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Cisco Wireless LAN Controller (WLC) and Cisco ACS 5.x (TACACS+) Configuration Example for Web Authentication

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Jan 27, 2011 7:42 AM
Jan 27th, 2011


Introduction

This document provides a configuration example of Cisco ACS 5.x (TACACS+) with Cisco Wireless LAN Controller 4400 series (WLC) for Web Authentication.

TACACS+ is a client/server protocol that provides centralized security for users that attempt to gain management access to a router or network access server. TACACS+ provides these AAA services:

·         Authentication of users attempting to log in to the network equipment

·         Authorization to determine what level of access users should have

·         Accounting to keep track of all changes the user makes

·         This document assumes that the basic configuration of the WLC is already completed.

·         In order to configure TACACS+ in the Cisco WLC controller, you need to complete these steps:

Cisco 4400 series Wireless LAN controller

1.    Add a TACACS+ Authentication Server

2.    Add a TACACS+ Authorization Server

3.    Configure the Order of Authentication

Add a TACACS+ Authentication Server

Complete these steps in order to add a TACACS+ Authentication Server:

1.    Use the GUI, and go to Security > TACACS+ > Authentication.

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2.    Add the details of the ACS (tacacs+) server. the IP address of the TACACS+ server and enter the shared secret key. If required, change the default port of TCP/49. The shared secret will be same as defined for WLC in ACS server.


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3.    Click Apply.

You can accomplish this from CLI using the

config tacacs auth add <Server Index> <IP addr> <port> [ascii/hex] <secret> command:

(Cisco Controller) >config tacacs auth add 1 2.2.2.2 49 ascii cisco123

Add a TACACS+ Authentication Server

1.    From the GUI, go to Security > TACACS+ > Authorization.

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2.    Add the IP address of the TACACS+ server and enter the shared secret key. If required, change the default port of TCP/49


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3.  Click Apply.

You can accomplish this from CLI using the

config tacacs athr add <Server Index> <IP addr> <port> [ascii/hex] <secret> command:

(Cisco Controller) >config tacacs athr add 1 2.2.2.2 49 ascii cisco123

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Add a TACACS+ Accounting Server

Complete these steps in order to add a TACACS+ Accounting Server:

1.  Use the GUI, and go to Security > TACACS+ > Accounting.

2.  Add the IP address of the server and enter the shared secret key. If required, change the default port of TCP/49.

3.  Click Apply.

This step explains how to configure the AAA order of authentication when there are multiple databases configured. The order of authentication can be local and RADIUS, or local and TACACS. The default controller configuration for order of authentication is local and RADIUS.

Complete these steps in order to configure the order of authentication:

1.  From the GUI, go to Security > Priority Order > Management User.

2.  Select the Authentication Priority. In this example, TACACS+ has been selected.

3.  Click Apply in order for the selection to take place.

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You can accomplish this from CLI using the config aaa auth mgmt <server1> <server2> command:

(Cisco Controller) >config aaa auth mgmt tacacs local

This section provides the steps involved in the TACACS+ ACS 5.x Server to create services and custom attributes, and assign the roles to the users or groups.

Complete this step:-

1.  Add the Controller management IP address as AAA client with Authentication mechanism as TACACS+ (Cisco IOS).


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2.  Create a Shell Profile called Permit-WLC under Policy Elements > Authorization and Permissions > Device Administration > Shell Profiles.


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3.  Under Custom Attributes add the Roles manually with attribute "role1", requirement "Mandatory" and the value "ALL".


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4.  Create the Access Policies. Edit the Authorization section of the Access Policy, Add a rule that matches Protocol TACACS and NDG:Device Type <WLC>, on that rule under Results set the Shell Profile to be Permit-WLC.


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Once it is configured you can test the authentication and confirm with the number of hit counts.


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First-Match Rule Tables

Cisco ACS 5.1 provides policy decisions by using first-match rule tables to evaluate a set of rules. Rule tables contain conditions and results. Conditions can be either simple or compound. Simple conditions consist of attribute operator value and are either true or false. Compound conditions contain more complex conditions combined with AND or OR operators.


The administrator selects simple conditions to be included in a policy. The conditions are displayed as columns in a rule table where the column headings are the condition name, which is usually the name of the attribute. The rules are displayed under the column headings, and each cell indicates the operator and value that are combined with the attribute to form the condition. If ANY appears in a cell, it indicates that no operations or comparisons are performed on that attribute.


Above figure shows a column-based rule table with defined condition types.

Column

Description

Status

You can define the   status   of a rule as enabled, disabled, or monitored:

Enabled—ACS     evaluates an enabled rule, and when the rule conditions match the   access   request, ACS applies the rule result.

Disabled—The     rule appears in the rule table, but ACS skips this rule and does not   evaluate   it.

Monitor     Only—ACS evaluates a monitored rule. If the rule conditions match the   access   request, ACS creates a log record with information   relating to the match. ACS   does not apply the result, and the   processing continues to the following   rules. Use this status   during a running-in period for a rule to see whether   it is   needed.

Name

A descriptive name.   You   can specify any name that describes the rule's purpose. By   default, ACS   generates rule name strings <rule-number>.

Conditions

Identity Group

In this example,   this is   matching against one of the internal identity groups.

NDG: Location

Location network   device   group. The two predefined NDGs are Location and Device   Type.

Results

Shell Profile

The shell profile is   used   for device administration-type policies and contains   permissions for TACACS+   shell access request, such as Cisco IOS   privilege level.

Hit Counts

Displays the number   of   times a rule matched an incoming request since the last reset   of the policy's   hit counters. ACS counts hits for any monitored   or enabled rule whose   conditions all matched an incoming request.   Hit counts for:

Enabled     rules reflect the matches that occur when ACS processes requests.

Monitored     rules reflect the counts that would result for these rules if they   were   enabled when ACS processed the requests.

The primary server   in an   ACS deployment displays the hit counts, which represent the   total matches for   each rule across all servers in the deployment.   On a secondary server, all   hit counts in policy tables appear as   zeroes.

NOTE:-

The default rule specifies the policy result that ACS uses when no other rules exist, or when the attribute values in the access request do not match any rules.


Cisco ACS evaluates a set of rules in the first-match rule table as follows:

1. http://www.cisco.com/en/US/i/templates/blank.gifACS compares the values of the attributes associated with the current access request with a set of conditions expressed in a rule.

2. http://www.cisco.com/en/US/i/templates/blank.gifIf the attribute values do not match the conditions, ACS proceeds to the next rule in the rule table.

3. http://www.cisco.com/en/US/i/templates/blank.gifIf the attribute values match the conditions, ACS applies the result that is specified for that rule, and ignores all remaining rules.

4. http://www.cisco.com/en/US/i/templates/blank.gifIf the attribute values do not match any of the conditions, ACS applies the result that is specified for the policy default rule.


Related Topics

Cisco Unified Wireless Network TACACS+ Configuration

User Guide for the Cisco Secure Access Control System 5.1-Understanding ACS Policy Model

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