ISE and Catalyst 9800 Series Integration Guide

[howon]

Content

• Introduction
• Setup
• Components used:
• Notes:
• Catalyst 9800 Configuration
• Steps 1 - 3: Define AAA
• Step 4: Create Webauth Parameter Map (Required for BYOD)
• Step 5: Create VLANs
• Step 6: Create WLANs
• Step 7: Create Policy Profiles
• Step 8: Create Policy Tag
• Step 9: Assign Policy Tag to AP
• Step 10a: Create Redirect ACL for Guest flow
• Step 10b: Create Redirect ACL for BYOD flow
• Step 11a: Create URL Filter for BYOD flow
• Step 11b: Create URL Filter for Social Network Guest access - Facebook
• ISE Configuration
• dACL (Downloadable ACL) for redirected state
• Authorization Profile with URL Filter
• Authorization Profile with dACL using AAA 'Method-List' Cisco VSA
• Catalyst 9800 Configuration for FlexConnect Local switching
• Modify Policy Profile
• Create Flex Profile
• Create Site Tag
• Assign Site Tag to AP
• Modify Redirect ACL
• Troubleshooting

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Introduction

Cisco Catalyst 9800 (C9800) series wireless controller configuration is different from AireOS and this document shows how to configure C9800 to work with ISE. For more information on Cisco Catalyst 9800 series, please go to: https://www.cisco.com/c/en/us/products/wireless/catalyst-9800-series-wireless-controllers/index.html

Setup

Components used:

WLC: Catalyst 9800-CL running 16.10.1

AP: Cisco 1815i

ISE: 2.4p3 (Previous versions of ISE should work with C9800 as well)

The document does not cover details on how to bootstrap the ISE, C9800, and AP. The document assumes the C9800 is accessible from the management PC and AP is associated to the C9800. The document also assumes underlying network elements are already configured, which includes, VLANs, SVIs, Subnets, DHCP, routing, and DNS. The following diagram and table shows settings for the components.

C9800 IP	192.168.201.61
ISE IP	192.168.201.93
DNS IP	192.168.201.71
OPEN SSID	OPEN
SECURE SSID	SECURE
Guest VLAN	30
Guest Subnet	192.168.30.0/24
User VLAN	10
User Subnet	192.168.10.0/24

Notes:

• If static ACL needs to be applied to a session, use AireSpace-ACL-Name (6) attribute to send down a ACL name. The ACL needs to be pre-created on C9800
• C9800 supports dACL for only central switching
• Support for dACL requires use of 'default' as AAA authorization list name or use of method-list VSA. See authorization list section for more information
• If dVLAN needs to be applied to a session, use AireSpace-VLAN-Name (5) attribute to send down a VLAN name/ID. The VLAN needs to be pre-created on C9800. Alternatively standard RADIUS 3 tuple attributes can be used for VLAN assignment using VLAN name/ID
• Redirect ACL follows Catalyst IOS syntax instead of AireOS syntax. So permit statement means the matching traffic is redirected, while deny means it will be allowed without redirect
• With local mode, unlike AireOS, DNS ACL entries are not tied to the redirect ACL. URL entries needs to be defined in the URL Filters and called upon via separate RADIUS attribute during the authentication. More information on this at the end of the document on ISE section.
• With FlexConnect mode, URL filter is tied to the redirect ACL within the flex profile, so URL filter does not need to be called upon via separate RADIUS attribute
• URL redirect feature requires that the http (optionally https) server service on the 9800 be enabled. It is enabled by default but to enable it run 'ip http server' (For HTTP redirect) and 'ip http secure-server' (For HTTPS redirect)

Catalyst 9800 Configuration

Following diagram shows the C9800 configuration at a high level. Each box represents individual configuration profile with relevant options shown and how each profile feeds into other profiles to make a working configuration. The bullet points within the profile that are in bold represents sub profile being fed into the profile. It also includes the suggested order to create the profiles that maps to the main section of the document.

Steps 1 - 3: Define AAA

1. Go to Configuration > Security > AAA > Servers / Groups > Servers, Click Add
   Enter following information (Any configuration not defined in the table assumes default settings):
   

   Name	ISE01
   IP	192.168.201.93
   Key	***** (Match with ISE)
   Support for CoA	Checked

2. Click Server Groups, Click Add
   Enter following information:
   

   Name	ISE
   Available Servers	ISE01

3. Go to Configuration > Security > AAA > AAA Method List > Authentication, Click Add
   Create Authentication list using following information that will be used for both OPEN SSID and SECURE SSID:
   

   Name	default
   Type	dot1x
   Group-Type	Group
   Available Server Groups	ISE

   Note: If clients are failing to associate and authentication request does not show up on ISE Live Log, try setting the authentication list name to 'default' as shown above.

