Voice Line:     415-967-6898 / FAX: 415-967-0160
   USMAIL Address: Stokely Consulting
                   211 Thompson Square / Mountain View CA 94043


Feb  2   Celeste's Guide to Terminals & Modems in Solaris 2.x Page 2

A. Setting up a terminal on Solaris 2.x
=======================================

*********************************************************************
***                      IMPORTANT NOTES:                         ***
***   1. All single quotes in these directions are BACK QUOTES,   ***
***     not FORWARD QUOTES, except where specifically noted.      ***
***                                                               ***
***   2. Be sure and execute these commands as root, from a       ***
***     BOURNE shell (sh), not ksh, tcsh, or csh. (If you put the ***
***     commands into a Bourne shell script, that's fine, too.)   ***
***                                                               ***
***   3. If, after following these instructions, you get          ***
***     terminal failures, and you're not using a script, then    ***
***     make sure that root's default shell is /sbin/sh and not   ***
***     csh.                                                      ***
*********************************************************************

BEFORE YOU BEGIN: SETTING UP THE TERMINAL
        - Set the terminal for the speed you wish (example below
          assumes you are using 9600 baud)
        - The only lines you really need in the terminal-to-Sun cable
          are 2, 3, and 7. Be sure to cross lines 2 and 3 in your cable.
        - Set the terminal for Xon/Xoff flow control
        - Set the terminal for 7 bits, Even Parity. (1 stop bit, if
          you have that setting.) If you want a different parity or
          word length, see Section D of this document.

ENABLING SOLARIS FOR A TERMINAL:
        - Save the following script as add_terminal
        - make it executable with "chmod u+x add_terminal"
        - Edit add_terminal to meet your particular needs
        - Execute add_terminal
        - If the terminal doesn't give you a login when you hit <return>
          try rebooting the machine once.



Feb  2   Celeste's Guide to Terminals & Modems in Solaris 2.x Page 3

#!/bin/sh
##########################################################################
# add_terminal shell script. Must be run as root.
#
# This script invokes pmadm with the following parameters.
# Change these parameters as needed for your particular needs.
#
# PARAMETER                MEANING
# ---------                -------
# PORT                     Port you want to set up. "a" or "b"
# TTYSPEED                 Speed setting, from /etc/ttydefs
# -s tty$PORT              Terminal is on tty$PORT
# -d /dev/term/$PORT       Actual port device. you may want
# -l $TTYSPEED             Speed/stty setting from /etc/ttydefs. choose a
#                          $TTYSPEED entry that meets your needs
# -T tvi925                Your default terminal type for this port. This
#                          is a terminfo terminal type
# -i 'terminal disabled'   Message sent to the tty port if the port is
#                          ever disabled
#
#    QUOTE-ALERT: The single quotes in the "terminal-disabled" message are
#                 FORWARD QUOTES
##########################################################################
# set PORT = either a or b
#----------------------------------------
#PORT="a"
PORT="b"
#----------------------------------------
# choose your speed setting. See /etc/ttydefs for more settings,
# or build your own from the examples in the rest of this document
#      contty5H =  19200 bps, 7 bits even parity
#      contty3H =  2400 bps, 7 bits even parity
#      conttyH =   9600 bps, 7 bits even parity
#----------------------------------------
TTYSPEED="conttyH"
#----------------------------------------
# change ownership of outgoing side of port to user uucp, group tty
# change ownership of incoming side of port to user root, group tty
#----------------------------------------
chown uucp /dev/cua/$PORT; chgrp tty /dev/cua/$PORT
chown root /dev/term/$PORT; chgrp tty /dev/term/$PORT
#----------------------------------------
# Remove any existing port monitor on the port
#----------------------------------------
pmadm -r -p zsmon -s tty$PORT
#----------------------------------------
# Create the new port monitor
#
#     QUOTE-ALERT: The single quotes in the port-disabled message
#                  [terminal disabled] are FORWARD QUOTES
#----------------------------------------
pmadm -a -p zsmon -s tty$PORT -i root -fu -v `ttyadm -V` \
-m "`ttyadm -l $TTYSPEED -d /dev/term/$PORT -T tvi925 \
-i 'terminal disabled' -s /usr/bin/login -S y`"


