Table Of Contents
Configuring WLANs
WLAN Overview
Configuring WLANs
Creating WLANs
Using the GUI to Create WLANs
Using the CLI to Create WLANs
Configuring DHCP
Internal DHCP Server
External DHCP Servers
DHCP Assignment
Security Considerations
Using the GUI to Configure DHCP
Using the CLI to Configure DHCP
Configuring DHCP Scopes
Configuring MAC Filtering for WLANs
Enabling MAC Filtering
Creating a Local MAC Filter
Configuring a Timeout for Disabled Clients
Assigning WLANs to Interfaces
Configuring Peer-to-Peer Blocking
Guidelines for Using Peer-to-Peer Blocking
Using the GUI to Configure Peer-to-Peer Blocking
Using the CLI to Configure Peer-to-Peer Blocking
Configuring Layer 2 Security
Static WEP Keys
Dynamic 802.1X Keys and Authorization
Configuring a WLAN for Both Static and Dynamic WEP
WPA1 and WPA2
CKIP
Configuring a Session Timeout
Using the GUI to Configure a Session Timeout
Using the CLI to Configure a Session Timeout
Configuring Layer 3 Security
VPN Passthrough
Web Authentication
Assigning a QoS Profile to a WLAN
Using the GUI to Assign a QoS Profile to a WLAN
Using the CLI to Assign a QoS Profile to a WLAN
Configuring QoS Enhanced BSS
Guidelines for Configuring QBSS
Additional Guidelines for Using 7921 and 7920 Wireless IP Phones
Using the GUI to Configure QBSS
Using the CLI to Configure QBSS
Configuring IPv6 Bridging
Guidelines for Using IPv6 Bridging
Using the GUI to Configure IPv6 Bridging
Using the CLI to Configure IPv6 Bridging
Configuring Cisco Client Extensions
Using the GUI to Configure CCX Aironet IEs
Using the GUI to View a Client's CCX Version
Using the CLI to Configure CCX Aironet IEs
Using the CLI to View a Client's CCX Version
Configuring WLAN Override
Using the GUI to Configure WLAN Override
Using the CLI to Configure WLAN Override
Configuring Access Point Groups
Creating Access Point Groups
Assigning Access Points to Access Point Groups
Configuring Conditional Web Redirect with 802.1X Authentication
Configuring the RADIUS Server
Using the GUI to Configure Conditional Web Redirect
Using the CLI to Configure Conditional Web Redirect
Disabling Accounting Servers per WLAN
Configuring WLANs
This chapter describes how to configure up to 16 WLANs for your Cisco UWN Solution. It contains these sections:
•
WLAN Overview
•Configuring WLANs
WLAN Overview
The Cisco UWN Solution can control up to 16 WLANs for lightweight access points. Each WLAN has a separate WLAN ID (1 through 16), a separate WLAN SSID (WLAN name), and can be assigned unique security policies.
Lightweight access points broadcast all active Cisco UWN Solution WLAN SSIDs and enforce the policies that you define for each WLAN.
Note Cisco recommends that you assign one set of VLANs for WLANs and a different set of VLANs for management interfaces to ensure that controllers properly route VLAN traffic.
Configuring WLANs
These sections describe how to configure WLANs:
•Creating WLANs
•Configuring DHCP
•Configuring MAC Filtering for WLANs
•Assigning WLANs to Interfaces
•Configuring Peer-to-Peer Blocking
•Configuring Layer 2 Security
•Configuring a Session Timeout
•Configuring Layer 3 Security
•Assigning a QoS Profile to a WLAN
•Configuring QoS Enhanced BSS
•Configuring IPv6 Bridging
•Configuring Cisco Client Extensions
•Configuring WLAN Override
•Configuring Access Point Groups
•Configuring Conditional Web Redirect with 802.1X Authentication
•Disabling Accounting Servers per WLAN
Creating WLANs
This section provides instructions for creating up to 16 WLANs using either the controller GUI or CLI.
You can configure WLANs with different service set identifiers (SSIDs) or with the same SSID. An SSID identifies the specific wireless network that you want the controller to access. Creating WLANs with the same SSID enables you to assign different Layer 2 security policies within the same wireless LAN. To distinguish among WLANs with the same SSID, you must create a unique profile name for each WLAN.
WLANs with the same SSID must have unique Layer 2 security policies so that clients can make a WLAN selection based on information advertised in beacon and probe responses. These are the available Layer 2 security policies:
•None (open WLAN)
•Static WEP or 802.1X
Note Because static WEP and 802.1X are both advertised by the same bit in beacon and probe responses, they cannot be differentiated by clients. Therefore, they cannot both be used by multiple WLANs with the same SSID.
•CKIP
•WPA/WPA2
Note Although WPA and WPA2 cannot both be used by multiple WLANs with the same SSID, two WLANs with the same SSID could be configured with WPA/TKIP with PSK and WPA/TKIP with 802.1X, respectively, or with WPA/TKIP with 802.1X or WPA/AES with 802.1X, respectively.
Using the GUI to Create WLANs
Follow these steps to create WLANs using the GUI.
