Cisco IOS Terminal Services Configuration Guide, Release 12.4T
Monitoring Control Characters on Asynchronous Lines
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Monitoring Control Characters on Asynchronous Lines

Table Of Contents

Monitoring Control Characters on Asynchronous Lines

Contents

Prerequisites for Monitoring Control Characters on Asynchronous Lines

Information About Monitoring Control Characters on Asynchronous Lines

Asynchronous Line Monitoring

Control Characters

The Keyboard Lock

Benefits of the Monitoring Control Characters on Asynchronous Lines Feature

How to Configure Monitoring Control Characters on Asynchronous Lines

Configuring the Display of Control Characters

Deactivating the Keyboard Lock

Configuration Examples for Monitoring Control Characters on Asynchronous Lines

Configuring the Display of Control Characters: Example

Deactivating the Keyboard Lock: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference


Monitoring Control Characters on Asynchronous Lines


The Asynchronous Line Monitoring feature introduced in Cisco IOS Release 12.2(4)T allows the monitoring of inbound and outbound asynchronous character mode traffic on another terminal line. The Monitoring Control Characters on Asynchronous Lines feature enhances the Asynchronous Line Monitoring feature by introducing the ability to monitor control characters along with printable characters. In addition, a keyboard lock has been introduced to prevent characters that are entered at the monitoring workstation from being displayed to the user of the line that is being monitored.

Feature History for Monitoring Control Characters on Asynchronous Lines

Release
Modification

12.3(8)T

This feature was introduced.


Finding Support Information for Platforms and Cisco IOS Software Images

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Contents

Prerequisites for Monitoring Control Characters on Asynchronous Lines

Information About Monitoring Control Characters on Asynchronous Lines

How to Configure Monitoring Control Characters on Asynchronous Lines

Configuration Examples for Monitoring Control Characters on Asynchronous Lines

Additional References

Command Reference

Prerequisites for Monitoring Control Characters on Asynchronous Lines

You should understand the Asynchronous Line Monitoring feature before configuring the Monitoring Control Characters on Asynchronous Lines feature.

Information About Monitoring Control Characters on Asynchronous Lines

To configure the Monitoring Control Characters on Asynchronous Lines feature, you should understand the following concepts:

Asynchronous Line Monitoring

Control Characters

The Keyboard Lock

Benefits of the Monitoring Control Characters on Asynchronous Lines Feature

Asynchronous Line Monitoring

Figure 1 shows a scenario for asynchronous character mode traffic in which a remote user on Workstation 1 uses reverse Telnet to access an asynchronous port of Router A, causing a TTY Daemon process (such as TTY Daemon 1) to run on the asynchronous port of Router A. The user then dials in to an asynchronous port on Router B. The user commands are interpreted by an EXEC process (such as EXEC process 1) on Router B. To monitor the inbound or outbound asynchronous traffic on this port on Router A, you must log in to Router A through another terminal line—for example, another terminal line when logging in from Workstation 2—and enter the monitor traffic line command. The command is interpreted by a second EXEC process (such as EXEC process 2).

Figure 1 Reverse Telnet to a Router Followed by a Dial over a PSTN Connection

Control Characters

The ACSII character set consists of printable and nonprintable characters. Prior to Cisco IOS Release 12.3(8)T, only the printable ASCII characters could be monitored. The Monitoring Control Characters on Asynchronous Lines feature introduces the ability to monitor the nonprintable (control) ASCII characters.

The Keyboard Lock

When asynchronous character traffic is being monitored, the user of the remote monitoring station can enter more commands on the line they are using. In releases prior to Cisco IOS Release 12.3(8)T, the output of the additional commands is displayed not only to the user of the remote monitoring station but also to the user of the terminal line that is being monitored.

In Release 12.3(8)T the default behavior of the monitor traffic line command has been changed so that commands entered by the user on the remote monitoring station are not displayed to the user on the terminal line being monitored. The display of commands entered by the user on the remote monitoring station to the user on the terminal line being monitored can be enabled if desired.