Feb  2   Celeste's Guide to Terminals & Modems in Solaris 2.x Page 4

B. Setting Up a Bidirectional Modem on Solaris 2.x
==================================================

BEFORE YOU BEGIN: SETTING UP THE MODEM
  Be sure that the modem is configured in the following way:

    - Hardware DTR. When the Sun drops DTR the modem should hang up and
      reset the modem.
    - Hardware Carrier Detect. The modem only raises the CD line when
      there is an active carrier signal on the phone connection. When carrier
      drops, either when the other end of the connection terminated or if
      the phone connection is broken, the Sun will be notified and
      act appropriately.  The CD signal is also used for coordinating dial-in
      and dial-out use on a single serial port and modem.
    - Respond with numeric result codes. (Usually this is ATV0)
    - Sends BASIC result codes ONLY. (Sometimes this is ATX0 or ATQ0)
    - Does not echo commands. (Usually this is ATE0)
    - Modem is locked at a single speed setting between Sun and modem.
      Speed may vary as needed between local and remote modem, but
      should remain constant between Sun and modem.

ENABLING SOLARIS FOR A BIDIRECTIONAL MODEM

*********************************************************************
***                      IMPORTANT NOTES:                         ***
***   1. All single quotes in these directions are BACK QUOTES,   ***
***      not FORWARD QUOTES, except where specifically noted.     ***
***                                                               ***
***   2. Be sure and execute these commands as root, from a       ***
***      BOURNE shell (sh), not ksh, tcsh, or csh. (If you use    ***
***      the a Bourne shell script, that's ok.)                   ***
***                                                               ***
***   3. If, after following these instructions, you get          ***
***      modem failures, or if step #7 gives an error message     ***
***      about "ttyadm: -V: invalid parameter", then make sure    ***
***      that root's default shell is /sbin/sh and not csh.       ***
*********************************************************************

1. Login as root and type:
        prompt# eeprom ttya-ignore-cd=true
        prompt# eeprom ttya-rts-dtr-off=true
   >> go to step 2

2. Reboot the system by typing:
        prompt# init 6
   >> Go to step 3

3. Make sure the modem is properly connected and configured.
   Make sure the cable is ok. (A 25-pin cable, wired "straight through"
   is fine. A Null Modem cable will NOT work.)
   >> Go to step 4


Feb  2   Celeste's Guide to Terminals & Modems in Solaris 2.x Page 5

4. Is zsmon configured and running?
   (The following instructions assume that the modem is on serial port A.)
   Login as root and type:
        prompt# sacadm -l -t ttymon

   If you get a message like:
      "Invalid request, zsmon does not exist"
      then the zsmon port monitor is not configured.
   >> Go to step 5

   If you get a result like:
       PMTAG   PMTYPE    FLGS RCNT STATUS     COMMAND
       zsmon   ttymon    -    0    ENABLED    /usr/lib/saf/ttymon
   >>  Go to step 6

5.  To configure the zsmon port monitor

      prompt# sacadm -a -p zsmon -t ttymon -c /usr/lib/saf/ttymon \
              -v `ttyadm -V` -y "dial in/out on serial port a"

      (Note: The string "zsmon" is known as a PMTAG.
             "dial in/out on serial port a" is a helpful comment.)
    >>  Go to step 6

6. Is ttymon configured and running?
   Type:
      prompt# pmadm -l -s ttya        (where ttya is the SVCTAG)

   a) If there is no service, you will get a result like:
           Service <ttya> does not exist.
      >> Go to step 7.

   b) If you got a result like:

      PMTAG    PMTYPE      SVCTAG      FLGS ID         <PMSPECIFIC>
      zsmon    ttymon      ttya        u    root   /dev/term/a I - /

      Then you need to remove the existing service by typing:
            prompt# pmadm -r -p zsmon -s ttya
                                 ^        ^
                               (PMTAG)  (SVCTAG)
      >> Go to step 7.

