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Contents
- MSCHAP Version 2
- Finding Feature Information
- Prerequisites for MSCHAP Version 2
- Restrictions for MSCHAP Version 2
- Information About MSCHAP Version 2
- How to Configure MSCHAP Version 2
- Configuring MSCHAP V2 Authentication
- Verifying MSCHAP V2 Configuration
- Configuring Password Aging for Crypto-Based Clients
- Configuration Examples
- Configuring Local Authentication Example
- Configuring RADIUS Authentication Example
- Configuring Password Aging with Crypto Authentication Example
- Additional References
- Feature Information for MSCHAP Version 2
MSCHAP Version 2
The MSCHAP Version 2 feature (introduced in Cisco IOS Release 12.2(2)XB5) allows Cisco routers to utilize Microsoft Challenge Handshake Authentication Protocol Version 2 (MSCHAP V2) authentication for PPP connections between a computer using a Microsoft Windows operating system and a network access server (NAS).
For Cisco IOS Release 12.4(6)T, MSCHAP V2 now supports a new feature: AAA Support for MSCHAPv2 Password Aging. Prior to Cisco IOS Release 12.4(6)T, when Password Authentication Protocol (PAP)-based clients sent username and password values to the authentication, authorization, and accounting (AAA) subsystem, AAA generated an authentication request to the RADIUS server. If the password expired, the RADIUS server replied with an authentication failure message. The reason for the authentication failure was not passed back to AAA subsystem; thus, users were denied access because of authentication failure but were not informed why they were denied access.
The Password Aging feature, available in Cisco IOS Release 12.4(6)T, notifies crypto-based clients that the password has expired and provides a generic way for the user to change the password. The Password Aging feature supports only crypto-based clients.
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 MSCHAP Version 2
- Configure an interface type and enter interface configuration mode by using the interface command.
- Configure the interface for PPP encapsulation by using the encapsulation command.
- Be sure that the client operating system supports all MSCHAP V2 capabilities.
- For Cisco IOS Release 12.4(6)T, the Password Aging feature only supports RADIUS authentication for crypto-based clients.
- To ensure that the MSCHAP Version 2 features correctly interpret the authentication failure attributes sent by the RADIUS server, you must configure the ppp max-bad-auth command and set the number of authentication retries at two or more.
- In order for the MSCHAP Version 2 feature to support the ability to change a password, the authentication failure attribute, which is sent by the RADIUS server, must be correctly interpreted as described in Configuring MSCHAP V2 Authentication.
In addition, the radius server vsa send authentication command must be configured, allowing the RADIUS client to send a vendor-specific attribute to the RADIUS server. The Change Password feature is supported only for RADIUS authentication.
- The Microsoft Windows 2000, Microsoft Windows XP, and Microsoft Windows NT operating systems have a known caveat that prevents the Change Password feature from working. You must download a patch from Microsoft at the following URL:
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q326770
For more information on completing these tasks, see the section "PPP Configuration " in the Cisco IOS Dial Technologies Configuration Guide , Release 12.4T. The RADIUS server must be configured for authentication. Refer to vendor-specific documentation for information on configuring RADIUS authentication on the RADIUS server.
Restrictions for MSCHAP Version 2
- MSCHAP V2 authentication is not compatible with MSCHAP V1 authentication.
- The change password option is supported only for RADIUS authentication and is not available for local authentication.
Information About MSCHAP Version 2
MSCHAP V2 authentication is the default authentication method used by the Microsoft Windows 2000 operating system. Cisco routers that support this authentication method enable Microsoft Windows 2000 operating system users to establish remote PPP sessions without configuring an authentication method on the client.
MSCHAP V2 authentication introduced an additional feature not available with MSCHAP V1 or standard CHAP authentication: the Change Password feature. This features allows the client to change the account password if the RADIUS server reports that the password has expired.
How to Configure MSCHAP Version 2
- Configuring MSCHAP V2 Authentication
- Verifying MSCHAP V2 Configuration
- Configuring Password Aging for Crypto-Based Clients
Configuring MSCHAP V2 Authentication
To configure the NAS to accept MSCHAP V2 authentication for local or RADIUS authentication and to allow proper interpretation of authentication failure attributes and vendor-specific RADIUS attributes for RADIUS authentication, use the following commands beginning in global configuration mode.
DETAILED STEPS
Verifying MSCHAP V2 Configuration
DETAILED STEPS
| Command or Action | Purpose | |
|---|---|---|
Step 1 |
show
running-config
interface
type
number
Example: Router# show running-config interface Asynch65 |
Verifies the configuration of MSCHAP V2 as the authentication method for the specified interface. |
Step 2 |
debug
ppp
negotiation
Example: Router# debug ppp negotiation |
Verifies successful MSCHAP V2 negotiation. |
Step 3 |
debug
ppp
authentication
Example: Router# debug ppp authentication |
Verifies successful MSCHAP V2 authentication. |
Configuring Password Aging for Crypto-Based Clients
The AAA security services facilitate a variety of login authentication methods. Use the aaa authentication logincommand to enable AAA authentication no matter which of the supported login authentication methods you decide to use. With the aaa authentication logincommand, you create one or more lists of authentication methods that are tried at login. These lists are applied using the login authentication line configuration command.
