Installed latest openconnect 7.05 from ports onto MacOS 10.8.2.
Starting OpenConnect results in error messge:
Failed to open tun device: Invalid argument
.. but i did not want to install/use the 'tun' interface, but instead MacOS standard utun interface as supported by openconnect since 7.0
When i downloaded openconnect from http://www.infradead.org/openconnect/ and tried to compile myself, ./configure complained about IF_UTUN... not to compile, so the config file created did not include UTUN support. I did manually changed it and it compiled fine and worked fine. I do suspect that the port binary of openconnect might have had the same problem in compilation. I did not try to investigate why that compile problem exist (autoconfigure scripts are too complex).
Note that openconnect does not install a vpnc script, but it does depend on another port that does. openconnect switched from using the vpnc port to using the vpnc-scripts port in r137024 (#47180). Did that help?