Chapter 12 Managing Serial Ports With the Service Access Facility (Tasks)

This chapter describes how to manage serial port services with the Service Access Facility (SAF).

This is a list of the step-by-step instructions in this chapter.

• How to Add a ttymon Port Monitor

• How to View ttymon Port Monitor Status

• How to Stop a ttymon Port Monitor

• How to Start a ttymon Port Monitor

• How to Disable a ttymon Port Monitor

• How to Enable a ttymon Port Monitor

• How to Remove a ttymon Port Monitor

• How to Add a Service

• How to View the Status of a TTY Port Service

• How to Enable a Port Monitor Service

• How to Disable a Port Monitor Service

This is a list of the overview information in this chapter.

• Using the Service Access Facility

• Overall SAF Administration (sacadm)

• Port Monitor Service Administration (pmadm)

• TTY Monitor and Network Listener Port Monitors

For reference information about the SAF, see Service Access Facility Administration (Reference).

Using the Service Access Facility

You can set up terminals and modems with the Solaris Management Console's Serial Ports Tool, Admintool, or the SAF commands.

The SAF is the tool that is used to administer terminals, modems, and other network devices. The top-level SAF program is the Service Access Controller (SAC). The SAC controls port monitors that you administer through the sacadm command. Each port monitor can manage one or more ports.

You administer the services associated with ports through the pmadm command. While services provided through SAC can differ from network to network, the SAC and its administrative commands, sacadm and pmadm, are network independent.

The following table describes the SAF control hierarchy. The sacadm command is used to administer the SAC, which controls the ttymon and listen port monitors.

The services of ttymon and listen are in turn controlled by the pmadm command. One instance of ttymon can service multiple ports. One instance of listen can provide multiple services on a network interface.

Overall SAF Administration (sacadm)

The sacadm command is the top level of the SAF. The sacadm command primarily is used to add and remove port monitors such as ttymon and listen. Other sacadm functions include listing the current status of port monitors and administering port monitor configuration scripts.

Service Access Controller (SAC Program)

The Service Access Controller program (SAC) oversees all port monitors. A system automatically starts SAC upon entering multiuser mode.

When the SAC is invoked, it first looks for, and interprets, each system's configuration script. You can use configuration script to customizes the SAC environment. This script is empty by default. The modifications made to the SAC environment are inherited by all the “children” of the SAC. This inherited environment might be modified by the children.

After the SAC has interpreted the per-system configuration script, the SAC program reads its administrative file and starts the specified port monitors. For each port monitor, SAC runs a copy of itself, forking a child process. Each child then interprets its per-port monitor configuration script, if such a script exists.

Any modifications to the environment specified in the per-port monitor configuration script affect the port monitor and will be inherited by all its children. Finally, the child process runs the port monitor program by using the command found in the SAC administrative file.

SAC Initialization Process

The following steps summarize what happens when SAC is first started:

1. The SAC program is spawned by init at run level two.

2. The SAC program reads /etc/saf/_sysconfig, the per-system configuration script.

3. The SAC program reads /etc/saf/_sactab, the SAC administrative file.

4. The SAC program forks a child process for each port monitor it starts.

5. Each port monitor reads /etc/saf/pmtag/_config, the per-port monitor configuration script.

Port Monitor Service Administration (pmadm)

The pmadm command enables you to administer port monitors' services. In particular, you use the pmadm command to add or remove a service and to enable or disable a service. You can also install or replace per-service configuration scripts, or print information about a service.

Each instance of a service must be uniquely identified by a port monitor and a port. When you use the pmadm command to administer a service, you specify a particular port monitor with the pmtag argument, and a particular port with the svctag argument.

For each port monitor type, the SAF requires a specialized command to format port monitor-specific configuration data. This data is used by the pmadm command. For ttymon and listen type port monitors, these specialized commands are ttyadm and nlsadmin, respectively.

ttymon Port Monitor

Whenever you attempt to log in by using a directly connected modem or alphanumeric terminal, ttymon goes to work.

