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Table of Contents

Terminal Access Security Commands

Terminal Access Security Commands

This chapter describes the commands used to control access to the router.

enable

To log on to the router at a specified level, use the enable EXEC command.

enable [level]
Syntax Description
level (Optional) Defines the privilege level that a user logs in to on the router.
Default

Level 15

Command Mode

EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.


Note The enable command is associated with privilege level 0. If you configure AAA authorization for a privilege level greater than 0, this command will not be included in the privilege level command set.
Example

In the following example, the user is logging on to privilege level 5 on a router:

enable 5
Related Commands

A dagger (+) indicates that the command is documented outside this chapter.

disable +
privilege level (global)
privilege level (line)

enable password

Use the enable password global configuration command to set a local password to control access to various privilege levels. Use the no form of this command to remove the password requirement.

enable password [level level] {password | encryption-type encrypted-password}
no enable password [level level]

Syntax Description
level level (Optional) Level for which the password applies. You can specify up to 16 privilege levels, using numbers 0 through 15. Level 1 is normal EXEC-mode user privileges. If this argument is not specified in the command or the no form of the command, the privilege level defaults to 15 (traditional enable privileges).
password Password users type to enter enable mode.
encryption-type (Optional) Cisco-proprietary algorithm used to encrypt the password. Currently the only encryption type available is 7. If you specify encryption-type, the next argument you supply must be an encrypted password (a password already encrypted by a Cisco router).
encrypted-password Encrypted password you enter, copied from another router configuration.
Default

No password is defined. The default is level 15.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Use this command with the level option to define a password for a specific privilege level. After you specify the level and the password, give the password to the users who need to access this level. Use the privilege level (global) configuration command to specify commands accessible at various levels.

You will not ordinarily enter an encryption type. Typically you enter an encryption type only if you copy and paste into this command a password that has already been encrypted by a Cisco router.

 
Caution If you specify an encryption type and then enter a cleartext password, you will not be able to reenter enable mode. You cannot recover a lost password that has been encrypted by any method.

If the service password-encryption command is set, the encrypted form of the password you create with the enable password command is displayed when a show startup-config command is entered.

You can enable or disable password encryption with the service password-encryption command.

An enable password is defined as follows:

When the system prompts you to enter the enable password, you need not precede the question mark with the Ctrl-V; you can simply enter abc?123 at the password prompt.
Examples

In the following example, the password pswd2 is enabled for privilege level 2:

enable password level 2 pswd2

In the following example the encrypted password $1$i5Rkls3LoyxzS8t9, which has been copied from a router configuration file, is set for privilege level 2 using encryption type 7:

enable password level 2 7 $1$i5Rkls3LoyxzS8t9
Related Commands

A dagger (+) indicates that the command is documented outside this chapter.

disable +
enable +
enable secret
privilege level (global)
service password-encryption
show privilege
show startup-config
+

enable secret

Use the enable secret global configuration command to specify an additional layer of security over the enable password command. Use the no form of the command to turn off the enable secret function.

enable secret [level level] {password | encryption-type encrypted-password}
no enable secret [level level]

Syntax Description
level level (Optional) Level for which the password applies. You can specify up to sixteen privilege levels, using numbers 0 through 15. Level 1 is normal EXEC-mode user privileges. If this argument is not specified in the command or in the no form of the command, the privilege level defaults to 15 (traditional enable privileges). The same holds true for the no form of the command.
password Password users type to enter enable mode. This password should be different from the password created with the enable password command.
encryption-type (Optional) Cisco-proprietary algorithm used to encrypt the password. Currently the only encryption type available for this command is 5 . If you specify encryption-type, the next argument you supply must be an encrypted password (a password encrypted by a Cisco router).
encrypted-password Encrypted password you enter, copied from another router configuration.
Default

No password is defined. The default level is 15.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.0.

Use this command in conjunction with the enable password command to provide an additional layer of security over the enable password. The enable secret command provides better security by storing the enable secret password using a non-reversible cryptographic function. The added layer of security encryption provides is useful in environments where the password crosses the network or is stored on a TFTP server.

You will not ordinarily enter an encryption type. Typically you enter an encryption type only if you paste into this command an encrypted password that you copied from a router configuration file.

 
Caution If you specify an encryption-type and then enter a cleartext password, you will not be able to reenter enable mode. You cannot recover a lost password that has been encrypted by any method.

