Thunderbolt 3 is a relatively new technology to connect peripherals to a computer. Devices connected via Thunderbolt can be DMA masters and thus read system memory without interference of the operating system (or even the CPU). Version 3 of the interface provides security levels in order to mitigate the aforementioned security risk that connected devices pose to the system. As result of this connected devices need to be to be authorized by userspace via a new kernel interface. The new kernel interface additionally supports updating the firmware of devices and the host controller. After an overview of the thunderbolt technology the specifics of the userspace enablement on GNU/Linux will be presented.