libnfnetlink is the low-level library for netfilter related
kernel/userspace communication. It provides a generic messaging
infrastructure for in-kernel netfilter subsystems (such as
nfnetlink_log, nfnetlink_queue, nfnetlink_conntrack) and their
respective users and/or management tools in userspace.

This library is not meant as a public API for application developers.
It is only used by other netfilter.org projects, such as
libnetfilter_log, libnetfilter_queue or libnetfilter_conntrack.