If you use the same password for the enable password and enable secret commands, you receive an error message warning that this practice is not recommended, but the password will be accepted. By using the same password, however, you undermine the additional security the enable secret command provides.


Note After you set a password using enable secret command, a password set using the enable password command works only if the enable secret is disabled or an older version of Cisco IOS software is being used, such as when running an older rxboot image. Additionally, you cannot recover a lost password that has been encrypted by any method.

If service password-encryption is set, the encrypted form of the password you create here is displayed when a show startup-config command is entered.

You can enable or disable password encryption with the service password-encryption command.

An enable password is defined as follows:

When the system prompts you to enter the enable password, you need not precede the question mark with the Ctrl-V; you can simply enter abc?123 at the password prompt.
Examples

The following example specifies the enable secret password of gobbledegook:

enable secret gobbledegook

After specifying an enable secret password, users must enter this password to gain access. Any passwords set through enable password will no longer work.

Password: gobbledegoo

In the following example the encrypted password $1$FaD0$Xyti5Rkls3LoyxzS8, which has been copied from a router configuration file, is enabled for privilege level 2 using encryption type 5:

enable password level 2 5 $1$FaD0$Xyti5Rkls3LoyxzS8
Related Commands

A dagger (+) indicates that the command is documented outside this chapter.

enable +
enable password

ip identd

To enable identification support, use the ip identd global configuration command. Use the no form of this command to disable this feature.

ip identd
no ip identd

Syntax Description

This command has no arguments or keywords.

Default

Identification support is not enabled.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.1.

The ip identd command returns accurate information about the host TCP port; however, no attempt is made to protect against unauthorized queries.

Example

In the following example, identification support is enabled:

ip identd

login authentication

To enable TACACS+ authentication for logins, use the login authentication line configuration command. Use the no form of this command to either disable TACACS+ authentication for logins or to return to the default.

login authentication {default | list-name}
no login authentication {default | list-name}

Syntax Description
default Uses the default list created with the aaa authentication login command.
list-name Uses the indicated list created with the aaa authentication login command.
Default

Uses the default set with aaa authentication login.

Command Mode

Line configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

This command is a per-line command used with AAA that specifies the name of a list of TACACS+ authentication methods to try at login. If no list is specified, the default list is used (whether or not it is specified in the command line).

 
Caution If you use a list-name value that was not configured with the aaa authentication login command, you will disable login on this line.

Entering the no version of login authentication has the same effect as entering the command with the default argument.

Before issuing this command, create a list of authentication processes by using the global configuration aaa authentication login command.

Examples

The following example specifies that the default AAA authentication is to be used on line 4:

line 4
login authentication default

The following example specifies that the AAA authentication list called list1 is to be used on line 7:

line 7
login authentication list1
Related Command

aaa authentication login

privilege level (global)

To set the privilege level for a command, use the privilege level global configuration command. Use the no form of this command to revert to default privileges for a given command.

privilege mode level level command
no privilege
mode level level command
Syntax Description
mode Configuration mode. (See the alias command in the Configuration Fundamentals Command Reference for a description of mode.
level Privilege level associated with the specified command. You can specify up to sixteen privilege levels, using numbers 0 through 15.
command Command to which privilege level is associated.
Defaults

Level 15 is the level of access permitted by the enable password.

Level 1 is normal EXEC-mode user privileges.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

The description of the alias command, in the Configuration Fundametals Command Reference, shows the options for the mode argument in the privilege level global configuration command.

The password for a privilege level defined using the privilege level global configuration command is configured using the enable password command.

Level 0 can be used to specify a more-limited subset of commands for specific users or lines. For example, you can allow user "guest" to use only the show users and exit commands.


Note There are five commands associated with privilege level 0: disable, enable, exit, help, and logout. If you configure AAA authorization for a privilege level greater than 0, these five commands will not be included.

When you set a command to a privilege level, all commands whose syntax is a subset of that command are also set to that level. For example, if you set the show ip route command to level 15, the show commands and show ip commands are automatically set to privilege level 15--unless you set them individually to different levels.