Step 1 Click Wireless > WLANs to open the WLANs page (see Figure 6-1).
Figure 6-1 WLANs Page
This page lists all of the WLANs currently configured on the controller. Figure 6-1 illustrates multiple WLANs using the same SSID. Specifically, it shows two SSIDs named "user" but with different profile names (user1 and user2). Notice that their security policies are also different.
Note If you want to delete a WLAN, hover your cursor over the blue drop-down arrow for that WLAN and choose Remove.
Step 2 To create a new WLAN, click New. The WLANs > New page appears (see Figure 6-2).
Figure 6-2 WLANs > New Page
Step 3 From the Type drop-down box, choose WLAN to create a WLAN.
Note If you want to create a guest LAN for wired guest users, choose Guest LAN and follow the instructions in the "Configuring Wired Guest Access" section on page 9-23.
Step 4 In the Profile Name field, enter up to 32 alphanumeric characters for the profile name to be assigned to this WLAN. The profile name must be unique.
Step 5 In the WLAN SSID field, enter up to 32 alphanumeric characters for the SSID to be assigned to this WLAN.
Step 6 Click Apply to commit your changes. The WLANs > Edit page appears (see Figure 6-3).
Note You can also access the WLANs > Edit page from the WLANs page by clicking the name of the WLAN that you want to edit.
Figure 6-3 WLANs > Edit Page
Step 7 Use the parameters on the General, Security, QoS, and Advanced tabs to configure this WLAN. Refer to the sections in the rest of this chapter for instructions on configuring specific features for WLANs.
Step 8 On the General tab, check the Status check box to enable this WLAN. Be sure to leave it unchecked until you have finished making configuration changes to the WLAN.
Step 9 Click Apply to commit your changes.
Step 10 Click Save Configuration to save your changes.
Using the CLI to Create WLANs
Use these commands to create WLANs using the CLI.
1. To view the list of existing WLANs and to see whether they are enabled or disabled, enter this command:
show wlan summary
2. To create a new WLAN, enter this command:
config wlan create wlan_id profile_name ssid
Note If you do not specify an ssid, the profile_name parameter is used for both the profile name and the SSID.
Note When WLAN 1 is created in the configuration wizard, it is created in enabled mode. Disable it until you have finished configuring it. When you create a new WLAN using the config wlan create command, it is created in disabled mod. Leave it disabled until you have finished configuring it.
Note If you want to create a guest LAN for wired guest users, follow the instructions in the "Configuring Wired Guest Access" section on page 9-23.
3. To disable a WLAN (for example, before making any modifications to a WLAN), enter this command:
config wlan disable wlan_id
Note If the management and AP-manager interfaces are mapped to the same port and are members of the same VLAN, you must disable the WLAN before making a port-mapping change to either interface. If the management and AP-manager interfaces are assigned to different VLANs, you do not need to disable the WLAN.
4. To enable a WLAN (for example, after you have finished making configuration changes to the WLAN), enter this command:
config wlan enable wlan_id
5. To delete a WLAN, enter this command:
config wlan delete wlan_id
Configuring DHCP
WLANs can be configured to use the same or different Dynamic Host Configuration Protocol (DHCP) servers or no DHCP server. Two types of DHCP servers are available: internal and external.
Internal DHCP Server
The controllers contain an internal DHCP server. This server is typically used in branch offices that do not already have a DHCP server. The wireless network generally contains 10 access points or fewer, with the access points on the same IP subnet as the controller. The internal server provides DHCP addresses to wireless clients, direct-connect access points, appliance-mode access points on the management interface, and DHCP requests that are relayed from access points. Only lightweight access points are supported. When you want to use the internal DHCP server, you must set the management interface IP address of the controller as the DHCP server IP address.
DHCP option 43 is not supported on the internal server. Therefore, the access point must use an alternative method to locate the management interface IP address of the controller, such as local subnet broadcast, DNS, priming, or over-the-air discovery.
Note Refer to Chapter 7 or the Controller Deployment Guide at this URL for more information on how access points find controllers:
http://www.cisco.com/en/US/products/ps6366/prod_technical_reference_list.html
External DHCP Servers
The operating system is designed to appear as a DHCP Relay to the network and as a DHCP server to clients with industry-standard external DHCP servers that support DHCP Relay. This means that each controller appears as a DHCP Relay agent to the DHCP server. This also means that the controller appears as a DHCP server at the virtual IP Address to wireless clients.
Because the controller captures the client IP address obtained from a DHCP server, it maintains the same IP address for that client during intra-controller, inter-controller, and inter-subnet client roaming.
DHCP Assignment
You can configure DHCP on a per-interface or per-WLAN basis. The preferred method is to use the primary DHCP server address assigned to a particular interface.
Per-Interface Assignment
You can assign DHCP servers for individual interfaces. The management interface, AP-manager interface, and dynamic interfaces can be configured for a primary and secondary DHCP server, and the service-port interface can be configured to enable or disable DHCP servers.
Note Refer to Chapter 3 for information on configuring the controller's interfaces.
