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Week 6 – NPS and RADIUS

• Install and Configure a Network Policy Server

• Configure RADIUS Clients and Servers

• NPS Authentication Methods

• Monitor and Troubleshoot a Network Policy Server

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What Is a VPN Connection?

Large Branch Office

Medium Branch Office

Small Branch Office

Home Office with VPN Client

Remote User with VPN Client

Corporate Headquarters

VPN

VPN Server

VPN Server

VPN Server

VPN Server

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Components of a VPN Connection

VPN Tunnel

VPN ClientVPN Server

IP Configuration

DHCP Server

Domain Controller

Authentication Virtual Network

Client Operating SystemRouting andRemote Access

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Tunneling Protocols for a VPN Connection

PPTP:

GRE header

IP header

PPP trailer

PPP payload (IPv4 packet)

Encrypted

PPP frame

IP header

PPP header

L2TP header

PPP payload (IP diagram, IPX datagram,

NetBEUI frame)

UDP header

L2TP:

PPP frame

L2TP frame

UDP message

SSTP:

• Encapsulates PPP frames in IP datagrams, and uses port 443 (TCP) for tunnel management and PPP data frames

• Encryption is performed by the SSL channel of the HTTPS protocol

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Components of a Dial-Up Connection

Dial-Up ClientDial-Up Client

Address and Name Server AllocationAddress and Name Server AllocationDHCPServer

DomainController

AuthenticationAuthentication

Remote AccessServer

Remote AccessServer

WAN Options:Telephone, ISDN,

X.25, or ATM

WAN Options:Telephone, ISDN,

X.25, or ATM

LAN and Remote AccessProtocols

LAN and Remote AccessProtocols

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What Is the Connection Manager Administration Kit?

The Connection Manager Administration Kit:

The connection profile can be distributed to users in the following ways:

• Allows you to customize users’ remote connection experience by creating predefined connections on remote servers and networks

• Creates an executable file that can be run on a client computer to establish a network connection that you have designed

• Reduces the likelihood of user errors when they configure their own connection objects

• As part of an image for new computers

• On removable media for the user to install manually

• With software distribution tools, such as Systems Management Server or System Center Configuration Manager 2007

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Process for Configuring a Connection Profile

Use the CMAK Connection Profile Wizard to configure:

• The target operating system

• Support for VPN

• Support for Dial-up, including the custom phone book

• Proxy

• Custom Help file

• Custom support information

The CMAK Connection Profile Wizard assists in the process of creating custom connection profiles for usersThe CMAK Connection Profile Wizard assists in the process of creating custom connection profiles for users

What Is a Network Policy?

A network policy consists of the following elements:

• Conditions

• Constraints

• Settings

Process for Creating and Configuring a Network Policy

Determine authorization by user or group

Determine appropriate settings for the user account’s network access permissions

Configure the New Network Policy Wizard:

• Configure Network Policy conditions

• Configure Network Policy constraints

• Configure Network Policy settings

How Are Network Policies Processed?

Are there policies to process?

START

Does connection attempt match policy conditions?

Yes

Reject connection

attempt

Is the remote access permission for the user account set to Deny Access?

Is the remote access permission for the user account set to Allow Access?

Yes

Yes

NoGo to next policy

No

Yes

Is the remote access permission on the policy set to Deny remote access permission?

Does the connection attempt match the user object and profile settings?

No

Yes

Accept connection attempt

Reject connection attempt

No

Yes

No

No

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Network Policy Server Usage Scenarios

NPS is used for the following scenarios:

• Network Access Protection

• Enforcement for IPsec traffic

• Enforcement for 802.1x wired and wireless

• Enforcement for DHCP

• Enforcement for VPN

• Secure Wired and Wireless Access

• RADIUS

• Terminal Server Gateway

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Tools Used for Managing a Network Policy Server

Tools used to manage NPS include:

• Netsh command line to configure all aspects of NPS, such as:

• NPS Server Commands

• RADIUS Client Commands

• Connection Request Policy Commands

• Remote RADIUS Server Group Commands

• Network Policy Commands

• Network Access Protection Commands

• Accounting Commands

• NPS MMC Console

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What Is a RADIUS Client?

• RADIUS clients are network access servers, such as:

• Wireless access points

• 802.1x authenticating switches

• VPN servers

• Dial-up servers

• NPS is a RADIUS server

• RADIUS clients send connection requests and accounting messages to RADIUS servers for authentication, authorization, and accounting

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What Is a RADIUS Proxy?

A RADIUS proxy is required for:

• Service providers offering outsourced dial-up, VPN, or wireless network access services

• Providing authentication and authorization for user accounts that are not Active Directory members

• Performing authentication and authorization using a database that is not a Windows account database

• Load-balancing connection requests among multiple RADIUS servers

A RADIUS proxy receives connection attempts from RADIUS clients and forwards them to the appropriate RADIUS server or another RADIUS proxy for further routing

A RADIUS proxy receives connection attempts from RADIUS clients and forwards them to the appropriate RADIUS server or another RADIUS proxy for further routing

• Providing RADIUS for outsourced service providers and limiting traffic types through the firewall

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Configuring Connection Request Processing

Configuration Description

Local vs. RADIUS authentication

• Local authentication takes place against the local security account database or Active Directory. Connection policies exist on that server.

