Abstract
<jats:p>This paper investigates the mitigation of DDoS attacks in TCP/IP networks, which pose a significant threat to modern information systems. An analysis of the primary types of DDoS attacks and existing detection and neutralization approaches is conducted. The study justifies the implementation of the Proof-of-Work (PoW) mechanism as an effective tool for rate-limiting requests by establishing a computational barrier for clients. In TCP/IP environments, the PoW mechanism leverages computational cost asymmetry, where a client performs resource-intensive computations before transmitting a request, while server-side verification remains rapid and low-overhead. An approach is proposed to integrate PoW into the TCP connection establishment process, specifically during the three-way handshake phase, to reduce the volume of half-open connections and enhance resilience against SYN flood attacks. System performance was modeled with varying numbers of concurrent clients, and the results confirm the effectiveness of the proposed approach in reducing server load and increasing the attack cost for adversaries. The findings demonstrate the viability of utilizing PoW as a core component of comprehensive cyber defense systems and outline perspectives for its further development. Keywords: information security, cryptographic protection, cyber threat, network attack, user behavior analytics, server, TCP/IP, TLS, PoW, Zero Trust, DDoS.</jats:p>