Per-WLAN Assignment
You can also define a DHCP server on a WLAN. This server will override the DHCP server address on the interface assigned to the WLAN.
Security Considerations
For enhanced security, Cisco recommends that you require all clients to obtain their IP addresses from a DHCP server. To enforce this requirement, all WLANs can be configured with a DHCP Addr. Assignment Required setting, which disallows client static IP addresses. If DHCP Addr. Assignment Required is selected, clients must obtain an IP address via DHCP. Any client with a static IP address is not be allowed on the network. The controller monitors DHCP traffic because it acts as a DHCP proxy for the clients.
Note WLANs that support management over wireless must allow management (device-servicing) clients to obtain an IP address from a DHCP server. See the "Using Management over Wireless" section on page 5-35 for instructions on configuring management over wireless.
If slightly less security is tolerable, you can create WLANs with DHCP Addr. Assignment Required disabled. Clients then have the option of using a static IP address or obtaining an IP address from a designated DHCP server.
You are also allowed to create separate WLANs with DHCP Addr. Assignment Required disabled and a DHCP server IP address of 0.0.0.0. These WLANs drop all DHCP requests and force clients to use a static IP address. Note that these WLANs do not support management over wireless connections.
Note Refer to Chapter 4 for instructions on globally configuring DHCP proxy.
This section provides both GUI and CLI instructions for configuring DHCP.
Using the GUI to Configure DHCP
Follow these steps to configure DHCP using the GUI.
Step 1 Follow the instructions in the "Using the GUI to Configure the Management, AP-Manager, Virtual, and Service-Port Interfaces" section on page 3-10 or "Using the GUI to Configure Dynamic Interfaces" section on page 3-15 to configure a primary DHCP server for a management, AP-manager, or dynamic interface that will be assigned to the WLAN.
Note When you want to use the internal DHCP server, you must set the management interface IP address of the controller as the DHCP server IP address.
Step 2 Click WLANs to open the WLANs page.
Step 3 Click the profile name of the WLAN for which you wish to assign an interface. The WLANs > Edit (General) page appears.
Step 4 On the General tab, uncheck the Status check box and click Apply to disable the WLAN.
Step 5 Re-click the profile name of the WLAN.
Step 6 On the General tab, choose the interface for which you configured a primary DHCP server to be used with this WLAN from the Interface drop-down box.
Step 7 Click the Advanced tab to open the WLANs > Edit (Advanced) page.
Step 8 If you want to define a DHCP server on the WLAN that will override the DHCP server address on the interface assigned to the WLAN, check the DHCP Server Override check box and enter the IP address of the desired DHCP server in the DHCP Server IP Addr edit box. The default value for the check box is disabled.
Note The preferred method for configuring DHCP is to use the primary DHCP address assigned to a particular interface instead of the DHCP server override.
Step 9 If you want to require all clients to obtain their IP addresses from a DHCP server, check the DHCP Addr. Assignment Required check box. When this feature is enabled, any client with a static IP address is not allowed on the network. The default value is disabled.
Step 10 Click Apply to commit your changes.
Step 11 On the General tab, check the Status check box and click Apply to re-enable the WLAN.
Step 12 Click Save Configuration to save your changes.
Using the CLI to Configure DHCP
Follow these steps to configure DHCP using the CLI.
Step 1 Follow the instructions in the "Using the CLI to Configure the Management, AP-Manager, Virtual, and Service-Port Interfaces" section on page 3-12 or "Using the CLI to Configure Dynamic Interfaces" section on page 3-17 to configure a primary DHCP server for a management, AP-manager, or dynamic interface that will be assigned to the WLAN.
Step 2 To disable the WLAN, enter this command:
config wlan disable wlan-id
Step 3 To specify the interface for which you configured a primary DHCP server to be used with this WLAN, enter this command:
config wlan interface wlan-id interface-name
Step 4 If you want to define a DHCP server on the WLAN that will override the DHCP server address on the interface assigned to the WLAN, enter this command:
config wlan dhcp_server wlan-id dhcp-server-ip-address
Note The preferred method for configuring DHCP is to use the primary DHCP address assigned to a particular interface instead of the DHCP server override. If you enable the override, you can use the show wlan command to verify that the DHCP server has been assigned to the WLAN.
Step 5 To re-enable the WLAN, enter this command:
config wlan enable wlan-id
Configuring DHCP Scopes
Controllers have built-in DHCP relay agents. However, when network administrators desire network segments that do not have a separate DHCP server, the controllers can have built-in DHCP scopes that assign IP addresses and subnet masks to wireless clients. Typically, one controller can have one or more DHCP scopes that each provide a range of IP addresses.
DHCP scopes are needed for internal DHCP to work. Once DHCP is defined on the controller, we can then point the primary DHCP server IP address on the management, AP-manager, and dynamic interfaces to controller's management interface. You can configure up to 16 DHCP scopes using the controller GUI or CLI.
Using the GUI to Configure DHCP Scopes
Follow these steps to configure DHCP scopes using the GUI.
