Abstract: The paper proposes a conceptual framework forming the grounds of the protocol-based protection of the information and telecommunications network. The purpose of this article is to develop theoretical foundations of the protocol-based protection. Based on a review of the existing descriptions of vulnerabilities and approaches to assessing the security of information and telecommunications networks and the known types of threats the author identifies their contradictions and shortcomings. The author proposes the classification and the definition of the concept of a protocol-based impact, gives some examples of such impacts and the main definitions revealing the essence of this concept. Analysis is the main research method. The author considers the shortcomings of the definitions of the existing normative documents. The scientific novelty lies in the fact that the study considers the new class of vulnerabilities and the related threats to the information and telecommunications network. The proposed definitions help describe the technological peculiarities and the existing features which will hereafter allow dividing its protection into the information and the technological ones. The results of the study can be used for the further development of theoretical foundations of the protocol-based protection of the information and telecommunications network.