Provided are techniques for authenticating an unknown device. For a first device in an internet of things network that includes a second device and forms a list of trusted devices, a distance between the first device and the second device is determined. A level of trust for the second device is identified based on the distance, wherein the level of trust specifies a level of data sharing. Reputation ranking is performed for the second device based on the level of trust. The reputation ranking is used to assign a trust score to the second device. Based on determining that the trust score exceeds a trust threshold, access is provided to the second device.