Step 1 Click Controller > Internal DHCP Server to open the DHCP Scopes page (see Figure 6-4).
Figure 6-4 DHCP Scopes Page
This page lists any DHCP scopes that have already been configured.
Note If you ever want to delete an existing DHCP scope, hover your cursor over the blue drop-down arrow for that scope and choose Remove.
Step 2 To add a new DHCP scope, click New. The DHCP Scope > New page appears.
Step 3 In the Scope Name field, enter a name for the new DHCP scope.
Step 4 Click Apply. When the DHCP Scopes page reappears, click the name of the new scope. The DHCP Scope > Edit page appears (see Figure 6-5).
Figure 6-5 DHCP Scope > Edit Page
Step 5 In the Pool Start Address field, enter the starting IP address in the range assigned to the clients.
Note This pool must be unique for each DHCP scope and must not include the static IP addresses of routers or other servers.
Step 6 In the Pool End Address field, enter the ending IP address in the range assigned to the clients.
Note This pool must be unique for each DHCP scope and must not include the static IP addresses of routers or other servers.
Step 7 In the Network field, enter the network served by this DHCP scope. This is the IP address used by the management interface with Netmask applied, as configured on the Interfaces page.
Step 8 In the Netmask field, enter the subnet mask assigned to all wireless clients.
Step 9 In the Lease Time field, enter the amount of time (from 0 to 65536 seconds) that an IP address is granted to a client.
Step 10 In the Default Routers field, enter the IP address of the optional router(s) connecting the controllers. Each router must include a DHCP forwarding agent, which allows a single controller to serve the clients of multiple controllers.
Step 11 In the DNS Domain Name field, enter the optional domian name system (DNS) domain name of this DHCP scope for use with one or more DNS servers.
Step 12 In the DNS Servers field, enter the IP address of the optional DNS server(s). Each DNS server must be able to update a client's DNS entry to match the IP address assigned by this DHCP scope.
Step 13 In the Netbios Name Servers field, enter the IP address of the optional Microsoft Network Basic Input Output System (NetBIOS) name server(s), such as a Windows Internet Naming Service (WINS) server.
Step 14 From the Status drop-down box, choose Enabled to enable this DHCP scope or Disabled to disable it.
Step 15 Click Apply to commit your changes.
Step 16 Click Save Configuration to save your changes.
Using the CLI to Configure DHCP Scopes
Follow these steps to configure DHCP scopes using the CLI.
Step 1 To create a new DHCP scope, enter this command:
config dhcp create-scope scope
Note If you ever want to delete a DHCP scope, enter this command: config dhcp delete-scope scope.
Step 2 To specify the starting and ending IP address in the range assigned to the clients, enter this command:
config dhcp address-pool scope start end
Note This pool must be unique for each DHCP scope and must not include the static IP addresses of routers or other servers.
Step 3 To specify the network served by this DHCP scope (the IP address used by the management interface with Netmask applied) and the subnet mask assigned to all wireless clients, enter this command:
config dhcp network scope network netmask
Step 4 To specify the amount of time (from 0 to 65536 seconds) that an IP address is granted to a client, enter this command:
config dhcp lease scope lease_duration
Step 5 To specify the IP address of the optional router(s) connecting the controllers, enter this command:
config dhcp default-router scope router_1 [router_2] [router_3]
Each router must include a DHCP forwarding agent, which allows a single controller to serve the clients of multiple controllers.
Step 6 To specify the optional domain name system (DNS) domain name of this DHCP scope for use with one or more DNS servers, enter this command:
config dhcp domain scope domain
Step 7 To specify the IP address of the optional DNS server(s), enter this command:
config dhcp dns-servers scope dns1 [dns2] [dns3]
Each DNS server must be able to update a client's DNS entry to match the IP address assigned by this DHCP scope
Step 8 To specify the IP address of the optional Microsoft Network Basic Input Output System (NetBIOS) name server(s), such as a Windows Internet Naming Service (WINS) server, enter this command:
config dhcp netbios-name-server scope wins1 [wins2] [wins3]
Step 9 To enable or disable this DHCP scope, enter this command:
config dhcp {enable | disable} scope
Step 10 To save your changes, enter this command:
save config
Step 11 To see the list of configured DHCP scopes, enter this command:
show dhcp summary
Information similar to the following appears:
Scope Name Enabled Address Range
Scope 1 No 0.0.0.0 -> 0.0.0.0
Scope 2 No 0.0.0.0 -> 0.0.0.0
Step 12 To display the DHCP information for a particular scope, enter this command:
show dhcp scope
Information similar to the following appears:
Enabled....................................... No
Lease Time.................................... 0
Pool Start.................................... 0.0.0.0
Pool End...................................... 0.0.0.0
Network....................................... 0.0.0.0
Netmask....................................... 0.0.0.0
Default Routers............................... 0.0.0.0 0.0.0.0 0.0.0.0
DNS Domain....................................
