Netfilter IPv4 packet duplication to alternate destination

modulename: nf_dup_ipv4.ko

configname: CONFIG_NF_DUP_IPV4

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>Network packet filtering framework (Netfilter)
└─>IP: Netfilter Configuration
└─>Netfilter IPv4 packet duplication to alternate destination
In linux kernel since version 4.1 (release Date: 2015-06-21)  
This option enables the nf_dup_ipv4 core, which duplicates an IPv4
packet to be rerouted to another destination.

source code: