Research Article Web Spider Defense Technique in Wireless Sensor Networks Alejandro Canovas, 1 Jaime Lloret, 1 Elsa Macias, 2 and Alvaro Suarez 2 1 Integrated Management Coastal Research Institute, Universidad Polit´ ecnica de Valencia, Spain 2 Departamento de Ingenier´ ıa Telem´ atica, Universidad de Las Palmas de Gran Canaria, Spain Correspondence should be addressed to Alejandro Canovas; alcasol@posgrado.upv.es Received 22 April 2014; Accepted 1 July 2014; Published 23 July 2014 Academic Editor: S. Khan Copyright © 2014 Alejandro Canovas et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Wireless sensor networks (WSNs) are currently widely used in many environments. Some of them gather many critical data, which should be protected from intruders. Generally, when an intruder is detected in the WSN, its connection is immediately stopped. But this way does not let the network administrator gather information about the attacker and/or its purposes. In this paper, we present a bioinspired system that uses the procedure taken by the web spider when it wants to catch its prey. We will explain how all steps performed by the web spider are included in our system and we will detail the algorithm and protocol procedure. A real test bench has been implemented in order to validate our system. It shows the performance for diferent response times, the CPU and RAM consumption, and the average and maximum values for ping and tracert time responses using constant delay and exponential jitter. 1. Introduction A wireless sensor network (WSN) is distributed in nature. It consists of several electronic devices with a memory, a pro- cessor, and one or more elements that sense the environment [1, 2]. One of their main issues taken into account in their deployment is their power limitation and their need to save energy [3, 4]. Sensor nodes can communicate among them using a particular or standard communication technology network interface card. Te sensed values can be forwarded to a central manager that usually is a computer (or similar device). Te computer allocates a manager that is in charge to manage the WSN. Te most common strategy to read values of sensed elements consists of interrogating the manager in order to obtain a set of sensed values. In this sense, a WSN is used to collect and monitor the related information about a specifc environment. Tis procedure has relevance in several cases: vigilance, oceanographic values of a strategic installation, police related information, and many more. Generally, WSNs are used to sense private data. Some of them can also transmit critical data. Tus, it is very important to secure the collection of data and detect and avoid external intrusions. An intruder may be able to access unauthorized data, spread erroneous data and/or malicious code, implement unauthorized changes to data or sensor sofware, or steal data. Moreover, an intruder could initiate attacks to the network from that sensor node and open new doors to other intruders. Tis must be done taking into consideration four requirements: data confdentiality, data authentication, data integrity, and denial-of-service (DoS) attack avoidance [5]. Diferent surveys on WSN security are presented in [6–13]. In [14, 15] a list of attacks and counterattacks are surveyed. Tis work is focused on intrusion attacks in WSNs. A network intrusion detection system (IDS) is an essential element in a computer security strategy [16]. An IDS is a device or a sofware application that monitors network and system activities for malicious activities or policy violations. Te IDS produces reports to a central system that allow humans to intervene or that can be responded by computer systems in an attempt to stop the intrusion. In a WSN, this attack means that an attacker (malicious user) wants to illegally read the data sensed by a set of sensors. We suppose the malicious user can interrogate the sensors in the WSN bypassing the control of the WSN manager/administrator. Te difcult task here is to discover when a malicious attack is Hindawi Publishing Corporation International Journal of Distributed Sensor Networks Volume 2014, Article ID 348606, 7 pages http://dx.doi.org/10.1155/2014/348606