The netfilter.org "libnetfilter_cthelper" project

libnetfilter_cthelper is the userspace library that provides the programming interface to the user-space helper infrastructure available since Linux kernel 3.6. With this library, you register, configure, enable and disable user-space helpers. This library is used by conntrack-tools.

libnetfilter_cthelper requires libmnl and a kernel that includes the nfnetlink_cthelper subsystem (i.e. 3.6 or later).

For the nfnetlink_cthelper subsystem.

You can check the library documentation generated in doxygen format.

The current development version of libnetfilter_cthelper can be accessed at https://git.netfilter.org/libnetfilter_cthelper/.

libnfnetlink_cthelper has been written by Pablo Neira Ayuso.