Common configuration for the VPN server

  • Article

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Common configuration for the VPN server

To deploy a VPN solution for Electronic, Inc., the network administrator performs an analysis and makes design decisions regarding:

  • The network configuration

  • The remote access policy configuration

  • The domain configuration

  • The security configuration

The network configuration

The key elements of the network configuration are:

  • The Electronic, Inc. corporate intranet uses the private networks of 172.16.0.0 with a subnet mask of 255.240.0.0 and 192.168.0.0 with a subnet mask of 255.255.0.0. The corporate campus network segments use subnets of 172.16.0.0 and the branch offices use subnets of 192.168.0.0.

  • The VPN server computer is directly attached to the Internet by using a T3 (also known as a DS-3) dedicated WAN link.

  • The IP address of the WAN adapter on the Internet is 207.209.68.1 as allocated by the Internet service provider (ISP) for Electronic, Inc. The IP address of the WAN adapter is referred to on the Internet by the domain name vpn.electronic.microsoft.com.

  • The VPN server computer is directly attached to an intranet network segment that contains a RADIUS server, a file and Web server for business partner access, and a router that connects to the rest of the Electronic, Inc. corporate campus intranet. The intranet network segment has the IP network ID of 172.31.0.0 with the subnet mask of 255.255.0.0.

  • The VPN server computer is configured with a static pool of IP addresses to allocate to remote access clients and calling routers. The static pool of IP addresses is a subset of the intranet network segment (an on-subnet address pool).

The following illustration shows the network configuration of the Electronic, Inc. VPN server.

Network configuration of “Electronic” VPN server

Note

Based on the network configuration of the Electronic, Inc. corporate campus intranet, the VPN server computer is configured as follows.

1. Install hardware in the VPN server

The network adapter that is used to connect to the intranet segment and the WAN adapter that is used to connect to the Internet are installed according to the adapter manufacturer's instructions. Once drivers are installed and functioning, both adapters appear as local area connections in the Network Connections folder.

2. Configure TCP/IP on the LAN and WAN adapter

For the LAN adapter, an IP address of 172.31.0.1 with a subnet mask 255.255.0.0 is configured. For the WAN adapter, an IP address of 207.209.68.1 with a subnet mask 255.255.255.255 is configured. A default gateway is not configured for either adapter. DNS and WINS server addresses are also configured.

3. Install the Routing and Remote Access service

The Routing and Remote Access Server Setup Wizard is run. Within the wizard, the Remote Access (dial-up or VPN) option is selected. For more information, see Enable the Routing and Remote Access service.

While running the wizard, a static IP address pool with a starting IP address of 172.31.255.1 and an ending IP address of 172.31.255.254 is configured. This creates a static address pool for up to 253 VPN clients.

For more information, see Create a static IP address pool.

The default method of authenticating remote access and demand-dial connections is to use Windows authentication, which is appropriate in this configuration containing only one VPN server. For information on the use of RADIUS authentication for Electronic, Inc., see Dial-up and VPNs with RADIUS. For more information on the use of Windows and RADIUS authentication, see Authentication vs. authorization.

4. Enable the EAP authentication method

To enable the use of smart card-based remote access VPN clients and certificate-based calling routers, the network administrator enables Extensible Authentication Protocol (EAP) on the VPN server.

For more information, see Enable EAP.

5. Configure static routes on the VPN server to reach intranet and Internet locations

To reach intranet locations, a static route is configured with the following settings:

  • Interface: The LAN adapter attached to the intranet

  • Destination: 172.16.0.0

  • Network mask: 255.240.0.0

  • Gateway: 172.31.0.2

  • Metric: 1

This static route simplifies routing by summarizing all destinations on the Electronic, Inc. intranet. This static route is used so that the VPN server does not need to be configured with a routing protocol.

To reach Internet locations, a static route is configured with the following settings:

  • Interface: The WAN adapter attached to the Internet

  • Destination: 0.0.0.0

  • Network mask: 0.0.0.0

  • Gateway: 0.0.0.0

  • Metric: 1

This static route summarizes all destinations on the Internet. This route allows the VPN server to respond to a remote access client or demand-dial router VPN connection from anywhere on the Internet.

Note

  • Because the WAN adapter creates a point-to-point connection to the ISP, any address can be entered for the gateway. The gateway address of 0.0.0.0 is an example. 0.0.0.0 is the unspecified IP address.

Setting the phone number for the PPTP and L2TP devices

To aid in the configuration of remote access policies to confine VPN connections from Internet users, the port properties for the WAN Miniport (PPTP) and WAN Miniport (L2TP) devices are modified with the IP address of the VPN server's Internet interface in the Phone number for this device field. For more information, see Set the phone number on a port.

Configure a static route on the intranet router to reach all branch offices

To reach branch office locations from the intranet router, a static route is configured with the following settings:

  • Interface: The LAN adapter attached to the intranet

  • Destination: 192.168.0.0

  • Network mask: 255.255.0.0

  • Gateway: 172.31.0.1

  • Metric: 1

This static route simplifies routing by summarizing all destinations at branch offices of Electronic, Inc.

The remote access policy configuration

Electronic, Inc. has migrated to a Windows 2000 native domain and the network administrator for Electronic, Inc. decides on an access-by-policy administrative model. The remote access permission on all user accounts is set to Control access through Remote Access Policy. The granting of remote access permission to connection attempts is controlled by the remote access permission setting on the first matching remote access policy. Remote access policies are used to apply different VPN connection settings based on group membership, and the default remote access policies are deleted.

For more information, see Introduction to remote access policies.

The domain configuration

To take advantage of the ability to apply different connection settings to different types of VPN connections, the following Active Directory groups are created:

  • VPN_Users

    Used for remote access VPN connections

  • VPN_Routers

    Used for router-to-router VPN connections from Electronic, Inc. branch offices

  • VPN_Partners

    Used for router-to-router VPN connections from Electronic, Inc. business partners

Note

  • All users and groups in this implementation example are created in the electronic.microsoft.com Active Directory domain.

The security configuration

To enable L2TP/IPSec connections, the use of smart cards by remote access clients, and the use of EAP-TLS by routers, the Electronic, Inc. domain is configured to auto-enroll computer certificates to all domain members.

For more information, see Deploying Certificate-based Authentication for VPN Connections.

Notes

  • On Windows Server 2003, Web Edition, and Windows Server 2003, Standard Edition, you can create up to 1,000 Point-to-Point Tunneling Protocol (PPTP) ports, and you can create up to 1,000 Layer Two Tunneling Protocol (L2TP) ports. However, Windows Server 2003, Web Edition, can accept only one virtual private network (VPN) connection at a time. Windows Server 2003, Standard Edition, can accept up to 1,000 concurrent VPN connections. If 1,000 VPN clients are connected, further connection attempts are denied until the number of connections falls below 1,000.

  • The example companies, organizations, products, people and events depicted herein are fictitious. No association with any real company, organization, product, person or event is intended or should be inferred.