This paper presents a brief survey on jamming attacks and measures to be taken for avoiding such attacks. The wireless networks are vulnerable to jamming and eavesdropping attacks. Presently, the lot of attacks are already there which challenge the network security. Jamming attacks can be viewed as unauthorized access of intruders in the transmission network. To defeat jamming attacks, optimal power allocation strategies are discussed in this paper which can be used as an anti-jamming mechanism for strengthening wireless network against various intrusion actions.