Contents

Introduction

Prerequisites

Requirements

Components Used

Background Information

Configure

Certificate for AnyConnect

Certificate Installation on ASA

ASA Configuration for Single Authentication and Certificate Validation

Test

Debug

ASA Configuration for Double Authentication and Certificate Validation

Test

Debug

ASA Configuration for Double Authentication and Pre-Fill

Test

Debug

ASA Configuration for Double Authentication and Certificate Mapping

Test

Debug

Troubleshoot

Valid Certificate Not Present

Related Information

Introduction

This document describes a configuration for ASA AnyConnect Secure Mobility Client access that uses double authentication with certificate validation.

Prerequisites

Requirements

Cisco recommends that you have knowledge of these topics:

- Basic knowledge of ASA command-line interface (CLI) configuration and Secure Socket Layer (SSL) VPN configuration

- Basic knowledge of X509 certificates

Components Used

The information in this document is based on these software versions:

- Cisco Adaptive Security Appliance (ASA) software, version 8.4 and later

- Windows 7 with Cisco AnyConnect Secure Mobility Client 3.1

It is assumed that you used an external Certificate Authority (CA) in order to generate:

- A public-key cryptography standard #12 (PKCS #12) base64-encoded certificate for ASA (AnyConnect.pfx)

- A PKCS #12 certificate for AnyConnect

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, ensure that you understand the potential impact of any command.

Background Information

This document describes a configuration example for Adaptive Security Appliance (ASA) Cisco AnyConnect Secure Mobility Client access that uses double authentication with certificate validation. As an AnyConnect user, you must provide the correct certificate and credentials for the primary and secondary authentication in order to get VPN access. This document also provides an example of certificate mapping with the pre-fill feature.

Configure

Note: Use the Command Lookup Tool in order to obtain more information on the commands used in this section. Only registered Cisco users can access internal Cisco tools and information.

Certificate for AnyConnect

In order to install an example certificate, double-click the AnyConnect.pfx file, and install that certificate as a personal certificate.

Use the Certificate Manager (certmgr.msc) in order to verify the installation:

By default, AnyConnect tries to find a certificate in the Microsoft user store. There is no need to make any changes in the AnyConnect profile.

Certificate Installation on ASA

This example shows how ASA can import a base64 PKCS #12 certificate:

BSNS-ASA5580-40-1(config)# crypto ca import CA pkcs12 123456

Enter the base 64 encoded pkcs12.

End with the word "quit" on a line by itself:

MIIJAQIBAzCCCMcGCSqGSIb3DQEHAaCCCLgEggi0MIIIsDCCBa8GCSqGSIb3DQEH

...

<output ommitted>

...

83EwMTAhMAkGBSsOAwIaBQAEFCS/WBSkrOIeT1HARHbLF1FFQvSvBAhu0j9bTtZo

3AICCAA=

quit

INFO: Import PKCS12 operation completed successfully

Use the show crypto ca certificates command in order to verify the import:

BSNS-ASA5580-40-1(config)# show crypto ca certificates

CA Certificate

Status: Available

Certificate Serial Number: 00cf946de20d0ce6d9

Certificate Usage: General Purpose

Public Key Type: RSA (1024 bits)

Signature Algorithm: SHA1 with RSA Encryption

Issuer Name:

cn=TAC

ou=RAC

o=TAC

l=Warsaw

st=Maz

c=PL

Subject Name:

cn=TAC

ou=RAC

o=TAC

l=Warsaw

st=Maz

c=PL

Validity Date:

start date: 08:11:26 UTC Nov 16 2012

end   date: 08:11:26 UTC Nov 16 2013

Associated Trustpoints: CA

Certificate

Status: Available

Certificate Serial Number: 00fe9c3d61e131cda9

Certificate Usage: General Purpose

Public Key Type: RSA (1024 bits)

Signature Algorithm: SHA1 with RSA Encryption

Issuer Name:

cn=TAC

ou=RAC

o=TAC

l=Warsaw

st=Maz

c=PL

Subject Name:

cn=IOS

ou=UNIT

o=TAC

l=Wa

st=Maz

c=PL

Validity Date:

start date: 12:48:31 UTC Nov 29 2012

end   date: 12:48:31 UTC Nov 29 2013

Associated Trustpoints: CA

Note: The Output Interpreter Tool supports certain show commands. Use the Output Interpreter Tool in order to view an analysis of show command output. Only registered Cisco users can access internal Cisco tools and information.

ASA Configuration for Single Authentication and Certificate Validation

ASA uses both authentication, authorization, and accounting (AAA) authentication and certificate authentication. Certificate validation is mandatory. AAA authentication uses a local database.

This example shows single authentication with certificate validation.

ip local pool POOL 10.1.1.10-10.1.1.20

username cisco password cisco

webvpn

enable outside

AnyConnect image disk0:/AnyConnect-win-3.1.01065-k9.pkg 1

AnyConnect enable

tunnel-group-list enable

group-policy Group1 internal

group-policy Group1 attributes

vpn-tunnel-protocol ssl-client ssl-clientless

address-pools value POOL

tunnel-group RA type remote-access

tunnel-group RA general-attributes

authentication-server-group LOCAL

default-group-policy Group1

authorization-required

tunnel-group RA webvpn-attributes

authentication aaa certificate

group-alias RA enable

In addition to this configuration, it is possible to perform Lightweight Directory Access Protocol (LDAP) authorization with the username from a specific certificate field, such as the certificate name (CN). Additional attributes can then be retrieved and applied to the VPN session. For more information on authentication and certificate authorization, refer to ASA AnyConnect VPN and OpenLDAP Authorization with Custom Schema and Certificates Configuration Example.

Test

Note: The Output Interpreter Tool supports certain show commands. Use the Output Interpreter Tool in order to view an analysis of show command output. Only registered Cisco users can access internal Cisco tools and information.

In order to test this configuration, provide the local credentials (username cisco with password cisco). The certificate must be present:

Enter the show vpn-sessiondb detail AnyConnect command on the ASA:

BSNS-ASA5580-40-1(config-tunnel-general)# show vpn-sessiondb detail AnyConnect

Session Type: AnyConnect Detailed

Username     : cisco                  Index        : 10

Assigned IP  : 10.1.1.10               Public IP    : 10.147.24.60

Protocol     : AnyConnect-Parent SSL-Tunnel DTLS-Tunnel

License      : AnyConnect Premium

Encryption   : RC4 AES128             Hashing      : none SHA1

Bytes Tx     : 20150                  Bytes Rx     : 25199

Pkts Tx      : 16                     Pkts Rx      : 192

Pkts Tx Drop : 0                      Pkts Rx Drop : 0

Group Policy : Group1                 Tunnel Group : RA

Login Time   : 10:16:35 UTC Sat Apr 13 2013

Duration     : 0h:01m:30s

Inactivity   : 0h:00m:00s

NAC Result   : Unknown

VLAN Mapping : N/A                    VLAN         : none

AnyConnect-Parent Tunnels: 1

SSL-Tunnel Tunnels: 1

DTLS-Tunnel Tunnels: 1

AnyConnect-Parent:

Tunnel ID    : 10.1

Public IP    : 10.147.24.60

Encryption   : none                   TCP Src Port : 62531

TCP Dst Port : 443                    Auth Mode    : Certificate

and userPassword

Idle Time Out: 30 Minutes             Idle TO Left : 28 Minutes

Client Type  : AnyConnect

Client Ver   : 3.1.01065

Bytes Tx     : 10075                  Bytes Rx     : 1696

Pkts Tx      : 8                      Pkts Rx      : 4

Pkts Tx Drop : 0                      Pkts Rx Drop : 0

SSL-Tunnel:

Tunnel ID    : 10.2

Assigned IP  : 10.1.1.10               Public IP    : 10.147.24.60

Encryption   : RC4                    Hashing      : SHA1

Encapsulation: TLSv1.0                TCP Src Port : 62535

TCP Dst Port : 443                    Auth Mode    : Certificate

and userPassword

Idle Time Out: 30 Minutes             Idle TO Left : 28 Minutes

Client Type  : SSL VPN Client

Client Ver   : Cisco AnyConnect VPN Agent for Windows 3.1.01065

Bytes Tx     : 5037                   Bytes Rx     : 2235

Pkts Tx      : 4                      Pkts Rx      : 11

Pkts Tx Drop : 0                      Pkts Rx Drop : 0

DTLS-Tunnel:

Tunnel ID    : 10.3

Assigned IP  : 10.1.1.10               Public IP    : 10.147.24.60

Encryption   : AES128                 Hashing      : SHA1

Encapsulation: DTLSv1.0               UDP Src Port : 52818

UDP Dst Port : 443                    Auth Mode    : Certificate

and userPassword

Idle Time Out: 30 Minutes             Idle TO Left : 29 Minutes

Client Type  : DTLS VPN Client

Client Ver   : 3.1.01065

Bytes Tx     : 0                      Bytes Rx     : 21268

Pkts Tx      : 0                      Pkts Rx      : 177

Pkts Tx Drop : 0                      Pkts Rx Drop : 0

NAC:

Reval Int (T): 0 Seconds              Reval Left(T): 0 Seconds

SQ Int (T)   : 0 Seconds              EoU Age(T)   : 92 Seconds

Hold Left (T): 0 Seconds              Posture Token:

Redirect URL :

Debug

Note: Refer to Important Information on Debug Commands before you use debug commands.

In this example, the certificate was not cached in the database. A corresponding CA has been found, the correct Key usage was used (ClientAuthentication), and the certificate has been validated successfully:

debug aaa authentication

debug aaa authorization

debug webvpn  255

debug webvpn AnyConnect 255

debug crypto ca 255

Detailed debug commands, such as the debug webvpn 255 command, can generate many logs in a production environment and place a heavy load on an ASA. Some WebVPN debugs have been removed for clarity:

CERT_API: Authenticate session 0x0934d687, non-blocking cb=0x00000000012cfc50

CERT API thread wakes up!

CERT_API: process msg cmd=0, session=0x0934d687

CERT_API: Async locked for session 0x0934d687

CRYPTO_PKI: Checking to see if an identical cert is

already in the database...

CRYPTO_PKI: looking for cert in handle=0x00007ffd8b80ee90, digest=

ad 3d a2 da 83 19 e0 ee d9 b5 2a 83 5c dd e0 70    |  .=........*.\..p

CRYPTO_PKI: Cert record not found, returning E_NOT_FOUND

CRYPTO_PKI: Cert not found in database.

CRYPTO_PKI: Looking for suitable trustpoints...

CRYPTO_PKI: Storage context locked by thread CERT API

CRYPTO_PKI: Found a suitable authenticated trustpoint CA.

CRYPTO_PKI(make trustedCerts list)CRYPTO_PKI:check_key_usage: ExtendedKeyUsage

OID = 1.3.6.1.5.5.7.3.1

CRYPTO_PKI:check_key_usage:Key Usage check OK

CRYPTO_PKI: Certificate validation: Successful, status: 0. Attempting to

retrieve revocation status if necessary

CRYPTO_PKI:Certificate validated. serial number: 00FE9C3D61E131CDB1, subject name:

cn=test1,ou=Security,o=Cisco,l=Krakow,st=PL,c=PL.

CRYPTO_PKI: Storage context released by thread CERT API

CRYPTO_PKI: Certificate validated without revocation check

This is the attempt to find a matching tunnel-group. There are no specific certificate mapping rules, and the tunnel-group that you provide is used:

CRYPTO_PKI: Attempting to find tunnel group for cert with serial number:

00FE9C3D61E131CDB1, subject name: cn=test1,ou=Security,o=Cisco,l=Krakow,st=PL,

c=PL, issuer_name: cn=TAC,ou=RAC,o=TAC,l=Warsaw,st=Maz,c=PL.

CRYPTO_PKI: No Tunnel Group Match for peer certificate.

CERT_API: Unable to find tunnel group for cert using rules (SSL)

These are the SSL and general session debugs:

%ASA-7-725012: Device chooses cipher : RC4-SHA for the SSL session with client

outside:10.147.24.60/64435

%ASA-7-717025: Validating certificate chain containing 1 certificate(s).

%ASA-7-717029: Identified client certificate within certificate chain. serial

number: 00FE9C3D61E131CDB1, subject name: cn=test1,ou=Security,o=Cisco,l=Krakow,

st=PL,c=PL.

%ASA-7-717030: Found a suitable trustpoint CA to validate certificate.

%ASA-6-717022: Certificate was successfully validated. serial number:

00FE9C3D61E131CDB1, subject name: cn=test1,ou=Security,o=Cisco,l=Krakow,st=PL,

c=PL.

%ASA-6-717028: Certificate chain was successfully validated with warning,

revocation status was not checked.

%ASA-6-725002: Device completed SSL handshake with client outside:

10.147.24.60/64435

%ASA-7-717036: Looking for a tunnel group match based on certificate maps for

peer certificate with serial number: 00FE9C3D61E131CDB1, subject name: cn=test1,

ou=Security,o=Cisco,l=Krakow,st=PL,c=PL, issuer_name: cn=TAC,ou=RAC,o=TAC,

l=Warsaw,st=Maz,c=PL.

%ASA-4-717037: Tunnel group search using certificate maps failed for peer

certificate: serial number: 00FE9C3D61E131CDB1, subject name: cn=test1,

ou=Security,o=Cisco,l=Krakow,st=PL,c=PL, issuer_name: cn=TAC,ou=RAC,o=TAC,

l=Warsaw,st=Maz,c=PL.

%ASA-6-113012: AAA user authentication Successful : local database : user = cisco

%ASA-6-113009: AAA retrieved default group policy (Group1) for user = cisco

%ASA-6-113008: AAA transaction status ACCEPT : user = cisco

%ASA-7-734003: DAP: User cisco, Addr 10.147.24.60:

Session Attribute aaa.cisco.grouppolicy = Group1

%ASA-7-734003: DAP: User cisco, Addr 10.147.24.60:

Session Attribute aaa.cisco.username = cisco

%ASA-7-734003: DAP: User cisco, Addr 10.147.24.60:

Session Attribute aaa.cisco.username1 = cisco

%ASA-7-734003: DAP: User cisco, Addr 10.147.24.60:

Session Attribute aaa.cisco.username2 =

%ASA-7-734003: DAP: User cisco, Addr 10.147.24.60:

Session Attribute aaa.cisco.tunnelgroup = RA

%ASA-6-734001: DAP: User cisco, Addr 10.147.24.60, Connection AnyConnect: The

following DAP records were selected for this connection: DfltAccessPolicy

%ASA-6-113039: Group <Group1> User <cisco> IP <10.147.24.60> AnyConnect parent

session started.

ASA Configuration for Double Authentication and Certificate Validation

This is an example of double authentication, where the primary authentication server is LOCAL, and the secondary authentication server is LDAP. Certificate validation is still enabled.

This example shows the LDAP configuration:

aaa-server LDAP protocol ldap

aaa-server LDAP (outside) host 10.147.24.60

ldap-base-dn DC=test-cisco,DC=com

ldap-scope subtree

ldap-naming-attribute uid

ldap-login-password *****

ldap-login-dn CN=Manager,DC=test-cisco,DC=com

server-type openldap

Here is the addition of a secondary authentication server:

tunnel-group RA general-attributes

authentication-server-group LOCAL

secondary-authentication-server-group LDAP

default-group-policy Group1

authorization-required

tunnel-group RA webvpn-attributes

authentication aaa certificate

You do not see authentication-server-group LOCAL in the configuration because it is a default setting.

Any other AAA server can be used for authentication-server-group. For secondary-authentication-server-group, it is possible to use all AAA servers except for a Security Dynamics International (SDI) server. In that case, the SDI could still be the primary authentication server.

Test

Note: The Output Interpreter Tool supports certain show commands. Use the Output Interpreter Tool in order to view an analysis of show command output. Only registered Cisco users can access internal Cisco tools and information.

In order to test this configuration, provide the local credentials (username cisco with password cisco) and LDAP credentials (username cisco with password from LDAP). The certificate must be present:

Enter the show vpn-sessiondb detail AnyConnect command on the ASA.

Results are similar to those for single authentication. Refer to ASA Configuration for Single Authentication and Certificate Validation, Test .