7. Make a script which will remove any existing port monitor and create a new
   bidirectional port service.

   (Putting this in a script is a Very Good Idea because if you make a mistake,
   you can easily fix the problem and rerun the script. Don't try to do this
   without a script--there are too many typing errors waiting to be made in
   this command.

   Type in the following script as a file (for instance, /sbin/add_modem),
   make it executable, then run it.


Feb  2   Celeste's Guide to Terminals & Modems in Solaris 2.x Page 6

#!/bin/sh
##########################################################################
# add_modem shell script. Must be run as root from bourne shell
# This script invokes pmadm with the following parameters.
# Change these parameters as needed for your particular needs.
# PARAMETER                MEANING
# ---------                -------
# PORT                     Port you want to set up. "a" or "b"
# TTYSPEED                 Speed setting, from /etc/ttydefs
# -p zsmon                 PMTAG / name of this port monitor
# -s ttya                  SVCTAG / modem is on ttya. you may want ttyb
# -d /dev/term/$PORT       Actual port device.
# -l contty5H              Ttylabel, defined in /etc/ttydefs file. (speed
#                          setting. contty5H=19200 baud.
# -b                       Flag for bidirectional port use
# -S n                     Turn software carrier off (modem supplies hardware
#                          carrier detect signal)
# "dial in/out on serial port"  This is a comment you'll see on pmadm -l
##########################################################################
# set PORT = either a or b
PORT="a"
#----------------------------------------
# choose your speed setting. See /etc/ttydefs for more, or build your
# own from the examples in the rest of this document
#      contty5H =  19200 bps, 7 bits even parity
#      conttyH =   9600 bps, 7 bits even parity
#----------------------------------------
TTYSPEED="conttyH"
#----------------------------------------
# change ownership of outgoing side of port to user uucp, group tty
# change ownership of incoming side of port to user root, group tty
#----------------------------------------
chown uucp /dev/cua/$PORT; chgrp tty /dev/cua/$PORT
chown root /dev/term/$PORT; chgrp tty /dev/term/$PORT
#----------------------------------------
# Remove any existing port monitor on this port
#----------------------------------------
pmadm -r -p zsmon -s tty$PORT
#----------------------------------------
# Create the new port monitor
#----------------------------------------
pmadm -a -p zsmon -s tty$PORT -i root -v `ttyadm -V` -fu -m \
"`ttyadm -d /dev/term/$PORT -s /usr/bin/login -l  $TTYSPEED -b \
-S n -m ldterm,ttcompat`" -y "dial in/out on serial port"
#end of add_modem script
#####################################################################

    Make the script executable by typing
        prompt# chmod 700 /sbin/add_modem
    then run it with:
        prompt# /sbin/add_modem

    For more information, see Section D, "Tip and /etc/remote".


Feb  2   Celeste's Guide to Terminals & Modems in Solaris 2.x Page 7

C. Setting up a modem for dial-out only
=======================================
BEFORE YOU BEGIN: SETTING UP THE MODEM
  Be sure that the modem is configured for the following:
    - Hardware DTR, when the Sun drops DTR the modem should hang up and
      reset the modem.
    - Hardware Carrier Detect, the modem only raises the CD line when
      there is an active carrier signal on the phone connection. When carrier
      drops, either when the other end of the connection terminated or if
      the phone connection is broken, the Sun will be notified and
      act appropriately.  The CD signal is also used for coordinating dial-in
      and dial-out use on a single serial port and modem.
    - Respond with numeric result codes. (Usually this is ATV0)
    - Sends BASIC result codes ONLY. (Sometimes this is ATX0 or ATQ0)
    - Does not echo commands. (Usually this is ATE0)
    - Modem is locked at a single speed setting between Sun and modem.
      Speed may vary as needed between local and remote modem, but
      should remain constant between Sun and modem.
    - Modem is set to not answer the phone. (Usually this is S0=0)

ENABLING SOLARIS FOR A DIAL-OUT-ONLY MODEM
  If there is no port monitor running on the port, then the Sun will not
  try to spawn a login.

