If you have a VPN at your workplace, chances are good that it’s one of those Cisco 3000 VPN Concentrator things, which seem to be an industry standard for VPN equipment. Chances are also good that you’ve likely been forced to use the evil, evil proprietary Cisco VPN client, which has been known to be a source of angsta majora for Mac OS X and Linux users. (And if you think Windows users have it good, think again: the Cisco VPN client completely hosed a friend’s 64-bit Windows XP system to the point where it wouldn’t even boot.)

Enter vpnc, an open-source VPN client that works just fine on both Mac OS X and Linux. Linux people, I assume that you know what you’re doing — all you should need is a TUN/TAP kernel driver and you’re good to go. Mac OS X folks, you’ll need to be comfortable with the UNIX terminal to use it; unfortunately no GUI has been written for it yet. If you’re a Terminal geek, here’s a small guide for you:

• Download and install a tun/tap driver for Mac OS X.
• Download and install libgcrypt. If you have DarwinPorts (neé MacPorts) installed, simply do “port install libgcrypt”. Otherwise, grab it from the libgcrypt FTP site and install it manually.
• You’ll need to check out the latest version of the vpnc code from its Subversion repository: “svn checkout http://svn.unix-ag.uni-kl.de/vpnc/”. The latest official release (0.3.3, as of this writing) will not compile properly on Mac OS X, which is why you need the code from the Subversion trunk.
• After doing the standard “make && make install” mantra, run your Cisco VPN .pcf profile through the pcf2vpnc tool and save the resulting .vpnc file in /etc/vpnc.
• ./vpnc YourProfile.vpnc, and that should be it. While you’re debugging it, the --nodetach and --debug 1 options may be useful.

Muchas gracias to Mario Maceratini at Rising Sun Pictures for hunting down vpnc for me.