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This document describes how to use Lightweight Directory Access Protocol (LDAP) Attribute Maps in order to configure granular Dynamic Accesss Policies on an Adaptive Security Appliance (ASA).
Cisco recommends that you have knowledge of these topics:
The information in this document is based on the ASA-5xxx hardware platform performing as a VPN concentrator/server for Remote Access SSL VPN (AnyConnect and Clientless/WebVPN) and IPsec sessions.
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
LDAP is an open, vendor-neutral, industry-standard application protocol to access and maintain distributed directory information services over an IP network. Directory services play an important role in the development of intranet and Internet applications because they allow information about users, systems, networks, services, and applications to be shared throughout the network.
Frequently, administrators want to provide VPN users with different access permissions or WebVPN content. This can be done if you configure different VPN policies on the VPN server and assign these policy-sets to each user based on their credentials. While this can be done manually, it is more efficient to automate the process with Directory Services. In order to use LDAP to assign a group policy to a user, you need to configure a map that maps an LDAP attribute, such as the Active Directory (AD) attribute memberOf, to the IETF-Radius-Class or Group-Policy attribute that is understood by the VPN headend.
Note: On Cisco IOS Headends, the same thing can be achieved if you configure different policy groups under the WebVPN context and use LDAP attribute maps in order to determine which policy group the user will be assigned as described in the document. See Policy Group Assignment for AnyConnect Clients That Use LDAP on Cisco IOS Headends Configuration Example.
On the ASA, this is regularly achieved through the assignment of different group policies to different users. When LDAP authentication is in use, this can be achieved automatically with an LDAP attribute map. In order to use LDAP to assign a group policy to a user, you must map an LDAP attribute, such as the AD attribute memberOf to the Group-Policy attribute that is understood by the ASA. Once the attribute mapping is established, you must map the attribute value configured on the LDAP server to the name of a group policy on the ASA.
Note: The memberOf attribute corresponds to the group that the user is a a part of in the Active Directory. It is possible for a user to be a member of more than one group in the Active Directory. This causes multiple memberOf attributes to be sent by the server, but the ASA can only match one attribute to one group policy.
A. No, there are no limits. ldap-attribute-maps are dynamically allocated during the VPN remote access session that uses LDAP authentication/authorization.
A. No configuraiton limits.
A. No restriction. The LDAP code only verifies that the ldap-attribute-map name is valid.
A. Yes. Here, only AD is explained, but it applies to any LDAP server that uses multi-value attributes for policy decisions. The ldap-attribute-map has a limitation with multi-valued attributes like the AD memberOf. If a user is a memberOf of several AD groups (which is common) and the ldap-attribute-map matches more than one of them, the mapped value will be chosen based on the alphabetization of the matched entries. Since this behavior is not obvious or intuitive, it is important to have clear knowledge about how it works.
Summary: If the LDAP mapping results in multiple values for an attribute, the final attribute value will be chosen as follows:
Active Directory-LDAP returns these four memberOf instances for a user authentication or authorization request:
memberOf: value = CN=APP-SSL-VPN Managers,CN=Users,OU=stbu,DC=cisco,DC=com
memberOf: value = CN=Cisco-Eng,CN=Users,DC=stbu,OU=cisco,DC=com
memberOf: value = CN=Employees,CN=Users,OU=stbu,DC=cisco,DC=com
memberOf: value = CN=Engineering,CN=Users,OU=stbu,DC=cisco,DC=com
LDAP-MAP #1: Assume that this ldap-attribute-map is configured to map different ASA group-policies based on the memberOf setting:
ldap attribute-map Class
map-name memberOf Group-Policy
map-value memberOf CN=APP-SSL-VPN Managers,CN=Users,OU=stbu,DC=cisco,DC=com ASAGroup4
map-value memberOf CN=cisco-Eng,CN=Users,OU=stbu,DC=cisco,DC=com ASAGroup3
map-value memberOf CN=Employees,CN=Users,OU=stbu,DC=cisco,DC=com ASAGroup2
map-value memberOf CN=Engineering,CN=Users,OU=stbu,DC=cisco,DC=com ASAGroup1
In this case, matches will occur on all four group policy values (ASAGroup1 - ASAGroup4). However, the connection will be assigned to group-policy ASAGroup1 because it occurs first in alphabetical order.
