AIS is an automatic tracking system intended to help identify and locate vessels electronically to help avoid collisions on the water. AIS transponders on the ships include a GPS receiver and VHF transmitter, which transmits information to other vessels or base stations. Attackers could hijack AIS traffic and perform man-in-the-middle attacks that enable them to turn the tracking system into a liability. The attacks can be broken up into two categories: those that target the AIS Internet providers that collect and distribute AIS information.”]