4. Go to Configuration > Security > AAA > AAA Method List > Authorization, Click Add

5. Enter following information for AAA Authorization list that will be shared for both SSIDs:
   

   Name	default
   Type	Network
   Group-Type	Group
   Available Server Groups	ISE

   Note: The Authorization name 'default' is significant here since there is no Authorization list that can be defined within the 802.1X WLAN. By using 'default' as name, C9800 can use the ISE to get additional authorization details such as for dACL operation. If default authorization list cannot be used or desired, then named authorization can be created and can be referenced via RADIUS server as a Cisco VSA. The Cisco VSA to use is 'Method-List={authorization-method-list}', which can be configured in ISE advanced Attribute Settings. Please see examples at the end of the document.
6. Go to Configuration > Security > AAA > AAA Method List > Accounting, Click Add
7. Enter following information for AAA Authorization list that will be shared for both SSIDs:
   

   Name	default
   Type	Identity
   Available Server Groups	ISE

 

Step 4: Create Webauth Parameter Map (Required for BYOD)

This will only be used in the SECURE SSID to suppress Apple CNA (AKA mini browser) from popping up upon association to the WLAN. This is required as the Apple CNA is unable to fulfill the BYOD onboarding flow.

1. Go to Configuration > Security > Webauth > Webauth Parameter Map, Click Add
2. Enter Name ‘Captive-Bypass-Portal, Click Apply to Device
3. Click ‘Captive-Bypass-Portal’ parameter map from the list
4. Check Captive Bypass Portal, Click Update & Apply

Step 5: Create VLANs

1. Go to Configuration > Layer 2 > VLAN > VLAN, Click Add
2. Add two VLANs using following table for User VLAN and Guest VLAN. These VLANs will be mapped to SECURE SSID and OPEN SSID respectively using policy profiles and tags:
   

   VLAN ID	10	30
   Name	User	Guest
   State	Activated	Activated
   Port Members	Gi2	Gi2

   
   
3. Click Save & Apply to Device

Step 6: Create WLANs

1. Go to Configuration > Tags & Profiles > WLANs, Click Add
2. Add WLANs using following table for OPEN WLAN and SECURE WLAN. These WLANs will be mapped to the AP using tags (Any configuration not defined in the table assumes default settings):
   

   General	Profile Name	OPEN	SECURE
   	SSID	OPEN	SECURE
   	Status	Enabled	Enabled
   Security > Layer 2	Layer 2 Security Mode	None	WPA + WPA2
   	MAC Filtering	Enabled
   	Authorization List	default
   Security > Layer 3	Webauth Parameter Map		Captive-Bypass-Portal
   Security > AAA	Authentication List	default	default

   Note: There is no reference to Authorization List for 'SECURE' SSID. This is not an issue for AAA override operation that applies authorization directly from RADIUS ACCESS-ACCEPT response. However, this is an issue for applying dACL as it requires additional RADIUS communication which requires authorization list. To address this issue, either use special name 'default' as authorization list as configured above or configure ISE to send Cisco VSA 'Method-List={authorization-method-list}' with ACCESS-ACCEPT when dACL is used. See ISE section below for more information.
3. Click Save & Apply to Device

Step 7: Create Policy Profiles

1. Go to Configuration > Tags & Profiles > Policy, Click Add
2. Add Policy Profiles for both WLANs using following table. Policy profile covers device sensor, default VLAN, CoA, and RADIUS Accounting. Since VLANs are different, two profiles are created one for each WLAN. These profiles will be mapped to the WLANs using tags (Any configuration not defined in the table assumes default settings):
   

   General	Name	Guest	User
   	Status	Enabled	Enabled
   Access Policies	HTTP TLV Caching	Checked	Checked
   	RADIUS Profiling	Checked	Checked
   	DHCP TLV Caching	Checked	Checked
   	VLAN/VLAN Group	Guest	User
   Advanced	Allow AAA Override	Checked	Checked
   	NAC State	Checked	Checked
   	Accounting List	default	default

   Note: For device sensor based ISE profiling to work make sure to enable RADIUS profiling, HTTP TLV Caching, DHCP TLV Caching, and Accounting List in the policy profile
3. Click Save & Apply to Device

 

Step 8: Create Policy Tag

1. Go to Configuration > Tags & Profiles > Tags, under Policy Click Add
2. Enter Name: ISE Enabled
3. Within the 'ISE Enabled' Tag window, click Add to map following WLANs to matching policy profiles. This ties the WLAN to the respective Policy Profile.
   

