\section{Discussion and Future Work}

\subsection{Discussion}

The review of secured network infrastructure highlights a continuous evolution in defensive strategies, driven by increasingly sophisticated cyber threats. The progression from basic packet filtering to advanced Next-Generation Firewalls (NGFWs) and integrated Intrusion Detection/Prevention Systems (IDS/IPS) signifies a critical shift towards multi-layered, context-aware security \cite{ref22}. While foundational, traditional firewalls are often insufficient in isolation due to their stateless nature and limited application awareness. NGFWs represent the current peak, integrating deep packet inspection, threat intelligence, and user identity awareness to combat advanced persistent threats (APTs) and zero-day exploits more effectively.

Complementary technologies like Virtual Private Networks (VPNs) and Access Control Lists (ACLs) further enhance defense. VPNs are crucial for securing remote access and site-to-site communications, ensuring data confidentiality and integrity across untrusted networks [26]. ACLs provide granular control over network traffic, enforcing security policies at the network edge. The effectiveness of these technologies, however, depends on proper configuration, continuous monitoring, and timely updates.

Despite these advancements, the arms race between attackers and defenders persists. Complex network architectures, the proliferation of IoT devices, and cloud-based services introduce new attack surfaces. Human factors, such as social engineering and insider threats, remain significant challenges that technical controls alone cannot fully address. Network simulation tools like Packet Tracer and GNS3 are vital for proactive security testing and professional development, allowing vulnerability exploration and defense strategy validation in controlled environments.

\subsection{Future Work}

The dynamic nature of network security necessitates continuous research and development. Several areas warrant future investigation:

\begin{itemize}
    \item \textbf{AI and Machine Learning Integration:} Further research is needed to develop more robust, explainable, and adversarial-resilient AI models for threat prediction and automated response, including federated learning for collaborative threat intelligence.
    \item \textbf{Zero Trust Architectures:} Future work should focus on practical implementation, performance optimization, and integration with legacy systems for Zero Trust models, particularly micro-segmentation and identity-centric security.
    \item \textbf{Quantum-Resistant Cryptography:} Research into quantum-resistant cryptographic algorithms for VPNs and secure communication protocols is paramount to counter the theoretical threat of quantum computing.
    \item \textbf{Security in 5G and Beyond Networks:} New security challenges from 5G, IoT, and edge computing require developing new protocols and management frameworks tailored for highly distributed and virtualized environments.
    \item \textbf{Automated Vulnerability Management:} Enhancing automation in identifying, prioritizing, and patching vulnerabilities, leveraging AI for predictive analysis and self-healing networks, is critical.
    \item \textbf{Behavioral Analytics for Insider Threat Detection:} Further development in user and entity behavioral analytics (UEBA) is needed to more accurately detect and mitigate insider threats by understanding anomalous user behavior patterns.
\end{itemize}

Addressing these areas will significantly contribute to building more resilient, intelligent, and proactive secured network infrastructures against evolving threats.

