This repo contains a few files which were originally from http://gnunet.org/knock and needed some changes for my tests.
The patch for the kernel actually works now with some newer kernels, e.g. 3.18, 3.19. The one on the project website was built against 3.18rc3.
The patch for the Linux OpenSSH got more changes. Please follow this procedure to use it.
$ tar xjz </path/to/openssh-6.7p1.tar.gz>
$ cd openssh-6.7p1
$ patch -p1 < </path/to/openssh-linux-knock-patch.diff>
$ export CFLAGS=" -DHAVE_TCP_STEALTH=26"
$ ./configure
$ make
$ make install