The IOS and Its User Interface
29
Regardless of which access method is used, a CLI user initially is placed in user mode, or user
EXEC mode, after logging in.
EXEC
refers to the fact that the commands typed here are
executed, and some response messages are displayed onscreen. The alternative mode is
configuration mode
, which is covered in the next section.
Passwords can be required when accessing the CLI. In fact, the default configuration at IOS
12.x requires a password for Telnet and auxiliary port access, but no password is set--therefore,
you must configure passwords from the console first. Table 2-3 reviews the different types of
passwords and the configuration for each type.
The
login
command actually tells the router to display a prompt. The
password
commands
specify the text password to be typed by the user to gain access. The first command in each
configuration is a context-setting command, as described in the section "Configuration
Processes and the Configuration File," later in this chapter. Typically, all three passwords have
the same value.
Several concurrent Telnet connections to a router are allowed. The
line vty
0 4
command
signifies that this configuration applies to vtys (virtual teletypes--terminals) 0 through 4. Only
these five vtys are allowed by the IOS unless it is an IOS for a dial access server, such as a Cisco
AS5300. All five vtys typically have the same password, which is handy because users
connecting to the router via a Telnet cannot choose which vty they get.
User EXEC mode is one of two command EXEC modes in the IOS user interface.
Enable
mode
(also known as
privileged
mode or
privileged EXEC
mode) is the other. Enable mode is so
named because of the command used to reach this mode, as shown in Figure 2-4; privileged
mode earns its name because powerful, or privileged, commands can be executed there.
Table 2-3
CLI Password Configuration
Access From . . .
Password Type
Configuration
Console
Console password
line console
0
login
password
faith
Auxiliary
Auxiliary password
line aux
0
login
password
hope
Telnet
vty password
line vty
0 4
login
password
love
ch02.fm Page 29 Monday, March 20, 2000 4:57 PM