Internet routing paths stability model and relation to forwarding paths

Analysis of real datasets to characterize the local stability properties of the Internet routing paths suggests that extending the route selection criteria to account for such property would not increase the routing path length. Nevertheless, even if selecting a more stable routing path could be considered as valuable from a routing perspective, it does not necessarily imply that the associated forwarding path would be more stable. Hence, if the dynamics of the Internet routing and forwarding system show different properties, then one can not straightforwardly derive the one from the other. If this assumption is verified, then the relationship between the stability of the forwarding path (followed by the traffic) and the corresponding routing path as selected by the path-vector routing algorithm requires further characterization. For this purpose, we locally relate, i.e., at the router level, the stability properties of routing path with the corresponding forwarding path. The proposed stability model and measurement results verify this assumption and show that, although the main cause of instability results from the forwarding plane, a second order effect relates forwarding and routing path instability events. This observation provides the first indication that differential stability can safely be taken into account as part of the route selection process

Improving the accuracy of spoofed traffic inference in inter-domain traffic

Ascertaining that a network will forward spoofed traffic usually requires an active probing vantage point in that network, effectively preventing a comprehensive view of this global Internet vulnerability. We argue that broader visibility into the spoofing problem may lie in the capability to infer lack of Source Address Validation (SAV) compliance from large, heavily aggregated Internet traffic data, such as traffic observable at Internet Exchange Points (IXPs). The key idea is to use IXPs as observatories to detect spoofed packets, by leveraging Autonomous System (AS) topology knowledge extracted from Border Gateway Protocol (BGP) data to infer which source addresses should legitimately appear across parts of the IXP switch fabric. In this thesis, we demonstrate that the existing literature does not capture several fundamental challenges to this approach, including noise in BGP data sources, heuristic AS relationship inference, and idiosyncrasies in IXP interconnec- tivity fabrics. We propose Spoofer-IX, a novel methodology to navigate these challenges, leveraging Customer Cone semantics of AS relationships to guide precise classification of inter-domain traffic as In-cone, Out-of-cone ( spoofed ), Unverifiable, Bogon, and Unas- signed. We apply our methodology on extensive data analysis using real traffic data from two distinct IXPs in Brazil, a mid-size and a large-size infrastructure. In the mid-size IXP with more than 200 members, we find an upper bound volume of Out-of-cone traffic to be more than an order of magnitude less than the previous method inferred on the same data, revealing the practical importance of Customer Cone semantics in such analysis. We also found no significant improvement in deployment of SAV in networks using the mid-size IXP between 2017 and 2019. In hopes that our methods and tools generalize to use by other IXPs who want to avoid use of their infrastructure for launching spoofed-source DoS attacks, we explore the feasibility of scaling the system to larger and more diverse IXP infrastructures. To promote this goal, and broad replicability of our results, we make the source code of Spoofer-IX publicly available. This thesis illustrates the subtleties of scientific assessments of operational Internet infrastructure, and the need for a community focus on reproducing and repeating previous methods.A constatação de que uma rede encaminhará tráfego falsificado geralmente requer um ponto de vantagem ativo de medição nessa rede, impedindo efetivamente uma visão abrangente dessa vulnerabilidade global da Internet. Isto posto, argumentamos que uma visibilidade mais ampla do problema de spoofing pode estar na capacidade de inferir a falta de conformidade com as práticas de Source Address Validation (SAV) a partir de dados de tráfego da Internet altamente agregados, como o tráfego observável nos Internet Exchange Points (IXPs). A ideia chave é usar IXPs como observatórios para detectar pacotes falsificados, aproveitando o conhecimento da topologia de sistemas autônomos extraído dos dados do protocolo BGP para inferir quais endereços de origem devem aparecer legitimamente nas comunicações através da infra-estrutura de um IXP. Nesta tese, demonstramos que a literatura existente não captura diversos desafios fundamentais para essa abordagem, incluindo ruído em fontes de dados BGP, inferência heurística de relacionamento de sistemas autônomos e características específicas de interconectividade nas infraestruturas de IXPs. Propomos o Spoofer-IX, uma nova metodologia para superar esses desafios, utilizando a semântica do Customer Cone de relacionamento de sistemas autônomos para guiar com precisão a classificação de tráfego inter-domínio como In-cone, Out-of-cone ( spoofed ), Unverifiable, Bogon, e Unassigned. Aplicamos nossa metodologia em análises extensivas sobre dados reais de tráfego de dois IXPs distintos no Brasil, uma infraestrutura de médio porte e outra de grande porte. No IXP de tamanho médio, com mais de 200 membros, encontramos um limite superior do volume de tráfego Out-of-cone uma ordem de magnitude menor que o método anterior inferiu sob os mesmos dados, revelando a importância prática da semântica do Customer Cone em tal análise. Além disso, não encontramos melhorias significativas na implantação do Source Address Validation (SAV) em redes usando o IXP de tamanho médio entre 2017 e 2019. Na esperança de que nossos métodos e ferramentas sejam aplicáveis para uso por outros IXPs que desejam evitar o uso de sua infraestrutura para iniciar ataques de negação de serviço através de pacotes de origem falsificada, exploramos a viabilidade de escalar o sistema para infraestruturas IXP maiores e mais diversas. Para promover esse objetivo e a ampla replicabilidade de nossos resultados, disponibilizamos publicamente o código fonte do Spoofer-IX. Esta tese ilustra as sutilezas das avaliações científicas da infraestrutura operacional da Internet e a necessidade de um foco da comunidade na reprodução e repetição de métodos anteriores

