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Error 51: Unable to communicate with the VPN subsystem

Error 51: Unable to communicate with the VPN subsystem
Error 51: Unable to communicate with the VPN subsystem
Posted by in IT Support

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, Multiple post-graduate degrees, Mind/Body/Spirit enthusiast, & a member of Mensa. Loves Skiing, Scuba, and Food. Steve’s First job out of college was programming satellites for AT&T. Founded IPSOFACTO in 1996, Y2K boom, e-Commerce super success, 2.1 boom. Steve is ready to Mediate high quality for all life, our one planet, and human kindness. Loves to dance and tell jokes. Steve believes that Excellent Communication is key to human success (and failure). Steve has 3 sons who are his STARS. They will carry the world into a brilliant future. Since 1996, Steve has been a volunteer drug and alcoholism counselor in the Bay Area. The power of the Great Spirit is in you. Steve is a good friend to have.

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