System Administration Guide: Advanced Administration

Chapter 1 Managing Terminals and Modems (Overview)

This chapter provides overview information for managing terminals and modems.

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

For step-by-step instructions on how to set up terminals and modems with the Serial Ports tool, see Chapter 2, Setting Up Terminals and Modems (Tasks).

For step-by-step instructions on how to set up terminals and modems with the Service Access Facility (SAF), see Chapter 3, Managing Serial Ports With the Service Access Facility (Tasks).

What's New in Managing Terminals and Modems?

This section describes new or changed features for managing terminals and modems in the Oracle Solaris release. For a complete listing a new features and a description of Oracle Solaris releases, see Oracle Solaris 10 9/10 What’s New.

SPARC: Coherent Console

Solaris 10 8/07: The coherent console subsystem feature implements a part of the kernel console subsystem to facilitate rendering console output. The coherent console uses the Oracle Solaris kernel mechanisms to render console output rather than Programmable Read-Only Memory (PROM) interfaces. This reduces the console rendering dependence on the OpenBoot PROM (OBP). The coherent console uses a kernel-resident frame-buffer driver to generate console output. The generated console output is more efficient than using OBP rendering. The coherent console also avoids idling CPUs during the SPARC console output and enhances the user experience.

SPARC: Changes to How $TERM Value for Console Is Set

Solaris 10 8/07: The $TERM value is now dynamically derived and depends on the terminal emulator that the console is using. On x86 based systems, the $TERM value is sun-color because the kernel's terminal emulator is always used.

On SPARC based systems the $TERM value is as follows:

sun-color: This value is used for $TERM if the system uses the kernel's terminal emulator.
sun: This value is used for $TERM if the system uses the PROM's terminal emulator.

This change does not impact how the terminal type is set for the serial port. You can still use the svccfg command to modify the $TERM value, as shown in the following example:

# svccfg
svc:> select system/console-login
svc:/system/console-login> setprop ttymon/terminal_type = "xterm"
svc:/system/console-login> exit

`ttymon` Invocations on the System Console Managed by SMF

Oracle Solaris 10: ttymon invocations on the system console are managed by SMF. The addition of properties to the svc:/system/console-login:default service enables you to specify ttymon command arguments with the svccfg command. Note that these properties are specific to ttymon, not generic SMF properties.

Note –

You can no longer customize the ttymon invocation in the /etc/inittab file.

For step-by-step instructions on how to specify ttymon command arguments with SMF, see How to Set the ttymon Console Terminal Type.

For a complete overview of SMF, see Chapter 18, Managing Services (Overview), in System Administration Guide: Basic Administration. For information on the step-by-step procedures that are associated with SMF, see Chapter 19, Managing Services (Tasks), in System Administration Guide: Basic Administration.

Terminals, Modems, Ports, and Services

Terminals and modems provide both local and remote access to system and network resources. Setting up terminals and modem access is an important responsibility of a system administrator. This section explains some of the concepts behind modem and terminal management in the Oracle Solaris operating system.

Terminal Description

Your system's bitmapped graphics display is not the same as an alphanumeric terminal. An alphanumeric terminal connects to a serial port and displays only text. You don't have to perform any special steps to administer the graphics display.

Modem Description

Modems can be set up in three basic configurations:

Dial-out
Dial-in
Bidirectional

A modem connected to your home computer might be set up to provide dial-out service. With dial-out service, you can access other computers from your own home. However, nobody outside can gain access to your machine.

Dial-in service is just the opposite. Dial-in service allows people to access a system from remote sites. However, it does not permit calls to the outside world.

Bidirectional access, as the name implies, provides both dial-in and dial-out capabilities.

Ports Description

A port is a channel through which a device communicates with the operating system. From a hardware perspective, a port is a “receptacle” into which a terminal or modem cable might be physically connected.

However, a port is not strictly a physical receptacle, but an entity with hardware (pins and connectors) and software (a device driver) components. A single physical receptacle often provides multiple ports, allowing connection of two or more devices.

Common types of ports include serial, parallel, small computer systems interface (SCSI), and Ethernet.

A serial port, using a standard communications protocol, transmits a byte of information bit-by-bit over a single line.

Devices that have been designed according to RS-232-C or RS-423 standards, this include most modems, alphanumeric terminals, plotters, and some printers. These devices can be connected interchangeably, using standard cables, into serial ports of computers that have been similarly designed.

When many serial port devices must be connected to a single computer, you might need to add an adapter board to the system. The adapter board, with its driver software, provides additional serial ports for connecting more devices than could otherwise be accommodated.

Services Description

Modems and terminals gain access to computing resources by using serial port software. Serial port software must be set up to provide a particular “service” for the device attached to the port. For example, you can set up a serial port to provide bidirectional service for a modem.

Port Monitors

The main mechanism for gaining access to a service is through a port monitor. A port monitor is a program that continuously monitors for requests to log in or access printers or files.

When a port monitor detects a request, it sets whatever parameters are required to establish communication between the operating system and the device requesting service. Then, the port monitor transfers control to other processes that provide the services needed.

The following table describes the two types of port monitors included in the Oracle Solaris release.

Table 1–1 Port Monitor Types


Man Page	Port Monitor	Description
listen(1M)	`listen`	Controls access to network services, such as handling remote print requests prior to the Solaris 2.6 release. The default Oracle Solaris OS no longer uses this port monitor type.
ttymon(1M)	`ttymon`	Provides access to the login services needed by modems and alphanumeric terminals. The Serial Ports tool automatically sets up a `ttymon` port monitor to process login requests from these devices.

You might be familiar with an older port monitor called getty. The new ttymon port monitor is more powerful. A single ttymon port monitor can replace multiple occurrences of getty. Otherwise, these two programs serve the same function. For more information, see the getty(1M) man page.

Tools for Managing Terminals and Modems

The following table lists the tools for managing terminals and modems.

Table 1–2 Tools For Managing Terminals and Modems


Managing Terminals and Modems Method	Tool	For More Information
The most comprehensive	Service Access Facility (SAF) commands	Overview of the Service Access Facility
The quickest setup	Solaris Management Console's Serial Ports tool	Chapter 2, Setting Up Terminals and Modems (Tasks) and Solaris Management Console online help

Serial Ports Tool

The Serial Ports tool sets up the serial port software to work with terminals and modems by calling the pmadm command with the appropriate information.

The tool also provides the following:

Templates for common terminal and modem configurations
Multiple port setup, modification, or deletion
Quick visual status of each port

Overview of the Service Access Facility

The SAF is the tool used for administering terminals, modems, and other network devices.

In particular, the SAF enables you to set up the following:

ttymon and listen port monitors by using the sacadm command
ttymon port monitor services by using the pmadm and ttyadm commands
listen port monitor services by using the pmadm and nlsadmin commands
Troubleshoot tty devices
Troubleshoot incoming network requests for printing service
Troubleshoot the Service Access Controller by using the sacadm command

The SAF is an open-systems solution that controls access to system and network resources through tty devices and local-area networks (LANs). The SAF is not a program, but a hierarchy of background processes and administrative commands.