AAA LDAP Configuration Guide, Cisco IOS Release 15E

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AAA LDAP Configuration Guide, Cisco IOS Release 15E

Chapter Title

Configuring LDAP

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Updated:
December 10, 2014

Chapter: Configuring LDAP

Configuring LDAP

Lightweight Directory Access Protocol (LDAP) is integrated into Cisco software as an authentication, authorization, and accounting (AAA) protocol alongside the existing AAA protocols such as RADIUS, TACACS+, Kerberos, and Diameter. The AAA framework provides tools and mechanisms such as method lists, server groups, and generic attribute lists that enable an abstract and uniform interface to AAA clients irrespective of the actual protocol used for communication with the AAA server. LDAP supports authentication and authorization functions for AAA.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Prerequisites for Configuring LDAP

If you are using a secure Transport Layer Security (TLS) secure connection, you must configure X.509 certificates.

Restrictions for Configuring LDAP

  • LDAP referrals are not supported.

  • Unsolicited messages or notifications from the LDAP server are not handled.

  • LDAP authentication is not supported for interactive (terminal) sessions.

Information About LDAP

Transport Layer Security

Transport Layer Security (TLS) is an application-level protocol that enables secure transactions of data through privacy, authentication, and data integrity. It relies upon certificates, public keys, and private keys for clients to prove the identity. Certificates are issued by Certificate Authorities (CAs). Each certificate includes the name of the authority that issued it, the name of the entity to which the certificate was issued, the entity’s public key, and time stamps that indicate the certificate’s expiration date. TLS support for LDAP is mentioned in RFC 2830 as an extension to the LDAP protocol.

LDAP Operations

Bind

The bind operation is used to authenticate a user to the server. It is used to start a connection with the LDAP server. LDAP is a connection-oriented protocol. The client specifies the protocol version and the client authentication information. LDAP supports the following binds:

  • Authenticated bind

  • Anonymous bind

An authenticated bind is performed when a root distinguished name (DN) and password are available. In the absence of a root DN and password, an anonymous bind is performed. In LDAP deployments, the search operation is performed first and the bind operation later. This is because, if a password attribute is returned as part of the search operation, the password verification can be done locally on an LDAP client. Thus, there is no need to perform an extra bind operation. If a password attribute is not returned, the bind operation can be performed later. Another advantage of performing a search operation first and a bind operation later is that the DN received in the search result can be used as the user DN instead of forming a DN by prefixing the username (cn attribute) with the base DN. All entries stored in an LDAP server have a unique DN. The DN consists of two parts: the Relative Distinguished Name (RDN) and the location within the LDAP server where the record resides.

Most of the entries that you store in an LDAP server will have a name, and the name is frequently stored in the Common Name (cn) attribute. Because every object has a name, most objects you store in an LDAP will use their cn value as the basis for their RDN.

Search

A search operation is used to search the LDAP server. The client specifies the starting point (base DN) of the search, the search scope (either the object, its children, or the subtree rooted at the object), and a search filter.

For authorization requests, the search operation is directly performed without a bind operation. The LDAP server can be configured with certain privileges for the search operation to succeed. This privilege level is established with the bind operation.

An LDAP search operation can return multiple user entries for a specific user. In such cases, the LDAP client returns an appropriate error code to AAA. To avoid these errors, appropriate search filters that help to match a single entry must be configured.

Compare

The compare operation is used to replace a bind request with a compare request for an authentication. The compare operation helps to maintain the initial bind parameters for the connection.

LDAP Dynamic Attribute Mapping

Lightweight Directory Access Protocol (LDAP) is a powerful and flexible protocol for communication with AAA servers. LDAP attribute maps provide a method to cross-reference the attributes retrieved from a server to Cisco attributes supported by the security appliances.

When a user authenticates a security appliance, the security appliance, in turn, authenticates to the server and uses the LDAP protocol to retrieve the record for that user. The record consists of LDAP attributes associated with fields displayed on the user interface of the server. Each attribute retrieved includes a value that was entered by the administrator who updates the user records.

