IP: IPComp transformation

modulename: ipcomp.ko

configname: CONFIG_INET_IPCOMP

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>IP: IPComp transformation
In linux kernel since version 2.6.12  
Support for IP Payload Compression Protocol (IPComp) (RFC3173),
typically needed for IPsec.

If unsure, say Y.

source code:
net/ipv4/ipcomp.c