Enterprise Informatization-Build a VPN at the lowest cost

I have been doing Enterprise Informatization for five years. I have never written any summary. I think I should summarize my technologies and give some suggestions to enterprises that need enterprise informatization.
Case Description
Provide technical consultation to an enterprise. The enterprise is a chain enterprise. It uses a CS-type management system and a local telecom man VPN. Later, the enterprise developed chain stores in other places, metropolitan networks in different cities are expensive, and enterprises require real-time data transmission. (A chain enterprise does not need real-time data transmission, there is no big difference between the sales and real-time in regular transmission, but the cost is very high.) The so-called VPN device on the market usually costs more than 20 thousand, what else does the client charge fees? There is no more than RMB for a dozen stores, and it is really making money for people who don't know how to do it. A word, black.
The problem is how to find the best way to achieve the most economic results. win2003 + isa2006 is undoubtedly the best solution, with VPN and firewall. The cost of such a combination is very small, and the benefits of being born in China are shown here.

Enterprise Structure Design Diagram
To be continued...
VPN Technology
Terminal Technology
Port redirection

Proxy Service

Client Internet Access Control (defines a domain name set for ISA and can only access a specified website)
Enterprises are prohibited from running QQ

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows NT \ CurrentVersion \ Image File Execution options \ qq.exe]
"Debugger" = "cmd.exe"

Resume QQ operation
@ Echo off
Reg Delete "HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows NT \ CurrentVersion \ Image File Execution options \ qq.exe"/F