CONFIG_NF_NAT_MASQUERADE_IPV6 (not configurable)

modulename: nf_nat_masquerade_ipv6.ko

and/or

configname: CONFIG_NF_NAT_MASQUERADE_IPV6

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>Network packet filtering framework (Netfilter)
└─>The IPv6 protocol
└─>IPv6: Netfilter Configuration
└─>NF_NAT_MASQUERADE_IPV6
In linux kernel since version 3.10 (release Date: 2013-06-30)