   WLAN Profile	Policy Profile
   OPEN	Guest
   SECURE	User

   
4. Click Save & Apply to Device

Step 9: Assign Policy Tag to AP

Finally, apply the tag to the AP. This section shows instructions on tying it to a single AP. Using Advanced Wireless Setup Wizard on C9800, same tag can be applied to multiple APs at the same time.

1. Go to Configuration > Wireless > Access Points
2. Click on the AP Name or MAC address
3. Under General > Tags, Select 'ISE Enabled'
   
4. Click Update & Apply to Device

Step 10a: Create Redirect ACL for Guest flow

1. Go to Configuration > Security > ACL, Click Add
2. Use ACL Name: ACL_WEBAUTH_REDIRECT
3. For ACL Type, select IPv4 Extended
4. Enter following rules in the ACL for Guest only access redirect ACL
   

   Sequence	Action	Source IP	Destination IP	Protocol	Source Port	Destination Port
   10	deny	any	192.168.201.93	tcp		eq 8443
   20	deny	any	192.168.201.71	udp		eq domain (53)
   30	permit	any	any	tcp		eq www (80)

5. Click Save & Apply to Device

Step 10b: Create Redirect ACL for BYOD flow

1. Enter following rules in the ACL for Guest and BYOD (Sequence 20 is needed for any endpoints using Network Setup Assistant for BYOD)
   

   Sequence	Action	Source IP	Destination IP	Protocol	Source Port	Destination Port
   10	deny	any	192.168.201.93	tcp		eq 8443
   20	deny	any	192.168.201.93	tcp		eq 8905
   30	deny	any	192.168.201.71	udp		eq domain (53)
   40	permit	any	any	tcp		eq www (80)

2. Click Save & Apply to Device

Step 11a: Create URL Filter for BYOD flow

Unlike AireOS which allows DNS entries to be part of redirect ACL, separate URL filter have to be created and be called upon via RADIUS attribute from ISE to permit access to Internet hosts using FQDNs.

1. Go to Configuration > Security > URL Filters, Click Add
2. Add URL Filter using following table (Example here is to allow access to Google Play store for BYOD):
   

   Name	BYOD-URL-Filter
   Type	PRE-AUTH
   Action	Permit
   URLs	*.google.com accounts.youtube.com gstatic.com *.googleapis.com *.appspot.com ggpht.com gvt1.com market.android.com android.pool.ntp.org *.googleusercontent.com *.google-analytics.com

   Note: The PRE-AUTH URL filter always works as if the 'Action' is Permit regardless of whether it is setup as Permit or Deny.
3. Click Save & Apply to Device

Step 11b: Create URL Filter for Social Network Guest access - Facebook

1. Go to Configuration > Security > URL Filters, Click Add
2. Add URL Filter using following table (Example here is to allow access to Facebook OAUTH2 login for Guest access):
   

   Name	Guest-URL-Filter
   Type	PRE-AUTH
   Action	Permit
   URLs	*.facebook.com *.akamai.com *.fbcdn.net *.akamaihd.net

3. Click Save & Apply to Device

ISE Configuration

dACL (Downloadable ACL) for redirected state

In the case of Catalyst 9800, it is recommended to combine the redirect ACL with dACL such as following to limit access during redirected state. Create dACL with following ACE on ISE and apply it to the redirect authorization profile below:

permit udp any host 192.168.201.71 eq domain
permit tcp any host 192.168.201.93 eq 8443
permit tcp any host 192.168.201.93 eq 8905
deny ip any any

Note: dACL is only supported in centrally switched traffic

Authorization Profile with URL Filter

Policy Setup on ISE is identical to the one for AireOS controller aside from the URL ACL that needs to be defined as separate RADIUS attribute. This is done by sending Cisco VSA "url-filter-preauth={URL_Filter_Name}". Here is an example of ISE Authorization profile for BYOD that allows Android devices to access the Google play store using the pre-auth URL filter defined above. Note the Cisco AV pair defined in the 'Advanced Attribute Settings' section.

Authorization Profile with dACL using AAA 'Method-List' Cisco VSA

As noted above in AAA section, to support dACL, authorization method list name should be set as 'default'. Alternatively, you can choose to use other names for authorization method list, however, doing so requires specifying authorization method list using RADIUS attribute. Here is an example of applying dACL by sending down authorization method list 'ISE-AUTHZ' within the ISE authorization profile. Note that the Cisco VSA 'Method-List' is case sensitive.