The Closed Resolver Project: Measuring the Deployment of Source Address Validation of Inbound Traffic

Source Address Validation (SAV) is a standard aimed at discarding packets with spoofed source IP addresses. The absence of SAV for outgoing traffic has been known as a root cause of Distributed Denial-of-Service (DDoS) attacks and received widespread attention. While less obvious, the absence of inbound filtering enables an attacker to appear as an internal host of a network and may reveal valuable information about the network infrastructure. Inbound IP spoofing may amplify other attack vectors such as DNS cache poisoning or the recently discovered NXNSAttack. In this paper, we present the preliminary results of the Closed Resolver Project that aims at mitigating the problem of inbound IP spoofing. We perform the first Internet-wide active measurement study to enumerate networks that filter or do not filter incoming packets by their source address, for both the IPv4 and IPv6 address spaces. To achieve this, we identify closed and open DNS resolvers that accept spoofed requests coming from the outside of their network. The proposed method provides the most complete picture of inbound SAV deployment by network providers. Our measurements cover over 55 % IPv4 and 27 % IPv6 Autonomous Systems (AS) and reveal that the great majority of them are fully or partially vulnerable to inbound spoofing. By identifying dual-stacked DNS resolvers, we additionally show that inbound filtering is less often deployed for IPv6 than it is for IPv4. Overall, we discover 13.9 K IPv6 open resolvers that can be exploited for amplification DDoS attacks - 13 times more than previous work. Furthermore, we enumerate uncover 4.25 M IPv4 and 103 K IPv6 vulnerable closed resolvers that could only be detected thanks to our spoofing technique, and that pose a significant threat when combined with the NXNSAttack.Comment: arXiv admin note: substantial text overlap with arXiv:2002.0044

Don't Forget to Lock the Front Door! Inferring the Deployment of Source Address Validation of Inbound Traffic

This paper concerns the problem of the absence of ingress filtering at the network edge, one of the main causes of important network security issues. Numerous network operators do not deploy the best current practice - Source Address Validation (SAV) that aims at mitigating these issues. We perform the first Internet-wide active measurement study to enumerate networks not filtering incoming packets by their source address. The measurement method consists of identifying closed and open DNS resolvers handling requests coming from the outside of the network with the source address from the range assigned inside the network under the test. The proposed method provides the most complete picture of the inbound SAV deployment state at network providers. We reveal that 32 673 Autonomous Systems (ASes) and 197 641 Border Gateway Protocol (BGP) prefixes are vulnerable to spoofing of inbound traffic. Finally, using the data from the Spoofer project and performing an open resolver scan, we compare the filtering policies in both directions

Design and implementation of InBlock, a distributed IP address registration system

