Error 51: Unable to communicate with the VPN subsystem

Error 51: Unable to communicate with the VPN subsystem

Issue: Error 51: Unable to communicate with the VPN subsystem

Affects: Mac OS X and cisco VPN client

Solutions to the issue:

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 one of the following:

(for older versions)

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

(for newer versions)

sudo kextload /System/Library/Extensions/CiscoVPN.kext

and give your password when it asks. This will stop and start the “VPN Subsystem”, or in other words restart the CiscoVPN.kext extension. Cisco seems to have problems when network adapters disappear and reappear, something that happens commonly in Wireless or Dial-up scenerios. Sometimes putting a system to sleep, disconnecting an Ethernet cable or simply reconnecting your wireless will cause CiscoVPN to loose track of the network adapters on the system.

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Steve Boullianne, High school drop-out. College drop-out. A go-go dancer in Amsterdam. LOVED computers, programmed satellites for AT&T. Founded IPSOFACTO in 1996, Y2K boom, Dot-Com boom, 2.0 boom. Likes his smallish company and human relationships; not into big anonymous IT. Loves to tell jokes. Loves and Hates technology; pick up the phone, ok? Thinks on line hook up sites have saved the world from AIDS and DateRape. Thinks his kids are better collaborators and world leaders thanks to video games. Is still a hip-hop dancer; is NOT a Brony. Loves San Francisco; Hates the homeless crisis. Tells young people to buy real estate, as soon as possible. Don’t rent. Hopes his final years are spent handing out blankets, food, clothes, and medical supplies.