Packet filtering

modulename: iptable_filter.ko

configname: CONFIG_IP_NF_FILTER

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>Network packet filtering framework (Netfilter)
└─>IP: Netfilter Configuration
└─>Packet filtering
In linux kernel since version 2.6.12  
Packet filtering defines a table `filter', which has a series of
rules for simple packet filtering at local input, forwarding and
local output. See the man page for iptables(8).

To compile it as a module, choose M here. If unsure, say N.

source code: