A remote access VPN server accepts VPN calls from VPN client machines. A remote access VPN server allows single client machines and users access to corporate network resources after the VPN connection is established. In contrast, a VPN gateway connects entire networks to each other and allows multiple hosts on each network to connect to other networks through a VPN site-to-site link.

You can use any VPN client software that supports PPTP or L2TP/IPSec to connect to a VPN server. The ideal VPN client software is the Microsoft VPN client, which is included with all versions of Windows. However, if you wish to use L2TP/IPSec with pre-shared keys and NAT traversal support, you should download and install the updated L2TP/IPSec client from the Microsoft download site. We'll go over the details on how to obtain this software later in the chapter.

In this section, we'll go over the procedures required to create a PPTP remote access VPN server on the ISA firewall. The specific steps we'll perform include:

• Enabling the ISA Firewall's VPN Server component

• Creating an Access Rule allowing VPN Clients access to the Internal network

• Enabling Dial-in Access for VPN User Accounts

• Testing a PPTP VPN Connection