ABSTRACT
Just as absolute does not exist, a completely secure network is not possible. With the growth of the internet and telecommunication, newer techniques to breach the security of a network have evolved. It is important to keep in minds that in the scenario of network vulnerability, even an unsophisticated and innocent-looking user can pose a serious threat to an unprotected network. However unintended the attack may be, its consequences can be severe and substantial. Attackers, equipped with knowledge of the latest technological advances, pose threats that may bypass detection mechanisms of a network and consequences of such attacks include fi nancial loss and loss of trust. This chapter deals with the primary goals of network security, different flavours of network vulnerabilities and understanding of countermeasures.
