illumos: 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)