As shown in the following figure, the init process is the first process to be started at boot time. Consulting its administrative file (/etc/inittab), the init process starts other processes as they are needed. Listed among those processes is the SAC.

SAC, in turn, automatically starts the port monitors designated in its administrative file, /etc/saf/_sactab. The following figure shows only a single ttymon port monitor.

After the ttymon port monitor has been started, it monitors the serial port lines for service requests.

Figure 12–1 How ttymon Helps Process a Login Request

When someone attempts to log in by using an alphanumeric terminal or a modem, the serial port driver passes the activity to the operating system. The ttymon port monitor notes the serial port activity, and attempts to establish a communications link. The ttymon port monitor determines what data transfer rate, line discipline, and handshaking protocol are required to communicate with the device.

After the proper parameters for communication with the modem or terminal are established, the ttymon port monitor passes these parameters to the login program and transfers control to it.

Port Initialization Process

When an instance of the ttymon port monitor is invoked by SAC, ttymon starts to monitor its ports. For each port, the ttymon port monitor first initializes the line disciplines, if they are specified, and the speed and terminal settings. The values used for initialization are taken from the appropriate entry in the /etc/ttydefs file.

The ttymon port monitor then writes the prompt and waits for user input. If the user indicates that the speed is inappropriate by pressing the Break key, the ttymon port monitor tries the next speed and writes the prompt again.

If autobaud is enabled for a port, the ttymon port monitor tries to determine the baud rate on the port automatically. Users must press Return before the ttymon port monitor can recognize the baud rate and print the prompt.

When valid input is received, the ttymon port monitor does the following tasks:

• Interprets the per-service configuration file for the port

• Creates an /etc/utmpx entry if required

• Establishes the service environment

• Invokes the service associated with the port

After the service terminates, the ttymon port monitor cleans up the /etc/utmpx entry, if one exists, and returns the port to its initial state.

Bidirectional Service

If a port is configured for bidirectional service, the ttymon port monitor will:

• Allow users to connect to a service

• Allow the uucico, cu, or ct commands to use the port for dialing out, if the port is free.

• Wait to read a character before printing a prompt

• Invoke the port's associated service, without sending the prompt message, when a connection is requested, if the connect-on-carrier flag is set

TTY Monitor and Network Listener Port Monitors

Though SAF provides a generic means for administering any future or third-party port monitors, only two are implemented in the Solaris environment: ttymon and listen.

TTY Port Monitor (ttymon)

The ttymon port monitor is STREAMS-based and does the following:

• Monitors ports

• Sets terminal modes, baud rates, and line disciplines

• Invokes the login process

The ttymon port monitor provides Solaris users the same services that getty did under previous versions of SunOS 4.1 software.

The ttymon port monitor runs under the SAC program and is configured with the sacadm command. Each instance of ttymon can monitor multiple ports. These ports are specified in the port monitor's administrative file. The administrative file is configured by using the pmadm and ttyadm commands.

ttymon and the Console Port

Console services are not managed by the Service Access Controller nor any explicit ttymon administration file. An entry in the /etc/inittab file is used to manage the console port by using ttymon in express mode. Express mode is a special ttymon mode that is invoked directly by a command that requires login service.

The default console entry in the /etc/inittab file is as follows:

co:234:respawn:/usr/lib/saf/ttymon -g -h -p "`uname -n` console login: "
 -T terminal_type -d /dev/console -l console -m ldterm,ttcompat

ttymon-Specific Administrative Command (ttyadm)

The ttymon administrative file is updated by sacadm and pmadm, as well as by the ttyadm command. The ttyadm command formats ttymon-specific information and writes it to the standard output, providing a means for presenting formatted ttymon-specific data to the sacadm and pmadm commands.

Thus, ttyadm does not administer ttymon directly. The ttyadm command complements the generic administrative commands, sacadm and pmadm. For more information, see ttyadm(1M).

Network Listener Service (listen)

The listen port monitor runs under SAC and does the following:

• Monitors the network for service requests

• Accepts requests when they arrive

• Invokes servers in response to those service requests

The listen port monitor is configured by using the sacadm command. Each instance of listen can provide multiple services. These services are specified in the port monitor's administrative file. This administrative file is configured by using the pmadm and nlsadmin commands.

