Netfilter Xtables support (required for ip_tables)

modulename: x_tables.ko

configname: CONFIG_NETFILTER_XTABLES

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>Network packet filtering framework (Netfilter)
└─>Core Netfilter Configuration
└─>Netfilter Xtables support (required for ip_tables)
In linux kernel since version 2.6.16 (release Date: 2006-03-19)  
This is required if you intend to use any of ip_tables,
ip6_tables or arp_tables.

source code:
net/netfilter/