Cisco IOS Software Configuration Guide for Cisco Aironet Access Points, 12.2(13)JA
Administering the Access Point
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Administering the Access Point

Table Of Contents

Administering the Access Point

Preventing Unauthorized Access to Your Access Point

Protecting Access to Privileged EXEC Commands

Default Password and Privilege Level Configuration

Setting or Changing a Static Enable Password

Protecting Enable and Enable Secret Passwords with Encryption

Configuring Username and Password Pairs

Configuring Multiple Privilege Levels

Setting the Privilege Level for a Command

Logging Into and Exiting a Privilege Level

Controlling Access Point Access with RADIUS

Default RADIUS Configuration

Configuring RADIUS Login Authentication

Defining AAA Server Groups

Configuring RADIUS Authorization for User Privileged Access and Network Services

Displaying the RADIUS Configuration

Controlling Access Point Access with TACACS+

Default TACACS+ Configuration

Configuring TACACS+ Login Authentication

Configuring TACACS+ Authorization for Privileged EXEC Access and Network Services

Displaying the TACACS+ Configuration

Configuring the Access Point for Wireless Network Management

Configuring the Access Point for Local Authentication and Authorization

Configuring the Access Point to Provide DHCP Service

Setting up the DHCP Server

Monitoring and Maintaining the DHCP Server Access Point

Show Commands

Clear Commands

Debug Command

Configuring the Access Point for Secure Shell

Understanding SSH

Configuring SSH

Configuring Client ARP Caching

Understanding Client ARP Caching

Optional ARP Caching

Configuring ARP Caching

Managing the System Time and Date

Understanding the System Clock

Understanding Network Time Protocol

Configuring NTP

Default NTP Configuration

Configuring NTP Authentication

Configuring NTP Associations

Configuring NTP Broadcast Service

Configuring NTP Access Restrictions

Configuring the Source IP Address for NTP Packets

Displaying the NTP Configuration

Configuring Time and Date Manually

Setting the System Clock

Displaying the Time and Date Configuration

Configuring the Time Zone

Configuring Summer Time (Daylight Saving Time)

Configuring a System Name and Prompt

Default System Name and Prompt Configuration

Configuring a System Name

Understanding DNS

Default DNS Configuration

Setting Up DNS

Displaying the DNS Configuration

Creating a Banner

Default Banner Configuration

Configuring a Message-of-the-Day Login Banner

Configuring a Login Banner


Administering the Access Point


This chapter describes how to administer your access point. This chapter contains these sections:

Preventing Unauthorized Access to Your Access Point

Protecting Access to Privileged EXEC Commands

Controlling Access Point Access with RADIUS

Controlling Access Point Access with TACACS+

Configuring the Access Point for Wireless Network Management

Configuring the Access Point for Local Authentication and Authorization

Configuring the Access Point to Provide DHCP Service

Configuring the Access Point for Secure Shell

Configuring Client ARP Caching

Managing the System Time and Date

Configuring a System Name and Prompt

Creating a Banner

Preventing Unauthorized Access to Your Access Point

You can prevent unauthorized users from reconfiguring your access point and viewing configuration information. Typically, you want network administrators to have access to the access point while you restrict access to users who connect through a terminal or workstation from within the local network.

To prevent unauthorized access to your access point, you should configure one of these security features:

Username and password pairs, which are locally stored on the access point. These pairs authenticate each user before that user can access the access point. You can also assign a specific privilege level (read only or read/write) to each username and password pair. For more information, see the "Configuring Username and Password Pairs" section. The default username is Cisco, and the default password is Cisco. Usernames and passwords are case-sensitive.

Username and password pairs stored centrally in a database on a security server. For more information, see the "Controlling Access Point Access with RADIUS" section.

Protecting Access to Privileged EXEC Commands

A simple way of providing terminal access control in your network is to use passwords and assign privilege levels. Password protection restricts access to a network or network device. Privilege levels define what commands users can issue after they have logged into a network device.


Note For complete syntax and usage information for the commands used in this section, refer to the Cisco IOS Security Command Reference for Release 12.2.


This section describes how to control access to the configuration file and privileged EXEC commands. It contains this configuration information:

Default Password and Privilege Level Configuration

Setting or Changing a Static Enable Password

Protecting Enable and Enable Secret Passwords with Encryption

Configuring Username and Password Pairs

Configuring Multiple Privilege Levels

Default Password and Privilege Level Configuration

Table 5-1 shows the default password and privilege level configuration.

Table 5-1 Default Password and Privilege Levels 

Feature
Default Setting

Username and password

Default username is Cisco and the default password is Cisco.

Enable password and privilege level

Default password is Cisco. The default is level 15 (privileged EXEC level). The password is encrypted in the configuration file.

Enable secret password and privilege level

The default enable password is Cisco. The default is level 15 (privileged EXEC level). The password is encrypted before it is written to the configuration file.

Line password

Default password is Cisco. The password is encrypted in the configuration file.


Setting or Changing a Static Enable Password

The enable password controls access to the privileged EXEC mode.


Note The no enable password global configuration command removes the enable password, but you should use extreme care when using this command. If you remove the enable password, you are locked out of the EXEC mode.


Beginning in privileged EXEC mode, follow these steps to set or change a static enable password:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

enable password password

Define a new password or change an existing password for access to privileged EXEC mode.

The default password is Cisco.

For password, specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. It can contain the question mark (?) character if you precede the question mark with the key combination Crtl-V when you create the password; for example, to create the password abc?123, do this:

1. Enter abc.

2. Enter Crtl-V.

3. Enter ?123.

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.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show running-config

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

The enable password is not encrypted and can be read in the access point configuration file.

This example shows how to change the enable password to l1u2c3k4y5. The password is not encrypted and provides access to level 15 (traditional privileged EXEC mode access):

AP(config)# enable password l1u2c3k4y5

Protecting Enable and Enable Secret Passwords with Encryption

To provide an additional layer of security, particularly for passwords that cross the network or that are stored on a Trivial File Transfer Protocol (TFTP) server, you can use either the enable password or enable secret global configuration commands. Both commands accomplish the same thing; that is, you can establish an encrypted password that users must enter to access privileged EXEC mode (the default) or any privilege level you specify.

We recommend that you use the enable secret command because it uses an improved encryption algorithm.

If you configure the enable secret command, it takes precedence over the enable password command; the two commands cannot be in effect simultaneously.

Beginning in privileged EXEC mode, follow these steps to configure encryption for enable and enable secret passwords:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

enable password [level level] {password | encryption-type encrypted-password}

or

enable secret [level level] {password | encryption-type encrypted-password}

Define a new password or change an existing password for access to privileged EXEC mode.

or

Define a secret password, which is saved using a nonreversible encryption method.

(Optional) For level, the range is from 0 to 15. Level 1 is normal user EXEC mode privileges. The default level is 15 (privileged EXEC mode privileges).

For password, specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. By default, no password is defined.

(Optional) For encryption-type, only type 5, a Cisco proprietary encryption algorithm, is available. If you specify an encryption type, you must provide an encrypted password—an encrypted password you copy from another access point configuration.

Note If you specify an encryption type and then enter a clear text password, you can not re-enter privileged EXEC mode. You cannot recover a lost encrypted password by any method.

Step 3 

service password-encryption

(Optional) Encrypt the password when the password is defined or when the configuration is written.

Encryption prevents the password from being readable in the configuration file.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

If both the enable and enable secret passwords are defined, users must enter the enable secret password.

Use the level keyword to define a password for a specific privilege level. After you specify the level and set a password, give the password only to users who need to have access at this level. Use the privilege level global configuration command to specify commands accessible at various levels. For more information, see the "Configuring Multiple Privilege Levels" section.

