WSNs perform an important role in many applications, such as battlefields surveillance, patient health monitoring, home automation, traffic control, environmental observation and building intrusion surveillance. WSNs are convenient, cost effective, and give ease of integration with other networks and their components. However, wireless technology also creates new threats. Since WSNs communicate by using radio frequencies therefore the risk of interference is more than with wired networks. If the message to be passed is not in an encrypted form, or is encrypted by using a weak algorithm, the attacker can read it, and it is the compromise to the confidentiality. Security objectives include: protecting confidentiality, assuring integrity, providing authentication and supporting availability of the information and information systems. In this paper we describe the types of existing security threats and how existing techniques can be used to prevent or mitigate these attacks in WSNs. General TermsNetwork security, Attacks on WSN, Security mechanisms. KeywordsNetwork security, Attacks on WSN, Security mechanisms, prevention of attacks from security threats.

Transport layer protocols of Wireless sensor networks, plays an important role in the achievement of high performance and the long life time of the network. This layer is specifically needed when a system is organized to access other networks. Two functions provided by this layer are; reliability and the congestion control. Many numbers of protocols are designed to achieve these two functions. This paper gives you a review of reliable transport layer protocols and congestion control transport layer protocols. First, it gives an introduction to the wireless sensor networks. Second, gives an idea about the various services provided by transport layer and the disadvantages of using traditional TCP (Transport control protocol) and UDP (User datagram protocol) of transport layer. Third are some existing transport layer protocols. Further is the conclusion of this review.

Recent advances in wireless sensor networks (WSN) over the last two decades has an more interest in the potential use in applications like combat field, security surveillance, border protection, disaster management. Moreover, researchers have termed the 21st century as the "Sensor Decade" Sensor nodes are remotely deployed in large numbers and expected to operate autonomously in harsh environments [3]. Now-a-days routing protocols are acting as designed, where essential designing issue is energy. In this paper, the survey on current routing protocols for sensor networks along with their classification and approaches is done. Each routing protocol is described under the appropriate category followed by possible future research areas.