LDAP-MAP #2: This ldap-attribute-map is the same, except the first memberOf does not have an explicit map-value assigned (no ASAGroup4). Note that when there is no explicit map-value defined, the attribute text received from LDAP is used.
ldap attribute-map Class
map-name memberOf Group-Policy
map-value memberOf CN=APP-SSL-VPN Managers,CN=Users,OU=stbu,DC=cisco,DC=com
map-value memberOf CN=cisco-Eng,CN=Users,OU=stbu,DC=cisco,DC=com ASAGroup3
map-value memberOf CN=Employees,CN=Users,OU=stbu,DC=cisco,DC=com ASAGroup2
map-value memberOf CN=Engineering,CN=Users,OU=stbu,DC=cisco,DC=com ASAGroup1
As in the previous case, matches occur on all four entries. In this case, since no mapped value is provided for the APP-SSL-VPN entry, the mapped value will default to CN=APP-SSL-VPN Managers,CN=Users,OU=stbu,DC=cisco,DC=com. Since CN=APP-SSL-VPN appears first in aphabetical order, APP-SSL-VPN will be selected as the policy value.
Refer to Cisco bug ID CSCub64284 for more information. Refer to PIX/ASA 8.0: Use LDAP Authentication to Assign a Group Policy at Login, which shows a simple LDAP case with memberOf that might work in your particular deployment.
Note: In a memberOf DN such as "CN=Engineering, OU=Office1, DC=cisco,DC=com", you can only make the decision on the first DN, that is CN=Engineering, not the Organizational Unit (OU). There is an enhancement to be able able to filter on any DN field.
Note: Each example described in this section is a standalone configuration, but can be mixed and matched with each other to produce the desired Access policy.
Tip: Attribute Names and Values are Case-Sensitive. If the mapping does not occur properly, be certain that the correct spelling and capitalization has been used in the LDAP attribute map for both the Cisco and LDAP attribute names and values.
Any standard LDAP attribute can be mapped to a well-known appliance Vendor Specific Attribute (VSA). One or more LDAP attribute(s) can be mapped to one or more Cisco LDAP attributes. For a complete list of Cisco LDAP VSAs, refer Supported Cisco Attributes for LDAP Authorization. This example shows how to enforce a banner for LDAP user1. User1 can be any VPN Remote Access type: IPsec, SVC, or WebVPN Clientless. This example uses the Properties/General/Office attribute/field to enforce the Banner1.
Note: You could use the AD Department attribute/field to map to Cisco IETF-Radius-Class VSA in order to enforce policies from an ASA/PIX group-policy. There are examples of this later in the document.
LDAP (for Microsoft AD and Sun) attribute-mapping is supported as of PIX/ASA Version 7.1.x. Any Microsoft/AD attribute can be mapped to a Cisco attribute. Here is the procedure to perform this:
On the AD/LDAP server:
B200-54(config)# show run ldap
ldap attribute-map Banner
map-name physicalDeliveryOfficeName Banner1
B200-54(config-time-range)# show runn aaa-server microsoft
aaa-server microsoft protocol ldap
aaa-server microsoft host audi-qa.frdevtestad.local
ldap-base-dn dc=frdevtestad,dc=local
ldap-scope subtree
ldap-naming-attribute sAMAccountName
ldap-login-password hello
ldap-login-dn cn=Administrator,cn=Users,dc=frdevtestad,dc=local
ldap-attribute-map Banner
This example demonstrates the authentication of user1 on the AD-LDAP server and retrieves the department field value so it can be mapped to an ASA/PIX group-policy from which policies will be enforced.
On the AD/LDAP server:
5520-1(config)# show runn ldap
ldap attribute-map Our-AD-Map
map-name department Group-Policy
5520-1(config)#
Note: As a result of the implementation of Cisco bug ID CSCsv43552, a new ldap-attribute-map attribute, Group-Policy, was introduced in order to replace IETF-Radius-Class. The CLI on ASA Version 8.2 supports the IETF-Radius-Class keyword as a valid choice in the map-name and map-value commands in order to read an 8.0 config file (software upgrade scenario). The Adaptive Security Device Manager (ASDM) code has already been updated to no longer display IETF-Radius-Class as a choice when you configure an attribute map entry. Additionally, ASDM will write out the IETF-Radius-Class attribute (if read in from an 8.0 config) as the Group-Policy attribute.