1. Login as root and  type:
        prompt# eeprom ttya-ignore-cd=true
        prompt# eeprom ttya-rts-dtr-off=true
   >> go to step 2

2. Reboot the system by typing:
        prompt# init 6
   >> Go to step 3

3. Make sure the modem is properly connected and configured.
   Make sure the cable is ok. (A 25-pin cable, wired "straight through"
   is fine. A Null Modem cable will NOT work.)
   >> Go to step 4

4. Is ttymon configured and running?
   Type:
      prompt# pmadm -l

   If you got a result like:
      PMTAG    PMTYPE    SVCTAG    FLGS ID     <PMSPECIFIC>
      zsmon    ttymon    ttya      u    root   /dev/term/a I - /.....

      Then you need to remove the existing service by typing:
            prompt# pmadm -r -p zsmon -s ttya
                                 ^        ^
                               (PMTAG)  (SVCTAG)
      >> Go to section D, "Tip and /etc/remote".

   If you see nothing listed for the port you're dealing with, then the
   Sun will not spawn a login on that port.


Feb  2   Celeste's Guide to Terminals & Modems in Solaris 2.x Page 8

D. Tip and /etc/remote
======================

 *************************************************************************
 * NOTE: Never run tip from a cmdtool. Use a shelltool, xterm, or some   *
 * other window without scrollbars. The scrollbars may confuse tip's     *
 * <carriage return> processing.                                         *
 *                                                                       *
 * There are exceptions to this, but if you never run tip in a scrollbar *
 * window, you won't have to remember all the ways it does and does not  *
 * work.                                                                 *
 *************************************************************************

1. Edit /etc/remote and find the entry beginning with "hardwire:". Change
   the portion which says:
        :dv=/dev/??????:
   to read
        :dv=/dev/cua/a:    (or /dev/cua/b if you're using the B port)

   Change the portion which says:
        :br#somenumber:
   to read
        :br#9600:   (or 19200, or whatever baud rate you plan to use)
   >> Go to step 2

2. Type:
   prompt#  tip hardwire
               you should see "connected"
   type:
      ATE1V1<carriage return>
               you should see "OK".
               Congratulations! You're talking with the modem!

    If you don't see "OK", you are not communicating with the modem.
    See if the modem is plugged in, verify the baud rate of the modem
    and the hardwire entry in /etc/remote, verify the modem cable.

3.  The cuaa entry (below) allows you to type "tip cuaa" and talk
    directly to a modem on port a at 2400 bps.

4.  "tip some_phone_number" will look for the tip0 entry and use that
    definition. (In the example below, it will use tip0, which points to
    UNIX-2400, which sets up a dialup 2400 bps hayes compatible modem.
    UNIX-2400 points to dialers, which references /dev/cua/a.

5. "tip mysystem"  (below) looks up the "mysystem" entry, and dials the
    number 14155551212 via a 9600 bps connection on /dev/cua/b.


Feb  2   Celeste's Guide to Terminals & Modems in Solaris 2.x Page 9

/etc/remote example:
--------------------

  The following sample file is set up for
    port a, 2400 bps hayes-compatible modem, 8 bits no parity ("p8" entry)
    port b, 9600 bps hayes-compatible modem, 7 bits even parity (no "p8" entry)

  cuaa:dv=/dev/cua/a:p8:br#2400:
  mysystem:pn=14155551212:tc=UNIX-9600:
  hardwire:\
        :dv=/dev/cua/b:br#9600:el=^C^S^Q^U^D:ie=%$:oe=^D:
  tip1200:tc=UNIX-1200:
  tip0|tip2400:tc=UNIX-2400:
  tip9600:tc=UNIX-9600:
  tip19200:tc=UNIX-19200:
  cu1200:tc=UNIX-1200:
  cu0|cu2400:tc=UNIX-2400:
  UNIX-1200:\
        :el=^D^U^C^S^Q^O@:du:at=hayes:ie=#$%:oe=^D:br#1200:tc=dialers:
  UNIX-2400:\
        :el=^D^U^C^S^Q^O@:du:at=hayes:ie=#$%:oe=^D:br#2400:tc=dialers:
  UNIX-9600:\
        :el=^D^U^C^S^Q^O@:du:at=hayes:ie=#$%:oe=^D:br#9600:tc=dialfast:
  UNIX-19200:\
        :el=^D^U^C^S^Q^O@:du:at=hayes:ie=#$%:oe=^D:br#19200:tc=dialers:
  dialers:\
        :dv=/dev/cua/a:
  dialfast:\
        :dv=/dev/cua/b:
  --------------------------------------------------------------------
  The attributes are:
  dv      device to use for the tty
  du      make a call flag (dial up)
  pn      phone numbers (@ =>'s search phones file; possibly taken from
                              PHONES environment variable)
  at      ACU type
  ie      input EOF marks (default is NULL)
  oe      output EOF string (default is NULL)
  cu      call unit (default is dv)
  br      baud rate (defaults to 300)
  tc      to continue a capability


