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Passwords restrict access to routers.
Passwords should always be configured for virtual terminal lines and
the console line. Passwords are also used to control access to
privileged EXEC mode so that only authorized users may make changes to
the configuration file. The following commands are used to set
an optional but recommended password on the console line:
Router(config)#line console
0
Router(config-line)#password <password>
Router(config-line)#login
A password must be set on one or more
of the virtual terminal (VTY) lines for users to gain remote access to
the router using Telnet. Typically Cisco routers support five VTY
lines numbered 0 through 4, although different hardware platforms
support different numbers on VTY connections. Often the same password
is used for all lines but sometimes one line is set uniquely to
provide a fall-back entry to the router if the other four connections
are in use. The following commands are used to set the password on the
VTY lines:
Router(config)#line vty 0 4
Router(config-line)#password <password>
Router(config-line)#login
The enable password and the enable
secret are used to restrict access to the privileged EXEC mode. The
enable password is only used if the enable secret has not been set. It
is recommended that the enable secret always be set and used because
it is encrypted while the enable password is not encrypted. These are
the commands that are used to set the enable passwords:
Router(config)#enable
password <password>
Router(config)#enable secret <password>
Sometimes it is undesirable for
passwords to be shown in clear text in the output from the
show running-config
or show startup-config
commands. This command is used to encrypt passwords in configuration
output:
Router(config)#service
password-encryption
The
service password-encryption
command applies a weak encryption to all unencrypted passwords. The
enable secret <password>
command uses a strong MD5 algorithm for encryption.
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Lab Activity
Lab Exercise: Configuring Router Passwords
This lab is to configure a password for
console login to user mode and configure a password for virtual
terminal (Telnet) sessions.
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Lab Activity
e-Lab Activity: Configuring Router Passwords
In this lab, the student will configure passwords for the
console, virtual terminals, and a secret password .
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Lab Activity
e-Lab Activity: Command-line Interface Command Modes
In this lab, the students will learn to enter some of the
most common modes the router supports.
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