Managing Terminals and Modems (Overview)
This chapter provides the overview information for managing terminals and modems. This is a list of the overview information in this chapter.
For step-by-step instructions about how to set up terminals and modems with Serial Ports Tool, see Chapter 11, Setting Up Terminals and Modems (Tasks).
For step-by-step instructions about how to set up terminals and modems with the Service Access Facility (SAF), see Chapter 12, Managing Serial Ports With the Service Access Facility (Tasks).
What's New in Managing Terminals and Modems?
The Solaris Management Console provides a Serial Ports Tool for setting up terminals and modems. For information on starting the Solaris Management Console, see "Starting the Solaris Management Console" in System Administration Guide: Basic Administration. For information on step-by-step instructions for setting up a terminal or modem, see the console online help.
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 Solaris environment.
Terminals
Your system's bit-mapped graphics display is not the same as an alphanumeric terminal, which connects to a serial port and displays only text. You don't have to perform any special steps to administer the graphics display.
Modems
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, meaning you can access other computers from your own home, but nobody outside can gain access to your machine.
Dial-in service is just the opposite. It allows people to access a system from remote sites, but it does not permit calls to the outside world.
Bidirectional access, as the name implies, provides both dial-in and dial-out capabilities.
Ports
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 plugged.
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 includes most modems, alphanumeric terminals, plotters, and some printers) can be plugged 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, it might be necessary 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
Modems and terminals gain access to computing resources via the serial port software. The 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 Solaris environment.
Table 10-1 Port Monitor Types
You might be familiar with an older port monitor called getty(1M). The new ttymon is more powerful; a single ttymon can replace multiple occurrences of getty. Otherwise, these two programs serve the same function.
Tools for Managing Terminals and Modems
The following table lists the tools for managing terminals and modems.
Table 10-2 Tools For Managing Terminals and Modems
Tool Description | Tool | For More Information |
|---|---|---|
The most comprehensive | Service Access Facility (SAF) commands | |
The quickest setup | Solaris Management Console's Serial Ports Tool | Chapter 11, Setting Up Terminals and Modems (Tasks)and Solaris Management Console online help |
The quickest setup | Admintool | Admintool online help |
Serial Ports Tool
Serial Ports Tool sets up the serial port software to work with terminals and modems by calling the pmadm command with the appropriate information. It also provides:
Templates for common terminal and modem configurations
Multiple port setup, modification, or deletion
Quick visual status of each port
Service Access Facility
The SAF is the tool used for administering terminals, modems, and other network devices. In particular, SAF enables you to set up:
ttymon and listen port monitors (using the sacadm command)
ttymon port monitor services (using the pmadm and ttyadm commands)
listen port monitor services (using the pmadm and nlsadmin commands)
And troubleshoot tty devices
And troubleshoot incoming network requests for printing service
And troubleshoot the Service Access Controller (using the sacadm command)