If you enable password encryption, it applies to all passwords including username passwords, authentication key passwords, the privileged command password, and console and virtual terminal line passwords.

To remove a password and level, use the no enable password [level level] or no enable secret [level level] global configuration command. To disable password encryption, use the no service password-encryption global configuration command.

This example shows how to configure the encrypted password $1$FaD0$Xyti5Rkls3LoyxzS8 for privilege level 2:

AP(config)# enable secret level 2 5 $1$FaD0$Xyti5Rkls3LoyxzS8

Configuring Username and Password Pairs

You can configure username and password pairs, which are locally stored on the access point. These pairs are assigned to lines or interfaces and authenticate each user before that user can access the access point. If you have defined privilege levels, you can also assign a specific privilege level (with associated rights and privileges) to each username and password pair.

Beginning in privileged EXEC mode, follow these steps to establish a username-based authentication system that requests a login username and a password:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

username name [privilege level] {password encryption-type password}

Enter the username, privilege level, and password for each user.

For name, specify the user ID as one word. Spaces and quotation marks are not allowed.

(Optional) For level, specify the privilege level the user has after gaining access. The range is 0 to 15. Level 15 gives privileged EXEC mode access. Level 1 gives user EXEC mode access.

For encryption-type, enter 0 to specify that an unencrypted password will follow. Enter 7 to specify that a hidden password will follow.

For password, specify the password the user must enter to gain access to the access point. The password must be from 1 to 25 characters, can contain embedded spaces, and must be the last option specified in the username command.

Step 3 

login local

Enable local password checking at login time. Authentication is based on the username specified in Step 2.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show running-config

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To disable username authentication for a specific user, use the no username name global configuration command.

To disable password checking and allow connections without a password, use the no login line configuration command.


Note You must have at least one username configured and you must have login local set to open a Telnet session to the access point. If you enter no username for the only username, you can be locked out of the access point.


Configuring Multiple Privilege Levels

By default, Cisco IOS software has two modes of password security: user EXEC and privileged EXEC. You can configure up to 16 hierarchical levels of commands for each mode. By configuring multiple passwords, you can allow different sets of users to have access to specified commands.

For example, if you want many users to have access to the clear line command, you can assign it level 2 security and distribute the level 2 password fairly widely. But if you want more restricted access to the configure command, you can assign it level 3 security and distribute that password to a more restricted group of users.

This section includes this configuration information:

Setting the Privilege Level for a Command

Logging Into and Exiting a Privilege Level

Setting the Privilege Level for a Command

Beginning in privileged EXEC mode, follow these steps to set the privilege level for a command mode:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

privilege mode level level command

Set the privilege level for a command.

For mode, enter configure for global configuration mode, exec for EXEC mode, interface for interface configuration mode, or line for line configuration mode.

For level, the range is from 0 to 15. Level 1 is for normal user EXEC mode privileges. Level 15 is the level of access permitted by the enable password.

For command, specify the command to which you want to restrict access.

Step 3 

enable password level level password

Specify the enable password for the privilege level.

For level, the range is from 0 to 15. Level 1 is for normal user EXEC mode privileges.

For password, specify a string from 1 to 25 alphanumeric characters. The string cannot start with a number, is case sensitive, and allows spaces but ignores leading spaces. By default, no password is defined.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show running-config

or

show privilege

Verify your entries.

The first command displays the password and access level configuration. The second command displays the privilege level configuration.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

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.

To return to the default privilege for a given command, use the no privilege mode level level command global configuration command.

This example shows how to set the configure command to privilege level 14 and define SecretPswd14 as the password users must enter to use level 14 commands:

AP(config)# privilege exec level 14 configure
AP(config)# enable password level 14 SecretPswd14

Logging Into and Exiting a Privilege Level

Beginning in privileged EXEC mode, follow these steps to log in to a specified privilege level and to exit to a specified privilege level:

 
Command
Purpose

Step 1 

enable level

Log in to a specified privilege level.

For level, the range is 0 to 15.

Step 2 

disable level

Exit to a specified privilege level.

For level, the range is 0 to 15.

Controlling Access Point Access with RADIUS

This section describes how to control administrator access to the access point using Remote Authentication Dial-In User Service (RADIUS). For complete instructions on configuring the access point to support RADIUS, see "Configuring RADIUS and TACACS+ Servers."

RADIUS provides detailed accounting information and flexible administrative control over authentication and authorization processes. RADIUS is facilitated through AAA and can be enabled only through AAA commands.


Note For complete syntax and usage information for the commands used in this section, refer to the Cisco IOS Security Command Reference for Release 12.2.


These sections describe RADIUS configuration:

Default RADIUS Configuration

Configuring RADIUS Login Authentication (required)

Defining AAA Server Groups (optional)

Configuring RADIUS Authorization for User Privileged Access and Network Services (optional)

Displaying the RADIUS Configuration

Default RADIUS Configuration

RADIUS and AAA are disabled by default.

To prevent a lapse in security, you cannot configure RADIUS through a network management application. When enabled, RADIUS can authenticate users accessing the access point through the CLI.

Configuring RADIUS Login Authentication

To configure AAA authentication, you define a named list of authentication methods and then apply that list to various interfaces. The method list defines the types of authentication to be performed and the sequence in which they are performed; it must be applied to a specific interface before any of the defined authentication methods are performed. The only exception is the default method list (which, by coincidence, is named default). The default method list is automatically applied to all interfaces except those that have a named method list explicitly defined.

A method list describes the sequence and authentication methods to be queried to authenticate a user. You can designate one or more security protocols to be used for authentication, thus ensuring a backup system for authentication in case the initial method fails. The software uses the first method listed to authenticate users; if that method fails to respond, the software selects the next authentication method in the method list. This process continues until there is successful communication with a listed authentication method or until all defined methods are exhausted. If authentication fails at any point in this cycle—meaning that the security server or local username database responds by denying the user access—the authentication process stops, and no other authentication methods are attempted.

Beginning in privileged EXEC mode, follow these steps to configure login authentication. This procedure is required.

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

aaa new-model

Enable AAA.

Step 3 

aaa authentication login {default | list-name} method1 [method2...]

Create a login authentication method list.

To create a default list that is used when a named list is not specified in the login authentication command, use the default keyword followed by the methods that are to be used in default situations. The default method list is automatically applied to all interfaces.

For list-name, specify a character string to name the list you are creating.

For method1..., specify the actual method the authentication algorithm tries. The additional methods of authentication are used only if the previous method returns an error, not if it fails.

Select one of these methods:

local—Use the local username database for authentication. You must enter username information in the database. Use the username password global configuration command.

radius—Use RADIUS authentication. You must configure the RADIUS server before you can use this authentication method. For more information, see the "Identifying the RADIUS Server Host" section.

Step 4 

line [console | tty | vty] line-number [ending-line-number]

Enter line configuration mode, and configure the lines to which you want to apply the authentication list.

Step 5 

login authentication {default | list-name}

Apply the authentication list to a line or set of lines.

If you specify default, use the default list created with the aaa authentication login command.

For list-name, specify the list created with the aaa authentication login command.

Step 6 

end

Return to privileged EXEC mode.

Step 7 

show running-config

Verify your entries.

Step 8 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To disable AAA, use the no aaa new-model global configuration command. To disable AAA authentication, use the no aaa authentication login {default | list-name} method1 [method2...] global configuration command. To either disable RADIUS authentication for logins or to return to the default value, use the no login authentication {default | list-name} line configuration command.

Defining AAA Server Groups

You can configure the access point to use AAA server groups to group existing server hosts for authentication. You select a subset of the configured server hosts and use them for a particular service. The server group is used with a global server-host list, which lists the IP addresses of the selected server hosts.

