## 6 Results
### Security of Data Exchange  
As seen from the presented results, the data exchange between the two studied PEDs and the control center is not secure. Important and critical information is exchanged in plain text. Thus, it can be easily intercepted and subsequently modified. Therefore, the information exchange needs to be secured.  
In this work, I propose the VPN technology to be used as the easiest and fastest way to secure the exchanged information. The results from implementing the VPN technology are shown in Figure 15.  
In the modeled \"WAN\" network (from Figure 2), a tunnel is created between R1 and R4 that passes through R1, R2, R3, R4, and vice versa. Figure 15 shows the results of the data exchange between the PDU and the control center. The results when accessing the UPS are exactly the same and therefore will not be shown. Note that 10.0.5.2 is the IP address of the interface g1/0 of R4 and 10.0.1.1 is  
This result is expected since for the PEDs that have network functionalities (i.e., can be controlled and monitored remotely), the generated traffic is only from sending statistics (measured values of various parameters) and control commands.  
Regarding the security of the exchanged data, whose study is the main task of this work, the studied PDU does not offer any security for the exchanged information. As can be seen from the obtained results, absolutely all of the exchanged information between the PDU and the control center is transmitted in plain text. The user data (username and password), the code used to display the menu, and the password change process itself are transmitted in plain text. In addition, the commands for controlling the power outputs to which the network devices are connected are also transmitted in plain text. Such a PDU, which is used by ISPs, is unacceptable for the modern reality because it would be very easy \"prey\" for hackers. Thus, network equipment becomes very easy to manipulate. It can be permanently rebooted, or in the worst case, permanently shut down. As a result of this action, the device will have to be manually switched on due to the inability to be switched on remotely. This process may be repeated many times until the cause of this permanent reboot or shutdown of network devices is determined, which may take a long time to establish. There is even the possibility of not being able to enter the PDU management menu because the username and the password may be changed. This device will then be unusable and the only remaining useful move is to substitute the PDU with another one. Of course, there is the possibility that everything described until now will be repeated again and again until the problem is finally solved. All of this will lead to the eventual compromise of part of the ISP's network and ensuing user dissatisfaction.  
There are many different solutions to this problem. The easiest and quickest solution is to use VPN technology. As can be seen from the results in Section 6.3, the information is already encrypted, and it is not transmitted in plain text. The data exchange is secure. The PDU can no longer be hacked so easily; it is even kind of \"hidden\", so its existence is not known, thanks to the working principle of VPN technology. The use of this technology secures the data exchange and even part of the ISP's communication network.