Layer 3: Network layer
More information on networking kernel can be found here.
Question
At which layer of TCP/IP does packet filtering works. I am writing a kernel module that has a nf_hook that will simply drop the packet based on the port - for example TCP or UDP. I want to know at what layer does the nf_hook works in TCP/IP stack?
Solution
Layer 3: Network layer
More information on networking kernel can be found here.