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.
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.
Q. Is there a configuration limit on the number of ldap-attribute-maps for the ASA?
A. No, there are no limits. ldap-attribute-maps are dynamically allocated during the VPN remote access session that uses LDAP authentication/authorization.
Q. Is there a limit on the numbers of attributes that can be mapped per ldap-attribute-map?
A. No configuraiton limits.
Q. Is there a restriction on how many ldap-servers to which a specific ldap-attribute-map can be applied?
A. No restriction. The LDAP code only verifies that the ldap-attribute-map name is valid.
Q. Are there limitations with ldap-attribute-maps and muti-valued attributes like AD memberOf?
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:
First, select the value(s) with the smallest number of characters.
If this results in more than one value, choose the value that is the lowest in alphabetical order.
Use Case Examples
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:
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.
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.
Use Dynamic Access Policy (DAP) - DAP does not have this limitation of parsing multi-valued attributes (like memberOf); but DAP currently cannot set a group-policy from within itself. This means the session would have to be properly segmented via the tunnel-group/group-policy association methods. In the future, DAP will have the capability to set any authorization attribute, including the group-policy, (Cisco bug ID CSCsi54718), so the need for an ldap-attribute-map for this purpose will eventually not be required.
As a possible alternative and if the deployment scenario allows it, whenever you must use an ldap-attribute-map to set the class attribute, you could also use a single-valued attribute (like Department) that represents your group differentiation on AD.
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.
Configure - Sample Use Cases
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.
1. User-Based Attributes Policy Enforcement
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:
Right-click > Properties.
Select a tab to be used in order to set an attribute (Example. General tab).
Select a field/attribute, for example the "Office" field, to be used in order to enforce time-range, and enter the banner text (example, Welcome to LDAP !!!!). The "Office" configuration on the GUI is stored in the AD/LDAP attribute "physicalDeliveryOfficeName".
On the ASA, in order to create an LDAP attribute mapping table, map the AD/LDAP attribute "physicalDeliveryOfficeName" to the ASA attribute "Banner1":
B200-54(config)# show run ldap ldap attribute-map Banner map-name physicalDeliveryOfficeName Banner1
Associate the LDAP attribute map to the aaa-server entry:
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
Establish the Remote Access session and verify that the Banner “Welcome to LDAP !!!!” is presented to the VPN user.
2. Place LDAP Users in a Specific Group-Policy - Generic Example
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:
Right-click > Properties.
Select a tab to be used in order to set an attribute (Example. Organization tab).
Select a field/attribute, for example "Department", to be used in order to enforce a group-policy, and enter the value of the group-policy (Group-Policy1) on the ASA/PIX. The "Department" configuration on the GUI is stored in the AD/LDAP attribute "department".
Define an ldap-attribute-map table.
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.
Define the group-policy Group_policy1 on the appliance and the required policy attributes.
Establish the VPN remote access tunnel and verify that the session inherits the attributes from Group-Policy1 (and any other applicable attributes from the default group-policy).
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.
Configure a NOACCESS Group-policy
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:
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.
3. Group-Based Attributes Policy Enforcement - Example
Note: Implementation/fix of Cisco bug ID CSCse08736 is required, so the ASA should run at least Version 7.2.2.
On the AD-LDAP server, Active Directory Users and Computers, set up a user record (VPNUserGroup) that represents a group where the VPN attributes are configured.
On the AD-LDAP server, Active Directory Users and Computers, define each user record's Department field to point to the group-record (VPNUserGroup) in Step 1. The user name in this example is web1.
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.
Define an ldap-attribute-map table:
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.
Configure the aaa-server with the ldap-attribute-map name to be used for LDAP Authentication, Authorization, and Accounting (AAA) operations:
On the ASA, verify the vpn-address-assigment is configured to include “vpn-addr-assign-aaa”:
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)#
Establish the IPsec/SVC Remote Authority (RA) sessions and verify the with “show vpn-sessiondb remote|svc” that the "Assigned IP" field is correct (10.20.30.6).
5. Active Directory Enforcement of “Remote Access Permission Dial-in, Allow/Deny Access ”
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:
On the AD server user1 Properties, Dial-In, select the appropriate allow Access or Deny access for each user.
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.
On the ASA, create an ldap-attribute-map with this mapping:
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?
map-value msNPAllowDialin FALSE 8
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).
A WebVPN/IPsec user, authenticaticated as user1 on AD, would fail due to the tunnel-protocol mismatch.
