Unfortunately, the Cisco AnyConnect client for Mac conflicts with Pow. And by "conflicts", I mean it causes a grey-screen-of-death kernel panic anytime you connect to the VPN and Pow is installed.
As an alternative, there is OpenConnect, a command-line client for Cisco's AnyConnect SSL VPN.
Here's how to get it set up on Mac OS X:
OpenConnect can be installed via homebrew:
brew update brew install openconnect
Install the Mac OS X TUN/TAP driver
(Optional) Running openconnect requires sudo, presumably because it affects resolution of DNS. So, I added password-less sudo ability for the openconnect command.
sudo visudo -f /etc/sudoers
And added this line:
%admin ALL=(ALL) NOPASSWD: /usr/local/bin/openconnect
(Optional) When connecting to your SSL VPN, openconnect may complain about a "self-signed certificate" being in the chain and force you to explicitly accept it every time. The self-signed cert is actually the root certficate and (hopefully) is one with implicit trust (i.e. trusted by browsers), so we can safely trust it by specifying the CA file after exporting it from KeyChain:
Open the Keychain Access App
Export Items...the certificate as a
.pemfile somewhere on your hard drive (I put it in
sudo openconnect --user=<VPN username> --cafile=<.pem file from step 4.3> <your vpn hostname>
The only thing you should be prompted for is your VPN password. I added the command to my aliases file.
To disconnect, just Ctrl-c in the window where you started the VPN connection.
I had an incident after an unclean VPN exit where later the VPN hostname could not be found. I guess the DNS resolver was messed up. I was forced to reboot to fix it so I could reconnect to the VPN.