Evaluating Neighbor Explainability for Graph Neural Networks

Explainability in Graph Neural Networks (GNNs) is a new field growing in the last few years. In this publication we address the problem of determining how important is each neighbor for the GNN when classifying a node and how to measure the performance for this specific task. To do this, various known explainability methods are reformulated to get the neighbor importance and four new metrics are presented. Our results show that there is almost no difference between the explanations provided by gradient-based techniques in the GNN domain. In addition, many explainability techniques failed to identify important neighbors when GNNs without self-loops are used

On the network geography of the Internet

Abstract—The geographic layout of the physical Internet inherently determines important network properties and traffic characteristics. To give insight into the geography of the Internet, we examine the spatial properties of the topology and routing. To represent the network we conducted a geographically dispersed traceroute campaign, and embedded the extracted topology into the geographic space by applying a novel IP geolocalization service, called Spotter. In this paper we present the frequency analysis of link lengths, quantify path circuitousness and explore the symmetry of end-to-end Internet routes. I

How to Catch when Proxies Lie: Verifying the Physical Locations of Network Proxies with Active Geolocation

Internet users worldwide rely on commercial network proxies both to conceal their true location and identity, and to control their apparent location. Their reasons range from mundane to security-critical. Proxy operators offer no proof that their advertised server locations are accurate. IP-to-location databases tend to agree with the advertised locations, but there have been many reports of serious errors in such databases. In this study we estimate the locations of 2269 proxy servers from ping-time measurements to hosts in known locations, combined with AS and network information. These servers are operated by seven proxy services, and, according to the operators, spread over 222 countries and territories. Our measurements show that one-third of them are definitely not located in the advertised countries, and another third might not be. Instead, they are concentrated in countries where server hosting is cheap and reliable (e.g. Czech Republic, Germany, Netherlands, UK, USA). In the process, we address a number of technical challenges with applying active geolocation to proxy servers, which may not be directly pingable, and may restrict the types of packets that can be sent through them, e.g. forbidding traceroute. We also test three geolocation algorithms from previous literature, plus two variations of our own design, at the scale of the whole world

ETOMIC advanced network monitoring system for future internet experimentation

Revised Selected Papers of 6th International ICST Conference, TridentCom 2010, Berlin, Germany, May 18-20, 2010,The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-17851-1_20ETOMIC is a network traffic measurement platform with high precision GPS-synchronized monitoring nodes. The infrastructure is publicly available to the network research community, supporting advanced experimental techniques by providing high precision hardware equipments and a Central Management System. Researchers can deploy their own active measurement codes to perform experiments on the public Internet. Recently, the functionalities of the original system were significantly extended and new generation measurement nodes were deployed. The system now also includes well structured data repositories to archive and share raw and evaluated data. These features make ETOMIC as one of the experimental facilities that support the design, development and validation of novel experimental techniques for the future Internet. In this paper we focus on the improved capabilities of the management system, the recent extensions of the node architecture and the accompanying database solutions.The authors thank the support of the EU ICT OneLab2 Project (No.224263), the EU ICT MOMENT Project (No.215225) and the National Office for Research and Technology (NAP2005/KCKHA005