Server groups also can include multiple host entries for the same server if each entry has a unique identifier (the combination of the IP address and UDP port number), allowing different ports to be individually defined as RADIUS hosts providing a specific AAA service. If you configure two different host entries on the same RADIUS server for the same service (such as accounting), the second configured host entry acts as a fail-over backup to the first one.

You use the server group server configuration command to associate a particular server with a defined group server. You can either identify the server by its IP address or identify multiple host instances or entries by using the optional auth-port and acct-port keywords.

Beginning in privileged EXEC mode, follow these steps to define the AAA server group and associate a particular RADIUS server with it:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

aaa new-model

Enable AAA.

Step 3 

radius-server host {hostname | ip-address} [auth-port port-number] [acct-port port-number] [timeout seconds] [retransmit retries] [key string]

Specify the IP address or host name of the remote RADIUS server host.

(Optional) For auth-port port-number, specify the UDP destination port for authentication requests.

(Optional) For acct-port port-number, specify the UDP destination port for accounting requests.

(Optional) For timeout seconds, specify the time interval that the access point waits for the RADIUS server to reply before retransmitting. The range is 1 to 1000. This setting overrides the radius-server timeout global configuration command setting. If no timeout is set with the radius-server host command, the setting of the radius-server timeout command is used.

(Optional) For retransmit retries, specify the number of times a RADIUS request is resent to a server if that server is not responding or responding slowly. The range is 1 to 1000. If no retransmit value is set with the radius-server host command, the setting of the radius-server retransmit global configuration command is used.

(Optional) For key string, specify the authentication and encryption key used between the access point and the RADIUS daemon running on the RADIUS server.

Note The key is a text string that must match the encryption key used on the RADIUS server. Always configure the key as the last item in the radius-server host command. Leading spaces are ignored, but spaces within and at the end of the key are used. If you use spaces in your key, do not enclose the key in quotation marks unless the quotation marks are part of the key.

To configure the access point to recognize more than one host entry associated with a single IP address, enter this command as many times as necessary, making sure that each UDP port number is different. The access point software searches for hosts in the order in which you specify them. Set the timeout, retransmit, and encryption key values to use with the specific RADIUS host.

Step 4 

aaa group server radius group-name

Define the AAA server-group with a group name.

This command puts the access point in a server group configuration mode.

Step 5 

server ip-address

Associate a particular RADIUS server with the defined server group. Repeat this step for each RADIUS server in the AAA server group.

Each server in the group must be previously defined in Step 2.

Step 6 

end

Return to privileged EXEC mode.

Step 7 

show running-config

Verify your entries.

Step 8 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Step 9 

 

Enable RADIUS login authentication. See the "Configuring RADIUS Login Authentication" section.

To remove the specified RADIUS server, use the no radius-server host hostname | ip-address global configuration command. To remove a server group from the configuration list, use the no aaa group server radius group-name global configuration command. To remove the IP address of a RADIUS server, use the no server ip-address server group configuration command.

In this example, the access point is configured to recognize two different RADIUS group servers (group1 and group2). Group1 has two different host entries on the same RADIUS server configured for the same services. The second host entry acts as a fail-over backup to the first entry.

AP(config)# aaa new-model
AP(config)# radius-server host 172.20.0.1 auth-port 1000 acct-port 1001
AP(config)# radius-server host 172.10.0.1 auth-port 1645 acct-port 1646
AP(config)# aaa group server radius group1
AP(config-sg-radius)# server 172.20.0.1 auth-port 1000 acct-port 1001
AP(config-sg-radius)# exit
AP(config)# aaa group server radius group2
AP(config-sg-radius)# server 172.20.0.1 auth-port 2000 acct-port 2001
AP(config-sg-radius)# exit

Configuring RADIUS Authorization for User Privileged Access and Network Services

AAA authorization limits the services available to a user. When AAA authorization is enabled, the access point uses information retrieved from the user's profile, which is in the local user database or on the security server, to configure the user's session. The user is granted access to a requested service only if the information in the user profile allows it.

You can use the aaa authorization global configuration command with the radius keyword to set parameters that restrict a user's network access to privileged EXEC mode.

The aaa authorization exec radius local command sets these authorization parameters:

Use RADIUS for privileged EXEC access authorization if authentication was performed by using RADIUS.

Use the local database if authentication was not performed by using RADIUS.


Note Authorization is bypassed for authenticated users who log in through the CLI even if authorization has been configured.


Beginning in privileged EXEC mode, follow these steps to specify RADIUS authorization for privileged EXEC access and network services:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

aaa authorization network radius

Configure the access point for user RADIUS authorization for all network-related service requests.

Step 3 

aaa authorization exec radius

Configure the access point for user RADIUS authorization to determine if the user has privileged EXEC access.

The exec keyword might return user profile information (such as autocommand information).

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show running-config

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To disable authorization, use the no aaa authorization {network | exec} method1 global configuration command.

Displaying the RADIUS Configuration

To display the RADIUS configuration, use the show running-config privileged EXEC command.

Controlling Access Point Access with TACACS+

This section describes how to control administrator access to the access point using Terminal Access Controller Access Control System Plus (TACACS+). For complete instructions on configuring the access point to support TACACS+, see "Configuring RADIUS and TACACS+ Servers."

TACACS+ provides detailed accounting information and flexible administrative control over authentication and authorization processes. TACACS+ is facilitated through AAA and can be enabled only through AAA commands.


Note For complete syntax and usage information for the commands used in this section, refer to the Cisco IOS Security Command Reference for Release 12.2.


These sections describe TACACS+ configuration:

Default TACACS+ Configuration

Configuring TACACS+ Login Authentication

Configuring TACACS+ Authorization for Privileged EXEC Access and Network Services

Displaying the TACACS+ Configuration

Default TACACS+ Configuration

TACACS+ and AAA are disabled by default.

To prevent a lapse in security, you cannot configure TACACS+ through a network management application.When enabled, TACACS+ can authenticate administrators accessing the access point through the CLI.

Configuring TACACS+ Login Authentication

To configure AAA authentication, you define a named list of authentication methods and then apply that list to various interfaces. The method list defines the types of authentication to be performed and the sequence in which they are performed; it must be applied to a specific interface before any of the defined authentication methods are performed. The only exception is the default method list (which, by coincidence, is named default). The default method list is automatically applied to all interfaces except those that have a named method list explicitly defined. A defined method list overrides the default method list.

A method list describes the sequence and authentication methods to be queried to authenticate a user. You can designate one or more security protocols to be used for authentication, thus ensuring a backup system for authentication in case the initial method fails. The software uses the first method listed to authenticate users; if that method fails, the software selects the next authentication method in the method list. This process continues until there is successful communication with a listed authentication method or until all defined methods are exhausted. If authentication fails at any point in this cycle—meaning that the security server or local username database responds by denying the user access—the authentication process stops, and no other authentication methods are attempted.

Beginning in privileged EXEC mode, follow these steps to configure login authentication. This procedure is required.

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

aaa new-model

Enable AAA.

Step 3 

aaa authentication login {default | list-name} method1 [method2...]

Create a login authentication method list.

To create a default list that is used when a named list is not specified in the login authentication command, use the default keyword followed by the methods that are to be used in default situations. The default method list is automatically applied to all interfaces.

For list-name, specify a character string to name the list you are creating.

For method1..., specify the actual method the authentication algorithm tries. The additional methods of authentication are used only if the previous method returns an error, not if it fails.

Select one of these methods:

local—Use the local username database for authentication. You must enter username information into the database. Use the username password global configuration command.

tacacs+—Use TACACS+ authentication. You must configure the TACACS+ server before you can use this authentication method.

Step 4 

line [console | tty | vty] line-number [ending-line-number]

Enter line configuration mode, and configure the lines to which you want to apply the authentication list.

Step 5 

login authentication {default | list-name}

Apply the authentication list to a line or set of lines.

