Content filter SDKÂ can be used mainly to save time, writing one is a tedious job, it requires knowledge in network intercepting and after you spend around three months building your component, you will spend even more debugging it in the field.
TCP filter SDKÂ can be used to filter, block, modify, and inspect any TCP traffic. It also has number of optional modules to perform various advanced tasks such as SSL Decryption, DNS Interception, Parental control and more.
How to intercept data on Internet? This can be done using number of technologies:
- Winsock LSP – Is good when you want to operate at user level and inspect streams and not packets.
- TDI – Soon to be phased out, it’s a driver like technology that can be used either in packet or stream level.
- NDIS – Kernel driver that inspects packets and has total control over the network.
- WFP – Microsoft new filterting platform, but until Windows XP is phased out, I forsee it will not gain momentum.
HTTP Filtering SDKÂ is needed when you want to filter/modify HTTP traffic. The challenge when trying to modify HTTP is that you first need to remove all the HTTP encodings like GZIP, Inflate, SDCH, Chunked transfer and more.
Once you removed the encodings you also need to adjust the headers so the browser will know how to interpert the new encodings.