How to Configure LDAP

Configuring Router-to-LDAP Server Communication

The LDAP host is normally a multiuser system running LDAP server software such as Active Directory (Microsoft) and OpenLDAP. Configuring router-to-LDAP server communication can have several components:

  • Hostname or IP address

  • Port number

  • Timeout period

  • Base DN

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    ldap server name

    4.    ipv4 ipv4-address

    5.    transport port port-number

    6.    timeout retransmit seconds

    7.    exit


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example:
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 configure terminal


    Example:
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3 ldap server name


    Example:
    Device(config)# ldap server server1
     

    Configures a device to use the LDAP protocol and enters LDAP server configuration mode.

     
    Step 4 ipv4 ipv4-address


    Example:
    Device(config-ldap-server)# ipv4 192.0.2.1
     

    Specifies the LDAP server IP address using IPv4.

     
    Step 5 transport port port-number


    Example:
    Device(config-ldap-server)# transport port 200
     

    Configures the transport protocol for connecting to the LDAP peer.

     
    Step 6 timeout retransmit seconds


    Example:
    Device(config-ldap-server)# timeout retransmit 20
     

    Specifies the number of seconds a router waits for a reply to an LDAP request before retransmitting the request.

     
    Step 7 exit


    Example:
    Device(config-ldap-server)# exit
     

    Exits LDAP server configuration mode.

     

    Configuring LDAP Protocol Parameters

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    aaa

      4.    ldap server name

      5.    bind authenticate root-dn password [0 string | 7 string] string

      6.    search-filter user-object-type string

      7.    base-dn string

      8.    mode secure [no-negotiation]

      9.    secure cipher 3des-ede-cbc-sha

      10.    exit


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example:
      Device> enable
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.

       
      Step 2 configure terminal


      Example:
      Device# configure terminal
       

      Enters global configuration mode.

       
      Step 3 aaa


      Example: 
      Device(config)# aaa new-model
       

      Enables AAA.

       
      Step 4 ldap server name


      Example:
      Device(config)# ldap server server1
       

      Defines a Lightweight Directory Access Protocol (LDAP) server and enters LDAP server configuration mode.

       
      Step 5 bind authenticate root-dn password [0 string | 7 string] string


      Example:
      Device(config-ldap-server)# bind authenticate root-dn “cn=administrator,cn=users,dc=nac-blr2,dc=example,dc=com password”
       

      Specifies a shared secret text string used between the device and an LDAP server. Use the 0 line option to configure an unencrypted shared secret. Use the 7 line option to configure an encrypted shared secret.

       
      Step 6 search-filter user-object-type string


      Example:
      Device(config-ldap-server)# search-filter user-object-type string1
       

      Specifies the search filter to be used in the search requests.

       
      Step 7 base-dn string


      Example:
      Device(config-ldap-server)# base-dn “dc=sns,dc=example,dc=com”
       

      Specifies the base distinguished name (DN) of the search.

       
      Step 8 mode secure [no-negotiation]


      Example:
      Device(config-ldap-server)# mode secure no-negotiation
       

      Configures LDAP to initiate the transport layer security (TLS) connection and specifies the secure mode.

       
      Step 9 secure cipher 3des-ede-cbc-sha


      Example:
      Device(config-ldap-server)# secure cipher 3des-ede-cbc-sha
       

      Specifies the ciphersuite in the case of a secure connection.

       
      Step 10 exit


      Example:
      Device(config-ldap-server)# exit
       

      Exits LDAP server configuration mode and enters global configuration mode.

       

      Configuring a AAA Server Group

      Configuring the router to use AAA server groups enables you to group existing servers. You need to select a subset of the configured server hosts and use them for a particular service. A server group is used in conjunction with a global server-host list. The server group lists the IP addresses of the selected server hosts. Server groups can also include multiple host entries for the same server, as long as each entry has a unique identifier.

