Tribblix: manual page: ttymon.8

TTYMON(8) Maintenance Commands and Procedures TTYMON(8)

NAME

ttymon - port monitor for terminal ports

SYNOPSIS

/usr/lib/saf/ttymon

/usr/lib/saf/ttymon -g [-d device] [-h] [-t timeout]
[-l ttylabel] [-p prompt] [-m modules] [-T termtype]

DESCRIPTION

ttymon is a STREAMS-based TTY port monitor. Its function is to
monitor ports, to set terminal modes, baud rates, and line
disciplines for the ports, and to connect users or applications to
services associated with the ports. Normally, ttymon is configured
to run under the Service Access Controller, sac(8), as part of the
Service Access Facility (SAF). It is configured using the sacadm(8)
command. Each instance of ttymon can monitor multiple ports. The
ports monitored by an instance of ttymon are specified in the port
monitor's administrative file. The administrative file is configured
using the pmadm(8) and ttyadm(8) commands. When an instance of
ttymon is invoked by the sac command, it starts to monitor its ports.
For each port, ttymon first initializes the line disciplines, if they
are specified, and the speed and terminal settings. For ports with
entries in /etc/logindevperm, device owner, group and permissions are
set. (See logindevperm(5).) The values used for initialization are
taken from the appropriate entry in the TTY settings file. This file
is maintained by the sttydefs(8) command. Default line disciplines on
ports are usually set up by the autopush(8) command of the Autopush
Facility.

ttymon then writes the prompt and waits for user input. If the user
indicates that the speed is inappropriate by pressing the BREAK key,
ttymon tries the next speed and writes the prompt again. When valid
input is received, ttymon interprets the per-service configuration
file for the port, if one exists, creates a utmpx entry if required
(see utmpx(5)), establishes the service environment, and then invokes
the service associated with the port. Valid input consists of a
string of at least one non-newline character, terminated by a
carriage return. After the service terminates, ttymon cleans up the
utmpx entry, if one exists, and returns the port to its initial
state.

If autobaud is enabled for a port, ttymon will try to determine the
baud rate on the port automatically. Users must enter a carriage
return before ttymon can recognize the baud rate and print the
prompt. Currently, the baud rates that can be determined by autobaud
are 110, 1200, 2400, 4800, and 9600.

If a port is configured as a bidirectional port, ttymon will allow
users to connect to a service, and, if the port is free, will allow
uucico(8), cu(1C), or ct(1C) to use it for dialing out. If a port is
bidirectional, ttymon will wait to read a character before it prints
a prompt.

If the connect-on-carrier flag is set for a port, ttymon will
immediately invoke the port's associated service when a connection
request is received. The prompt message will not be sent.

If a port is disabled, ttymon will not start any service on that
port. If a disabled message is specified, ttymon will send out the
disabled message when a connection request is received. If ttymon is
disabled, all ports under that instance of ttymon will also be
disabled.

Service Invocation

The service ttymon invokes for a port is specified in the ttymon
administrative file. ttymon will scan the character string giving the
service to be invoked for this port, looking for a %d or a %% two-
character sequence. If %d is found, ttymon will modify the service
command to be executed by replacing those two characters by the full
path name of this port (the device name). If %% is found, they will
be replaced by a single %. When the service is invoked, file
descriptor 0, 1, and 2 are opened to the port device for reading and
writing. The service is invoked with the user ID, group ID and
current home directory set to that of the user name under which the
service was registered with ttymon. Two environment variables, HOME
and TTYPROMPT, are added to the service's environment by ttymon. HOME
is set to the home directory of the user name under which the service
is invoked. TTYPROMPT is set to the prompt string configured for the
service on the port. This is provided so that a service invoked by
ttymon has a means of determining if a prompt was actually issued by
ttymon and, if so, what that prompt actually was.

See ttyadm(8) for options that can be set for ports monitored by
ttymon under the Service Access Controller.

