In this chapter, we discussed how Microsoft Proxy Server could coexist with other applications in the network. We mentioned that Proxy Server allows you to implement Point to Point Tunneling Protocol to provide secure access to your network from the Internet. We discussed different varieties of PPTP and Proxy Server coexistence. You can install a PPTP server or client on the internal network, but you have to enable IP forwarding and ensure that your PPTP-enabled computer is visible from the Internet. The reason for this unsecured solution is that PPTP requests can not be redirected by the WinSock client software and therefore can not take advantage of Proxy server proxying. In this scenario you may want to increase security by implementing Proxy packet filtering. Another option is to install PPTP software along with the RRAS software on the Proxy Server computer. This provides a more secure solution for your network.

We also discussed how an Exchange Server could coexist with Proxy Server. We saw there were several ways to accomplish this. If you install Exchange Server in your internal network, you can take advantage of the WinSock Proxy service server hosting. The key point in this scenario is the creation of wspclnt.ini files. These files are placed in the directories that contain the Exchange Server executable files. They redirect WinSock requests and remote them to Proxy Server. Don’t forget that you need to modify your DNS settings to direct Internet clients to the Proxy Server external interface. In this case Proxy Server acts on behalf of Exchange Server. In this scenario you can, also, take advantage of dynamic packet filtering.

Alternatively, you may want to consider installing Exchange Server on the Proxy Server computer itself, or install Exchange Server in parallel with the Proxy Server computer. These solutions will also work but they don’t provide the attendant security advantages of putting the Exchange Server behind Proxy Server

We also looked at how other applications and services can be used in conjunction with Proxy Server. You saw for example that SQL server and FTP server can be put behind Proxy without loosing their functionality.

Finally we provided you with guidelines to allow non-Windows servers to coexist with Proxy Server by introducing the concept of a “demilitarized zone.”