      If two different host entries on the same LDAP server are configured for the same service (for example, accounting) the second host entry configured acts as failover backup to the first one. Using this example, if the first host entry fails to provide accounting services, the network access server will try the second host entry configured on the same device for accounting services. (The LDAP host entries will be tried in the order in which they are configured.) To define a server host with a server group name, enter the following commands. The listed server must exist in global configuration mode.

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    aaa new-model

        4.    aaa group server ldap group-name

        5.    server name

        6.    exit


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 enable


        Example:
        Device> enable
         

        Enables privileged EXEC mode.

        • Enter your password if prompted.

         
        Step 2 configure terminal


        Example:
        Device# configure terminal
         

        Enters global configuration mode.

         
        Step 3 aaa new-model


        Example:
        Device(config)# aaa new-model
         

        Enables AAA.

         
        Step 4 aaa group server ldap group-name


        Example:
        Device(config)# aaa group server ldap name1
         

        Defines the AAA server group with a group name and enters LDAP server group configuration mode. All members of a group must be the of same type, that is, RADIUS, LDAP, or TACACS+.

         
        Step 5 server name


        Example:
        Device(config-ldap-sg)# server server1
         

        Associates a particular LDAP server with the defined server group. Each security server is identified by its IP address and UDP port number.

         
        Step 6 exit


        Example:
        Device(config-ldap-sg)# exit
         

        Exits LDAP server group configuration mode.

         

        Configuring Search and Bind Operations for an Authentication Request

        SUMMARY STEPS

          1.    enable

          2.    configure terminal

          3.    aaa new-model

          4.    ldap server name

          5.    authentication bind-first

          6.    authentication compare

          7.    exit


        DETAILED STEPS
           Command or ActionPurpose
          Step 1 enable


          Example:
          Device> enable
           

          Enables privileged EXEC mode.

          • Enter your password if prompted.

           
          Step 2 configure terminal


          Example:
          Device# configure terminal
           

          Enters global configuration mode.

           
          Step 3 aaa new-model


          Example: 
          Device(config)# aaa new-model
           

          Enables AAA.

           
          Step 4 ldap server name


          Example:
          Device(config)# ldap server server1
           

          Defines a Lightweight Directory Access Protocol (LDAP) server and enter LDAP server configuration mode.

           
          Step 5 authentication bind-first


          Example:
          Device(config-ldap-server)# authentication bind-first
           

          Configures the sequence of search and bind operations for an authentication request.

           
          Step 6 authentication compare


          Example:
          Device(config-ldap-server)# authentication compare
           

          Replaces the bind request with the compare request for authentication.

           
          Step 7 exit


          Example:
          Device(config-ldap-server)# exit
           

          Exits LDAP server configuration mode.

           

          Configuring a Dynamic Attribute Map on an LDAP Server

          You must create LDAP attribute maps that map your existing user-defined attribute names and values to Cisco attribute names and values that are compatible with the security appliance. You can then bind these attribute maps to LDAP servers or remove them as required. For more information about user-based firewalls, see the “User-Based Firewall Support” chapter in Security Configuration Guide: Zone-Based Policy Firewall.


          Note

          To use the attribute mapping features correctly, you need to understand the Cisco LDAP attribute names and values as well as the user-defined attribute names and values.

          SUMMARY STEPS

            1.    enable

            2.    configure terminal

            3.    ldap attribute map map-name

            4.    map type ldap-attr-type aaa-attr-type

            5.    exit

            6.    ldap server name

            7.    ipv4 ipv4-address

            8.    bind authenticate root-dn user-name password [0 string | 7 string] string

            9.    base-dn string

            10.    attribute map map-name

            11.    exit


          DETAILED STEPS
             Command or ActionPurpose
            Step 1 enable


            Example:
            Device> enable
             

            Enables privileged EXEC mode.

            • Enter your password if prompted.

             
            Step 2 configure terminal


            Example:
            Device# configure terminal
             

            Enters global configuration mode.

             
            Step 3 ldap attribute map map-name


            Example:
            Device(config)# ldap attribute-map map1
             

            Configures a dynamic LDAP attribute map and enters attribute-map configuration mode.

