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Table of Contents

Working with the EXEC Facility
 Choosing a Method of Connecting to the Network
 Accessing Different Command Modes
Getting Context Sensitive Help

Working with the EXEC Facility

This chapter introduces the EXEC facility and describes some of the common command modes you use when working with the Cisco AccessPath Integrated Access System.

Topics in this chapter include the following:

Choosing a Method of Connecting to the Network

The prompt that appears when you first log in to any AccessPath system shelf is called the EXEC prompt. When you access the EXEC prompt, you are accessing the EXEC facility and starting an EXEC session. You can log in through the following ports on an Access Server Shelf:

This chapter discusses how to configure the Access Server Shelves to permit remote clients to dial in and gain access to network resources (such as printers and file servers).

You can enable remote clients to dial in and access network resources in two ways:

In general, you should give system administrators access to the EXEC facility, but give dialin clients access only to the network. The next section "Permitting Users to Connect Directly to the Network" describes how to enable users to log in to the network without ever seeing the Access Server Shelf.

Permitting Users to Connect Directly to the Network

When a user dials in to the AccessPath system, the Cisco IOS software running on the Access Server Shelf can detect the incoming protocol automatically if you configure it to autoselect the protocol. To autoselect the Point-to-Point Protocol (PPP), issue two commands: the async mode interactive asynchronous interface configuration command and the autoselect ppp line configuration command. After you have issued these commands, if the Cisco IOS software detects that the remote device is using PPP protocol, it can launch PPP sessions automatically.

Autoselect bypasses security dialogs for users who log in to an EXEC session on the AccessPath system. If you configure a line to detect PPP automatically, Cisco recommends that you use Challenge Handshake Authentication Protocol (CHAP) authentication. For complete security information, refer to Chapter 7.

Figure 2-1 shows the authentication process when autoselect is used.


Figure 2-1   Flowchart of EXEC Facility and Autoselect Authentication Options


If you issue the autoselect ppp line configuration command, you must first issue the async mode interactive asynchronous interface configuration command. The async mode interactive command enables the interface to select a protocol type dynamically. If you do not enter the async mode interactive command before you issue the autoselect ppp command, the following warning message appears: "%Autoselect w/o the interface command `Async mode interactive' is useless." Refer to Chapter 5 for more information.

Figure 2-2 shows an example of what clients see when they connect to the network using PPP.


Figure 2-2   Client Connection to an IP Network Using Windows 95 PPP Application


After clients using PPP connect to the network, they have access to all IP network resources, such as UNIX hosts for Telnet or FTP sessions, other PCs on the network, or Windows NT servers.

Connecting to the EXEC Facility

If you permit users to dial in to the EXEC facility, they can use terminal services (such as Telnet), run an asynchronous protocol over the line, or use one of many other access services. For example, users who arte permitted to dial in to the EXEC facility can enter the ppp command to initiate a PPP session with a device on the network.

To enable users to log in to the EXEC facility, issue the autoselect during-login line configuration command. When Cisco IOS software detects a carriage return, the user is connected to the EXEC facility. You also access the EXEC facility any time you log in to the AccessPath system through the Failsafe/Console Management Shelf to configure it.

There are two primary levels to the EXEC facility:

  • User level EXEC mode, which is what you see when you first log in to an Access Server Shelf, whether from a remote client, or through a console port connection:
nas01>
  • Privileged level EXEC mode, which provides access to configuration mode. To enter privileged level EXEC mode, you issue the enable command, enter the enable password, and press Return, as shown in the following example:
nas01> enable
Password:
nas01#

AccessPath system network administrators should protect privileged level EXEC mode with a password that only network administrators know. This gives users access only to the user-level EXEC mode so that they can issue commands to connect with other network devices (such as the ppp command) and prevents them from changing the configuration of the AccessPath system.

For an overview of configuration mode, refer to the next section, "Accessing Different Command Modes." For information about configuring security, refer to Chapter 7.

Accessing Different Command Modes

In addition to the EXEC facility, you can access several different command modes on AccessPath system shelves. Each command mode permits you to configure different components. Table 2-1 lists the most common components and configuration modes.

You configure global parameters in global configuration mode, interface parameters in interface configuration mode, and line parameters in line configuration mode. For more information about using these configuration modes, refer to Configuration Fundamentals Configuration Guide, which is part of the Cisco IOS documentation in Cisco IOS Releases 11.1 and later.

Table 2-1   Common Command Modes

Command Mode Access Method Prompt Exit Method

User EXEC

Log in.

Router>

Use the logout command.

Privileged EXEC

From user EXEC mode, enter the enable EXEC command.

Router#

To exit back to user EXEC mode, use the disable, exit, or logout command.

Global configuration

From privileged EXEC mode, enter the configure terminal command.

Router(config)#

To exit to privileged EXEC mode, use the exit or end command or press Ctrl-Z.

Interface configuration

Enter the interface type number command, such as interface ethernet 0.

Router(config-if)#

To exit to global configuration mode, use the exit command.

To exit directly to privileged EXEC mode, use the end command or press Ctrl-Z.

Line configuration

Enter the line start-number end-number command, such as line 1 16.

Router(config-line)#

To exit to global configuration mode, use the exit command.

To exit directly to privileged EXEC mode, use the end command or press Ctrl-Z.

Getting Context Sensitive Help

You can get help in any of the command modes listed in Table 2-1. The help available in the Cisco IOS software describes the syntax for each command. If you enter the first few letters of a command, Help displays the complete name of the command. To get context sensitive help, type ? (a question mark) at the prompt. There are two types of help available—full help and partial help:

  • Full help—Type a ? at the configuration prompt, or after entering part of a command, followed by a space. The configuration parser displays options available with the command.

Typing ? at the command prompt displays all available commands for that command mode. The following example shows sample output for the commands available in privileged EXEC mode:

nas01# ?
Exec commands:
  access-enable    Create a temporary Access-List entry
  access-template  Create a temporary Access-List entry
  bfe              For manual emergency modes setting
  clear            Reset functions
...
  write            Write running configuration to memory, network, or terminal
  x3               Set X.3 parameters on PAD
  xremote          Enter XRemote mode

For example, if you are in global configuration mode and want to see all the keywords and arguments for the ip command, you could type ip ?. The following example shows the resulting output:

nas01(config)#ip ?
Global IP configuration subcommands:
access-list Named access-list
accounting-list       Select hosts for which IP accounting information
is kept
accounting-threshold  Sets the maximum number of accounting entries
accounting-transits   Sets the maximum number of transit entries
address-pool Specify default IP address pooling mechanism
alias Alias an IP address to a TCP port
as-path BGP autonomous system path filter
 . . .
nas01(config)#ip
  • Partial help—Type part of the name of a command followed by a ? (without an intervening space). The configuration parser identifies the rest of the command you enter. For example, if you are in global configuration mode and want to see the complete spelling of the command, you could type e?. The following example shows the resulting output:
nas01(config)# e?
enable  end  endnode  exit
nas01(config)#e

Refer to the chapter "Configuring the User Interface" in the Configuration Fundamentals Configuration Guide for more information about any aspect of working with the user interface in the Cisco IOS software. The Configuration Fundamentals Configuration Guide is part of the Cisco IOS documentation in Cisco IOS Releases 11.1 and later.


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Posted: Tue Jan 21 00:21:34 PST 2003
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