Mac OS X – Cisco VPN Client

February 20, 2010 / Cisco, Mac OS X / By

If you are running Cisco’s VPN Client 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 VPN Client, open a Terminal window, (Applications -> Utilities -> Terminal) and type the following from root user:

# /System/Library/StartupItems/CiscoVPN/CiscoVPN restart

Stopping Cisco Systems VPN Driver
kextunload: unload kext /System/Library/Extensions/CiscoVPN.kext succeeded
Starting Cisco Systems VPN Driver
kextload: /System/Library/Extensions/CiscoVPN.kext loaded successfully