VPNs can be divided into several categories to help define what type of connection you've created. The following is a list of the most common categories:
The PIX firewall can perform all the functions of the previously mentioned categories, including linking site-to-site VPNs and remote user access VPNs. The PIX is capable of interlinking with other PIX firewalls, clients , routers, and even third-party firewalls, to name a few. Figure 12.3 shows various combinations using the PIX firewall.
Figure 12.3. Using the PIX for VPNs.