DNS........................................... 0.0.0.0 0.0.0.0 0.0.0.0
Netbios Name Servers.......................... 0.0.0.0 0.0.0.0 0.0.0.0
Configuring MAC Filtering for WLANs
When you use MAC filtering for client or administrator authorization, you need to enable it at the WLAN level first. If you plan to use local MAC address filtering for any WLAN, use the commands in this section to configure MAC filtering for a WLAN.
Enabling MAC Filtering
Use these commands to enable MAC filtering on a WLAN:
•Enter config wlan mac-filtering enable wlan-id to enable MAC filtering.
•Enter show wlan to verify that you have MAC filtering enabled for the WLAN.
When you enable MAC filtering, only the MAC addresses that you add to the WLAN are allowed to join the WLAN. MAC addresses that have not been added are not allowed to join the WLAN.
Creating a Local MAC Filter
Controllers have built-in MAC filtering capability, similar to that provided by a RADIUS authorization server.
Use these commands to add MAC addresses to a WLAN MAC filter:
•Enter config macfilter add mac_addr wlan_id [interface_name] [description] [IP_addr] to create a MAC filter entry on the controller, where the following parameters are optional:
–interface_name—The name of the interface.
–description—A brief description of the interface in double quotes.
–IP_addr—The IP address of the local MAC filter database.
•Enter config macfilter ip-address mac_addr IP_addr to assign an IP address to an existing MAC filter entry, if one was not assigned in the config macfilter add command.
•Enter show macfilter to verify that MAC addresses are assigned to the WLAN.
Configuring a Timeout for Disabled Clients
You can configure a timeout for disabled clients. Clients who fail to authenticate three times when attempting to associate are automatically disabled from further association attempts. After the timeout period expires, the client is allowed to retry authentication until it associates or fails authentication and is excluded again. Use these commands to configure a timeout for disabled clients:
•Enter config wlan blacklist wlan-id timeout to configure the timeout for disabled clients. Enter a timeout from 1 to 65535 seconds, or enter 0 to permanently disable the client.
•Use the show wlan command to verify the current timeout.
Assigning WLANs to Interfaces
Use these commands to assign a WLAN to an interface:
•Enter this command to assign a WLAN to a interface:
config wlan interface {wlan-id | foreignAp} interface-id
–Use the interface-id option to assign the WLAN to a specific interface.
–Use the foreignAp option to use a third-party access point.
•Enter show wlan summary to verify interface assignment status.
Configuring Peer-to-Peer Blocking
In controller software releases prior to 4.2, peer-to-peer blocking is applied globally to all clients on all WLANs and causes traffic between two clients on the same VLAN to be transferred to the upstream VLAN rather than being bridged by the controller. This behavior usually results in traffic being dropped at the upstream switch because switches do not forward packets out the same port on which they are received.
In controller software release 4.2, peer-to-peer blocking is applied to individual WLANs, and each client inherits the peer-to-peer blocking setting of the WLAN to which it is associated. In 4.2, you also have more control over how traffic is directed. For example, you can choose to have traffic bridged locally within the controller, dropped by the controller, or forwarded to the upstream VLAN. Figure 6-6 illustrates each option.
Figure 6-6 Peer-to-Peer Blocking Examples
Guidelines for Using Peer-to-Peer Blocking
Follow these guidelines when using peer-to-peer blocking:
•In controller software releases prior to 4.2, the controller forwards Address Resolution Protocol (ARP) requests upstream (just like all other traffic). In controller software release 4.2, ARP requests are directed according to the behavior set for peer-to-peer blocking.
•Peer-to-peer blocking does not apply to multicast traffic.
•Locally switched hybrid-REAP WLANs and hybrid-REAP access points in standalone mode do not support peer-to-peer blocking.
•If you upgrade to controller software release 4.2 from a previous release that supports global peer-to-peer blocking, each WLAN is configured with the peer-to-peer blocking action of forwarding traffic to the upstream VLAN.
Using the GUI to Configure Peer-to-Peer Blocking
Follow these steps to configure a WLAN for peer-to-peer blocking using the GUI.
Step 1 Click WLANs to open the WLANs page.
Step 2 Click the name of the WLAN for which you want to configure peer-to-peer blocking.
Step 3 Click the Advanced tab to open the WLANs > Edit (Advanced) page (see Figure 6-7).
Figure 6-7 WLANs > Edit (Advanced) Page
Step 4 Choose one of the following options from the P2P Blocking drop-down box:
•Disabled—Disables peer-to-peer blocking and bridges traffic locally within the controller whenever possible. This is the default value.
Note Traffic is never bridged across VLANs in the controller.
•Drop—Causes the controller to discard the packets.
•Forward-UpStream—Causes the packets to be forwarded on the upstream VLAN. The device above the controller decides what action to take regarding the packets.
Step 5 Click Apply to commit your changes.
Step 6 Click Save Configuration to save your changes.
Using the CLI to Configure Peer-to-Peer Blocking
Follow these steps to configure a WLAN for peer-to-peer blocking using the CLI.
Step 1 To configure a WLAN for peer-to-peer blocking, enter this command:
config wlan peer-blocking {disable | drop | forward-upstream} wlan_id
Note See the description of each parameter in the "Using the GUI to Configure Peer-to-Peer Blocking" section above.