A L2TPoverIPsec, authenticaticated as user1 on AD, would fail due to the Deny rule.
A WebVPN/IPsec user, authenticaticated as user2 on AD, would succeed (Allow rule + matched tunnel protocol).
A L2TPoverIPsec, authenticaticated as user2 on AD, would fail due to the tunnel-protocol mismatch.
Support for Tunnel Protocol, as defined in RFCs 2867 and 2868.
6. Active Directory Enforcement of “Member Of ”/Group Membership to Allow or Deny Access
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.
Configure the AD user to be “Member Of” a specific group. Use a name that places it at the top of the group-hierarchy (ASA-VPN-Consultants). In AD-LDAP, Group membership is defined by the AD attribute “memberOf”. It is important that the group be at the top of the list, since you can currently only apply the rules to the first group/"memberOf" string. In Release 7.3, you will be able to perform multiple-group filtering and enforcement.
On the ASA, create an ldap-attribute-map with the the minimum mapping:
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?
User=joe_consultant, part of AD, which is member of AD group “ASA-VPN-Consultants” will be allowed access only if the user uses IPsec (tunnel-protocol=4=IPSec).
User=joe_consultant, part of AD, will fail VPN access during any other remote access client (PPTP/L2TP, L2TP/IPSec, WebVPN/SVC, and so on).
User=bill_the_hacker will NOT be allowed in since the user has no AD membership.
7. Active Directory Enforcement of “Logon Hours/Time-of-Day Rules”
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:
Select the user.
Right-click > Properties.
Select a tab to be used in order to set an attribute (Example. General tab).
Select a field/attribute, for example the "Office" field, to be used in order to enforce time-range, and enter the name of the time-range (for example, Boston). The "Office" configuration on the GUI is stored in the AD/LDAP attribute "physicalDeliveryOfficeName".
On the ASA
Create an LDAP attribute mapping table.
Map the AD/LDAP attribute "physicalDeliveryOfficeName" to the ASA attribute "Access-Hours".
B200-54(config-time-range)# show run ldap ldap attribute-map TimeOfDay map-name physicalDeliveryOfficeName Access-Hours
On the ASA, associate the LDAP attribute map to the aaa-server entry:
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
On the ASA, create a time-range object that has the name value that is assigned to the user (Office value in step 1):
B200-54(config-time-range)# show runn time-range ! time-range Boston periodic weekdays 8:00 to 17:00 !
Establish the VPN remote access session:
The session should succeed if within the time-range.
The session should fail if outside the time-range.
8. Use the ldap-map Configuration to Map a User into a Specific Group-policy and Use the authorization-server-group Command, in the Case of Double Authentication
In this scenario, double authentication is used. The first authentication server used is RADIUS and the second authentication sever used is a LDAP server.
Configure the LDAP server as well as the RADIUS server. Here is an example:
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:
%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:
Now, if the first authentication server (RADIUS, in this example) did send the user-specific attributes, for example the IEFT-class attribute, in that case, the user will be mapped to the group-policy sent by RADIUS. So even though the secondary server has a LDAP map configured and the user's LDAP attributes do map the user to a different group-policy, the group-policy sent by the first authentication server will be enforced.
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.
If the first authentication server is SDI or OTP, which cannot pass the user-specific attribute, then the user would fall into the default group-policy of the tunnel-group. In this case, NoAccess even though the LDAP mapping is correct.
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.
If both of the servers are the same RADIUS or LDAP servers, then you do not need the authorization-server-group command in order for the group-policy lock to work.
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.
Debug the LDAP Transaction
These debugs can be used in order to help isolate issues with the DAP configuraiton:
debug ldap 255
debug dap trace
debug aaa authentication
ASA is Not Able to Authenticate Users from LDAP Server
In case the ASA is not able to authenticate users from LDAP serve, here are some sample debugs:
ldap 255 output: Session Start New request Session, context 0xcd66c028, reqType = 1 Fiber started Creating LDAP context with uri=ldaps://172.30.74.70:636  Connect to LDAP server: ldaps://172.30.74.70:636, status = Successful supportedLDAPVersion: value = 3 supportedLDAPVersion: value = 2 Binding as administrator Performing Simple authentication for sysservices to 172.30.74.70 Simple authentication for sysservices returned code (49) Invalid credentials Failed to bind as administrator returned code (-1) Can't contact LDAP server Fiber exit Tx=222 bytes Rx=605 bytes, status=-2 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.