For rest of the ISE configuration, please use following guide for rest of the ISE configurations:

Guest: https://community.cisco.com/t5/security-documents/ise-guest-access-prescriptive-deployment-guide/ta-p/3640475

BYOD: https://community.cisco.com/t5/security-documents/cisco-ise-byod-prescriptive-deployment-guide/ta-p/3641867

Posture: https://community.cisco.com/t5/security-documents/ise-posture-prescriptive-deployment-guide/ta-p/3680273

Catalyst 9800 Configuration for FlexConnect Local switching

This section describes additional configuration needed to configure the WLAN as FlexConnect Local switching and integrate it with ISE. This section will utilize existing configurations made above. Please note that dACL is not supported with locally switched traffic.

Modify Policy Profile

1. Go to Configuration > Tags & Profiles > Policy, Click profile name that maps to the WLAN to change to local switching
2. Under WLAN Switching Policy section, uncheck Central Switching
3. Click Update & Apply to Device
4. Repeat above steps for other policy profiles that maps to the WLANs to be converted to local switching

Create Flex Profile

1. Go to Configuration > Tags & Profiles > Flex, Click Add
2. Add Flex Profile using following table
   

   General	Name	Flex
   Policy ACL	ACL Name	ACL_WEBAUTH_REDIRECT
   	Central WebAuth	Checked
   	Pre Auth URL Filter	(If this is for BYOD, select BYOD-URL-Filter, else blank)
   VLAN	VLAN Name	User	Guest
   	VLAN Id	10	30

   Note: When 'Central WebAuth' is checked, the C9800 automatically creates a Flex ACL that is in reverse of selected redirect  ACL. The permit statements are changed to deny and deny statements are changed to permit. This is due to differences between the two redirect ACL types and slight modification is needed on the ACL to make it work with FlexConnect mode. This option should only be checked for ACL that is going to be used for redirect purpose and for post-authentication ACL, this option should not be checked. See ACL section below for more information.
3. Click Save & Apply to Device

Create Site Tag

1. Go to Configuration > Tags & Profiles > Tags, Click Site, Click Add
2. Add Site Tag using following table
   

   Name	Branch
   Flex Profile	Flex
   Enable Local Site	Unchecked

   Note: Unchecking 'Enable Local Site' will reveal Flex Profile option
3. Click Save & Apply to Device

Assign Site Tag to AP

1. Go to Configuration > Wireless > Access Points
2. Click on the AP Name or MAC address
3. Under General > Tags > Site, Select 'Branch'
4. Click Update & Apply to Device
   Note: The AP will disconnect for few minutes and when reconnected to the controller, it will be in FlexConnect mode
   

Modify Redirect ACL

When ACL is translated to the FlexConnect ACL, it requires return traffic to be allowed for it to work. If deny is missing for return traffic the endpoint in Central_WebAuth state will not be able to finish the redirect flow. Following changes to the existing ACL will make ACL wotk for both local mode and FlexConnect mode.

1. Go to Configuration > Security > ACL, Click ACL name ACL_WEBAUTH_REDIRECT
2. For any deny statement ensure that deny ACE entry is added for return traffic. See sequence 11 & 12 for example:
   

   Sequence	Action	Source IP	Destination IP	Protocol	Source Port	Destination Port
   10	deny	any	192.168.201.93	tcp		eq 8443
   11	deny	192.168.201.93	any	tcp	eq 8443
   20	deny	any	192.168.201.71	udp		eq domain (53)
   21	deny	192.168.201.71	any	udp	eq domain (53)
   30	permit	any	any	tcp		eq www (80)

3. Click Update & Apply to Device

Troubleshooting

For more information on the C9800/ISE integration and troubleshooting, please go to: https://www.cisco.com/c/en/us/support/wireless/catalyst-9800-series-wireless-controllers/products-configuration-examples-list.html

[jjohnston1127]

Thanks, this is a very good and helpful write-up.

Something also to note is that the http server must be enabled on the controller to process the redirects.  It may be on by default, but I had a customer disable it and we spent some time troubleshooting why the redirects were not happening.

ip http server
ip http active-session-modules none

[howon]

@jjohnston1127 Yes, it is enabled by default. And much of the configuration is done via GUI which assumes it is enabled. But, I've added it in the notes section.

[Ehsan Momeni Bashusqeh]

So Helpful, Thanks

[_Warren]

This is excellent as usual @howon!

[andydoesntlikeuucp]

Hi Howon

in the article u dont mention how u apply ACL_WEBAUTH_REDIRECT in case of centrally switched WLAN. So it's difficult to conclude how it works finally. There is though n article written by one of wifininjas (https://wifininjas.net/2019/08/13/wn-blog-009-c9800-wlc-guest-mab-cwa-ise/ ) where he describes case where he applies his redirect ACL on global level. It's not possible to comment n article though (to ask the Q :0). Could u pls kindly explain it?