## 2 Related Works  
Numerous studies in the literature make suggestions regarding security systems across various protocol stack layers and network typologies, including cryptography performance analysis; this section provides an overview of key contributions related to VPNs and ONs. In [4], a novel experimental WAN solution as Software-Defined Wide Area Network (SD-WAN based on ONOSOpenDaylight [[https://opennetworking.org/onos/](https://opennetworking.org/onos/)]([https://opennetworking.org/onos/](https://opennetworking.org/onos/)) (accessed on 23 June 2024) and OpenVswitch 2.12.0 [[https://www.openvswitch.org/](https://www.openvswitch.org/)]([https://www.openvswitch.org/](https://www.openvswitch.org/)) (accessed on 23 June 2024) latest version as SDN controller) is proposed, entirely based on secure tunnels, implemented by the Generic Routing Encapsulation (GRE) tunneling protocol [5]. The proposal's effectiveness is validated through two SD-WAN testbeds, covering a very long distance (from northeast to south Italy). The authors demonstrate that the SD-WAN can ensure a rapid recovery from and resilience to network failures by leveraging an innovative Berkeley Packet Filtering (BPF)-based monitoring technique. The authors also demonstrate that SD-WAN has several advantages in terms of recovery time and high performance compared to other solutions (e.g., Multi-Protocol Label Switching--MPLS). The study in [6] evaluates network layer-based VPNs, which enable secure communications between remote LANs using IP tunnels over a shared medium (e.g., Internet). The authors' primary focus lies in demonstrating the efficiency of various VPNs, backed by several studies on contemporary practices, followed by an analysis of the Wireguard protocol. The authors of [7] provide a comprehensive analysis of MACVLAN and IPvlan modes, focusing on their architecture characteristics and utility in enabling container communication across diverse network segments within complex application scenarios. The proposed work details the setup of container overlay networks in single-machine and multi-machine environments, offering insights into the intricacies of these modes. By evaluating key network indicators such as round-trip time (RTT), bandwidth, and jitter using tools like Ping and Iperf, the research assesses the end-to-end communication performance of containers. The experimental results indicate that the IPvlan mode demonstrates superior network performance compared to MACVLAN, presenting a more extensive and adaptable application scenario for container overlay networks. This finding highlights the significance of selecting the appropriate network mode based on specific performance and scalability requirements within containerized environments. The detailed contribution given in [8] presents a comprehensive approach to studying VPNs in general. It emphasizes that understanding VPN technology necessitates consideration of the values and motivations of individuals within organizations. A significant discovery highlights the divergent perceptions and interpretations of the terms _VPN_, _security_, and _privacy_ among corporate employees. In [9] the attention id focuses on the widespread utilization of Secure Socket Layer (SSL)-VPN to ensure both authentication and data confidentiality between the client (typically a web browser) and the server (SSL Server). VPN technology is extensively examined in [10; 11]. Specifically, these works delve into the vulnerabilities and suboptimal performance experienced under heavy loads by web browser-based SSL VPNs, which are limited to support only Windows operating systems. The authors of [12] justify the selection of the IPsec-IKEv2 suite over other potential implementations, such as SSL/TLS VPN or SSH Tunnel, by emphasizing the security of the IP communication layer. This choice is motivated by the desire for _transparency_ of the layers above the IP within IPsec-IKEv2, as well as the ability to promptly update encryption in case of a compromise in the data channel.