After the RADIUS server requests a new password, AAA queries the crypto client, which in turn prompts the user to enter a new password.
To configure login authentication and password aging for crypto-based clients, use the following commands beginning in global configuration mode.
 Note | The AAA Password Expiry infrastructure notifies the Easy VPN client that the password has expired and provides a generic way for the user to change the password. Please use RADIUS-server domain-stripping feature wisely in combination with AAA password expiry support. |
DETAILED STEPS
| Command or Action | Purpose | |
|---|---|---|
Step 1 |
enable
Example: Router> enable |
Enables privileged EXEC mode.
|
Step 2 |
configure
terminal
Example: Router# configure terminal |
Enters global configuration mode. |
Step 3 |
aaa
new-model
Example: Router(config)# aaa new-model |
Enables AAA globally. |
Step 4 |
aaa
authentication
login
{default | list-name} passwd-expiry method1 [method2...] Example: Router(config)# aaa authentication login userauthen passwd-expiry group radius |
Enables password aging for crypto-based clients on a local authentication list. |
Step 5 |
crypto
map
map-name
client
authentication
list
list-name
Example:
Example: Router(config)# crypto map clientmap client authentication list userauthen |
Configures user authentication (a list of authentication methods) on an existing crypto map. |
Configuration Examples
- Configuring Local Authentication Example
- Configuring RADIUS Authentication Example
- Configuring Password Aging with Crypto Authentication Example
Configuring Local Authentication Example
The following example configures PPP on an asynchronous interface and enables MSCHAP V2 authentication locally:
interface Async65 ip address 10.0.0.2 255.0.0.0 encapsulation ppp async mode dedicated no peer default ip address ppp max-bad-auth 3 ppp authentication ms-chap-v2 username client password secret
Configuring RADIUS Authentication Example
The following example configures PPP on an asynchronous interface and enables MSCHAP V2 authentication via RADIUS:
interface Async65 ip address 10.0.0.2 255.0.0.0 encapsulation ppp async mode dedicated no peer default ip address ppp max-bad-auth 3 ppp authentication ms-chap-v2 exit aaa authentication ppp default group radius radius-server host 10.0.0.2 255.0.0.0 radius-server key secret radius-server vsa send authentication
Configuring Password Aging with Crypto Authentication Example
The following example configures password aging by using AAA with a crypto-based client:
aaa authentication login userauthen passwd-expiry group radius ! aaa session-id common ! crypto isakmp policy 3 encr 3des authentication pre-share group 2 ! crypto isakmp client configuration group 3000client key cisco123 dns 10.1.1.10 wins 10.1.1.20 domain cisco.com pool ippool acl 153 ! crypto ipsec transform-set myset esp-3des esp-sha-hmac ! crypto dynamic-map dynmap 10 set transform-set myset ! crypto map clientmap client authentication list userauthen ! radius-server host 10.140.15.203 auth-port 1645 acct-port 1646 radius-server domain-stripping prefix-delimiter $ radius-server key cisco123 radius-server vsa send authentication radius-server vsa send authentication 3gpp2 ! end
Additional References
Related Documents
|
Related Topic |
Document Title |
|---|---|
|
Configuring PPP interfaces |
PPP Configuration in the Cisco IOS Dial Technologies Configuration Guide , Release 12.4T. |
|
Descriptions of the tasks and commands necessary to configure and maintain Cisco networking devices |
Cisco IOS Dial Technologies Command Reference |
|
Lists of IOS Security Commands |
Cisco IOS Security Command Reference |
|
Configuring PPP authentication using AAA |
Configuring PPP Authentication Using AAA in the Configuring Authentication module in the Cisco IOS Security Configuration Guide: Securing User Services , Release 12.4T. |
|
Configuring RADIUS Authentication |
Configuring RADIUS module in the Cisco IOS Security Configuration Guide: Securing User Services, Release 12.4T. |
MIBs
Technical Assistance
|
Description |
Link |
|---|---|
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Feature Information for MSCHAP Version 2
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 MSCHAP Version 2 |
|
Feature Name |
Releases |
Feature Information |
|---|---|---|
|
MSCHAP Version 2 |
12.2(2)XB5 12.2(13)T 12.4(6)T |
The MSCHAP Version 2 feature (introduced in Cisco IOS Release 12.2(2)XB5) allows Cisco routers to utilize Microsoft Challenge Handshake Authentication Protocol Version 2 (MSCHAP V2) authentication for PPP connections between a computer using a Microsoft Windows operating system and a network access server (NAS). In 12.2(2)XB5, this feature was introduced. In 12.2(13)T, this feature was integrated into Cisco IOS Release 12.2(13)T. In 12.4(6)T, this feature was updated to include the crypto-based Password Aging feature. The following commands were introduced or modified: aaa authentication login, and ppp authentication ms-chap-v2. |
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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.