             
            Step 4 map type ldap-attr-type aaa-attr-type


            Example:
            Device(config-attr-map)# map type department supplicant-group
             

            Defines an attribute map.

             
            Step 5 exit


            Example:
            Device(config-attr-map)# exit
             

            Exits attribute-map configuration mode.

             
            Step 6 ldap server name


            Example:
            Device(config)# ldap server ldap_dir_1
             

            Specifies the LDAP server name and enters LDAP server configuration mode.

             
            Step 7 ipv4 ipv4-address


            Example:
            Device(config-ldap-server)# ipv4 192.0.2.1
             

            Specifies the IP address of the LDAP server.

             
            Step 8 bind authenticate root-dn user-name password [0 string | 7 string] string


            Example:
            Device(config-ldap-server)# bind authenticate root-dn "cn=user1,cn=users,dc=sns,dc=example,dc=com" password example123
             

            Binds the attribute testmap to the LDAP server.

             
            Step 9 base-dn string


            Example:
            Device(config-ldap-server)# base-dn "dc=sns,dc=example,dc=com"
             

            (Optional) Configures the base DN that you want to use to perform search operations in the LDAP server.

             
            Step 10 attribute map map-name


            Example:
            Device(config-ldap-server)# attribute map map1
             

            Attaches the attribute map to a particular LDAP server.

             
            Step 11 exit


            Example:
            Device(config-ldap-server)# exit
             

            Exits LDAP server configuration mode.

             

            Monitoring and Maintaining LDAP Scalability Enhancements

            The following show and debug commands can be entered in any order.

            SUMMARY STEPS

              1.    enable

              2.    clear ldap server

              3.    debug ldap

              4.    show ldap server

              5.    show ldap attributes


            DETAILED STEPS
              Step 1   enable

              Enables privileged EXEC mode.

              • Enter your password if prompted.



              Example: 
              Device> enable
              Step 2   clear ldap server

              Clears the Lightweight Directory Access Protocol (LDAP) server of the TCP connection.



              Example:
              Device# clear ldap server
              Step 3   debug ldap

              Displays information associated with LDAP.



              Example: 
              Device# debug ldap
              Step 4   show ldap server

              Displays the LDAP server state information and various other counters for the server.



              Example: 
              Device# show ldap server
              Step 5   show ldap attributes

              Displays information about default LDAP attribute mapping.



              Example: 
              Device# show ldap attributes
 
LDAP Attribute                   Format      AAA Attribute                 
==============                   ======      =============                 
airespaceBwDataBurstContract     Ulong       bsn-data-bandwidth-burst-contr
userPassword                     String      password                      
airespaceBwRealBurstContract     Ulong       bsn-realtime-bandwidth-burst-c
employeeType                     String      employee-type                 
airespaceServiceType             Ulong       service-type                  
airespaceACLName                 String      bsn-acl-name                  
priv-lvl                         Ulong       priv-lvl                      
memberOf                         String DN   supplicant-group              
cn                               String      username                      
airespaceDSCP                    Ulong       bsn-dscp                      
policyTag                        String      tag-name                      
airespaceQOSLevel                Ulong       bsn-qos-level                 
airespace8021PType               Ulong       bsn-8021p-type                
airespaceBwRealAveContract       Ulong       bsn-realtime-bandwidth-average
airespaceVlanInterfaceName       String      bsn-vlan-interface-name       
airespaceVapId                   Ulong       bsn-wlan-id                   
airespaceBwDataAveContract       Ulong       bsn-data-bandwidth-average-con
sAMAccountName                   String      sam-account-name              
meetingContactInfo               String      contact-info                  
telephoneNumber                  String      telephone-number              
Map: att_map_1
department                       String DN   element-req-qos

              Configuration Examples for LDAP

              Example: Device-to-LDAP Server Communication

              The following example shows how to create server group server1 and specify the IP address, transport port 200, and retransmit values:

              Device> enable
Device# configure terminal
Device(config)# aaa new-model
Device(config)# ldap server server1
Device(config-ldap-server)# ipv6 2001:DB8:0:0:8:800
Device(config-ldap-server)# transport port 200
Device(config-ldap-server)# timeout retransmit 20
Device(config-ldap-server)# exit

              Example: LDAP Protocol Parameters

              The following example shows how to configure the LDAP parameters:

              ldap server server1 
 bind authenticate root-dn “cn=administrator,cn=users,dc=nac-blr2,dc=cisco,dc=com password 123”
 search-filter user-object-type objectclass
 base-dn "dc=sns,dc=example,dc=com"
 mode secure no-negotiation
 secure cipher 3des-ede-cbc-sha

              Example: AAA Server Group

              The following example shows how to configure the AAA server group:

              aaa new-model
 aaa group server ldap server1

              Example: Search and Bind Operations for an Authentication Request

              The following example shows how to configure the sequence of search and bind operations for an authentication request: 

              Device> enable
Device# configure terminal
Device(config)# aaa new-model
Device(config)# ldap server server1
Device(config-ldap-server)# authentication bind-first
Device(config-ldap-server)# authentication compare
Device(config-ldap-server)# exit

              Example: Dynamic LDAP Attribute Map and LDAP Server

              The following example shows how to attach the attribute map to a particular LDAP server:

              ldap attribute-map map1
 map type department element-req-qos
exit
ldap server ldap_dir_1
ipv4 192.0.2.1
 bind authenticate root-dn "cn=administrator,cn=users,dc=nac-blr2,dc=example,dc=com" password example123
 base-dn "dc=sns,dc=example,dc=com"
 attribute map map1

              The following example shows how to attach the attribute map to an LDAP host running Active Directory (Microsoft) server software for successful user authentication:

              ldap attribute-map map1
 map type sAMAccountName username
exit
ldap server ldap_dir_1
ipv4 192.0.2.1
 bind authenticate root-dn "cn=administrator,cn=users,dc=nac-blr2,dc=example,dc=com" password example123
 base-dn "dc=sns,dc=example,dc=com"
 attribute map map1

              Additional References for Configuring LDAP

              Related Documents

              Related Topic

              Document Title

              Cisco IOS commands

              Cisco IOS Master Command List, All Releases

              Security commands

              AAA

              “Configuring Authentication” module

              RFCs

              RFC

              Title

              RFC 2830

              Lightweight Directory Access Protocol (v3): Extension for Transport Layer Security

              RFC 4511

              Lightweight Directory Access Protocol (LDAP)

              RFC 4513

              Lightweight Directory Access Protocol (LDAP): Authentication Methods and Security Mechanisms

              RFC 4514

              Lightweight Directory Access Protocol (LDAP): String Representation of Distinguished Names

              RFC 4515

              Lightweight Directory Access Protocol (LDAP): String Representation of Search Filters

              RFC 4517

              Lightweight Directory Access Protocol (LDAP): Syntaxes and Matching Rules

              RFC 4519

              Lightweight Directory Access Protocol (LDAP): Schema for User Applications

              Technical Assistance

              Description

              Link

              The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

              http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

              Feature Information for Configuring LDAP

              The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

              Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

              Table 1 Feature Information for Configuring LDAP

              Feature Name

              Releases

              Feature Information

              LDAP Integration with Active Directory

              Cisco IOS 15.0(1)EX

              Lightweight Directory Access Protocol (LDAP) is a standard-based protocol used to access directories. It is based on the client server model similar to RADIUS. LDAP is deployed on Cisco devices to send authentication requests to a central LDAP server that contains all user authentication and network service access information.

              The LDAP Integration with Active Directory feature provides authentication and authorization support for authentication, authorization, and accounting (AAA).

              The following commands were introduced or modified: aaa group server ldap, authentication bind-first, authentication compare, bind authenticate, base-dn, clear ldap server, debug ldap, ipv4, mode secure, ldap server, search-filter, secure cipher, show ldap server, transport port, timeout, retransmit.

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