Remote Access VPN on ASA - Authentication using LDAP Server
Table of Contents [hide]
- Introduction
- Prerequisites
- Components Used
- Configuration Remote Access VPN on ASA
- Configuring ISAKMP Policy and Enabling ISAKMP on the Outside Interface
- Configuring an Address Pool
- Adding a User
- Creating a Transform Set
- Creating a Tunnel group
- Creating a Dynamic crypto map
- Creating a Crypto Map Entry to Use the Dynamic Crypto Map
- Configuring LDAP server on the ASA
- Assigning LDAP server under tunnel group
- Verifcation
- Troubleshoot
- Debug - Successful authentication
- Debug - Authentication fails - Incorrect Password
- Debug - Authentication Fail - User not found on LDAP server
- Source Discussion:
Introduction
This document provides an example on how to Configure Remote Access VPN on ASA and do the Authentication using LDAP server
Prerequisites
ASA and LDAP server both should be reachable.
Components Used
1. ASA 8.2
2. LDAP (Microsoft)
Configuration Remote Access VPN on ASA
interface configuration:
hostname(config)# interface ethernet0 hostname(config-if)# ip address 10.10.4.200 255.255.0.0 hostname(config-if)# nameif outside hostname(config)# no shutdown
Configuring ISAKMP Policy and Enabling ISAKMP on the Outside Interface
hostname(config)# isakmp policy 1 authentication pre-share hostname(config)# isakmp policy 1 encryption 3des hostname(config)# isakmp policy 1 hash sha hostname(config)# isakmp policy 1 group 2 hostname(config)# isakmp policy 1 lifetime 43200 hostname(config)# isakmp enable outside
Configuring an Address Pool
hostname(config)# ip local pool testpool 192.168.0.10-192.168.0.15
Adding a User
hostname(config)# username testuser password 12345678
Creating a Transform Set
hostname(config)# crypto ipsec transform-set FirstSet esp-3des esp-md5-hmac
Creating a Tunnel group
hostname(config)# tunnel-group testgroup type ipsec-ra hostname(config)# tunnel-group testgroup general-attributes hostname(config-general)# address-pool testpool hostname(config)# tunnel-group testgroup ipsec-attributes hostname(config-ipsec)# pre-shared-key 44kkaol59636jnfx
Creating a Dynamic crypto map
hostname(config)# crypto dynamic-map dyn1 1 set transform-set FirstSet hostname(config)# crypto dynamic-map dyn1 1 set reverse-route
Creating a Crypto Map Entry to Use the Dynamic Crypto Map
hostname(config)# crypto map mymap 1 ipsec-isakmp dynamic dyn1 hostname(config)# crypto map mymap interface outside
Configuring LDAP server on the ASA
ciscoasa(config-aaa-server-group)#aaa-server LDAP (inside) host 192.168.1.2
ciscoasa(config-aaa-server-host)#ldap-base-dn dc=ftwsecurity, dc=cisco, dc=com
ciscoasa(config-aaa-server-host)#ldap-login-dn cn=admin, cn=users, dc=ftwsecurity, dc=cisco, dc=com
ciscoasa(config-aaa-server-host)#ldap-login-password **********
ciscoasa(config-aaa-server-host)#ldap-naming-attribute sAMAccountName
ciscoasa(config-aaa-server-host)#ldap-scope subtree
ciscoasa(config-aaa-server-host)#server-type microsoft
ciscoasa(config-aaa-server-host)#exit
Assigning LDAP server under tunnel group
ciscoasa(config)#tunnel-group testgroup general-attributes
ciscoasa(config-tunnel-general)#authentication-server-group LDAP
Verifcation
Test with CLI:
You can use the test command on the command line in order to test your AAA setup. A test request is sent to the AAA server, and the result appears on the command line.
ciscoasa#test aaa-server authentication LDAP host 192.168.1.2
username cisco password cisco123INFO: Attempting Authentication test to IP address <192.168.1.2>
(timeout: 12 seconds)
INFO: Authentication Successful
Troubleshoot
If unsure of the current DN string to use, you can issue the dsquery command on a Windows Active Driectory server from a command prompt in order to verify the appropriate DN String of a user object.
C:\Documents and Settings\Administrator>dsquery user -samid cisco!--- Queries Active Directory for samid id "cisco""CN=cisco,CN=Users,DC=ftwsecurity,DC=cisco,DC=com"
The debug ldap 255 command can help to troubleshoot authentication problems in this scenario. This command enables LDAP debugging and allows you to watch the process that the ASA uses to connect to the LDAP server.
Debug - Successful authentication
ciscoasa#debug ldap 255[7] Session Start [7] New request Session, context 0xd4b11730, reqType = 1 [7] Fiber started [7] Creating LDAP context with uri=ldap://192.168.1.2:389 [7] Connect to LDAP server: ldap://192.168.1.2:389, status = Successful [7] defaultNamingContext: value = DC=ftwsecurity,DC=cisco,DC=com [7] supportedLDAPVersion: value = 3 [7] supportedLDAPVersion: value = 2 [7] supportedSASLMechanisms: value = GSSAPI [7] supportedSASLMechanisms: value = GSS-SPNEGO [7] supportedSASLMechanisms: value = EXTERNAL [7] supportedSASLMechanisms: value = DIGEST-MD5 !--- The ASA connects to the LDAP server for admin bind and search for cisco. [7] Binding as administrator [7] Performing Simple authentication for admin to 192.168.1.2 [7] LDAP Search: Base DN = [dc=ftwsecurity, dc=cisco, dc=com] Filter = [sAMAccountName=cisco] Scope = [SUBTREE] [7] User DN = [CN=cisco,CN=Users,DC=ftwsecurity,DC=cisco,DC=com][7] Talking to Active Directory server 192.168.1.2 [7] Reading password policy for cisco, dn:CN=cisco,CN=Users, DC=ftwsecurity,DC=cisco,DC=com !--- The ASA binds to the LDAP server as cisco to test the password. [7] Binding as user [7] Performing Simple authentication for kate to 192.168.1.2 [7] Checking password policy for user cisco [7] Binding as administrator [7] Performing Simple authentication for admin to 192.168.1.2 [7] Authentication successful for kate to 192.168.1.2 [7] Retrieving user attributes from server 192.168.1.2[7] Retrieved Attributes: [7] objectClass: value = top [7] objectClass: value = person [7] objectClass: value = organizationalPerson [7] objectClass: value = user [7] cn: value = cisco [7] givenName: value = cisco [7] distinguishedName: value = CN=cisco,CN=Users,DC=ftwsecurity, DC=cisco,DC=com [7] instanceType: value = 4 [7] whenCreated: value = 20070815155224.0Z [7] whenChanged: value = 20070815195813.0Z [7] displayName: value = cisco [7] uSNCreated: value = 16430 [7] memberOf: value = CN=Castaways,CN=Users,DC=ftwsecurity,DC=cisco,DC=com [7] memberOf: value = CN=Employees,CN=Users,DC=ftwsecurity,DC=cisco,DC=com [7] uSNChanged: value = 20500 [7] name: value = cisco [7] objectGUID: value = ..z...yC.q0..... [7] userAccountControl: value = 66048 [7] badPwdCount: value = 1 [7] codePage: value = 0 [7] countryCode: value = 0 [7] badPasswordTime: value = 128321799570937500 [7] lastLogoff: value = 0 [7] lastLogon: value = 128321798130468750 [7] pwdLastSet: value = 128316667442656250 [7] primaryGroupID: value = 513 [7] objectSid: value = ............Q..p..*.p?E.Z... [7] accountExpires: value = 9223372036854775807 [7] logonCount: value = 0 [7] sAMAccountName: value = cisco [7] sAMAccountType: value = 805306368 [7] userPrincipalName: value = cisco@ftwsecurity.cisco.com [7] objectCategory: value = CN=Person,CN=Schema,CN=Configuration, DC=ftwsecurity,DC=cisco,DC=com [7] dSCorePropagationData: value = 20070815195237.0Z [7] dSCorePropagationData: value = 20070815195237.0Z [7] dSCorePropagationData: value = 20070815195237.0Z [7] dSCorePropagationData: value = 16010108151056.0Z [7] Fiber exit Tx=685 bytes Rx=2690 bytes, status=1 [7] Session End
