Sensor networks contain of a large number of embedded computers called devices. The devices are equipped with short-range low-power radios for communications. Sensor networks present the challenge of building large-scale distributed systems that are tightly coupled with the physical world in an extremely resource constrained environment and need to function for a long time providing a desirable level of performance. The ZigBee standard is a standard that supports wireless networked embedded systems that have come into importance over the past five years. The security of the sensors is in some applications is very important. This report starts with a general description of the ZigBee standard and IEEE 802.15.4. It describes the routing algorithm and security toolbox in ZigBee and the security problems ZigBee has.