# Deploying Secure Distributed Systems: Comparative Analysis of GNS3 and SEED Internet Emulator
## 2 Background
### Emulated and Virtualized Systems
#### 2.1.2 Hypervisors and Data Privacy  
A hypervisor, also known as a _Virtual Machine Monitor (VMM)_, is a software, hardware, or firmware system that enables the execution of virtual machines. Two types of hypervisors exist: Type 1 (hardware) and Type 2 (software) [14]. _VMware ESXi_ is an enterprise-grade virtualization system that provides a kernel and other operating system components. An open-source alternative, _VMware Workstation Player_, similar to _VirtualBox_, can be employed for private cloud deployments, offering a cost-effective data security solution [15]. _KVM_ is a virtualization model integrated into the Linux kernel. It supports secure multi-processor hypervisor cores, thereby enhancing data integrity and confidentiality in cloud computing, making it a suitable choice for businesses and SMEs [16]. _Hyper-V_, a Microsoft virtualization solution, has been found to be vulnerable to DoS attacks, allowing users running malicious code on a guest VM to cause a disruption. To ensure data confidentiality in multi-client environments, encryption can be integrated to prevent unauthorized data access [17]. While _VirtualBox_, an open-source hosted supervisor, is useful for educational and research purposes, it presents security risks, such as being a potential single point of failure and being susceptible to DoS attacks, access takeover by low-privileged users, and unauthorized access to the entire _VirtualBox_ data [18]. _QEMU_, another open-source hosted supervisor used in this study for GNS3 network emulation, demonstrates robustness and unexploitability when subjected to a TCP amplification attack that targets the three-way handshake (SYN/SYN-ACK/ACK) [19]. [PERSON] et al. [20] investigated the threat modeling of virtualized systems, highlighting the vulnerabilities of hypervisors and the significant impact that cyber-attacks targeting hypervisors can have by allowing hackers to control all hosted VMs. They discussed different levels of attack, including application-level, kernel-level, virtualization layer, hypervisor, and lower-level attacks. [PERSON] et al. [21] proposed a security solution based on Mandatory Access Control (MAC) to defend guest VMs and hypervisors from cyber-attacks. Their solution assigns MAC policies reflecting the intended purpose of the VM and notifies the monitoring VM if access is denied, protecting the virtual environment from unauthorized access. They also suggested future opportunities for implementing MAC policies for guest VMs using the least privilege principle and Extensible MarkupLanguage (XML) to enforce access control across VM migration. [PERSON] et al. [22] introduced a Behavior-Based Access Control (BABAC) solution that combines Attribute-Based Access Control (ABAC) and Behavior-Based Access Control (BBAC) for network virtualization environments. This solution captures dynamic user behaviors and attributes to determine access rights, providing identity and authorization management within VMs. In this subsection, we highlight the vulnerabilities, exploitation, and remediation techniques of emulated networks and virtualized systems which can be observed in Table 1.  
[PERSON] et al. [23] discussed security issues in virtualization, highlighting the significant risk of implicit trust placed in Virtual Machines (VMs). They also emphasized the dangers associated with VM cloning, stressing the importance of accounting for all VM instances to ensure security. Additionally, the abstraction of VMs from the underlying hardware introduces vulnerabilities that can be exploited by cyber threats. [PERSON] et al. [24] investigated vulnerabilities in virtualized computer networks, particularly the breach of isolation that allows a VM to monitor and access other VMs and the host machine. They also identified a Denial of Service (DoS) vulnerability arising from the sharing of resources, including the CPU, memory, disk, and network, between the VM and the host.