Step 2 To save your changes, enter this command:
save config
Step 3 To see the status of peer-to-peer blocking for a WLAN, enter this command:
show wlan wlan_id
Information similar to the following appears:
WLAN Identifier.................................. 1
Profile Name..................................... test
Network Name (SSID).............................. test
Status........................................... Enabled
Peer-to-Peer Blocking Action..................... Disabled
Radio Policy..................................... All
Local EAP Authentication...................... Disabled
Configuring Layer 2 Security
This section explains how to assign Layer 2 security settings to WLANs.
Note Clients using the Microsoft Wireless Configuration Manager and 802.1X must use WLANs configured for 40- or 104-bit key length. Configuring for 128-bit key length results in clients that can associate but not authenticate.
Static WEP Keys
Controllers can control static WEP keys across access points. Use these commands to configure static WEP for WLANs:
•Enter this command to disable 802.1X encryption:
config wlan security 802.1X disable wlan-id
•Enter this command to configure 40/64, 104/128, or 128/152-bit WEP keys:
config wlan security static-wep-key encryption wlan-id {40 | 104 | 128} {hex | ascii} key key-index
–Use the 40, 104, or 128 options to specify 40/64-bit, 104/128-bit, or 128/152-bit encryption. The default setting is 104/128.
–Use the hex or ascii option to specify the character format for the WEP key.
–Enter 10 hexadecimal digits (any combination of 0-9, a-f, or A-F) or five printable ASCII characters for 40-bit/64-bit WEP keys; enter 26 hexadecimal or 13 ASCII characters for 104-bit/128-bit keys; enter 32 hexadecimal or 16 ASCII characters for 128-bit/152-bit keys.
–Enter a key index (sometimes called a key slot) of 1 through 4.
Dynamic 802.1X Keys and Authorization
Controllers can control 802.1X dynamic WEP keys using Extensible Authentication Protocol (EAP) across access points and support 802.1X dynamic key settings for WLANs.
Note To use LEAP with lightweight access points and wireless clients, make sure to choose Cisco-Aironet as the RADIUS server type when configuring the CiscoSecure Access Control Server (ACS).
•Enter show wlan wlan-id to check the security settings of each WLAN. The default security setting for new WLANs is 802.1X with dynamic keys enabled. To maintain robust Layer 2 security, leave 802.1X configured on your WLANs.
•To disable or enable the 802.1X authentication, use this command:
config wlan security 802.1X {enable | disable} wlan-id
After you enable 802.1X authentication, the controller sends EAP authentication packets between the wireless client and the authentication server. This command allows all EAP-type packets to be sent to and from the controller.
•If you want to change the 802.1X encryption level for a WLAN, use this command:
config wlan security 802.1X encryption wlan-id [40 | 104 | 128]
–Use the 40 option to specify 40/64-bit encryption.
–Use the 104 option to specify 104/128-bit encryption. (This is the default encryption setting.)
–Use the 128 option to specify 128/152-bit encryption.
•If you want to configure Cisco Aironet 802.11a/b/g Wireless LAN Client Adapters (CB21AG and PI21AG) running PEAP-GTC to authenticate to a controller through a one-time password to a token server, use these commands:
–config advanced eap identity-request-timeout—Configures the EAP identity request timeout value in seconds. The default setting is 1 second.
–config advanced eap identity-request-retries—Configures the EAP identity request maximum retries value. The default setting is 20.
–config advanced eap request-timeout—Configures the EAP request timeout value in seconds. The default setting is 1 second.
–config advanced eap request-retries—Configures the EAP request maximum retries value. The default setting is 2.
–show advanced eap—Shows the values that are currently configured for the config advanced eap commands. Information similar to the following appears:
EAP-Identity-Request Timeout (seconds)........... 1
EAP-Identity-Request Max Retries................. 20
EAP-Request Timeout (seconds).................... 1
EAP-Request Max Retries.......................... 2
Configuring a WLAN for Both Static and Dynamic WEP
You can configure up to four WLANs to support static WEP keys, and you can also configure dynamic WEP on any of these static-WEP WLANs. Follow these guidelines when configuring a WLAN for both static and dynamic WEP:
•The static WEP key and the dynamic WEP key must be the same length.
•When you configure both static and dynamic WEP as the Layer 2 security policy, no other security policies can be specified. That is, you cannot configure web authentication. However, when you configure either static or dynamic WEP as the Layer 2 security policy, you can configure web authentication.
WPA1 and WPA2
Wi-Fi Protected Access (WPA or WPA1) and WPA2 are standards-based security solutions from the Wi-Fi Alliance that provide data protection and access control for wireless LAN systems. WPA1 is compatible with the IEEE 802.11i standard but was implemented prior to the standard's ratification; WPA2 is the Wi-Fi Alliance's implementation of the ratified IEEE 802.11i standard.