The current mechanism to secure Border Gateway Protocol relies on the resource public key infrastructure (RPKI) for route origin authorization. The RPKI implements a hierarchical model that intrinsically makes lower layers in the hierarchy susceptible to errors and abuses from entities placed in higher layers. In this article, we present InBlock, a distributed autonomous organization that provides decentralized management of IP addresses based on blockchain, embedding an alternative trust model to the hierarchical one currently implemented by the RPKI. By leveraging on blockchain technology, InBlock requires consensus among the involved parties to change existent prefix allocation information. InBlock also fulfills the same objectives as the current IP address allocation system, i.e., uniqueness, fairness, conservation, aggregation, registration, and minimized overhead. InBlock is implemented as a set of blockchain smart contracts in Ethereum, performing all the functions needed for the management of a global pool of addresses without human intervention. Any entity may request an allocation of addresses to the InBlock registry by solely performing a (crypto) currency transfer to the InBlock. We describe our InBlock implementation and we perform several experiments to show that it enables fast address registering and incurs in very low management costs.Publicad

BGP-Multipath Routing in the Internet

BGP-Multipath, or BGP-M, is a routing technique for balancing traffic load in the Internet. It enables a Border Gateway Protocol (BGP) border router to install multiple ‘equally-good’ paths to a destination prefix. While other multipath routing techniques are deployed at internal routers, BGP-M is deployed at border routers where traffic is shared on multiple border links between Autonomous Systems (ASes). Although there are a considerable number of research efforts on multipath routing, there is so far no dedicated measurement or study on BGP-M in the literature. This thesis presents the first systematic study on BGP-M. I proposed a novel approach to inferring the deployment of BGP-M by querying Looking Glass (LG) servers. I conducted a detailed investigation on the deployment of BGP-M in the Internet. I also analysed BGP-M’s routing properties based on traceroute measurements using RIPE Atlas probes. My research has revealed that BGP-M has already been used in the Internet. In particular, Hurricane Electric (AS6939), a Tier-1 network operator, has deployed BGP-M at border routers across its global network to hundreds of its neighbour ASes on both IPv4 and IPv6 Internet. My research has provided the state-of-the-art knowledge and insights in the deployment, configuration and operation of BGP-M. The data, methods and analysis introduced in this thesis can be immensely valuable to researchers, network operators and regulators who are interested in improving the performance and security of Internet routing. This work has raised awareness of BGP-M and may promote more deployment of BGP-M in future because BGP-M not only provides all benefits of multipath routing but also has distinct advantages in terms of flexibility, compatibility and transparency

Systems for characterizing Internet routing

2018 Spring.Includes bibliographical references.Today the Internet plays a critical role in our lives; we rely on it for communication, business, and more recently, smart home operations. Users expect high performance and availability of the Internet. To meet such high demands, all Internet components including routing must operate at peak efficiency. However, events that hamper the routing system over the Internet are very common, causing millions of dollars of financial loss, traffic exposed to attacks, or even loss of national connectivity. Moreover, there is sparse real-time detection and reporting of such events for the public. A key challenge in addressing such issues is lack of methodology to study, evaluate and characterize Internet connectivity. While many networks operating autonomously have made the Internet robust, the complexity in understanding how users interconnect, interact and retrieve content has also increased. Characterizing how data is routed, measuring dependency on external networks, and fast outage detection has become very necessary using public measurement infrastructures and data sources. From a regulatory standpoint, there is an immediate need for systems to detect and report routing events where a content provider's routing policies may run afoul of state policies. In this dissertation, we design, build and evaluate systems that leverage existing infrastructure and report routing events in near-real time. In particular, we focus on geographic routing anomalies i.e., detours, routing failure i.e., outages, and measuring structural changes in routing policies

Optimal route reflection topology design

An Autonomous System (AS) is a group of Internet Protocol-based networks with a single and clearly defined external routing policy, usually under single ownership, trust or administrative control. The AS represents a connected group of one or more blocks of IP addresses, called IP prefixes, that have been assigned to that organization and provides a single routing policy to systems outside the AS. The Internet is composed of the interconnection of several thousands of ASes, which use the Border Gateway Protocol (BGP) to exchange network prefixes (aggregations of IP addresses) reachability advertisements. BGP advertisements (or updates) are sent over BGP sessions administratively set between pairs of routers. BGP is a path vector routing protocol and is used to span different ASes. A path vector protocol defines a route as a pairing between a destination and the attributes of the path to that destination. Interior Border Gateway Protocol (iBGP) refers to the BGP neighbor relationship within the same AS. When BGP neighbor relationship are formed between two peers belonging to different AS are called Exterior Border Gateway Protocol (eBGP). In the last case, BGP routers are called Autonomous System Border Routers (ASBRs), while those running only iBGP sessions are referred to as Internal Routers (IRs). Traditional iBGP implementations require a full-mesh of sessions among routers of each AS