Firewall For Windows
信息来源：邪恶八进制信息安全团队（
www.eviloctal.com）
Introduction:
I suppose any experienced Internet user knows what is firewall and when it is required. Those of you who interest in exact definition of this term I address to well-known on-line technical terms encyclopedia on
www.whatis.com . If you are not lazy to do this you will even find two relative definitions (firewall and personal firewall). I’m not going to provide here exact classification and just enumerate some typical representatives. As far as this article is Windows systems relative the following does not pretend to cover all. Among server-oriented products I could mention WinGate, WinRoute, Vicomsoft Internet Gateway, WinProxy and etc… All these products differ in their functionality and price, and in addition to internal network intrusion protection usually realize single Internet connection sharing. From personal firewall group I can mention AtGuard, Outpost Firewall, ZoneAlarm, Tiny Personal Firewall, Sygate Personal Firewall and etc. I’m not going to discuss these solutions here; end users are responsible for this. We will concentrate on the technical part of question, in particular how to organize traffic filtering in operating systems from Windows family. I should mention, that I’m not going to describe each approach in detail; this would take pretty much amount of time. I’ll try to point different approaches advantages and disadvantages and additional information sources. Only one variant, so-called NDIS-hooking approach will be reviewed in detail. At this time its realized at least by one third-party company
www.pcausa.com, which offers some source code resources for developers. Please, note that if Part I of this paper is suitable for the majority of Windows developers then Part II and Part III require deep knowledge of Windows internals and strong driver development skills. For those people who would like to experiment with network packet filtering or need to develop custom solution (network security, internet connection sharing, VPN and etc.) and have no desire or no opportunity to learn driver development we offer WinpkFilter
