Security management for Internet-of-things devices can include device-level security, hub-level security, and service-level security. Internet-of-things devices can communicate threats to each other and/or to an Internet-of-things hub on a gateway. The gateway can receive a communication associated with an Internet-of-things device, the communication request including a request for the Internet-of-things device to connect with another device. Based on connection data included in security communications received from the Internet-of-things device, the gateway can determine if the communication associated with the Internet-of-things device should be allowed. If the communication associated with the Internet-of-things device should not be allowed, an action can be taken to limit the communication, If the communication should be allowed, the communication can be allowed.