How to connect to MacBook to a Windows 7 machine that is connected to a Ubuntu machine via VPN?
This might work by using putty as a tunnel on the Windows machine, and allowing remote hosts to connect to the tunnel. If the cisco vpn connection is set to disable local network traffic (which is quite common) then it almost certainly won't work. Also Cisco VPN client doesn't support Internet Connection Sharing. It seems like a complicated way of doing things - why not just enable the VPN directly from the Mac - the client is built-in to the OS and takes way quicker to connect than Cisco's own client.