If you specify default, use the default list created with the aaa authentication login command.

For list-name, specify the list created with the aaa authentication login command.

Step 6 

end

Return to privileged EXEC mode.

Step 7 

show running-config

Verify your entries.

Step 8 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To disable AAA, use the no aaa new-model global configuration command. To disable AAA authentication, use the no aaa authentication login {default | list-name} method1 [method2...] global configuration command. To either disable TACACS+ authentication for logins or to return to the default value, use the no login authentication {default | list-name} line configuration command.

Configuring TACACS+ Authorization for Privileged EXEC Access and Network Services

AAA authorization limits the services available to a user. When AAA authorization is enabled, the access point uses information retrieved from the user's profile, which is located either in the local user database or on the security server, to configure the user's session. The user is granted access to a requested service only if the information in the user profile allows it.

You can use the aaa authorization global configuration command with the tacacs+ keyword to set parameters that restrict a user's network access to privileged EXEC mode.

The aaa authorization exec tacacs+ local command sets these authorization parameters:

Use TACACS+ for privileged EXEC access authorization if authentication was performed by using TACACS+.

Use the local database if authentication was not performed by using TACACS+.


Note Authorization is bypassed for authenticated users who log in through the CLI even if authorization has been configured.


Beginning in privileged EXEC mode, follow these steps to specify TACACS+ authorization for privileged EXEC access and network services:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

aaa authorization network tacacs+

Configure the access point for user TACACS+ authorization for all network-related service requests.

Step 3 

aaa authorization exec tacacs+

Configure the access point for user TACACS+ authorization to determine if the user has privileged EXEC access.

The exec keyword might return user profile information (such as autocommand information).

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show running-config

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To disable authorization, use the no aaa authorization {network | exec} method1 global configuration command.

Displaying the TACACS+ Configuration

To display TACACS+ server statistics, use the show tacacs privileged EXEC command.

Configuring the Access Point for Wireless Network Management

You can enable the access point for wireless network management. The wireless network manager (WNM) manages the devices on your wireless LAN.

Enter this command to configure the access point to interact with the WNM:

AP(config)# wlccp wnm ip address ip-address

Enter this command to check the authentication status between the WDS access point and the WNM:

AP# show wlccp wnm status

Possible statuses are not authenticated, authentication in progress, authentication fail, authenticated, and security keys setup.

Configuring the Access Point for Local Authentication and Authorization

You can configure AAA to operate without a server by configuring the access point to implement AAA in local mode. The access point then handles authentication and authorization. No accounting is available in this configuration.


Note You can configure your access point as a local authenticator for 802.1x-enabled client devices to provide a backup for your main server or to provide authentication service on a network without a RADIUS server. See "Configuring an Access Point as a Local Authenticator," for detailed instructions on configuring your access point as a local authenticator.


Beginning in privileged EXEC mode, follow these steps to configure the access point for local AAA:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

aaa new-model

Enable AAA.

Step 3 

aaa authentication login default local

Set the login authentication to use the local username database. The default keyword applies the local user database authentication to all interfaces.

Step 4 

aaa authorization exec local

Configure user AAA authorization to determine if the user is allowed to run an EXEC shell by checking the local database.

Step 5 

aaa authorization network local

Configure user AAA authorization for all network-related service requests.

Step 6 

username name [privilege level] {password encryption-type password}

Enter the local database, and establish a username-based authentication system.

Repeat this command for each user.

For name, specify the user ID as one word. Spaces and quotation marks are not allowed.

(Optional) For level, specify the privilege level the user has after gaining access. The range is 0 to 15. Level 15 gives privileged EXEC mode access. Level 0 gives user EXEC mode access.

For encryption-type, enter 0 to specify that an unencrypted password follows. Enter 7 to specify that a hidden password follows.

For password, specify the password the user must enter to gain access to the access point. The password must be from 1 to 25 characters, can contain embedded spaces, and must be the last option specified in the username command.

Step 7 

end

Return to privileged EXEC mode.

Step 8 

show running-config

Verify your entries.

Step 9 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To disable AAA, use the no aaa new-model global configuration command. To disable authorization, use the no aaa authorization {network | exec} method1 global configuration command.

Configuring the Access Point to Provide DHCP Service

These sections describe how to configure the access point to act as a DHCP server:

Setting up the DHCP Server

Monitoring and Maintaining the DHCP Server Access Point

Setting up the DHCP Server

By default, access points are configured to receive IP settings from a DHCP server on your network. You can also configure an access point to act as a DHCP server to assign IP settings to devices on both your wired and wireless LANs.

The 1100 series access point becomes a mini-DHCP server by default when it is configured with factory default settings and it cannot receive IP settings from a DHCP server. As a mini-DHCP server, the 1100 series access point provides up to 20 IP addresses between 10.0.0.11 and 10.0.0.30 to a PC connected to its Ethernet port and to wireless client devices configured to use either no SSID or tsunami as the SSID, and with all security settings disabled. The mini-DHCP server feature is disabled automatically when you assign a static IP address to the 1100 series access point. Because it has a console port to simplify initial setup, the 1200 series access point does not become a DHCP server automatically.

For detailed information on DHCP-related commands and options, refer to the Configuring DHCP chapter in the Cisco IOS IP Configuration Guide, Release 12.2. Click this URL to browse to the "Configuring DHCP" chapter:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a00800ca75c.html

Beginning in privileged EXEC mode, follow these steps to configure an access point to provide DHCP service:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

ip dhcp excluded-address low_address [ high_address ]

Exclude the access point's IP address from the range of addresses the access point assigns. Enter the IP address in four groups of characters, such as 10.91.6.158.

The access point assumes that all IP addresses in a DHCP address pool subnet are available for assigning to DHCP clients. You must specify the IP addresses that the DHCP Server should not assign to clients.

(Optional) To enter a range of excluded addresses, enter the address at the low end of the range followed by the address at the high end of the range.

Step 3 

ip dhcp pool pool_name

Create a name for the pool of IP addresses that the access point assigns in response to DHCP requests, and enter DHCP configuration mode.

Step 4 

network subnet_number
[ mask | prefix-length ]

Assign the subnet number for the address pool. The access point assigns IP addresses within this subnet.

(Optional) Assign a subnet mask for the address pool, or specify the number of bits that comprise the address prefix. The prefix is an alternative way of assigning the network mask. The prefix length must be preceded by a forward slash (/).

Step 5 

lease { days [ hours ] [ minutes ] |
infinite }

Configure the duration of the lease for IP addresses assigned by the access point.

days—configure the lease duration in number of days

(optional) hours—configure the lease duration in number of hours

(optional) minutes—configure the lease duration in number of minutes

infinite—set the lease duration to infinite

Step 6 

end

Return to privileged EXEC mode.

Step 7 

show running-config

Verify your entries.

Step 8 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Use the no form of these commands to return to default settings.

This example shows how to configure the access point as a DHCP server:

AP# configure terminal
AP(config)# ip dhcp excluded-address 172.16.1.100 172.16.1.117
AP(config)# ip dhcp pool wishbone
AP(dhcp-config)# network 172.16.1.0 255.255.255.0
AP(dhcp-config)# lease 10
AP(dhcp-config)# end

Monitoring and Maintaining the DHCP Server Access Point

These sections describe commands you can use to monitor and maintain the DHCP server access point:

Show Commands

Clear Commands

Debug Command

Show Commands

In Exec mode, enter the commands in Table 5-2 to display information about the access point as DHCP server.

Table 5-2 Show Commands for DHCP Server

Command
Purpose

show ip dhcp conflict [ address ]

Displays a list of all address conflicts recorded by a specific DHCP Server. Enter the access point's IP address to show conflicts recorded by the access point.

show ip dhcp database [ url ]

Displays recent activity on the DHCP database.