Feb  2   Celeste's Guide to Terminals & Modems in Solaris 2.x Page 10

E. Setting other serial port modes
==================================
Serial port modes (the terminal I/O options found in stty(1) ) are set in the
file /etc/ttydefs. The name of the serial port mode (like contty5H) is used
as the argument to the "-l" option in the "ttyadm" portion of the "pmadm
-a" command. (This is the "speed" setting you use when you add a new port
monitor.) See the stty man page for all the available terminal I/O options.

The format of the entries in ttydefs is defined as:
   ttylabel:initial-flags:final-flags:autobaud:nextlabel

   ttylabel     The string ttymon tries to match against the TTY port's
                ttylabel field in the port monitor administrative file.
                It often describes the speed at which the terminal is
                supposed to run, for example, 1200.

  initial-flags Contains the initial termio(7) settings to which the
                terminal is to be set. For example, the system administrator
                will be able to specify what the default erase and kill
                characters will be. initial-flags must be specified in the
                syntax recognized by the stty command.

   final-flags  final-flags must be specified in the same format as
                initial-flags. ttymon sets these final settings after a
                connection request has been made and immediately prior to
                invoking a port's service.

   autobaud     If the autobaud field contains the character `A', autobaud
                will  be enabled.  Otherwise, autobaud will be disabled.
                ttymon determines what line speed to set the TTY port to by
                analyzing the carriage returns entered. If autobaud has been
                disabled, the hunt sequence is used for baud rate determination.

   nextlabel    If the user indicates that the current terminal setting is
                not appropriate by sending a BREAK, ttymon searchs for a
                ttydefs entry whose ttylabel field matches the nextlabel field.
                If a match is found, ttymon uses that field as its ttylabel
                field.  A series of speeds is often linked together in this
                way into a closed set called a hunt sequence. For example,
                4800 may be linked to 1200, which in turn is linked to 2400,
                which is finally linked to 4800.

 WARNING: These stty modes are processed from left to right within each set
 of "initial-flags" or "final-flags". So, the order of the modes in each
 entry is significant.

 ***************************************************************************
 **  IMPORTANT NOTE: When setting the mode to 8bits, do NOT enter it as   **
 **  ".... -parity ... sane", but as "... sane... -parity" because "sane" **
 **  resets the port to 7 bits.                                           **
 ***************************************************************************


Feb  2   Celeste's Guide to Terminals & Modems in Solaris 2.x Page 11

/etc/ttydefs examples:
----------------------

1. contty5H, as supplied by Sun, is 19200 bps, 7 bits even parity
        contty5H:19200 opost onlcr:19200 hupcl sane::conttyH

   This is equivalent to:
        contty5H:19200 evenp opost onlcr:19200 sane evenp hupcl::conttyH
             or
        contty5H:19200 parenb -parodd opost onlcr:19200 sane parenb
        -parodd hupcl::conttyH

2. To change contty5H to "7 bits, no parity" (-parenb):
        contty5H:19200 -parenb opost onlcr:19200 sane -parenb hupcl::conttyH

3. To change contty5H to "7bits, odd parity" (parenb parodd, or oddp):
        contty5H:19200 parenb parodd opost onlcr:19200 sane parenb parodd
        hupcl::conttyH
           or
        contty5H:19200 oddp opost onlcr:19200 sane oddp hupcl::conttyH

4. To change contty5H to "8 bits, no parity" (-parenb cs8, or -parity):
 contty5H:19200 -parenb cs8 opost onlcr:19200 sane -parenb cs8 hupcl::conttyH
           or
 contty5H:19200 -parity opost onlcr:19200 sane -parity hupcl::conttyH

 WARNING: These stty modes are processed from left to right within each set
 of "initial-flags" or "final-flags". So, the order of the modes in each
 entry is significant.

