This is probably a bit dated now, last work done May, 2006 - Might give Mac OS X (Intel) a try soon ...
This is still experimental, expect instabilities. This is the third release of JNOS for MAC OS X (Darwin) on powerpc platforms. It's a dirty port just to see how well it runs, which it seems to, and not bad. Latest work includes TUN interface. Done on Mac OS X 10.4 (Tiger) Darwin 8.6.0 kernel, gcc 4.0.0 compiler.
Click here for the latest source (2.0e with patches). Use gunzip to uncompress it, then 'tar xvf jnos20e1.ppc.tar' which should create a jnos2 subdirectory.
Change to the jnos2 subdirectory, then 'make clean' followed by 'make' which should generate a JNOS binary (executable).
Click here for a binary. Use gunzip to uncompress it, then 'tar xvf jnosbin.ppc.tar' which should create the jnos binary.
Click here for an older (2.0d) binary from DL1THM himself, on a Darwin 8.5.0 kernel, gcc 4.0.1 compiler.
If you wish to use TUN between JNOS and Mac OS X, you will need to compile and install the Nissler tun/tap drivers and extensions, since Mac OS X (when I last worked on this) does not come with it. The original drivers and extensions were located at http://www-user.rhrk.uni-kl.de/~nissler/tuntap at one time, but that site no longer exists. Try this link instead to sourceforge.net, where the pages appear to have been relocated.
The Nissler code makes it possible for the openVPN project to work on Mac OS X systems. Please read the install instructions very carefully, since this involves adding kernel extensions to your Mac OS X system !
Click here for a simple autoexec.nos that networks JNOS and Mac OS X through the TUN interface. The only real difference between this file and it's linux counterpart is in the "shell ifconfig tun0 ..." command. Mac OS X does not use the 'pointopoint' argument.