Debug

Debugs for WebVPN session and authentication are similar. Refer to ASA Configuration for Single Authentication and Certificate Validation, Debug. One additional authentication process appears:

%ASA-6-113012: AAA user authentication Successful : local database : user = cisco

%ASA-6-302013: Built outbound TCP connection 1936 for outside:10.147.24.60/389

(10.147.24.60/389) to identity:10.48.67.153/54437 (10.48.67.153/54437)

%ASA-6-113004: AAA user authentication Successful : server =  10.147.24.60 :

user = cisco

%ASA-6-113009: AAA retrieved default group policy (Group1) for user = cisco

%ASA-6-113008: AAA transaction status ACCEPT : user = cisco

Debugs for LDAP show details that can vary with the LDAP configuration:

[34] Session Start

[34] New request Session, context 0x00007ffd8d7dd828, reqType = Authentication

[34] Fiber started

[34] Creating LDAP context with uri=ldap://10.147.24.60:389

[34] Connect to LDAP server: ldap://10.147.24.60:389, status = Successful

[34] supportedLDAPVersion: value = 3

[34] Binding as Manager

[34] Performing Simple authentication for Manager to 10.147.24.60

[34] LDAP Search:

Base DN = [DC=test-cisco,DC=com]

Filter  = [uid=cisco]

Scope   = [SUBTREE]

[34] User DN = [uid=cisco,ou=People,dc=test-cisco,dc=com]

[34] Server type for 10.147.24.60 unknown - no password policy

[34] Binding as cisco

[34] Performing Simple authentication for cisco to 10.147.24.60

[34] Processing LDAP response for user cisco

[34] Authentication successful for cisco to 10.147.24.60

[34] Retrieved User Attributes:

[34]    cn: value = John Smith

[34]    givenName: value = John

[34]    sn: value = cisco

[34]    uid: value = cisco

[34]    uidNumber: value = 10000

[34]    gidNumber: value = 10000

[34]    homeDirectory: value = /home/cisco

[34]    mail: value = name@dev.local

[34]    objectClass: value = top

[34]    objectClass: value = posixAccount

[34]    objectClass: value = shadowAccount

[34]    objectClass: value = inetOrgPerson

[34]    objectClass: value = organizationalPerson

[34]    objectClass: value = person

[34]    objectClass: value = CiscoPerson

[34]    loginShell: value = /bin/bash

[34]    userPassword: value = {SSHA}pndf5sfjscTPuyrhL+/QUqhK+i1UCUTy

[34] Fiber exit Tx=315 bytes Rx=911 bytes, status=1

[34] Session End

ASA Configuration for Double Authentication and Pre-Fill

It is possible to map certain certificate fields to the username that is used for primary and secondary authentication:

username test1 password cisco

tunnel-group RA general-attributes

authentication-server-group LOCAL

secondary-authentication-server-group LDAP

default-group-policy Group1

authorization-required

username-from-certificate CN

secondary-username-from-certificate OU

tunnel-group RA webvpn-attributes

authentication aaa certificate

pre-fill-username ssl-client

secondary-pre-fill-username ssl-client

group-alias RA enable

In this example, the client uses the certificate: cn=test1,ou=Security,o=Cisco,l=Krakow,st=PL,c=PL.

For primary authentication, the username is taken from the CN, which is why local user test1 was created.

For secondary authentication, the username is taken from the organizational unit (OU, which is why user Security was created on the LDAP server.

It is also possible to force AnyConnect to use pre-fill commands in order to pre-fill the primary and secondary username. In a real world scenario, the primary authentication server is usually an AD or LDAP server, while the secondary authentication server is the Rivest, Shamir, and Adelman (RSA) server that uses token passwords. In this scenario, the user must provide AD/LDAP credentials (which the user knows), an RSA token password (which the user has) and a certificate (on the machine that is used).

Test

Observe that you cannot change the primary or secondary username because it is pre-filled from the certificate CN and OU fields:

Debug

This example shows the pre-fill request sent to AnyConnect:

%ASA-7-113028: Extraction of username from VPN client certificate has been

requested.  [Request 5]

%ASA-7-113028: Extraction of username from VPN client certificate has started.

[Request 5]

%ASA-7-113028: Extraction of username from VPN client certificate has finished

successfully.  [Request 5]

%ASA-7-113028: Extraction of username from VPN client certificate has completed.