Note Use this command in privileged EXEC mode.

show ip dhcp server statistics

Displays count information about server statistics and messages sent and received.


Clear Commands

In privileged Exec mode, use the commands in Table 5-3 to clear DHCP server variables.

Table 5-3 Clear Commands for DHCP Server

Command
Purpose

clear ip dhcp binding
{ address | * }

Deletes an automatic address binding from the DHCP database. Specifying the address argument clears the automatic binding for a specific (client) IP address. Specifying an asterisk (*) clears all automatic bindings.

clear ip dhcp conflict
{ address | * }

Clears an address conflict from the DHCP database. Specifying the address argument clears the conflict for a specific IP address. Specifying an asterisk (*) clears conflicts for all addresses.

clear ip dhcp server statistics

Resets all DHCP Server counters to 0.


Debug Command

To enable DHCP server debugging, use this command in privileged EXEC mode:

debug ip dhcp server { events | packets | linkage }

Use the no form of the command to disable debugging for the access point DHCP server.

Configuring the Access Point for Secure Shell

This section describes how to configure the Secure Shell (SSH) feature.


Note For complete syntax and usage information for the commands used in this section, refer to the "Secure Shell Commands" section in the Cisco IOS Security Command Reference for Release 12.2.


Understanding SSH

SSH is a protocol that provides a secure, remote connection to a Layer 2 or a Layer 3 device. There are two versions of SSH: SSH version 1 and SSH version 2. This software release supports only SSH version 1.

SSH provides more security for remote connections than Telnet by providing strong encryption when a device is authenticated. The SSH feature has an SSH server and an SSH integrated client. The client supports these user authentication methods:

RADIUS (for more information, see the "Controlling Access Point Access with RADIUS" section)

Local authentication and authorization (for more information, see the "Configuring the Access Point for Local Authentication and Authorization" section)

For more information about SSH, refer to the "Configuring Secure Shell" section in the Cisco IOS Security Configuration Guide for Release 12.2.


Note The SSH feature in this software release does not support IP Security (IPSec).


Configuring SSH

Before configuring SSH, download the crypto software image from Cisco.com. For more information, refer to the release notes for this release.

For information about configuring SSH and displaying SSH settings, refer to the "Configuring Secure Shell" section in the Cisco IOS Security Configuration Guide for Release 12.2.

Configuring Client ARP Caching

You can configure the access point to maintain an ARP cache for associated client devices. Maintaining an ARP cache on the access point reduces the trafic load on your wireless LAN. ARP caching is disabled by default.

This section contains this information:

Understanding Client ARP Caching

Configuring ARP Caching

Understanding Client ARP Caching

ARP caching on the access point reduces the traffic on your wireless LAN by stopping ARP requests for client devices at the access point. Instead of forwarding ARP requests to client devices, the access point responds to requests on behalf of associated client devices.

When ARP caching is disabled, the access point forwards all ARP requests through the radio port to associated clients, and the client to which the ARP request is directed responds. When ARP caching is enabled, the access point responds to ARP requests for associated clients and does not forward requests to clients. When the access point receives an ARP request for an IP address not in the cache, the access point drops the request and does not forward it.

Optional ARP Caching

When a non-Cisco client device is associated to an access point and is not passing data, the access point might not know the client's IP address. If this situation occurs frequently on your wireless LAN, you can enable optional ARP caching. When ARP caching is optional, the access point responds on behalf of clients with IP addresses known to the access point but forwards out its radio port any ARP requests addressed to unknown clients. When the access point learns the IP addresses for all associated clients, it drops ARP requests not directed to its associated clients.

Configuring ARP Caching

Beginning in privileged EXEC mode, follow these steps to configure the access point to maintain an ARP cache for associated clients:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

dot11 arp-cache [ optional ]

Enable ARP caching on the access point.

(Optional) Use the optional keyword to enable ARP caching only for the client devices whose IP addresses are known to the access point.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show running-config

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

This example shows how to configure ARP caching on an access point:

AP# configure terminal
AP(config)# dot11 arp-cache
AP(config)# end

Managing the System Time and Date

You can manage the system time and date on your access point automatically, using the Network Time Protocol (NTP), or manually, by setting the time and date on the access point.


Note For complete syntax and usage information for the commands used in this section, refer to the Cisco IOS Configuration Fundamentals Command Reference for Release 12.2.


This section contains this configuration information:

Understanding the System Clock

Understanding Network Time Protocol

Configuring NTP

Configuring Time and Date Manually

Understanding the System Clock

The heart of the time service is the system clock. This clock runs from the moment the system starts up and keeps track of the date and time.

The system clock can then be set from these sources:

Network Time Protocol

Manual configuration

The system clock can provide time to these services:

User show commands

Logging and debugging messages

The system clock determines time internally based on Universal Time Coordinated (UTC), also known as Greenwich Mean Time (GMT). You can configure information about the local time zone and summer time (daylight saving time) so that the time is correctly displayed for the local time zone.

The system clock keeps track of whether the time is authoritative or not (that is, whether it has been set by a time source considered to be authoritative). If it is not authoritative, the time is available only for display purposes and is not redistributed. For configuration information, see the "Configuring Time and Date Manually" section.

Understanding Network Time Protocol

The NTP is designed to time-synchronize a network of devices. NTP runs over User Datagram Protocol (UDP), which runs over IP. NTP is documented in RFC 1305.

An NTP network usually gets its time from an authoritative time source, such as a radio clock or an atomic clock attached to a time server. NTP then distributes this time across the network. NTP is extremely efficient; no more than one packet per minute is necessary to synchronize two devices to within a millisecond of one another.

NTP uses the concept of a stratum to describe how many NTP hops away a device is from an authoritative time source. A stratum 1 time server has a radio or atomic clock directly attached, a stratum 2 time server receives its time through NTP from a stratum 1 time server, and so on. A device running NTP automatically chooses as its time source the device with the lowest stratum number with which it communicates through NTP. This strategy effectively builds a self-organizing tree of NTP speakers.

NTP avoids synchronizing to a device whose time might not be accurate by never synchronizing to a device that is not synchronized. NTP also compares the time reported by several devices and does not synchronize to a device whose time is significantly different than the others, even if its stratum is lower.

The communications between devices running NTP (known as associations) are usually statically configured; each device is given the IP address of all devices with which it should form associations. Accurate timekeeping is possible by exchanging NTP messages between each pair of devices with an association. However, in a LAN environment, NTP can be configured to use IP broadcast messages instead. This alternative reduces configuration complexity because each device can simply be configured to send or receive broadcast messages. However, in that case, information flow is one-way only.

The time kept on a device is a critical resource; you should use the security features of NTP to avoid the accidental or malicious setting of an incorrect time. Two mechanisms are available: an access-list-based restriction scheme and an encrypted authentication mechanism.

Cisco's implementation of NTP does not support stratum 1 service; it is not possible to connect to a radio or atomic clock. We recommend that the time service for your network be derived from the public NTP servers available on the IP Internet. Figure 5-1 shows a typical network example using NTP.

If the network is isolated from the Internet, Cisco's implementation of NTP allows a device to act as though it is synchronized through NTP, when in fact it has determined the time by using other means. Other devices then synchronize to that device through NTP.

When multiple sources of time are available, NTP is always considered to be more authoritative. NTP time overrides the time set by any other method.

Several manufacturers include NTP software for their host systems, and a publicly available version for systems running UNIX and its various derivatives is also available. This software allows host systems to be time-synchronized as well.

Figure 5-1 Typical NTP Network Configuration

Configuring NTP

Cisco Aironet 1100 Series Access Points do not have a hardware-supported clock, and they cannot function as an NTP master clock to which peers synchronize themselves when an external NTP source is not available. These access points also have no hardware support for a calendar. As a result, the ntp update-calendar and the ntp master global configuration commands are not available.

