We propose an algorithmic security model based on the widely deployed technologies DNS(SEC) and Web PKI to cover the three dimensions identification, resolution, and transaction. Our model enables quantification and qualification of the security assurance provided by an online service provider. To verify the applicability of our model, we investigate the online presence of Alerting Authorities in the U.S., selected German Emergency Service providers, and UN member states. We observe partially enhanced security relative to global Internet trends, yet find cause for concern as only about 6% of unique hosts cater to secure resolution.

We present the design, implementation, and analysis of DNS over CoAP (DoC), a new proposal for secure and privacy-friendly name resolution of constrained IoT devices. Our findings indicate that plain DoC is on par with common DNS solutions for the constrained IoT but significantly outperforms when additional standard features of CoAP are used such as caching. With OSCORE, we can save more than 10 kBytes of code memory compared to DTLS. We also discuss a compression scheme for very restricted links that reduces data by up to 70%.

We revisit the performance of the QUIC connection setup and relate the design choices for fast and secure connections to common Web deployments. We analyze over 1M Web domains with 272k QUIC-enabled services and find two worrying results. First, current practices of creating, providing, and fetching Web certificates undermine reduced round trip times during the connection setup since sizes of 35% of server certificates exceed the amplification limit. Second, non-standard server implementations lead to larger amplification factors than QUIC permits, which increase even further in IP spoofing scenarios.

We introduce Spoki, a reactive network telescope operating in real-time to examine Internet-wide scan traffic. Spoki responds to asynchronous TCP SYN packets and engages in TCP handshakes initiated in the second phase of two-phase scans. It scales to large prefixes where it has the unique opportunity to record the first data sequence submitted within the TCP handshake ACK. We analyze two-phase scanners during a three months period using globally deployed Spoki reactive telescopes as well as flow data sets from IXPs and ISPs. We find that a predominant fraction of TCP SYNs on the Internet has irregular characteristics.

We present a fully open-source, configurable software platform and experiments to analyze multi-hop BLE network behavior. Our experiments reveal unexpected performance drawbacks. Even in scenarios with underutilized links, BLE connections break randomly. This results into large transmission delays on the network layer and thus hinders real-world deployments in the constrained IoT. As key reason for this behavior we identify the BLE connection interval. We propose randomizing connection intervals as mitigation strategy and demonstrate that this prevents connection losses and sporadic link degradation, improving the overall network behavior.

We take a first look at Alerting Authorities (AA) in the US and investigate security measures related to trustworthy and secure communication. We study the domain namespace structure, DNSSEC penetration, and web certificates. We introduce an integrative threat model to better understand whether and how the online presence and services of AAs are harmed. As an illustrative example, we investigate 1,388 Alerting Authorities. We observe partial heightened security relative to the global Internet trends, yet find cause for concern as about 78% of service providers fail to deploy measures of trustworthy service provision.

We introduce an algorithmic framework for network tomography, BeCAUSe, which implements Bayesian Computation for Autonomous Systems. Using our original combination of active probing and stochastic simulation, we present the first study to expose the deployment of Route Flap Damping (RFD). In contrast to the expectation of the Internet community, we find that at least 9% of measured ASs enable RFD, most using deprecated vendor default configuration parameters. We also successfully apply BeCAUSe to a second challenge, measuring deployment of route origin validation.

We present the first in-depth statistical analysis of all Remote Triggered Black Hole (RTBH) filtering events at a large European IXP by correlating measurements of the data and the control plane for a period of 104 days. We identify a surprising practice that significantly deviates from the expected mitigation use patterns. First, only one third of all 34k visible RTBH events correlate with indicators of DDoS attacks. Second, we witness over 2000 blackhole events announced for prefixes not of servers but of clients situated in DSL networks. Third, that blackholing is a much less reliable tool for mitigating DDoS attacks than expected.

We provide the first comprehensive overview of RIOT. We cover the key components of interest to potential developers and users: the kernel, hardware abstraction, and software modularity, both conceptually and in practice for various example configurations. We explain operational aspects like system boot-up, timers, power management, and the use of networking. Finally, the relevant APIs as exposed by the OS are discussed along with the larger ecosystem around RIOT, including development and open source community aspects.

Recent analysis attempts to use uncontrolled experiments to characterize Route Origin Validation (ROV) adoption by comparing valid routes and invalid routes. However, we argue that gaining a solid understanding of ROV adoption is impossible using currently available data sets and techniques. Instead, we devise a verifiable methodology of controlled experiments for measuring ROV. Our measurements suggest that, although some ISPs are not observed using invalid routes in uncontrolled experiments, they are actually using different routes for (non-security) traffic engineering purposes, without performing ROV.