CONFIG_INET_TUNNEL (not configurable)

modulename: tunnel4.ko

configname: CONFIG_INET_TUNNEL

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>INET_TUNNEL
In linux kernel since version 2.6.12  
source code:
net/ipv4/tunnel4.c

is depended by
CONFIG_NET_IPVTI