This section contains this configuration information:

Default NTP Configuration

Configuring NTP Authentication

Configuring NTP Associations

Configuring NTP Broadcast Service

Configuring NTP Access Restrictions

Configuring the Source IP Address for NTP Packets

Displaying the NTP Configuration

Default NTP Configuration

Table 5-4 shows the default NTP configuration.

Table 5-4 Default NTP Configuration 

Feature
Default Setting

NTP authentication

Disabled. No authentication key is specified.

NTP peer or server associations

None configured.

NTP broadcast service

Disabled; no interface sends or receives NTP broadcast packets.

NTP access restrictions

No access control is specified.

NTP packet source IP address

The source address is determined by the outgoing interface.


NTP is disabled by default.

Configuring NTP Authentication

This procedure must be coordinated with the administrator of the NTP server; the information you configure in this procedure must be matched by the servers used by the access point to synchronize its time to the NTP server.

Beginning in privileged EXEC mode, follow these steps to authenticate the associations (communications between devices running NTP that provide for accurate timekeeping) with other devices for security purposes:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

ntp authenticate

Enable the NTP authentication feature, which is disabled by default.

Step 3 

ntp authentication-key number md5 value

Define the authentication keys. By default, none are defined.

For number, specify a key number. The range is 1 to 4294967295.

md5 specifies that message authentication support is provided by using the message digest algorithm 5 (MD5).

For value, enter an arbitrary string of up to eight characters for the key.

The access point does not synchronize to a device unless both have one of these authentication keys, and the key number is specified by the ntp trusted-key key-number command.

Step 4 

ntp trusted-key key-number

Specify one or more key numbers (defined in Step 3) that a peer NTP device must provide in its NTP packets for this access point to synchronize to it.

By default, no trusted keys are defined.

For key-number, specify the key defined in Step 3.

This command provides protection against accidentally synchronizing the access point to a device that is not trusted.

Step 5 

end

Return to privileged EXEC mode.

Step 6 

show running-config

Verify your entries.

Step 7 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To disable NTP authentication, use the no ntp authenticate global configuration command. To remove an authentication key, use the no ntp authentication-key number global configuration command. To disable authentication of the identity of a device, use the no ntp trusted-key key-number global configuration command.

This example shows how to configure the access point to synchronize only to devices providing authentication key 42 in the device's NTP packets:

AP(config)# ntp authenticate
AP(config)# ntp authentication-key 42 md5 aNiceKey
AP(config)# ntp trusted-key 42

Configuring NTP Associations

An NTP association can be a peer association (this access point can either synchronize to the other device or allow the other device to synchronize to it), or it can be a server association (meaning that only this access point synchronizes to the other device, and not the other way around).

Beginning in privileged EXEC mode, follow these steps to form an NTP association with another device:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

ntp peer ip-address [version number] [key keyid] [source interface] [prefer]

or

ntp server ip-address [version number] [key keyid] [source interface] [prefer]

Configure the access point system clock to synchronize a peer or to be synchronized by a peer (peer association).

or

Configure the access point system clock to be synchronized by a time server (server association).

No peer or server associations are defined by default.

For ip-address in a peer association, specify either the IP address of the peer providing, or being provided, the clock synchronization. For a server association, specify the IP address of the time server providing the clock synchronization.

(Optional) For number, specify the NTP version number. The range is 1 to 3. By default, version 3 is selected.

(Optional) For keyid, enter the authentication key defined with the ntp authentication-key global configuration command.

(Optional) For interface, specify the interface from which to pick the IP source address. By default, the source IP address is taken from the outgoing interface.

(Optional) Enter the prefer keyword to make this peer or server the preferred one that provides synchronization. This keyword reduces switching back and forth between peers and servers.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show running-config

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

You need to configure only one end of an association; the other device can automatically establish the association. If you are using the default NTP version (version 3) and NTP synchronization does not occur, try using NTP version 2. Many NTP servers on the Internet run version 2.

To remove a peer or server association, use the no ntp peer ip-address or the no ntp server ip-address global configuration command.

This example shows how to configure the access point to synchronize its system clock with the clock of the peer at IP address 172.16.22.44 using NTP version 2:

AP(config)# ntp server 172.16.22.44 version 2

Configuring NTP Broadcast Service

The communications between devices running NTP (known as associations) are usually statically configured; each device is given the IP addresses of all devices with which it should form associations. Accurate timekeeping is possible by exchanging NTP messages between each pair of devices with an association. However, in a LAN environment, NTP can be configured to use IP broadcast messages instead. This alternative reduces configuration complexity because each device can simply be configured to send or receive broadcast messages. However, the information flow is one-way only.

The access point can send or receive NTP broadcast packets on an interface-by-interface basis if there is an NTP broadcast server, such as a router, broadcasting time information on the network. The access point can send NTP broadcast packets to a peer so that the peer can synchronize to it. The access point can also receive NTP broadcast packets to synchronize its own clock. This section provides procedures for both sending and receiving NTP broadcast packets.

Beginning in privileged EXEC mode, follow these steps to configure the access point to send NTP broadcast packets to peers so that they can synchronize their clock to the access point:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface interface-id

Enter interface configuration mode, and specify the interface to send NTP broadcast packets.

Step 3 

ntp broadcast [version number] [key keyid] [destination-address]

Enable the interface to send NTP broadcast packets to a peer.

By default, this feature is disabled on all interfaces.

(Optional) For number, specify the NTP version number. The range is 1 to 3. If you do not specify a version, version 3 is used.

(Optional) For keyid, specify the authentication key to use when sending packets to the peer.

(Optional) For destination-address, specify the IP address of the peer that is synchronizing its clock to this access point.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show running-config

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Step 7 

 

Configure the connected peers to receive NTP broadcast packets as described in the next procedure.

To disable the interface from sending NTP broadcast packets, use the no ntp broadcast interface configuration command.

This example shows how to configure an interface to send NTP version 2 packets:

AP(config)# interface gigabitethernet0/1
AP(config-if)# ntp broadcast version 2

Beginning in privileged EXEC mode, follow these steps to configure the access point to receive NTP broadcast packets from connected peers:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface interface-id

Enter interface configuration mode, and specify the interface to receive NTP broadcast packets.

Step 3 

ntp broadcast client

Enable the interface to receive NTP broadcast packets.

By default, no interfaces receive NTP broadcast packets.

Step 4 

exit

Return to global configuration mode.

Step 5 

ntp broadcastdelay microseconds

(Optional) Change the estimated round-trip delay between the access point and the NTP broadcast server.

The default is 3000 microseconds; the range is 1 to 999999.

Step 6 

end

Return to privileged EXEC mode.

Step 7 

show running-config

Verify your entries.

Step 8 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To disable an interface from receiving NTP broadcast packets, use the no ntp broadcast client interface configuration command. To change the estimated round-trip delay to the default, use the no ntp broadcastdelay global configuration command.

This example shows how to configure an interface to receive NTP broadcast packets:

AP(config)# interface gigabitethernet0/1
AP(config-if)# ntp broadcast client

Configuring NTP Access Restrictions

You can control NTP access on two levels as described in these sections:

Creating an Access Group and Assigning a Basic IP Access List

Disabling NTP Services on a Specific Interface

Creating an Access Group and Assigning a Basic IP Access List

Beginning in privileged EXEC mode, follow these steps to control access to NTP services by using access lists:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

ntp access-group {query-only | serve-only | serve | peer} access-list-number

Create an access group, and apply a basic IP access list.

The keywords have these meanings:

query-only—Allows only NTP control queries.

serve-only—Allows only time requests.

serve—Allows time requests and NTP control queries, but does not allow the access point to synchronize to the remote device.

peer—Allows time requests and NTP control queries and allows the access point to synchronize to the remote device.

For access-list-number, enter a standard IP access list number from 1 to 99.

Step 3 

access-list access-list-number permit source [source-wildcard]

Create the access list.

For access-list-number, enter the number specified in Step 2.

Enter the permit keyword to permit access if the conditions are matched.

For source, enter the IP address of the device that is permitted access to the access point.

(Optional) For source-wildcard, enter the wildcard bits to be applied to the source.

Note When creating an access list, remember that, by default, the end of the access list contains an implicit deny statement for everything if it did not find a match before reaching the end.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show running-config

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

The access group keywords are scanned in this order, from least restrictive to most restrictive:

1. peer—Allows time requests and NTP control queries and allows the access point to synchronize itself to a device whose address passes the access list criteria.

2. serve—Allows time requests and NTP control queries, but does not allow the access point to synchronize itself to a device whose address passes the access list criteria.

3. serve-only—Allows only time requests from a device whose address passes the access list criteria.

4. query-only—Allows only NTP control queries from a device whose address passes the access list criteria.

If the source IP address matches the access lists for more than one access type, the first type is granted. If no access groups are specified, all access types are granted to all devices. If any access groups are specified, only the specified access types are granted.

To remove access control to the access point NTP services, use the no ntp access-group {query-only | serve-only | serve | peer} global configuration command.

This example shows how to configure the access point to allow itself to synchronize to a peer from access list 99. However, the access point restricts access to allow only time requests from access list 42:

AP# configure terminal
AP(config)# ntp access-group peer 99
AP(config)# ntp access-group serve-only 42
AP(config)# access-list 99 permit 172.20.130.5
AP(config)# access list 42 permit 172.20.130.6

Disabling NTP Services on a Specific Interface

NTP services are enabled on all interfaces by default.

Beginning in privileged EXEC mode, follow these steps to disable NTP packets from being received on an interface:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface interface-id

Enter interface configuration mode, and specify the interface to disable.

Step 3 

ntp disable

Disable NTP packets from being received on the interface.

By default, all interfaces receive NTP packets.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show running-config

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To re-enable receipt of NTP packets on an interface, use the no ntp disable interface configuration command.

Configuring the Source IP Address for NTP Packets

When the access point sends an NTP packet, the source IP address is normally set to the address of the interface through which the NTP packet is sent. Use the ntp source global configuration command when you want to use a particular source IP address for all NTP packets. The address is taken from the specified interface. This command is useful if the address on an interface cannot be used as the destination for reply packets.

Beginning in privileged EXEC mode, follow these steps to configure a specific interface from which the IP source address is to be taken:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

ntp source type number

Specify the interface type and number from which the IP source address is taken.

By default, the source address is determined by the outgoing interface.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show running-config

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

The specified interface is used for the source address for all packets sent to all destinations. If a source address is to be used for a specific association, use the source keyword in the ntp peer or ntp server global configuration command as described in the "Configuring NTP Associations" section.

Displaying the NTP Configuration

You can use two privileged EXEC commands to display NTP information:

show ntp associations [detail]

show ntp status

For detailed information about the fields in these displays, refer to the Cisco IOS Configuration Fundamentals Command Reference for Release 12.1.

Configuring Time and Date Manually

If no other source of time is available, you can manually configure the time and date after the system is restarted. The time remains accurate until the next system restart. We recommend that you use manual configuration only as a last resort. If you have an outside source to which the access point can synchronize, you do not need to manually set the system clock.

This section contains this configuration information:

Setting the System Clock

Displaying the Time and Date Configuration

Configuring the Time Zone

Configuring Summer Time (Daylight Saving Time)

Setting the System Clock

If you have an outside source on the network that provides time services, such as an NTP server, you do not need to manually set the system clock.

Beginning in privileged EXEC mode, follow these steps to set the system clock:

 
Command
Purpose

Step 1 

clock set hh:mm:ss day month year

or

clock set hh:mm:ss month day year

Manually set the system clock using one of these formats.

For hh:mm:ss, specify the time in hours (24-hour format), minutes, and seconds. The time specified is relative to the configured time zone.

For day, specify the day by date in the month.

For month, specify the month by name.

For year, specify the year (no abbreviation).

Step 2 

show running-config

Verify your entries.

Step 3 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

This example shows how to manually set the system clock to 1:32 p.m. on July 23, 2001:

AP# clock set 13:32:00 23 July 2001

Displaying the Time and Date Configuration

To display the time and date configuration, use the show clock [detail] privileged EXEC command.

The system clock keeps an authoritative flag that shows whether the time is authoritative (believed to be accurate). If the system clock has been set by a timing source such as NTP, the flag is set. If the time is not authoritative, it is used only for display purposes. Until the clock is authoritative and the authoritative flag is set, the flag prevents peers from synchronizing to the clock when the peers' time is invalid.

The symbol that precedes the show clock display has this meaning:

*—Time is not authoritative.

(blank)—Time is authoritative.

.—Time is authoritative, but NTP is not synchronized.

Configuring the Time Zone

Beginning in privileged EXEC mode, follow these steps to manually configure the time zone:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

clock timezone zone hours-offset [minutes-offset]

Set the time zone.

The access point keeps internal time in universal time coordinated (UTC), so this command is used only for display purposes and when the time is manually set.

For zone, enter the name of the time zone to be displayed when standard time is in effect. The default is UTC.

For hours-offset, enter the hours offset from UTC.

(Optional) For minutes-offset, enter the minutes offset from UTC.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show running-config

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

The minutes-offset variable in the clock timezone global configuration command is available for those cases where a local time zone is a percentage of an hour different from UTC. For example, the time zone for some sections of Atlantic Canada (AST) is UTC-3.5, where the 3 means 3 hours and .5 means 50 percent. In this case, the necessary command is clock timezone AST -3 30.

To set the time to UTC, use the no clock timezone global configuration command.

Configuring Summer Time (Daylight Saving Time)

Beginning in privileged EXEC mode, follow these steps to configure summer time (daylight saving time) in areas where it starts and ends on a particular day of the week each year:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

clock summer-time zone recurring [week day month hh:mm week day month hh:mm [offset]]

Configure summer time to start and end on the specified days every year.

Summer time is disabled by default. If you specify clock summer-time zone recurring without parameters, the summer time rules default to the United States rules.

For zone, specify the name of the time zone (for example, PDT) to be displayed when summer time is in effect.

(Optional) For week, specify the week of the month (1 to 5 or last).

(Optional) For day, specify the day of the week (Sunday, Monday...).

(Optional) For month, specify the month (January, February...).

(Optional) For hh:mm, specify the time (24-hour format) in hours and minutes.

(Optional) For offset, specify the number of minutes to add during summer time. The default is 60.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show running-config

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

The first part of the clock summer-time global configuration command specifies when summer time begins, and the second part specifies when it ends. All times are relative to the local time zone. The start time is relative to standard time. The end time is relative to summer time. If the starting month is after the ending month, the system assumes that you are in the southern hemisphere.

This example shows how to specify that summer time starts on the first Sunday in April at 02:00 and ends on the last Sunday in October at 02:00:

AP(config)# clock summer-time PDT recurring 1 Sunday April 2:00 last Sunday October 2:00 

Beginning in privileged EXEC mode, follow these steps if summer time in your area does not follow a recurring pattern (configure the exact date and time of the next summer time events):

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

clock summer-time zone date [month date year hh:mm month date year hh:mm [offset]]

or

clock summer-time zone date [date month year hh:mm date month year hh:mm [offset]]

Configure summer time to start on the first date and end on the second date.

Summer time is disabled by default.

For zone, specify the name of the time zone (for example, PDT) to be displayed when summer time is in effect.

(Optional) For week, specify the week of the month (1 to 5 or last).

(Optional) For day, specify the day of the week (Sunday, Monday...).

(Optional) For month, specify the month (January, February...).

(Optional) For hh:mm, specify the time (24-hour format) in hours and minutes.

(Optional) For offset, specify the number of minutes to add during summer time. The default is 60.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show running-config

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

The first part of the clock summer-time global configuration command specifies when summer time begins, and the second part specifies when it ends. All times are relative to the local time zone. The start time is relative to standard time. The end time is relative to summer time. If the starting month is after the ending month, the system assumes that you are in the southern hemisphere.

To disable summer time, use the no clock summer-time global configuration command.

This example shows how to set summer time to start on October 12, 2000, at 02:00, and end on April 26, 2001, at 02:00:

AP(config)# clock summer-time pdt date 12 October 2000 2:00 26 April 2001 2:00

Configuring a System Name and Prompt

You configure the system name on the access point to identify it. By default, the system name and prompt are ap.

If you have not configured a system prompt, the first 20 characters of the system name are used as the system prompt. A greater-than symbol (>) is appended. The prompt is updated whenever the system name changes, unless you manually configure the prompt by using the prompt global configuration command.


Note For complete syntax and usage information for the commands used in this section, refer to the Cisco IOS Configuration Fundamentals Command Reference and the Cisco IOS IP and IP Routing Command Reference for Release 12.1.


This section contains this configuration information:

Default System Name and Prompt Configuration

Configuring a System Name

Understanding DNS

Default System Name and Prompt Configuration

The default access point system name and prompt is ap.

Configuring a System Name

Beginning in privileged EXEC mode, follow these steps to manually configure a system name:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

hostname name

Manually configure a system name.

The default setting is ap.

The name must follow the rules for ARPANET host names. They must start with a letter, end with a letter or digit, and have as interior characters only letters, digits, and hyphens. Names can be up to 63 characters.

Note When you change the system name, the access point radios reset, and associated client devices disassociate and quickly reassociate.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show running-config

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

When you set the system name, it is also used as the system prompt.

To return to the default host name, use the no hostname global configuration command.

Understanding DNS

The DNS protocol controls the Domain Name System (DNS), a distributed database with which you can map host names to IP addresses. When you configure DNS on your access point, you can substitute the host name for the IP address with all IP commands, such as ping, telnet, connect, and related Telnet support operations.

IP defines a hierarchical naming scheme that allows a device to be identified by its location or domain. Domain names are pieced together with periods (.) as the delimiting characters. For example, Cisco Systems is a commercial organization that IP identifies by a com domain name, so its domain name is cisco.com. A specific device in this domain, such as the File Transfer Protocol (FTP) system, is identified as ftp.cisco.com.

To keep track of domain names, IP has defined the concept of a domain name server, which holds a cache (or database) of names mapped to IP addresses. To map domain names to IP addresses, you must first identify the host names, specify the name server that is present on your network, and enable the DNS.

This section contains this configuration information:

Default DNS Configuration

Setting Up DNS

Displaying the DNS Configuration

Default DNS Configuration

Table 5-5 shows the default DNS configuration.

Table 5-5 Default DNS Configuration 

Feature
Default Setting

DNS enable state

Disabled.

DNS default domain name

None configured.

DNS servers

No name server addresses are configured.


Setting Up DNS

Beginning in privileged EXEC mode, follow these steps to set up your access point to use the DNS:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

ip domain-name name

Define a default domain name that the software uses to complete unqualified host names (names without a dotted-decimal domain name).

Do not include the initial period that separates an unqualified name from the domain name.

At boot time, no domain name is configured; however, if the access point configuration comes from a BOOTP or Dynamic Host Configuration Protocol (DHCP) server, then the default domain name might be set by the BOOTP or DHCP server (if the servers were configured with this information).

Step 3 

ip name-server server-address1 [server-address2 ... server-address6]

Specify the address of one or more name servers to use for name and address resolution.

You can specify up to six name servers. Separate each server address with a space. The first server specified is the primary server. The access point sends DNS queries to the primary server first. If that query fails, the backup servers are queried.

Step 4 

ip domain-lookup

(Optional) Enable DNS-based host name-to-address translation on your access point. This feature is enabled by default.

If your network devices require connectivity with devices in networks for which you do not control name assignment, you can dynamically assign device names that uniquely identify your devices by using the global Internet naming scheme (DNS).

Step 5 

end

Return to privileged EXEC mode.

Step 6 

show running-config

Verify your entries.

Step 7 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

If you use the access point IP address as its host name, the IP address is used and no DNS query occurs. If you configure a host name that contains no periods (.), a period followed by the default domain name is appended to the host name before the DNS query is made to map the name to an IP address. The default domain name is the value set by the ip domain-name global configuration command. If there is a period (.) in the host name, Cisco IOS software looks up the IP address without appending any default domain name to the host name.

To remove a domain name, use the no ip domain-name name global configuration command. To remove a name server address, use the no ip name-server server-address global configuration command. To disable DNS on the access point, use the no ip domain-lookup global configuration command.

Displaying the DNS Configuration

To display the DNS configuration information, use the show running-config privileged EXEC command.


Note When DNS is configured on the access point, the show running-config command sometimes displays a server's IP address instead of its name.


Creating a Banner

You can configure a message-of-the-day (MOTD) and a login banner. The MOTD banner appears on all connected terminals at login and is useful for sending messages that affect all network users (such as impending system shutdowns).

The login banner also appears on all connected terminals. It appears after the MOTD banner and before the login prompts.


Note For complete syntax and usage information for the commands used in this section, refer to the Cisco IOS Configuration Fundamentals Command Reference for Release 12.2.


This section contains this configuration information:

Default Banner Configuration

Configuring a Message-of-the-Day Login Banner

Configuring a Login Banner

Default Banner Configuration

The MOTD and login banners are not configured.

Configuring a Message-of-the-Day Login Banner

You can create a single or multiline message banner that appears on the screen when someone logs into the access point.

Beginning in privileged EXEC mode, follow these steps to configure a MOTD login banner:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

banner motd c message c

Specify the message of the day.

For c, enter the delimiting character of your choice, such as a pound sign (#), and press the Return key. The delimiting character signifies the beginning and end of the banner text. Characters after the ending delimiter are discarded.

For message, enter a banner message up to 255 characters. You cannot use the delimiting character in the message.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show running-config

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To delete the MOTD banner, use the no banner motd global configuration command.

This example shows how to configure a MOTD banner for the access point using the pound sign (#) symbol as the beginning and ending delimiter:

AP(config)# banner motd #
This is a secure site. Only authorized users are allowed.
For access, contact technical support.
#
AP(config)#

This example shows the banner displayed from the previous configuration:

Unix> telnet 172.2.5.4
Trying 172.2.5.4...
Connected to 172.2.5.4.
Escape character is '^]'.

This is a secure site. Only authorized users are allowed.
For access, contact technical support.

User Access Verification

Password:

Configuring a Login Banner

You can configure a login banner to appear on all connected terminals. This banner appears after the MOTD banner and before the login prompt.

Beginning in privileged EXEC mode, follow these steps to configure a login banner:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

banner login c message c

Specify the login message.

For c, enter the delimiting character of your choice, such as a pound sign (#), and press the Return key. The delimiting character signifies the beginning and end of the banner text. Characters after the ending delimiter are discarded.

For message, enter a login message up to 255 characters. You cannot use the delimiting character in the message.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show running-config

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To delete the login banner, use the no banner login global configuration command.

This example shows how to configure a login banner for the access point using the dollar sign ($) symbol as the beginning and ending delimiter:

AP(config)# banner login $
Access for authorized users only. Please enter your username and password.
$
AP(config)#