• RADIUS authentication forwards the connection request to a RADIUS server for authentication against a security database. RADIUS maintains a central store of all the connection policies.

RADIUS server groups

Used where one or more RADIUS servers are capable of handling connection requests. The connection requests are load-balanced on criteria specified during the creation of the RADIUS server group if there is more than one RADIUS server in the group.

Default ports for accounting and authentication using RADIUS

The ports required for accounting and authentication requests being forwarded to a RADIUS server are UDP 1812/1645 and UDP 1813/1646.

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What Is a Connection Request Policy?

Connection Request policies include:

• Conditions, such as:

• Framed Protocol

• Service Type

• Tunnel Type

• Day and Time restrictions

Connection Request policies are sets of conditions and settings that designate which RADIUS servers perform the authentication and authorization of connection requests that NPS receives from RADIUS clients

Connection Request policies are sets of conditions and settings that designate which RADIUS servers perform the authentication and authorization of connection requests that NPS receives from RADIUS clients

• Settings, such as:

• Authentication

• Accounting

• Attribute Manipulation

• Advanced settings

Custom Connection Request policies are required to forward the request to another proxy or RADIUS server or server group for authorization and authentication, or to specify a different server for accounting information

Custom Connection Request policies are required to forward the request to another proxy or RADIUS server or server group for authorization and authentication, or to specify a different server for accounting information

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Password-Based Authentication Methods

Authentication methods for an NPS server include:

• MS-CHAPv2

• MS-CHAP

• CHAP

• PAP

• Unauthenticated access

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Using Certificates for Authentication

Certificate-based authentication in NPS:

• Certificate types:

• CA certificate: Verifies the trust path of other certificates

• Client computer certificate: Issued to the computer to prove its identity to NPS during authentication

• Server certificate: Issued to an NPS server to prove its identity to client computers during authentication

• User certificate: Issued to individuals to prove their identity to NPS servers for authentication

• Certificates can be obtained from public CA providers or you can host your own Active Directory certificate services

• To specify certificate-based authentication in a network policy, configure the authentication methods on the Constraints tab

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Required Certificates for NPS Authentication Methods

Type Requirements

Server certificates

• Must contain a Subject attribute that is not NULL

• Must chain to a trusted-root CA

• Configured with Server Authentication purpose in EKU extensions

• Configured with required algorithm of RSA with a minimum 2048 key length

• Subject Alternative Name extension, if used, must contain the DNS name

Client certificates

• Issued by an Enterprise CA or mapped to an account in Active Directory

• Must chain to a trusted-root CA

• For computer certificates, the Subject Alternative Name must contain the FQDN

• For user certificates, the Subject Alternative Name must contain the UPN

All certificates must meet the requirements for X.509 and must work for connections that use SSL/TLSAll certificates must meet the requirements for X.509 and must work for connections that use SSL/TLS

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Deploying Certificates for PEAP and EAP

• For Domain Computer and User accounts, use the auto-enrollment feature in Group Policy

• Nondomain member enrollment requires an administrator to request a user or computer certificate using the CA Web Enrollment tool

• The administrator must save the computer or user certificate to a floppy disk or other removable media, and manually install the certificate on the nondomain member computer

• The administrator can distribute user certificates on a smart card

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Methods Used to Monitor NPS

NPS monitoring methods include:

• Event logging

• The process of logging NPS events in the System Event log

• Useful for auditing and troubleshooting connection attempts

• Logging user authentication and accounting requests

• Useful for connection analysis and billing purposes

• Can be in a text format

• Can be in a database format within a SQL instance

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Configuring Log File Properties

Use the NPS console to configure logging:

Open NPS from the Administrative Tools menu

In the console tree, click Accounting

In the details pane, click Configure Local File Logging

On the Settings tab, select the information to be logged

On the Log File tab, select the log type and the frequency or size attributes of the log files to be generated

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33

44

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Log files should be stored on a separate partition from the system partition:

If RADIUS accounting fails due to a full hard disk, NPS stops processing connection requests

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Configuring SQL Server Logging

You can use SQL to log RADIUS accounting data:

• Requires SQL to have a stored procedure named report_event

• NPS formats accounting data as an XML document

• Can be a local or remote SQL Server database

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Configuring NPS Events to Record in the Event Viewer

How do I configure NPS events to be recorded in Event Viewer?

• NPS is configured by default to record failed connections and successful connections in the event log

• You can change this behavior on the General tab of the Properties sheet for the network policy

• Common request failure events

• What information does the failure event record?

• What information does the success event record?

What is Schannel logging, and how do I configure it?

• Schannel is a security support provider that supports a set of Internet security protocols

• You can configure Schannel logging in the following Registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\EventLogging