Hands-On Microsoft Windows Server 2003

Administration

Chapter 11

Administering Remote Access Services

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Objectives

• Configure remote access and virtual private network (VPN) connections

• Implement and troubleshoot remote access policies

• Configure and troubleshoot network address translation (NAT)

• Configure and troubleshoot Internet connection sharing

• Configure and manage Terminal Services

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Configuring Remote Access and Virtual Private Network Connections

• Remote access server– A computer running Windows Server 2003 and

the Routing and Remote Access Service (RRAS)• RRAS authenticates remote or mobile users

• Options for providing a connection to a network from a remote location– Dial-up connections

– Virtual private network (VPN) connections

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Configuring Remote Access and Virtual Private Network Connections (Continued)

• Dial-up connections– Communication established via communication

networks such as a Public Switched Telephone Network (PSTN)

– Point-to-Point Protocol (PPP)• Enables remote access clients and servers to

communicate over a dial-up connection from any operating system that supports the PPP standards

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Configuring Remote Access and Virtual Private Network Connections (Continued)

• VPN– Uses a LAN protocol and PPP, which are both

encapsulated within a VPN protocol, to send data over a public network

– Common VPN protocols• Point-to-Point Tunneling Protocol (PPTP)• Layer 2 Tunneling Protocol (L2TP)

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• PPTP and L2TP are both used to establish a secure tunnel between two endpoints over an insecure network

Configuring Remote Access and Virtual Private Network Connections (Continued)

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• Remote access is implemented on a Windows Server 2003 system by configuring RRAS

• Primary tasks for providing remote access:– Configure RRAS with the appropriate remote

access configuration

– Configure clients to connect to the RRAS server

– Configure user rights, security, and conditions to successfully and securely connect to the RRAS server

Configuring Remote Access and Virtual Private Network Connections (Continued)

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Configuring Dial-Up Connections

• Advantages of dial-up connections– Wide availability

• Disadvantages of dial-up connections – Slow speed

• 56-Kbps is the maximum connection speed using a single phone line

– Unreliability

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Configuring Dial-Up Connections (Continued)

• To provide remote access to clients– Configure the physical modem on the server to

which the clients connect

– Configure Windows Server 2003 as a remote access server

• Once the dial-up server is installed, you may want to– Configure IP-addressing options

– Configure protocol options

– Configure remote access clients

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Implementing Virtual Private Network Access• A VPN

– Can be created to• Ensure that data communication over a public network,

such as the Internet, is secure• Connect two LANs, forming a type of WAN connection

using the Internet as the backbone link between two locations

– Can be created over any existing connection to the Internet, such as

• Dial-up• Cable modem• Digital subscriber line (DSL)

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Virtual private network (VPN)

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Implementing Virtual Private Network Access (Continued)

• To configure the client for VPN– The VPN connection is configured as a new

network connection using the New Connection Wizard

• To configure the server for VPN– RRAS is used to configure the VPN server

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Configuring Remote Access Authentication

• Windows Authentication– Used by default for client requests

• Remote authentication dial-in user service (RADIUS) authentication– Can be chosen in environments with a configured

RADIUS server• Authentication protocols enabled on a Windows

Server 2003 RRAS system by default– EAP– MS-CHAP v2– MS-CHAP

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Configuring Remote Access Authentication (Continued)

• Authentication protocols supported by Windows .NET Server– MS-CHAP– MS-CHAP v2– CHAP– SPAP– PAP– EAP

• EAP-MD5• EAP-TLS

• You also have the option of implementing unauthenticated remote access

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Configuring Encryption Protocols

• Encryption protocols– Used to encrypt the data sent between a client

and an RAS server• When using MS-CHAP (v1 or v2) or EAP, two

forms of encryption can be used– Microsoft Point-to-Point Encryption (MPPE)

• Uses encryption keys varying in length from 40 bits to 128 bits

• Used when IP security is not available– IP Security (IPSec)

• Consists of a suite of cryptography-based protection services and protocols that provide machine-level authentication and data encryption

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Configuring Encryption Protocols (Continued)• Encryption levels supported on an RRAS server

– No Encryption– Basic– Strong– Strongest

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Troubleshooting Remote Access• Possible solutions to dial-up or VPN connection

problems– Verify that all dial-up credentials such as user

name and password are correct– Ensure that remote access is enabled on the

RRAS server– Check to see that ports such as PPTP or L2TP are

enabled for inbound remote access connections– If attempting to connect to a VPN server using

L2TP, ensure that the client has a computer certificate properly installed

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Troubleshooting Remote Access (Continued)

• Possible solutions to dial-up or VPN connection problems (Continued)– Ensure that the remote access server and remote

access client are configured with at least one common authentication and encryption method between the two

– Check the remote access policy to be sure that it is configured to allow access

– Verify that there are enough addresses in the static IP address range

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Troubleshooting Remote Access (Continued)

• Possible solutions to dial-up or VPN connection problems (Continued)– Ensure that a DHCP Relay Agent has been

configured

– Ensure that packet filters are not being used that may restrict access

– Check to be sure that the network adapter that is connected to the Internet is configured with a static IP address

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Implementing and Troubleshooting Remote Access Policies

• To grant users the ability to dial into an RRAS server, Windows Server 2003 uses both– Dial-in properties of user accounts

– Remote access policies

• By default, all user accounts in an Active Directory domain have the dial-in properties configured to the Control Access through Remote Access Policy setting

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Elements of a Remote Access Policy

– Conditions

• Attributes that are compared to a connection attempt– Permissions

• A combination of user account permissions as well as those defined in the policy

– Profile• Consists of settings such as dial-in constraints,

multilink properties, authentication protocols, and encryption properties

• Each element of a remote access policy must be evaluated before a user is allowed to dial in

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Creating a Remote Access Policy• When RRASs are installed, two default policies

are created– Connections to Microsoft Routing and Remote

Access server– Connections to other access servers

• Remote Access Policies container– Found within the Routing and Remote Access

snap-in– Lists all the remote access policies– Can be used to

• Configure the order of policy processing• Add, delete, or edit individual policies

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Creating a Remote Access Policy (Continued)

• Additional settings can be configured with the default profile to further control which clients can access the RRAS server

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Troubleshooting Remote Access Policies

• Possible solutions to problems with remote access policies– Verify that the connection attempt matches the

conditions of at least one remote access policy

– Check to be sure the user is not a member of any groups that have been denied access

– Ensure that the user attempting to connect has been granted permission to dial in either through a user account property or through a remote access policy

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Troubleshooting Remote Access Policies (Continued)

• Possible solutions to problems with remote access policies (Continued)– Verify dial-in settings configured for the user

account are not conflicting with those of the remote access policy

– Verify that the connection attempt matches all of the settings configured in the profile of the policy

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Configuring and Troubleshooting Network Address Translation

• Network address translation (NAT)– Allows a group of computers to access the

Internet using a single Internet connection and a single IP address

• Services provided by a computer running NAT– Address translation– IP addressing– Name resolution– Basic Firewall– Static Packet Filters

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Installing NAT

• If RRAS is not already installed– NAT can be configured by installing and enabling

RRAS

• If RRAS is already installed and configured– NAT can be added to the server manually

• Routing and Remote Access snap-in– Can be used to configure the NAT protocol

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Configuring NAT

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Troubleshooting NAT• Possible problems and solutions

– If clients are not receiving IP addresses from the NAT computer, verify that

• NAT addressing has been enabled• There is no other DHCP server running on the

network– If name resolution is not working for NAT clients,

check• That name resolution has been enabled using the

Name Resolution tab in the NAT properties dialog box

• The configuration of the NAT computer using the ipconfig command to verify DNS settings

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Troubleshooting NAT (Continued)

• Possible problems and solutions (Continued)– If packets are not being properly translated, verify

• That both the Internet and LAN interface have been added to the NAT protocol

• The range of IP addresses that has been configured on the NAT computer

• That IP packet filtering is not preventing certain Internet traffic from being sent and received

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Configuring Internet Connection Sharing

• Internet connection sharing (ICS)– Provides all computers on a LAN with complete

access to Internet resources using a single public IP address

– Provides the following for computers on the internal network

• NAT services• IP addressing• Name resolution

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Configuring Internet Connection Sharing (Continued)

• After installing ICS on the computer connected to the Internet– The IP address of the internal network adapter is

automatically set to 192.168.0.1– A simplified version of DHCP is installed, which

assigns internal clients an IP address (from the network ID of 192.168.0.0/24)

– A DNS proxy service is installed to pass internal DNS requests to the DNS server that the computer running ICS is configured to use

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Configuring Internet Connection Sharing (Continued)

• ICS and NAT are both used to connect a small or home office to the Internet

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Enabling ICS

• Enabling ICS– Relatively straightforward

– Does not require any configuration unless you want to change the applications and services that outside Internet users are able to access on an internal private network