Note: Add more attributes to the map as required. This example shows only the minimum to control this specific function (place a user in a specific ASA/PIX 7.1.x group-policy). The third example shows this type of map.
You can create a NOACCESS group-policy in order to deny the VPN connection when the user is not part of any of the LDAP groups. This configuration snippet is shown for your reference:
group-policy NOACCESS internal
group-policy NOACCESS attributes
vpn-simultaneous-logins 0
vpn-tunnel-protocol IPSec webvpn
You must apply this group policy as a default group policy to the tunnel-group. This allows users who get a mapping from the LDAP attribute map, for example those who belong to a desired LDAP group, to get their desired group policies and users who do not get any mapping, for example those who do not belong to any of the desired LDAP groups, to get NOACCESS group-policy from the tunnel-group, which blocks the access for them.
Tip: Since the vpn-simultaneous-logins attribute is set to 0 here, it must be explicitly defined in all the other group-policies as well; otherwise, it will be inherited from the default group-policy for that tunnel group, which in this case is the NOACCESS policy.
Note: Implementation/fix of Cisco bug ID CSCse08736 is required, so the ASA should run at least Version 7.2.2.
Note: The Department AD attribute was used only because logically "department" refers to the group-policy. In reality, any field could be used. The requirement is that this field has to map to the Cisco VPN attribute Group-Policy as shown in this example.
5520-1(config)# show runn ldap
ldap attribute-map Our-AD-Map
map-name department IETF-Radius-Class
map-name description\Banner1
map-name physicalDeliveryOfficeName IETF-Radius-Session-Timeout
5520-1(config)#
The two AD-LDAP attributes Description and Office (represented by AD names description and PhysicalDeliveryOfficeName) are the group record attributes (for VPNUSerGroup) which maps to Cisco VPN attributes Banner1 and IETF-Radius-Session-Timeout.
The department attribute is for the user record to map to the name of external group-policy on the ASA (VPNUSer), which then maps back to the VPNuserGroup record on the AD-LDAP server, where attributes are defined.
Note: The Cisco attribute (Group-Policy ) must be defined in the ldap-attribute-map. Its mapped AD-attribute can be any settable AD attribute. This example uses department because it is the most logical name that refers to group-policy.
5520-1(config)# show runn aaa-server LDAP-AD11
aaa-server LDAP-AD11 protocol ldap
aaa-server LDAP-AD11 host 90.148.1.11
ldap-base-dn cn=Users,dc=nelson,dc=cisco,dc=com
ldap-scope onelevel
ldap-naming-attribute sAMAccountName
ldap-login-password altiga
ldap-login-dn cn=Administrator,cn=Users,dc=nelson,dc=cisco,dc=com
ldap-attribute-map Our-AD-Map
5520-1(config)#
5520-1(config)# show runn tunnel-group
remoteAccessLDAPTunnelGroup
tunnel-group RemoteAccessLDAPTunnelGroup general-attributes
authentication-server-group LDAP-AD11
accounting-server-group RadiusACS28
5520-1(config)#
5520-1(config)# show runn tunnel-group
remoteAccessLDAPTunnelGroup
tunnel-group RemoteAccessLDAPTunnelGroup general-attributes
authentication-server-group none
authorization-server-group LDAP-AD11
accounting-server-group RadiusACS28
authorization-required
authorization-dn-attributes ea
5520-1(config)#
5520-1(config)# show runn group-policy VPNUserGroup
group-policy VPNUserGroup external server-group LDAP-AD11
5520-1(config)#
The AD attribute is msRADIUSFramedIPAddress. The attribute is configured in AD User Properties, Dial-in tab, "Assign a Static IP Address".
Here are the steps:
5540-1# show running-config ldap
ldap attribute-map Assign-IP
map-name msRADIUSFramedIPAddress IETF-Radius-Framed-IP-Address
5540-1#
5520-1(config)# show runn all vpn-addr-assign
vpn-addr-assign aaa
no vpn-addr-assign dhcp
vpn-addr-assign local
5520-1(config)#
Supports all VPN Remote Acccess sessions: IPSec, WebVPN, and SVC. Allow Access has a value of TRUE. Deny Acccess has a value of FALSE. The AD attribute name is msNPAllowDialin.
