I currently use a VPN service with Ubuntu 12.04 but have recently read articles stating that their is a flaw in ipv6 that makes the use of a VPN virtually useless. By default, does Ubuntu connect via ipv6 or ipv4 and if the former, is there any way to disable it? Are there any pros vs cons of disabling ipv6? As I do not understand all of the issues involved here, please forgive me if I have misused any terminology.