By default, WPA1 uses Temporal Key Integrity Protocol (TKIP) and message integrity check (MIC) for data protection while WPA2 uses the stronger Advanced Encryption Standard encryption algorithm using Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (AES-CCMP). Both WPA1 and WPA2 use 802.1X for authenticated key management by default. However, these options are also available: PSK, CCKM, and 802.1X+CCKM.
•802.1X—The standard for wireless LAN security, as defined by IEEE, is called 802.1X for 802.11, or simply 802.1X. An access point that supports 802.1X acts as the interface between a wireless client and an authentication server, such as a RADIUS server, to which the access point communicates over the wired network. If 802.1X is selected, only 802.1X clients are supported.
•PSK—When you choose PSK (also known as WPA pre-shared key or WPA passphrase), you need to configure a pre-shared key (or a passphrase). This key is used as the pairwise master key (PMK) between the clients and the authentication server.
•CCKM—Cisco Centralized Key Management (CCKM) uses a fast rekeying technique that enables clients to roam from one access point to another without going through the controller, typically in under 150 milliseconds (ms). CCKM reduces the time required by the client to mutually authenticate with the new access point and derive a new session key during reassociation. CCKM fast secure roaming ensures that there is no perceptible delay in time-sensitive applications such as wireless Voice over IP (VoIP), enterprise resource planning (ERP), or Citrix-based solutions. CCKM is a CCXv4-compliant feature. If CCKM is selected, only CCKM clients are supported.
Note The 4.2 release of controller software supports CCX versions 1 through 5. CCX support is enabled automatically for every WLAN on the controller and cannot be disabled. The controller stores the CCX version of the client in its client database and uses it to limit client functionality. Clients must support CCXv4 or v5 in order to use CCKM. See the "Configuring Cisco Client Extensions" section for more information on CCX.
•802.1X+CCKM—During normal operation, 802.1X-enabled clients mutually authenticate with a new access point by performing a complete 802.1X authentication, including communication with the main RADIUS server. However, when you configure your WLAN for 802.1X and CCKM fast secure roaming, CCKM-enabled clients securely roam from one access point to another without the need to reauthenticate to the RADIUS server. 802.1X+CCKM is considered optional CCKM because both CCKM and non-CCKM clients are supported when this option is selected.
On a single WLAN, you can allow WPA1, WPA2, and 802.1X/PSK/CCKM/802.1X+CCKM clients to join. All of the access points on such a WLAN advertise WPA1, WPA2, and 802.1X/PSK/CCKM/
802.1X+CCKM information elements in their beacons and probe responses. When you enable WPA1 and/or WPA2, you can also enable one or two ciphers, or cryptographic algorithms, designed to protect data traffic. Specifically, you can enable AES and/or TKIP data encryption for WPA1 and/or WPA2. TKIP is the default value for WPA1, and AES is the default value for WPA2.
You can configure WPA1+WPA2 through either the GUI or the CLI.
Using the GUI to Configure WPA1+WPA2
Follow these steps to configure a WLAN for WPA1+WPA2 using the controller GUI.
Step 1 Click WLANs to open the WLANs page.
Step 2 Click the profile name of the desired WLAN to open the WLANs > Edit page.
Step 3 Click the Security and Layer 2 tabs to open the WLANs > Edit (Security > Layer 2) page (see Figure 6-8).
Figure 6-8 WLANs > Edit (Security > Layer 2) Page
Step 4 Choose WPA+WPA2 from the Layer 2 Security drop-down box.
Step 5 Under WPA+WPA2 Parameters, check the WPA Policy check box to enable WPA1, check the WPA2 Policy check box to enable WPA2, or check both check boxes to enable both WPA1 and WPA2.
Note The default value is disabled for both WPA1 and WPA2. If you leave both WPA1 and WPA2 disabled, the access points advertise in their beacons and probe responses information elements only for the authentication key management method you choose in Step 7.
Step 6 Check the AES check box to enable AES data encryption or the TKIP check box to enable TKIP data encryption for WPA1, WPA2, or both. The default values are TKIP for WPA1 and AES for WPA2.
Step 7 Choose one of the following key management methods from the Auth Key Mgmt drop-down box: 802.1X, CCKM, PSK, or 802.1X+CCKM.
Step 8 If you chose PSK in Step 7, choose ASCII or HEX from the PSK Format drop-down box and then enter a pre-shared key in the blank field. WPA pre-shared keys must contain 8 to 63 ASCII text characters or 64 hexadecimal characters.
Step 9 Click Apply to commit your changes.
Step 10 Click Save Configuration to save your changes.
Using the CLI to Configure WPA1+WPA2
Follow these steps to configure a WLAN for WPA1+WPA2 using the controller CLI.
Step 1 Enter this command to disable the WLAN:
config wlan disable wlan_id
Step 2 Enter this command to enable or disable WPA for the WLAN:
config wlan security wpa {enable | disable} wlan_id
Step 3 Enter this command to enable or disable WPA1 for the WLAN:
config wlan security wpa wpa1 {enable | disable} wlan_id
Step 4 Enter this command to enable or disable WPA2 for the WLAN:
config wlan security wpa wpa2 {enable | disable} wlan_id
Step 5 Enter these commands to enable or disable AES or TKIP data encryption for WPA1 or WPA2:
•config wlan security wpa wpa1 ciphers {aes | tkip} {enable | disable} wlan_id
•config wlan security wpa wpa2 ciphers {aes | tkip} {enable | disable} wlan_id
The default values are TKIP for WPA1 and AES for WPA2.