Example

The commands in the following example set the configure command to privilege level 14 and establish SecretPswd14 as the password users must enter to use level 14 commands.

privilege exec level 14 configure
enable secret level 14 SecretPswd14
Related Commands

enable password
enable secret
privilege level (line)

privilege level (line)

To set the default privilege level for a line, use the privilege level line configuration command. Use the no form of this command to restore the default user privilege level to the line.

privilege level level
no privilege level

Syntax Description
level Privilege level associated with the specified line.
Defaults

Level 15 is the level of access permitted by the enable password.

Level 1 is normal EXEC-mode user privileges.

Command Mode

Line configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

Users can override the privilege level you set using this command by logging in to the line and enabling a different privilege level. They can lower the privilege level by using the disable command. If users know the password to a higher privilege level, they can use that password to enable the higher privilege level.

You can use level 0 to specify a subset of commands for specific users or lines. For example, you can allow user "guest" to use only the show users and exit commands.

You might specify a high level of privilege for your console line to restrict who uses the line.

Examples

The commands in the following example configure the auxiliary line for privilege level 5. Anyone using the auxiliary line has privilege level 5 by default.

line aux 0
privilege level 5

The command in the following example sets all show ip commands, which includes all show commands, to privilege level 7:

privilege exec level 7 show ip route

This is equivalent to the following command:

privilege exec level 7 show

The commands in the following example set show ip route to level 7 and the show and show ip commands to level 1:

privilege exec level 7 show ip route
privilege exec level 1 show ip 
Related Commands

enable password
privilege level (line)

service password-encryption

To encrypt passwords, use the service password-encryption global configuration command. Use the no form of this command to disable this service.

service password-encryption
no service password-encryption

Syntax Description

This command has no arguments or keywords.

Default

No encryption

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

The actual encryption process occurs when the current configuration is written or when a password is configured. Password encryption is applied to all passwords, including authentication key passwords, the privileged command password, console and virtual terminal line access passwords, and BGP neighbor passwords. This command is primarily useful for keeping unauthorized individuals from viewing your password in your configuration file.

When password encryption is enabled, the encrypted form of the passwords is displayed when a show startup-config command is entered.

 This command does not provide a high level of network security. If you use this command, you should also take additional network security measures.
Note You cannot recover a lost encrypted password. You must clear NVRAM and set a new password.
Example

The following example causes password encryption to take place:

service password-encryption
Related Commands

A dagger (+) indicates that the command is documented outside this chapter.

enable password
key-string
+
neighbor password +

show privilege

To display your current level of privilege, use the show privilege EXEC command.

show privilege
Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

Sample Display

The following is sample output from the show privilege command. The current privilege level is 15.

Router# show privilege
Current privilege level is 15
Related Commands

enable password level
enable secret level

username

To establish a username-based authentication system, enter the username global configuration command.

username name {nopassword | password password [encryption-type encrypted-password]}
username
name password secret
username
name [access-class number]
username
name [autocommand command]
username
name [callback-dialstring telephone-number]
username
name [callback-rotary rotary-group-number]
username
name [callback-line [tty] line-number [ending-line-number]]
username
name [nocallback-verify]
username
name [noescape] [nohangup]
username
name [privilege level]
Syntax Description
name Host name, server name, user ID, or command name. The name argument can be only one word. White spaces and quotation marks are not allowed.
nopassword No password is required for this user to log in. This is usually most useful in combination with the autocommand keyword.
password Specifies a possibly encrypted password for this username.
password Password a user enters.
encryption-type (Optional) Single-digit number that defines whether the text immediately following is encrypted, and, if so, what type of encryption is used. Currently defined encryption types are 0, which means that the text immediately following is not encrypted, and 7, which means that the text is encrypted using a Cisco-defined encryption algorithm.
encrypted password Encrypted password a user enters.
password (Optional) Password to access the name argument. A password must be from 1 to 25 characters, can contain embedded spaces, and must be the last option specified in the username command.
secret For CHAP authentication: specifies the secret for the local router or the remote device. The secret is encrypted when it is stored on the local router. The secret can consist of any string of up to 11 ASCII characters. There is no limit to the number of username and password combinations that can be specified, allowing any number of remote devices to be authenticated.
access-class (Optional) Specifies an outgoing access list that overrides the access list specified in the access-class line configuration command. It is used for the duration of the user's session.
number Access list number.
autocommand (Optional) Causes the specified command to be issued automatically after the user logs in. When the command is complete, the session is terminated. Because the command can be any length and contain embedded spaces, commands using the autocommand keyword must be the last option on the line.
command The command string. Because the command can be any length and contain embedded spaces, commands using the autocommand keyword must be the last option on the line.
callback-dialstring (Optional) For asynchronous callback only: permits you to specify a telephone number to pass to the DCE device.
telephone-number For asynchronous callback only: telephone number to pass to the DCE device.
callback-rotary (Optional) For asynchronous callback only: permits you to specify a rotary group number. The next available line in the rotary group is selected.
rotary-group-number For asynchronous callback only: integer between 1 and 100 that identifies the group of lines on which you want to enable a specific username for callback.
callback-line (Optional) For asynchronous callback only: specific line on which you enable a specific username for callback.
tty (Optional) For asynchronous callback only: standard asynchronous line.
line-number For asynchronous callback only: relative number of the terminal line (or the first line in a contiguous group) on which you want to enable a specific username for callback. Numbering begins with zero.
ending-line-number (Optional) Relative number of the last line in a contiguous group on which you want to enable a specific username for callback. If you omit the keyword (such as tty), then line-number and ending-line-number are absolute rather than relative line numbers.
nocallback-verify (Optional) Authentication not required for EXEC callback on the specified line.
noescape (Optional) Prevents a user from using an escape character on the host to which that user is connected.
nohangup (Optional) Prevents the security server from disconnecting the user after an automatic command (set up with the autocommand keyword) has completed. Instead, the user gets another login prompt.
privilege (Optional) Sets the privilege level for the user.
level (Optional) Number between 0 and 15 that specifies the privilege level for the user.
Default