[Request 5]

%ASA-7-113028: Extraction of username from VPN client certificate has been

requested.  [Request 6]

%ASA-7-113028: Extraction of username from VPN client certificate has started.

[Request 6]

%ASA-7-113028: Extraction of username from VPN client certificate has finished

successfully.  [Request 6]

%ASA-7-113028: Extraction of username from VPN client certificate has completed.

[Request 6]

Here you see that authentication uses the correct usernames:

%ASA-6-113012: AAA user authentication Successful : local database : user = test1

%ASA-6-302013: Built outbound TCP connection 2137 for outside:10.147.24.60/389

(10.147.24.60/389) to identity:10.48.67.153/46606 (10.48.67.153/46606)

%ASA-6-113004: AAA user authentication Successful : server =  10.147.24.60 :

user = Security

ASA Configuration for Double Authentication and Certificate Mapping

It is also possible to map specific client certificates to specific tunnel-groups, as shown in this example:

crypto ca certificate map CERT-MAP 10

issuer-name co tac

webvpn

certificate-group-map CERT-MAP 10 RA

This way, all user certificates signed by the Cisco Technical Assistance Center (TAC) CA are mapped to a tunnel-group named 'RA.'

Note: Certificate mapping for SSL is configured differently than certificate mapping for IPsec. For IPsec, it is configured with 'tunnel-group-map' rules in global config mode. For SSL, it is configured with 'certificate-group-map' under webvpn config mode.

Test

Observe that, once certificate mapping is enabled, you do not need to choose tunnel-group anymore:

Debug

In this example, the certificate mapping rule allows the tunnel-group to be found:

%ASA-7-717036: Looking for a tunnel group match based on certificate maps for

peer certificate with serial number: 00FE9C3D61E131CDB1, subject name: cn=test1,

ou=Security,o=Cisco,l=Krakow,st=PL,c=PL, issuer_name: cn=TAC,ou=RAC,o=TAC,

l=Warsaw,st=Maz,c=PL.

%ASA-7-717038: Tunnel group match found. Tunnel Group: RA, Peer certificate:

serial number: 00FE9C3D61E131CDB1, subject name: cn=test1,ou=Security,o=Cisco,

l=Krakow,st=PL,c=PL, issuer_name: cn=TAC,ou=RAC,o=TAC,l=Warsaw,st=Maz,c=PL.

Troubleshoot

This section provides information you can use in order to troubleshoot your configuration.

Valid Certificate Not Present

After you remove a valid certificate from Windows7, AnyConnect cannot find any valid certificates:

On the ASA, it looks like the session is terminated by the client (Reset-I):

%ASA-6-302013: Built inbound TCP connection 2489 for outside:10.147.24.60/52838

(10.147.24.60/52838) to identity:10.48.67.153/443 (10.48.67.153/443)

%ASA-6-725001: Starting SSL handshake with client outside:10.147.24.60/52838 for

TLSv1 session.

%ASA-7-725010: Device supports the following 4 cipher(s).

%ASA-7-725011: Cipher[1] : RC4-SHA

%ASA-7-725011: Cipher[2] : AES128-SHA

%ASA-7-725011: Cipher[3] : AES256-SHA

%ASA-7-725011: Cipher[4] : DES-CBC3-SHA

%ASA-7-725008: SSL client outside:10.147.24.60/52838 proposes the following 8

cipher(s).

%ASA-7-725011: Cipher[1] : AES128-SHA

%ASA-7-725011: Cipher[2] : AES256-SHA

%ASA-7-725011: Cipher[3] : RC4-SHA

%ASA-7-725011: Cipher[4] : DES-CBC3-SHA

%ASA-7-725011: Cipher[5] : DHE-DSS-AES128-SHA

%ASA-7-725011: Cipher[6] : DHE-DSS-AES256-SHA

%ASA-7-725011: Cipher[7] : EDH-DSS-DES-CBC3-SHA

%ASA-7-725011: Cipher[8] : RC4-MD5

%ASA-7-725012: Device chooses cipher : RC4-SHA for the SSL session with client

outside:10.147.24.60/52838

%ASA-6-302014: Teardown TCP connection 2489 for outside:10.147.24.60/52838 to

identity:10.48.67.153/443 duration 0:00:00 bytes 1448 TCP Reset-I

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