## 9 Conclusions  
This study contributes to the growing body of literature on IoT and network protocols by providing a comprehensive performance analysis in the specific context of Dark Net technologies and MQTT applications. Our research offers valuable empirical insights into the practical implications of using these technologies in IoT applications, particularly in scenarios where privacy and anonymity are paramount.  
We present a refined experimental methodology for evaluating dark web network performance in the context of distributed measurement systems based on IoT. This approach builds upon existing methods, adapting them to the unique challenges posed by Dark Net environments. Our methodology encompasses the analysis of throughput, quality of service, privacy, and security, allowing for a holistic assessment of the system's capabilities and limitations. Our experimental results capture several key features of Dark Net communications, including increased latency due to multiple relay hops, bandwidth limitations from encryption and routing overhead, and the impact of network instability characteristic of TOR circuits. While we do not directly quantify anonymity, our performance measurements implicitly reflect the trade-offs associated with enhanced privacy in Dark Net communications.  
While this study focuses on MQTT, future research could explore the performance and security implications of using other protocols like LWM2M in Dark Net environments. Such studies would provide valuable insights into the scalability and manageability of different protocols in secure, privacy-focused IoT deployments. Future work should investigate the scalability of MQTT and compare it with protocols like LWM2M in large-scale IoT deployments over Dark Net environments. This could include assessing the infrastructure requirements for handling increased traffic and evaluating the effectiveness of different protocols in managing large numbers of devices in secure, anonymized networks. In conclusion, our study provides empirical data and practical insights that can guide decision-making in IoT deployments where privacy and security are critical concerns. While TOR offers substantial anonymity and security benefits for MQTT broker communication, it also introduces performance, reliability, and complexity challenges. Future research should focus on optimizing these trade-offs, developing strategies to mitigate the identified limitations, and more explicitly investigating the peer-to-peer aspects of Dark Net communications in IoT contexts. Additionally, exploring alternative protocols and their performance in Dark Net environments will be crucial for advancing the field of secure and scalable IoT communication.  
**Author Contributions:** Conceptualization, A.F.G.; Methodology, D.M. and D.L.C.; Software, D.M.; Validation, E.G.; Formal analysis, D.M.; Investigation, A.F.G.; Data curation, D.L.C.; Writing--review & editing, E.G. and F.L.; Visualization, F.L.; Supervision, A.F.G.; Project administration, A.F.G. All authors have read and agreed to the published version of the manuscript.  
**Funding:** The research leading to these results has received funding from the National Recovery and Resilience Plan (Piano Nazionale di Ripresa e Resilienza, PNRR)--Project: \"SoBigData.it--Strengthening the Italian RI for Social Mining and Big Data Analytics\"--Prot. IR0000013--Avviso n. 3264 del 28/12/2021; by the PNRR project Tech4 You, CUP H23C22000370006, and \"EXTENDABLE--network of EXTENDed reAAlity-enaBLEI laboratories for remote practical training\" CUP E53D23014680001 funded by EU in NextGenerationEU plan through the Italian \"Bando Prin 2022--D.D. 1409 del 14-09-2022\" by MUR.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
**Conflicts of Interest:** The authors declare no conflict of interest.