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Configuring Internet Connection Sharing for a dial-up connection

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Troubleshooting ICS• Techniques to troubleshoot common problems

– After ICS is installed, use the ipconfig command to verify that the network adapter has been assigned the IP address of 192.168.0.1 and the subnet mask is 255.255.255.0

– If client computers are unable to connect to the Internet

• Use the ipconfig command to verify that– An IP address in the range of 192.168.0.2 through

192.168.0.254 has been assigned– The subnet mask is 255.255.255.0– The default gateway is set to 192.168.0.1

• Use the ping command to verify– TCP/IP connectivity with the computer running ICS

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Troubleshooting ICS (Continued)• Techniques to troubleshoot common problems

(Continued)– Verify that there is no DHCP server already

running on the network

– If clients are unable to access the Internet using an FQDN, verify that the IP address of a DNS server is configured in the TCP/IP properties of the connection to the Internet

– If clients can only connect to the Internet after you manually establish a connection, verify that demand dialing is enabled on the ICS computer

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Configuring Terminal Services and Remote Desktop for Administration

• Terminal Services– The ability of users to connect to a server for the

purpose of running applications– Not installed unless explicitly added to a server

by an administrator• Remote Desktop for Administration

– The ability of an administrator to connect to a server for administration purposes

– Installed as part of Windows Server 2003, but disabled by default

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Enabling Remote Desktop for Administration

• To enable Remote Desktop for Administration– Only a single setting in the Control Panel System

program needs to be changed

• Permissions regarding connecting to a server using Remote Desktop for Administration– By default, only members of the Administrators

group are granted access

– Additional users can be granted access via the System program

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Enabling Remote Desktop for Administration

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Enabling Remote Desktop for Administration (Continued)

• To connect to a server using Remote Desktop for Administration– Users must access the Remote Desktop

Connection software from their client system

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Installing Terminal Services

• To install Terminal Services– Use the Add/Remove Windows Components

section from within the Add or Remove Programs applet found in Control Panel

• To set up an application server– One Windows Server 2003 server on the network

must be configured as a Terminal Services licensing server

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Managing Terminal Services• Primary tools used for Terminal Services

administration– Terminal Services Manager– Terminal Services Configuration– Terminal Services Licensing

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Managing Terminal Services (Continued)• Connection settings for a Terminal Server are

configured from the properties of a Terminal Server connection object

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Managing Terminal Services (Continued)• Authentication

– Can be set to use either no authentication or standard Windows authentication when the clients are Windows 95, 98, NT, or 2000

• Encryption options include– Client Compatible

• All data sent from the client to the server is encrypted using a key based on the maximum strength supported on the client

– High• Data sent from the client to the server and from the

server to the client is encrypted using the highest encryption level available at the server

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Terminal Services Client Software

• %Systemroot%\system32\clients\tsclient\win32 folder on the Terminal Server– Contains the files necessary to install the Remote

Desktop Connection software that is used by clients to connect to a Windows Server 2003 Terminal Server

• Installing applications– When you install Windows Server 2003 Terminal

Server, applications need to be installed in a compatible mode for multiple users to access them simultaneously

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Terminal Services Client Software (Continued)

• Configuring Terminal Services User Properties– Extra tabs added when Terminal Server is

installed• Terminal Services Profile• Remote control• Sessions• Environment

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Summary• Remote access server

– A computer running Windows Server 2003 with Routing and Remote Access Services installed and enabled

– Authenticates remote and mobile users, providing a gateway to internal network resources

• Remote access solutions include dial-up,VPN, and NAT

• Each RAS server can be configured using the Routing and Remote Access console

• Windows .NET Server supports two VPN protocols: PPTP and L2TP

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Summary (Continued)• Authentication and encryption protocols can be

used to secure communications between the RAS server and a dial-up client

• Authentication protocols supported by Windows .NET Server– MS-CHAP v1 and v2, CHAP, SPAP, PAP, and

EAP• Dial-in access can be controlled through user

account properties and Remote Access policies• Remote Access policies consist of conditions,

permissions, and profiles

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Summary (Continued)• Network address translation (NAT) and Internet

connection sharing (ICS)– Provide a way of connecting computers in a small

or home office to the Internet using a single connection

• Terminal Server– Enables clients to access applications on a

terminal server

• Remote Desktop for Administrators– Gives administrators the ability to remotely

administer network servers