VPN Categories

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:

• Access VPN ” These VPNs provide a means for remote users to access the network in a secure manner. For example, say Jack wants to connect from home temporarily to the office to check his email. Jack can set up a VPN to interlink his home PC to the office and send data securely. This is called an access VPN (refer to Figure 12.1)

• Intranet VPN ” This allows a company to interconnect its remote networks. Intranet VPNs are commonly known as site-to-site VPNs and are used to link sites that are part of the same company. They don't just link a single user but whole networks. Figure 12.2 demonstrates a VPN across a site-to-site scenario.

  Figure 12.2. A site-to-site VPN.

  

• Extranet VPN ” This is similar to the intranet VPN. However, this VPN solution is used when interlinking two different companies. For example, if company A wants to interconnect with company B, it can use the Internet as a backbone and set up a site-to-site VPN called an extranet VPN.

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.