The introduction of the IPv6 protocol solved the problem of providing
addresses to network devices. With the emergence of the Internet
of Things (IoT), there was also the need to develop a protocol
that would assist in connecting low-power devices. The 6LoWPAN
protocols were created for this purpose. However, such protocols
inherited the vulnerabilities and threats related to Denial of Service
(DoS) attacks from the IPv4 and IPv6 protocols. In this paper, we
prepare a network environment for low-power IoT devices using
COOJA simulator and Contiki operating system to analyze the
energy consumption of devices. Besides, we propose an Intrusion
Detection System (IDS) associated with the AES symmetric encryption
algorithm for the detection of reflection DoS attacks. The
symmetric encryption has proven to be an appropriate method
due to low implementation overhead, not incurring in large power
consumption, and keeping a high level of system security. The main
contributions of this paper are: (i) implementation of a reflection
attack algorithm for IoT devices; (ii) implementation of an intrusion
detection system using AES encryption; (iii) comparison of
the power consumption in three distinct scenarios: normal message
exchange, the occurrence of a reflection attack, and running
IDS algorithm. Finally, the results presented show that the IDS
with symmetric cryptography meets the security requirements and
respects the energy limits of low-power sensors.