There are several ways to implement a firewall:
- Winsock LSPÂ – Can be used for an application layer firewall, but it’s mostly not used for various reasons.
- TDI Driver – Mostly used for personal firewalls, according to Microsoft it will be phased out in the next OS.
- Ndis IM – Mostly used for gateway firewalls.
- WFP – The new plaform Microsoft is promoting, in my opinion that until XP is retired this will not gain momentum.