dr. R. Holz (Ralph)

Over mij

I am a Full Professor at the University of Münster, and I also work part-time in the Design and Analysis of Communication Systems Group at the University of Twente.

Until 2019, I was a Lecturer in Networks and Security at the University of Sydney (that’s Asst. Prof. in other systems), Australia. Before that, I was a Researcher at NICTA (later CSIRO's Data61), also in Sydney, where I worked on network security and was part of the Security Business Team.

I hold a PhD from Technical University of Munich. I did both my post-grad and under-grad studies at Eberhard Karls University, Tuebingen, one of Germany’s classic universities.



My research interests revolve around understanding and improving the Internet for everyone, with a particular focus on security aspects. Most recently, I have been working on

  • Global-scale measurement of Internet service deployments and their security
  • Data-driven security mechanisms
  • Analysis of emerging technology and its implications

I view my work through the lens of real-world implications. The tech is not always what matters—it’s the embedding in our world that makes it meaningful. Hence, I work with other disciplines and industry alike to make the Internet a safer, more secure, and altogether more interesting and useful place.


Khadka, S. K. , Holz, R. , & Hesselman, C. (2024). Towards Security Transparency of Autonomous Systems on the Internet. In S. Katsikas, H. Abie, S. Ranise, L. Verderame, E. Cambiaso, R. Ugarelli, I. Praça, W. Li, W. Meng, S. Furnell, B. Katt, S. Pirbhulal, A. Shukla, M. Ianni, M. Dalla Preda, K.-K. R. Choo, M. Pupo Correia, A. Abhishta, G. Sileno, M. Alishahi, H. Kalutarage, ... N. Yanai (Eds.), Computer Security. ESORICS 2023 International Workshops: CPS4CIP, ADIoT, SecAssure, WASP, TAURIN, PriST-AI, and SECAI, The Hague, The Netherlands, September 25–29, 2023, Revised Selected Papers, Part II (pp. 510-513). (Lecture Notes in Computer Science; Vol. 14399). Springer Nature. https://doi.org/10.1007/978-3-031-54129-2_30
Sattler, P., Zirngibl, J. , Jonker, M., Gasser, O., Carle, G. , & Holz, R. (2023). Packed to the Brim: Investigating the Impact of Highly Responsive Prefixes on Internet-wide Measurement Campaigns. Proceedings of the ACM on Networking, 1(3), Article 24. https://doi.org/10.1145/3629146
Tarahomi, S. , Holz, R. , & Sperotto, A. (2023). Quantifying Security Risks in Cloud Infrastructures: A Data-driven Approach. In C. J. Bernardos, B. Marini, E. Rojas, F. L. Verdi, Z. Zhu, E. Oki, & H. Parzyjegla (Eds.), 2023 IEEE 9th International Conference on Network Softwarization (NetSoft) IEEE. https://doi.org/10.1109/NetSoft57336.2023.10175501
Pimienta, J., Brandt, J., Bethe, T. , Holz, R. , Continella, A., Jibb, L., & Grundy, Q. (2023). Mobile apps and children's privacy: A traffic analysis of data sharing practices among children's mobile iOS apps. Archives of disease in childhood, 108(11), 943-945. https://doi.org/10.1136/archdischild-2023-325960
Yazdani, R., Nosyk, Y. , Holz, R., Korczyński, M. , Jonker, M. , & Sperotto, A. (2023). Hazardous Echoes: The DNS Resolvers that Should Be Put on Mute. In 2023 7th Network Traffic Measurement and Analysis Conference (TMA) (pp. 1-10). IEEE. https://doi.org/10.23919/TMA58422.2023.10198955
Bertholdo, L. (2023). Anycast in the age of hypergiants: Towards tools and techniques for the other 99% of ASes. [PhD Thesis - Research UT, graduation UT, University of Twente]. University of Twente. https://doi.org/10.3990/1.9789036557320
Bertholdo, L., Ferreira, S. L. A., Ceron, J. M. , Holz, R., Granville, L. Z. , & van Rijswijk - Deij, R. M. (2022). On the Asymmetry of Internet eXchange Points - Why Should IXPs and CDNs Care? In 18th International Conference on Network and Service Management
Holz, R. , & Abhishta, A. (2021). A message from the program chairs of TAURIN 2021. In TAURIN 2021 - Proceedings of the 2021 ACM SIGCOMM Workshop on Technologies, Applications, and Uses of a Responsible Internet https://dl.acm.org/doi/proceedings/10.1145/3472951
Holz, R., Mellia, M., Bonaventure, O., Haddadi, H., Caesar, M., Gorinsky, S., Antichi, G., Camp, J., Claffy, K., Raman, B. , Sperotto, A., Vianna, A., & Uhlig, S. (2020). Update on ACM SIGCOMM CCR reviewing process: Towards a more open review process. Computer communication review, 50(3), 55-56. https://doi.org/10.1145/3411740.3411748

Pure Link

Google Scholar Link


I currently teach:

  • Empirical Security Analysis & Engineering (202100073)

I am a Fellow of the UK's Higher Education Academy.

Verbonden aan Opleidingen


Vakken Collegejaar  2023/2024

Vakken in het huidig collegejaar worden toegevoegd op het moment dat zij definitief zijn in het Osiris systeem. Daarom kan het zijn dat de lijst nog niet compleet is voor het gehele collegejaar.

Vakken Collegejaar  2022/2023



Universiteit Twente
Faculty of Electrical Engineering, Mathematics and Computer Science
Zilverling (gebouwnr. 11)
Hallenweg 19
7522NH  Enschede

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Universiteit Twente
Faculty of Electrical Engineering, Mathematics and Computer Science
Postbus 217
7500 AE Enschede