None

Command Mode

Global configuration

Usage Guidelines

The following commands first appeared in Cisco IOS Release 10.0:
username name {nopassword | password password [encryption-type encrypted-password]}
username name password secret
username name [access-class number]
username name [autocommand command]
username name [noescape] [nohangup]
username name [privilege level]

The following commands first appeared in Cisco IOS Release 11.1:
username name [callback-dialstring telephone-number]
username name [callback-rotary rotary-group-number]
username name [callback-line [tty] line-number [ending-line-number]]
username name [nocallback-verify]

The username command provides username and/or password authentication for login purposes only. (Note that it does not provide username and/or password authentication for enable mode when the enable use-tacacs command is also configured.)

Multiple username commands can be used to specify options for a single user.

Add a username entry for each remote system that the local router communicates with and requires authentication from. The remote device must have a username entry for the local router. This entry must have the same password as the local router's entry for that remote device.

This command can be useful for defining usernames that get special treatment. For example, you can use this command to define an "info" username that does not require a password, but connects the user to a general purpose information service.

The username command is required as part of the configuration for the Challenge Handshake Authentication Protocol (CHAP). Add a username entry or each remote system the local router requires authentication from.


Note To enable the local router to respond to remote CHAP challenges, one username name entry must be the same as the hostname name entry that has already been assigned to your router.

If there is no secret specified and the debug serial-interface command is enabled, an error is displayed when a link is established and the CHAP challenge is not implemented. CHAP debugging information is available using the debug serial-interface and debug serial-packet commands. For more information about debug commands, refer to the Debug Command Reference.

Examples

To implement a service similar to the UNIX who command, which can be entered at the login prompt and lists the current users of the router, the username command takes the following form:

username who nopassword nohangup autocommand show users

To implement an information service that does not require a password to be used, the command takes the following form:

username info nopassword noescape autocommand telnet nic.ddn.mil

To implement an ID that works even if the TACACS servers all break, the command takes the following form:

username superuser password superpassword

The following example configuration enables CHAP on interface serial 0. It also defines a password for the local server, Adam, and a remote server, Eve.

hostname Adam
interface serial 0
encapsulation ppp
ppp authentication chap
username Adam password oursystem
username Eve password theirsystem

When you look at your configuration file, the passwords will be encrypted and the display will look similar to the following:

hostname Adam
interface serial 0
encapsulation ppp
ppp authentication chap
username Adam password 7 1514040356
username Eve password 7 121F0A18
Related Commands

A dagger (+) indicates that the command is documented outside this chapter. Two daggers (++) indicate that the command is documented in the Debug Command Reference.

arap callback +
callback-forced-wait
+
debug callback ++
ppp callback +

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