System Console Invocation

The invocation of ttymon on the system console is managed under
smf(7) by the service svc:/system/console-login. It provides a number
of properties within the property group ttymon to control the
invocation, as follows:

NAME TYPE TTYMON OPTION
----------------------------------------------------------
device astring [-d device]
nohangup boolean [-h]
label astring [-l label]
modules astring [-m module1,module2]
prompt astring [-p prompt]
timeout count [-t timeout]
terminal_type astring [-T termtype]

If any value is the empty string or an integer set to zero, then the
option is not passed to the ttymon invocation. The -g option is
always specified for this invocation. The -d option always defaults
to /dev/console if it is not set.

See EXAMPLES.

SECURITY

ttymon uses pam(3PAM) for session management. The PAM configuration
policy, listed through /etc/pam.conf, specifies the modules to be
used for ttymon. Here is a partial pam.conf file with entries for
ttymon using the UNIX session management module.

ttymon session required /usr/lib/security/pam_unix_session.so.1

If there are no entries for the ttymon service, then the entries for
the "other" service will be used.

OPTIONS

The following options are supported:

-g
A special invocation of ttymon is provided with the -g
option. This form of the command should only be called
by applications that need to set the correct baud rate
and terminal settings on a port and then connect to
login service, but that cannot be pre-configured under
the SAC. The following combinations of options can be
used with -g:

-ddevice
device is the full path name of the port to which
ttymon is to attach. If this option is not specified,
file descriptor 0 must be set up by the invoking
process to a TTY port.

-h
If the -h flag is not set, ttymon will force a hangup
on the line by setting the speed to zero before setting
the speed to the default or specified speed.

-lttylabel
ttylabel is a link to a speed and TTY definition in the
ttydefs file. This definition tells ttymon at what
speed to run initially, what the initial TTY settings
are, and what speed to try next if the user indicates
that the speed is inappropriate by pressing the BREAK
key. The default speed is 9600 baud.

-mmodules
When initializing the port, ttymon will pop all modules
on the port, and then push modules in the order
specified. modules is a comma-separated list of
pushable modules. Default modules on the ports are
usually set up by the Autopush Facility.

-pprompt
Allows the user to specify a prompt string. The default
prompt is Login:.

-ttimeout
Specifies that ttymon should exit if no one types
anything in timeout seconds after the prompt is sent.

-Ttermtype
Sets the TERM environment variable to termtype.

EXAMPLES

Example 1: Setting the Terminal Type

The following example sets the value of the terminal type (-T) option
for the system console ttymon invocation:

svccfg -s svc:/system/console-login setprop \
ttymon/terminal_type = "xterm"
svcadm refresh svc:/system/console-login:default

ENVIRONMENT VARIABLES

If any of the LC_* variables (LC_CTYPE, LC_MESSAGES, LC_TIME,
LC_COLLATE, LC_NUMERIC, and LC_MONETARY) (see environ(7)) are not set
in the environment, the operational behavior of ttymon for each
corresponding locale category is determined by the value of the LANG
environment variable. If LC_ALL is set, its contents are used to
override both the LANG and the other LC_* variables. If none of the
above variables is set in the environment, the "C" (U.S. style)
locale determines how ttymon behaves.

LC_CTYPE
Determines how ttymon handles characters. When LC_CTYPE
is set to a valid value, ttymon can display and handle
text and filenames containing valid characters for that
locale. ttymon can display and handle Extended Unix Code
(EUC) characters where any individual character can be 1,
2, or 3 bytes wide. ttymon can also handle EUC characters
of 1, 2, or more column widths. In the "C" locale, only
characters from ISO 8859-1 are valid.

FILES

/etc/logindevperm

The command-line syntax is Stable. The SMF properties are Evolving.

NOTES

If a port is monitored by more than one ttymon, it is possible for
the ttymons to send out prompt messages in such a way that they
compete for input.

The pam_unix(7) module is no longer supported. Similar functionality
is provided by pam_authtok_check(7), pam_authtok_get(7),
pam_authtok_store(7), pam_dhkeys(7), pam_passwd_auth(7),
pam_unix_account(7), pam_unix_auth(7), and pam_unix_session(7).

February 17, 2023 TTYMON(8)