A darknet is a network similar to The Grid but not under control of the Network Connection and Regulation Board (NCRB). These networks are rare due to the high cost of the equipment required and rarely are capable of linking between systems. Usually a darknet will be run by a group or corporation with large amounts of resources that require ultra fast connections between locations.
Most often the initial connection from a ground station to the orbiting satellite is achieved through very similar means to a normal connection to The Grid. Most often the connecting system takes advantage of software or hardware modifications from groups such as the Engineers or the ModderMoles respectively. The modification usually removes the 1 GB/second limitation that is set on personal connections by the NCRB.
The connection to the orbiting satellite proves to be much more difficult to achieve than simply modifying an existing piece of equipment. The group that creates the darknet must put their own satellites into orbit. This satellite must have close to the same specifications hardware-wise as a traditional transceiver satellite. This is achievable due to the leaking of the NCRB transceiver plans several years ago. Factions allied to the Crossbones Exchange took credit for releasing the detailed specifications.