The network listener process can be used with any connection-oriented transport provider that conforms to the Transport Layer Interface (TLI) specification. In the Solaris environment, listen port monitors can provide additional network services not provided by the inetd service.

Special listen-Specific Administrative Command (nlsadmin)

The listen port monitor's administrative file is updated by sacadm and pmadm, as well as by the nlsadmin command. The nlsadmin command formats listen-specific information and writes it to standard output, providing a means of presenting formatted listen-specific data to the sacadm and pmadm commands.

Thus, nlsadmin does not administer listen directly. It complements the generic administrative commands, sacadm and pmadm.

Each network, configured separately, can have at least one instance of the network listener process associated with it. The nlsadmin command controls the operational states of listen port monitors.

The nlsadmin command can establish a listen port monitor for a given network, configure the specific attributes of that port monitor, and start and kill the monitor. The nlsadmin command can also report on the listen port monitors on a machine.

For more information, see nlsadmin(1M).

Administering ttymon Port Monitors

Use the sacadm command to add, list, remove, kill, start, enable, disable, enable, and remove a ttymon port monitor.

How to Add a ttymon Port Monitor

1. Become superuser.

2. Add a ttymon port monitor.

   # sacadm -a -p mbmon -t ttymon -c /usr/lib/saf/ttymon -v `ttyadm -V` -y "TTY Ports a & b"

   -a	Specifies the add port monitor option.
   -p	Specifies the pmtag mbmon as the port monitor tag.
   -t	Specifies the port monitor type as ttymon.
   -c	Defines the command string used to start the port monitor.
   -v	Specifies the version number of the port monitor.
   -y	Defines a comment to describe this instance of the port monitor.

How to View ttymon Port Monitor Status

1. Become superuser.

2. View the status of a ttymon port monitor.

   # sacadm -l -p mbmon

   -l	Specifies the list port monitor status flag.
   -p	Specifies the pmtag mbmon as the port monitor tag.

Example—Viewing ttymon Port Monitor Status

# sacadm -l -p mbmon
PMTAG  PMTYPE  FLGS RCNT STATUS    COMMAND
mbmon  ttymon  -    0    STARTING  /usr/lib/saf/ttymon #TTY Ports a & b

How to Stop a ttymon Port Monitor

1. Become superuser.

2. Stop a ttymon port monitor.

   # sacadm -k -p mbmon

   -k	Specifies the kill port monitor status flag.
   -p	Specifies the pmtag mbmon as the port monitor tag.

How to Start a ttymon Port Monitor

1. Become superuser.

2. Start a killed ttymon port monitor.

   # sacadm -s -p mbmon

   -s	Specifies the start port monitor status flag.
   -p	Specifies the pmtag mbmon as the port monitor tag.

How to Disable a ttymon Port Monitor

Disabling a port monitor prevents new services from starting, without affecting existing services.

1. Become superuser.

2. Disable a ttymon port monitor.

   # sacadm -d -p mbmon

   -d	Specifies the disable port monitor status flag.
   -p	Specifies the pmtag mbmon as the port monitor tag.

How to Enable a ttymon Port Monitor

Enabling a ttymon port monitor allows it to service new requests.

1. Become superuser.

2. Enable a ttymon port monitor.

   # sacadm -e -p mbmon

   -e	Specifies the enable port monitor status flag.
   -p	Specifies the pmtag mbmon as the port monitor tag.

How to Remove a ttymon Port Monitor

1. Become superuser.

2. Remove a ttymon port monitor.

   # sacadm -r -p mbmon

   -r	Specifies the remove port monitor status flag.
   -p	Specifies the pmtag mbmon as the port monitor tag.

Removing a port monitor deletes all the configuration files associated with it. Port monitor configuration files cannot be updated or changed by using the sacadm command. To reconfigure a port monitor, remove it and then add a new one.

