Leopard 10.5.1 Update Breaks Cisco VPN, with Fix

I updated my Mac to Leopard a few weeks ago. All good.

Yesterday I ran the update to 10.5.1. Not so good: It knocked out my Cisco VPN client. Permanently. Rebooting did not help. Reinstalling did not help. (I rely on VPN non-stop, even to retrieve my office email.)

So today I poked around for a while and after some deep searching found the fix. It’s easy, and worked for me on the first try. The solution was on Anders Brownworth’s site (thanks Anders!), and I’m reprinting an excerpt here in the hopes that it will make it easier to find for somebody else.

If you are running Cisco’s VPNClient on Mac OSX, you might be familiar with (or tormented by) “Error 51: Unable to communicate with the VPN subsystem”. The simple fix is to quit VPNClient, open a Terminal window, (Applications -> Utilities -> Terminal) and type the following:

sudo /System/Library/StartupItems/CiscoVPN/CiscoVPN restart

and give your password when it asks. This will stop and start the “VPN Subsystem”, or in other words restart the CiscoVPN.kext extension.