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(1M), as part of the Service Access Facility (SAF). It is configured using the sacadm(1M) 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(1M) and ttyadm(1M) 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(4).) The values used for initialization are taken from the appropriate entry in the TTY settings file. This file is maintained by the sttydefs(1M) command. Default line disciplines on ports are usually set up by the autopush(1M) 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(4)), 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(1M), 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.

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(1M) for options that can be set for ports monitored by ttymon under the Service Access Controller.

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.so.1

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

-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:

-d device

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.

-l ttylabel

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.

-m modules

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.

-p prompt

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

-t timeout

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

-T termtype

Sets the TERM environment variable to termtype.

If any of the LC_* variables ( LC_CTYPE, LC_MESSAGES, LC_TIME, LC_COLLATE, LC_NUMERIC, and LC_MONETARY ) (see environ(5)) 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.

/etc/logindevperm

See attributes(5) for descriptions of the following attributes:

ct(1C), cu(1C), autopush(1M), pmadm(1M), sac(1M), sacadm(1M), sttydefs(1M), ttyadm(1M), uucico(1M), pam(3PAM), logindevperm(4), pam.conf(4), utmpx(4), attributes(5), environ(5), pam_authtok_check(5), pam_authtok_get(5), pam_authtok_store(5), pam_dhkeys(5), pam_passwd_auth(5), pam_unix(5), pam_unix_account(5), pam_unix_auth(5), pam_unix_session(5)

System Administration Guide: Basic Administration

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(5) module might not be supported in a future release. Similar functionality is provided by pam_authtok_check(5), pam_authtok_get(5), pam_authtok_store(5), pam_dhkeys(5), pam_passwd_auth(5), pam_unix_account(5), pam_unix_auth(5), and pam_unix_session(5).