Internet of Things (IoT) innovation brings many facilities to our lives by connecting personal computers, smart phones and other devices like dishwashers, fridges to one network. Most of these devices like sensors have limited computational power that does not allow the use of contemporary security precautions such as encryption that leads to the gap in security of IoT network. In this study Denial of Service (DoS) attacks were performed to see in which condition devices are during an attack. Our main goal is to measure energy consumption during an attack. For this, we prepared a testbed platform and observed the cpu usage of a device during the attack. Synchronization (SYN) flood attack and Internet Control Message Protocol (ICMP) flood attack were performed.