Benefits of the Monitoring Control Characters on Asynchronous Lines Feature

The Monitoring Control Characters on Asynchronous Lines feature enhances the Asynchronous Line Monitoring feature. The following are benefits of the Monitoring Control Characters on Asynchronous Lines feature:

The ability to monitor control characters along with printable characters.

The ability to configure whether the display of commands entered by the user on the remote monitoring station are visible to the user on the terminal line being monitored.

How to Configure Monitoring Control Characters on Asynchronous Lines

This section contains the following procedures:

Configuring the Display of Control Characters (required)

Deactivating the Keyboard Lock (optional)

Configuring the Display of Control Characters

Perform this task to include control characters in the display.

SUMMARY STEPS

1. enable

2. monitor traffic line [aux | tty] line-number [in | out] [control-char] [interactive]

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

monitor traffic line [aux | tty] line-number [in | out] [control-char] [interactive]

Example:

Router# monitor traffic line tty 1 in control-char

Monitors inbound and outbound asynchronous character mode traffic on another terminal line.

control-char—Control characters are displayed along with asynchronous character mode traffic. Control character display is turned off by default.

interactive—Commands entered on the remote monitoring station are displayed to the user of the terminal line being monitored. By default, commands entered at the remote monitoring station are not displayed on the station being monitored (the keyboard lock is on).

Note To disable asynchronous line monitoring, enter the escape sequence (Ctrl-Shift-6, then x [Ctrl^x] by default).

Deactivating the Keyboard Lock

The keyboard lock is enabled by default. Perform this task to deactivate the keyboard lock.

SUMMARY STEPS

1. enable

2. monitor traffic line [aux | tty] line-number [in | out] [control-char] [interactive]

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

monitor traffic line [aux | tty] line-number [in | out] [control-char] [interactive]

Example:

Router# monitor traffic line tty 1 in interactive

Monitors inbound and outbound asynchronous character mode traffic on another terminal line.

control-char—Control characters are displayed along with asynchronous character mode traffic. Control character display is turned off by default.

interactive—Commands entered on the remote monitoring station are displayed to the user of the terminal line being monitored. By default, commands entered at the remote monitoring station are not displayed on the station being monitored (the keyboard lock is on).

Note To disable asynchronous line monitoring, enter the escape sequence (Ctrl-Shift-6, then x [Ctrl^x] by default).

Configuration Examples for Monitoring Control Characters on Asynchronous Lines

This section provides the following configuration examples:

Configuring the Display of Control Characters: Example

Deactivating the Keyboard Lock: Example

Configuring the Display of Control Characters: Example

The following example allows the user to monitor inbound asynchronous character mode traffic, including control characters, on tty line 10:

Router# monitor traffic line tty 10 in control-char

Deactivating the Keyboard Lock: Example

The following example allows the user to monitor inbound asynchronous character mode traffic on line 5. The interactive keyword turns off the keyboard lock, specifying that commands entered at the remote monitoring station will be displayed to the user of the line being monitored.

Router# monitor traffic line 5 in interactive

Additional References

The following sections provide references related to the Monitoring Control Characters on Asynchronous Lines feature.

Related Documents

Related Topic
Document Title

Asynchronous Line Monitoring feature documentation

Asynchronous Line Monitoring

Configuration tasks related to Dial Technologies

Cisco IOS Dial Technologies Configuration Guide

Dial Technologies commands: complete command syntax, command mode, defaults, usage guidelines, and examples

Cisco IOS Dial Technologies Command Reference

Configuration tasks related to Terminal Services

Cisco IOS Dial Technologies Configuration Guide

Terminal Services commands: complete command syntax, command mode, defaults, usage guidelines, and examples

Cisco IOS Terminal Services Command Reference


Standards

Standards
Title

None


MIBs

MIBs
MIBs Link

None

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs


RFCs

RFCs
Title

None


Technical Assistance

Description
Link

Technical Assistance Center (TAC) home page, containing 30,000 pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

http://www.cisco.com/public/support/tac/home.shtml


Command Reference

The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS Terminal Services Command Reference at http://www.cisco.com/en/US/docs/ios/termserv/command/reference/tsv_book.html. For information about all Cisco IOS commands, go to the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or to the Cisco IOS Master Commands List.

monitor traffic line