 ***************************************************************************
 **  IMPORTANT NOTE: When setting the mode to 8bits, do NOT enter it as   **
 **  ".... -parity ... sane", but as "... sane... -parity" because "sane" **
 **  resets the port to 7 bits.                                           **
 ***************************************************************************


Feb  2   Celeste's Guide to Terminals & Modems in Solaris 2.x Page 12

E. Random notes of various uses of serial ports
===============================================
1. Parity in UUCP:
   People often get confused about running UUCP in 7 bits vs. 8 bits vs.
   even vs. odd parity. Here's what's really going on and how to deal with it.

   Both the caller and receiver must agree on parity (even, odd, none) during
   the login sequence. 7 or 8 bit word length often doesn't matter, if you
   "do the right thing" with parity.

   Once the uucico's are running, UUCP's own protocol handles all these
   issues for you, but you need to be concerned with it during login.

   There are 4 parity-related options you can set up during the login chat:
       P_ZERO - No parity
       P_EVEN - Even parity
       P_ODD  - Odd parity
       P_ONE  - "1" or Mark parity

   It is usually safest to set up parity on a per-system-to-call basis, in
   the /etc/uucp/Systems file, but it can also be set for all uses of the
   port, in /etc/uucp/Dialers file.

    Example 1. Setting up a port within UUCP to run with no parity, on a
      per-system-connect basis.

      In the file /etc/uucp/Systems, include P_ZERO in the chat script,
      as in:

        outhost Any ACU 9600 5551212 "" P_ZERO ogin: mylogin ssword: mypass

      This means that when you first start trying to contact the machine
      "outhost" uucp expects nothing ("") and sets P_ZERO (no parity).

    Example 2. Setting up a port within UUCP to run with no parity, for all
      uses of this port.

      (This example assumes you are using the "tbfast" entry in your
      /etc/uucp/Devices file)

      In /etc/uucp/Dialers:
         tbfast  =W-,    "" P_ZERO "" \dA\pA\pA\pTE1V1X1......


Feb  2   Celeste's Guide to Terminals & Modems in Solaris 2.x Page 13

2. Flow control with UUCP:
   With UUCP, either use hardware flow control or no flow control. Please
   remember that there is no incoming hardware flow control on Sun CPU
   serial ports, only outgoing hardware flow control. (There is no such
   limitation on non-cpu ports which claim to have hardware flow control.)

   Sun has released a patch to enable hardware flow control on some
   systems' cpu serial ports. It may work on your system.

   The lack of incoming hardware flow control is not a problem with UUCP,
   usually, because the UUCP protocol is robust enough to request
   retransmission of packets when the data isn't correct.

   Using a good modem that has built-in UUCP protocol support (also known as
   spoofing) will also help. If all else fails, slow down the connection
   between the Sun and the modem to what you can support in your environment.

   The string "STTY=crtscts" tells UUCP to use hardware flow control. It's
   usually better to set this up on a per-port basis, rather than on a
   per-system basis, but UUCP will let you configure it however you want.

    Example 1. Setting up a port with UUCP to use hardware flow control for
      all uses of this port. (Preferred way)

      (This example assumes you are using the "tbfast" entry in your
      /etc/uucp/Devices file)

      In /etc/uucp/Dialers, add "STTY=crtscts" after the CONNECT\sFAST:

        tbfast  =W-,  "" \dA\pTE1.... \EATDT\T\r\c CONNECT\sFAST STTY=crtscts

    Example 2.  Setting up a port with UUCP to use hardware flow control, on
      a per-system-connect basis. (Do this if you feel you must, but there
      are very few good reasons for it.)

      In the file /etc/uucp/Systems, include "STTY=crtscts" in the chat
      script, as in:

       outhost Any ACU 9600 5551212 ogin: mylog ssword: mypass "" STTY=crtscts