Administering ttymon Services

Use pmadm to add services, list the services of one or more ports associated with a port monitor, and enable or disable a service.

How to Add a Service

1. Become superuser.

2. Add a standard terminal service to the mbmon port monitor.

   # pmadm -a -p mbmon -s a -i root -v `ttyadm -V` -m "`ttyadm -i 'Terminal disabled' -l contty -m ldterm,ttcompat -S y -d /dev/term/a -s /usr/bin/login`"

   ---

   Note –

   In this example, the input wraps automatically to the next line. Do not use a Return or line feed.

   ---

   -a	Specifies the add port monitor status flag.
   -p	Specifies the pmtag mbmon as the port monitor tag.
   -s	Specifies the svctag a as the port monitor service tag.
   -i	Specifies the identity to be assigned to svctag when the service runs.
   -v	Specifies the version number of the port monitor.
   -m	Specifies the ttymon-specific configuration data formatted by ttyadm.

   The preceding pmadm command contains an embedded ttyadm command. The options in this embedded command are as follows:

   -b	Specifies the bidirectional port flag.
   -i	Specifies the inactive (disabled) response message.
   -l	Specifies which TTY label in the /etc/ttydefs file to use.
   -m	Specifies the STREAMS modules to push before invoking this service.
   -d	Specifies the full path name to the device to use for the TTY port.
   -s	Specifies the full path name of the service to invoke when a connection request is received. If arguments are required, enclose the command and its arguments in quotation marks (“).

How to View the Status of a TTY Port Service

Use the pmadm command as shown in this procedure to list the status of a TTY port or all the ports that are associated with a port monitor.

1. Become superuser.

2. List one service of a port monitor.

   # pmadm -l -p mbmon -s a

   -l	Lists service information on the system.
   -p	Specifies the pmtag mbmon as the port monitor tag.
   -s	Specifies the svctag a as the port monitor service tag.

Example—Viewing the Status of a TTY Port Monitor Service

This example lists all services of a port monitor.

# pmadm -l -p mbmon
PMTAG  PMTYPE  SVCTAG FLAGS ID    <PMSPECIFIC> 
mbmon  ttymon  a      -     root  /dev/term/a - - /usr/bin/login - contty
ldterm,ttcompat login:  Terminal disabled tvi925 y  #

How to Enable a Port Monitor Service

1. Become superuser.

2. Enable a disabled port monitor service.

   # pmadm -e -p mbmon -s a

   -e	Specifies the enable flag.
   -p	Specifies the pmtag mbmon as the port monitor tag.
   -s	Specifies the svctag a as the port monitor service tag.

How to Disable a Port Monitor Service

1. Become superuser.

2. Disable a port monitor service.

   # pmadm -d -p mbmon -s a

   -d	Specifies the disable flag.
   -p	Specifies the pmtag mbmon as the port monitor tag.
   -s	Specifies the svctag a as the port monitor service tag.

Service Access Facility Administration (Reference)

Files Associated With SAF

SAF uses configuration files which can be modified by using the sacadm and pmadm commands. You should not need to edit the configuration files manually.

The /etc/saf/_sactab File

The /etc/saf/_sactab is as follows:

# VERSION=1
zsmon:ttymon::0:/usr/lib/saf/ttymon     #

The /etc/saf/pmtab/_pmtab File

The /etc/saf/pmtab/_pmtab file, such as /etc/saf/zsmon/_pmtab, looks similar to the following:

# VERSION=1
ttya:u:root:reserved:reserved:reserved:/dev/term/a:I::/usr/bin/login::9600:
ldterm,ttcompat:ttya login\: ::tvi925:y:# 

Service States

The sacadm command controls the states of services. The following table describes the possible states of services.

To determine the state of any particular service, use the following:

# pmadm -l -p portmon_name -ssvctag

Port Monitor States

The sacadm command controls the states of ttymon and listen port monitors. The following table describes the possible port monitor states.

To determine the state of any particular port monitor, use the following:

# sacadm -l -p portmon_name

Port States

Ports can be enabled or disabled depending on the state of the port monitor that controls the ports.