This example demonstrates the creation of an ldap-attribute-map that uses the Cisco Tunneling-Protocols to create Allow Access (TRUE) and Deny (FALSE) conditions. For example, if you map the tunnel-protocol=L2TPover IPsec (8), you can create a FALSE condition if you try to enforce access for WebVPN and IPsec. The reverse logic applies too.
Here are the steps:
Note: If you select the third option “Control access through the Remote Access Policy,” no value is returned from the AD server, so the permissions that are enforced are based on the ASA/PIX’s internal group-policy’s setting.
ldap attribute-map LDAP-MAP
map-name msNPAllowDialin Tunneling-Protocols
map-value msNPAllowDialin FALSE 8
map-value msNPAllowDialin TRUE 20
5540-1#
Note: Add more attributes to the map as required. This example shows only the minimum to control this specific function (Allow or Deny Access based on Dial-In setting).
What does the ldap-attribute-map mean or enforce?
Deny Access for a user1. The FALSE value condition maps to tunnel-protocol L2TPoverIPsec, (value 8).
Allow Access for user2 . The TRUE value condition maps to tunnel-protocol WebVPN + IPsec, (value 20).
This case is closely related to Case 5, provides for a more logical flow, and is the recommended method, since it establishes the group-membership check as a condition.
ldap attribute-map LDAP-MAP
map-name memberOf Tunneling-Protocols
map-value memberOf cn=ASA-VPN-Consultants,cn=Users,dc=abcd,dc=com 4
5540-1#
Note: Add more attributes to the map as required. This examples shows only the minimum to control this specific function (Allow or Deny Access based on Group membership).
What does the ldap-attribute-map mean or enforce?
This use case describes how to set up and enforce the Time of Day rules on AD/LDAP.
Here is the procedure to do this:
On the AD/LDAP server:
Example:
B200-54(config-time-range)# show run ldap
ldap attribute-map TimeOfDay
map-name physicalDeliveryOfficeName Access-Hours
B200-54(config-time-range)# show runn aaa-server microsoft
aaa-server microsoft protocol ldap
aaa-server microsoft host audi-qa.frdevtestad.local
ldap-base-dn dc=frdevtestad,dc=local
ldap-scope subtree
ldap-naming-attribute sAMAccountName
ldap-login-password hello
ldap-login-dn cn=Administrator,cn=Users,dc=frdevtestad,dc=local
ldap-attribute-map TimeOfDay
B200-54(config-time-range)# show runn time-range
!
time-range Boston
periodic weekdays 8:00 to 17:00
!
ASA5585-S10-K9# show runn aaa-server
aaa-server test-ldap protocol ldap
aaa-server test-ldap (out) host 10.201.246.130
ldap-base-dn cn=users, dc=htts-sec, dc=com
ldap-login-password *****
ldap-login-dn cn=Administrator, cn=Users, dc=htts-sec, dc=com
server-type microsoft
ldap-attribute-map Test-Safenet-MAP
aaa-server test-rad protocol radius
aaa-server test-rad (out) host 10.201.249.102
key *****
ASA5585-S10-K9# show runn ldap
ldap attribute-map Test-Safenet-MAP
map-name memberOf IETF-Radius-Class
map-value memberOf "CN=DHCP Users,CN=Users,DC=htts-sec,DC=com" Test-Policy-Safenet
ASA5585-S10-K9# show runn tunnel-group
tunnel-group Test_Safenet type remote-access
tunnel-group Test_Safenet general-attributes
address-pool RA_VPN_IP_Pool
authentication-server-group test-rad
secondary-authentication-server-group test-ldap use-primary-username
default-group-policy NoAccess
tunnel-group Test_Safenet webvpn-attributes
group-alias Test_Safenet enable
ASA5585-S10-K9# show runn group-policy
group-policy NoAccess internal
group-policy NoAccess attributes
wins-server none
dns-server value 10.34.32.227 10.34.32.237
vpn-simultaneous-logins 0
default-domain none
group-policy Test-Policy-Safenet internal
group-policy Test-Policy-Safenet attributes
dns-server value 10.34.32.227 10.34.32.237
vpn-simultaneous-logins 15
vpn-idle-timeout 30
vpn-tunnel-protocol ikev1 ssl-client ssl-clientless
split-tunnel-policy tunnelspecified
split-tunnel-network-list value Safenet-Group-Policy-SplitAcl
default-domain none
With this configuration, AnyConnect users who were mapped correctly with the use of LDAP attributes were not placed in the group-policy, Test-Policy-Safenet. Instead, they were still placed in the default group-policy, in this case NoAccess.
