DoS attack is a critical problem in WSN as the energy of the nodes are limited. Can any one suggest some valued steps that can be used to reduce DoS attacks of the sensor nodes?
Go through this article which will give you some idea of defending DoS attack using fuzzy logic - "A Sinkhole Attack Detection Scheme in Mintroute Wireless Sensor Networks - Murad A. Rassam1,2, Anazida Zainal1, Mohd. Aizaini Maarof1, and Mohammed Al-Shaboti2"
You can add the cookie solution as SCTP or its TCP version (see RFC 4987 TCP SYN Flooding Attacks and Common Mitigations). However, due to the fact that WSN are Ad-hoc networks, you can try a custom solution: Some kind of false SYN Tracking with MAC address, adding a new network service on your nodes:
* If you receive one false SYN (no ACK received with valid COOKIE) stop the service for a while and send back to the spoofed client a warning (you can have a small service in a separate port to do that - use some Message Authentication Code) that could involve your MAC range and some Private Key - This could be also a solution for the Cookie itself.
* Send to this new service the address involved and limit traffic for this address (routing) for a while.
* Track new packets with this address to its source using some other reounting protrocol.