Step 6 Enter this command to enable or disable 802.1X, PSK, or CCKM authenticated key management:
config wlan security wpa akm {802.1X | psk | cckm} {enable | disable} wlan_id
The default value is 802.1X.
Step 7 If you enabled PSK in Step 6, enter this command to specify a pre-shared key:
config wlan security wpa akm psk set-key {ascii | hex} psk-key wlan_id
WPA pre-shared keys must contain 8 to 63 ASCII text characters or 64 hexadecimal characters.
Step 8 If you enabled WPA2 with 802.1X authenticated key management or WPA1 or WPA2 with CCKM authenticated key management, the PMK cache lifetime timer is used to trigger reauthentication with the client when necessary. The timer is based on the timeout value received from the AAA server or the WLAN session timeout setting. To see the amount of time remaining before the timer expires, enter this command:
show pmk-cache all
Information similar to the following appears:
Type Station Lifetime VLAN Override IP Override
------ ------------------- -------- ------------------ ---------------
CCKM 00:07:0e:b9:3a:1b 150 0.0.0.0
If you enabled WPA2 with 802.1X authenticated key management, the controller supports opportunistic PMKID caching but not sticky (or non-opportunistic) PMKID caching. In sticky PMKID caching, the client stores multiple PMKIDs. This approach is not practical because it requires full authentication for each new access point and is not guaranteed to work in all conditions. In contrast, opportunistic PMKID caching stores only one PMKID per client and is not subject to the limitations of sticky PMK caching.
Step 9 Enter this command to enable the WLAN:
config wlan enable wlan_id
Step 10 Enter this command to save your settings:
save config
CKIP
Cisco Key Integrity Protocol (CKIP) is a Cisco-proprietary security protocol for encrypting 802.11 media. CKIP improves 802.11 security in infrastructure mode using key permutation, message integrity check (MIC), and message sequence number. Software release 4.0 or later supports CKIP with static key. For this feature to operate correctly, you must enable Aironet information elements (IEs) for the WLAN.
A lightweight access point advertises support for CKIP in beacon and probe response packets by adding an Aironet IE and setting one or both of the CKIP negotiation bits [key permutation and multi-modular hash message integrity check (MMH MIC)]. Key permutation is a data encryption technique that uses the basic encryption key and the current initialization vector (IV) to create a new key. MMH MIC prevents bit-flip attacks on encrypted packets by using a hash function to compute message integrity code.
The CKIP settings specified in a WLAN are mandatory for any client attempting to associate. If the WLAN is configured for both CKIP key permutation and MMH MIC, the client must support both. If the WLAN is configured for only one of these features, the client must support only this CKIP feature.
CKIP requires that 5-byte and 13-byte encryption keys be expanded to 16-byte keys. The algorithm to perform key expansion happens at the access point. The key is appended to itself repeatedly until the length reaches 16 bytes. All lightweight access points except the AP1000 support CKIP.
You can configure CKIP through either the GUI or the CLI.
Using the GUI to Configure CKIP
Follow these steps to configure a WLAN for CKIP using the controller GUI.
Step 1 Click WLANs to open the WLANs page.
Step 2 Click the profile name of the desired WLAN to open the WLANs > Edit page.
Step 3 Click the Advanced tab.
Step 4 Check the Aironet IE check box to enable Aironet IEs for this WLAN and click Apply.
Step 5 Click the General tab.
Step 6 Uncheck the Status check box, if checked, to disable this WLAN and click Apply.
Step 7 Click the Security and Layer 2 tabs to open the WLANs > Edit (Security > Layer 2) page (see Figure 6-9).
Figure 6-9 WLANs > Edit (Security > Layer 2) Page
Step 8 Choose CKIP from the Layer 2 Security drop-down box.
Step 9 Under CKIP Parameters, choose the length of the CKIP encryption key from the Key Size drop-down box.
Range: Not Set, 40 bits, or 104 bits
Default: Not Set
Step 10 Choose the number to be assigned to this key from the Key Index drop-down box. You can configure up to four keys.
Step 11 Choose ASCII or HEX from the Key Format drop-down box and then enter an encryption key in the Encryption Key field. 40-bit keys must contain 5 ASCII text characters or 10 hexadecimal characters. 104-bit keys must contain 13 ASCII text characters or 26 hexadecimal characters.
Step 12 Check the MMH Mode check box to enable MMH MIC data protection for this WLAN. The default value is disabled (or unchecked).
Step 13 Check the Key Permutation check box to enable this form of CKIP data protection. The default value is disabled (or unchecked).
Step 14 Click Apply to commit your changes.
Step 15 Click the General tab.
Step 16 Check the Status check box to enable this WLAN.
Step 17