See the snippet of the debugs (debug ldap 255) and syslogs at level informational:
--------------------------------------------------------------------------------
memberOf: value = CN=DHCP Users,CN=Users,DC=htts-sec,DC=com
[47] mapped to IETF-Radius-Class: value = Test-Policy-Safenet
[47] mapped to LDAP-Class: value = Test-Policy-Safenet
--------------------------------------------------------------------------------
Syslogs :
%ASA-6-113004: AAA user authentication Successful : server = 10.201.246.130 : user = test123
%ASA-6-113003: AAA group policy for user test123 is being set to Test-Policy-Safenet
%ASA-6-113011: AAA retrieved user specific group policy (Test-Policy-Safenet) for user =
test123
%ASA-6-113009: AAA retrieved default group policy (NoAccess) for user = test123
%ASA-6-113013: AAA unable to complete the request Error : reason = Simultaneous logins
exceeded for user : user = test123
%ASA-6-716039: Group <DfltGrpPolicy> User <test123> IP <10.116.122.154> Authentication:
rejected, Session Type: WebVPN.
These syslogs show failure as the user was being given the NoAccess group-policy which had simultaneous-login set to 0 even though syslogs say it retrieved a user specific group-policy.
In order to have the user assigned in the group-policy, based on the LDAP-map, you must have this command: authorization-server-group test-ldap (in this case, test-ldap is the LDAP server name). Here is an example:
ASA5585-S10-K9# show runn tunnel-group
tunnel-group Test_Safenet type remote-access
tunnel-group Test_Safenet general-attributes
address-pool RA_VPN_IP_Pool
authentication-server-group test-rad
secondary-authentication-server-group test-ldap use-primary-username
authorization-server-group test-ldap
default-group-policy NoAccess
tunnel-group Test_Safenet webvpn-attributes
group-alias Test_Safenet enable
In order to have the user place into a group-policy based on the LDAP map attribute, you must specify this command under the tunnel-group: authorization-server-group test-ldap.
In this case, you also would need the command, authorization-server-group test-ldap, under the tunnel-group for the user to be placed into the correct group-policy.
ASA5585-S10-K9# show vpn-sessiondb anyconnect
Session Type: AnyConnect
Username : test123 Index : 2
Assigned IP : 10.34.63.1 Public IP : 10.116.122.154
Protocol : AnyConnect-Parent SSL-Tunnel DTLS-Tunnel
License : AnyConnect Essentials
Encryption : 3DES 3DES 3DES Hashing : SHA1 SHA1 SHA1
Bytes Tx : 14042 Bytes Rx : 8872
Group Policy : Test-Policy-Safenet Tunnel Group : Test_Safenet
Login Time : 10:45:28 UTC Fri Sep 12 2014
Duration : 0h:01m:12s
Inactivity : 0h:00m:00s
NAC Result : Unknown
VLAN Mapping : N/A VLAN : none
Use this section in order to troubleshoot your configuration.
These debugs can be used in order to help isolate issues with the DAP configuraiton:
In case the ASA is not able to authenticate users from LDAP serve, here are some sample debugs:
ldap 255 output:[1555805] Session Start[1555805] New request Session, context
0xcd66c028, reqType = 1[1555805]
Fiber started[1555805] Creating LDAP context with uri=ldaps://172.30.74.70:636
[1555805] Connect to LDAP server:
ldaps://172.30.74.70:636, status = Successful[1555805] supportedLDAPVersion:
value = 3[1555805]
supportedLDAPVersion: value = 2[1555805] Binding as administrator[1555805]
Performing Simple
authentication for sysservices to 172.30.74.70[1555805] Simple authentication
for sysservices returned code (49)
Invalid credentials[1555805] Failed to bind as administrator returned code
(-1) Can't contact LDAP server[1555805]
Fiber exit Tx=222 bytes Rx=605 bytes, status=-2[1555805] Session End
From these debugs, either the LDAP Login DN format is incorrect or the password is incorrect so verify both in order to resolve the issue.