Debug - Authentication fails - Incorrect Password
ciscoasa#debug ldap 255[8] Session Start [8] New request Session, context 0xd4b11730, reqType = 1 [8] Fiber started [8] Creating LDAP context with uri=ldap://192.168.1.2:389 [8] Connect to LDAP server: ldap://192.168.1.2:389, status = Successful [8] defaultNamingContext: value = DC=ftwsecurity,DC=cisco,DC=com [8] supportedLDAPVersion: value = 3 [8] supportedLDAPVersion: value = 2 [8] supportedSASLMechanisms: value = GSSAPI [8] supportedSASLMechanisms: value = GSS-SPNEGO [8] supportedSASLMechanisms: value = EXTERNAL [8] supportedSASLMechanisms: value = DIGEST-MD5 !--- The ASA connects to the LDAP server as admin to search for cisco. [8] Binding as administrator [8] Performing Simple authentication for admin to 192.168.1.2 [8] LDAP Search: Base DN = [dc=ftwsecurity, dc=cisco, dc=com] Filter = [sAMAccountName=kate] Scope = [SUBTREE] [8] User DN = [CN=cisco,CN=Users,DC=ftwsecurity,DC=cisco,DC=com][8] Talking to Active Directory server 192.168.1.2 [8] Reading password policy for cisco, dn:CN=cisco,CN=Users, DC=ftwsecurity,DC=cisco,DC=com [8] Read bad password count 1 !--- The ASA attempts to bind as cisco, but the password is incorrect. [8] Binding as user [8] Performing Simple authentication for kate to 192.168.1.2 [8] Simple authentication for cisco returned code (49) Invalid credentials[8] Binding as administrator [8] Performing Simple authentication for admin to 192.168.1.2 [8] Reading bad password count for cisco, dn: CN=cisco,CN=Users, DC=ftwsecurity,DC=cisco,DC=com [8] Received badPwdCount=1 for user cisco [8] badPwdCount=1 before, badPwdCount=1 after for cisco [8] now: Tue, 28 Aug 2007 15:33:05 GMT, lastset: Wed, 15 Aug 2007 15:52:24 GMT, delta=1122041, maxage=3710851 secs [8] Invalid password for cisco [8] Fiber exit Tx=788 bytes Rx=2904 bytes, status=-1 [8] Session End
Debug - Authentication Fail - User not found on LDAP server
ciscoasa#debug ldap 255[9] Session Start [9] New request Session, context 0xd4b11730, reqType = 1 [9] Fiber started [9] Creating LDAP context with uri=ldap://192.168.1.2:389 [9] Connect to LDAP server: ldap://192.168.1.2:389, status = Successful [9] defaultNamingContext: value = DC=ftwsecurity,DC=cisco,DC=com [9] supportedLDAPVersion: value = 3 [9] supportedLDAPVersion: value = 2 [9] supportedSASLMechanisms: value = GSSAPI [9] supportedSASLMechanisms: value = GSS-SPNEGO [9] supportedSASLMechanisms: value = EXTERNAL [9] supportedSASLMechanisms: value = DIGEST-MD5 !--- The user Minakshi is not found. [9] Binding as administrator [9] Performing Simple authentication for admin to 192.168.1.2 [9] LDAP Search: Base DN = [dc=ftwsecurity, dc=cisco, dc=com] Filter = [sAMAccountName=minakshi] Scope = [SUBTREE] [9] Requested attributes not found[9] Fiber exit Tx=256 bytes Rx=607 bytes, status=-1 [9] Session End
Please post comments if there are any queries and rate if useful.
Scenario 2:
Problem:
Is it possible to strip the suffix from a username to authenticate against an active directory in ACS 5.4? I can find this when using an external proxy service, but not for network access.
Solution:
Username suffix/prefix stripping is possible when using:
LDAP
Radius Identity server
External Proxy
With AD, the option is unavailable.
Self proxy + AD is a workaround but that has some limitations and is a complex configuration.
