Giuseppe Antonio Di Luna

Conscious and Unconscious Counting on Anonymous Dynamic Networks

This paper addresses the problem of counting the size of a network where i processes have the same identifiers anonymous nodes and ii the network topology constantly changes dynamic network. Changes are driven by a powerful adversary that can look at internal process states and add and remove edges in order to contrast the convergence of the algorithm to the correct count. The paper proposes two leader-based counting algorithms. Such algorithms are based on a technique that mimics an energy-transfer between network nodes. The first algorithm assumes that the adversary cannot generate either disconnected network graphs or network graphs where nodes have degree greater than D. In such algorithm, the leader can count the size of the network and detect the counting termination in a finite time i.e., conscious counting algorithm. The second algorithm assumes that the adversary only keeps the network graph connected at any time and we prove that the leader can still converge to a correct count in a finite number of rounds, but it is not conscious when this convergence happens.

Robots with Lights: Overcoming Obstructed Visibility Without Colliding

Robots with lights is a model of autonomous mobile computational entties operating in the plane in Look-Compute-Move cycles: each agent has an externally visible light which can assume colors from a fixed set; the lights are persistent (i.e., the color is not erased at the end of a cycle), but otherwise the agents are oblivious. The investigation of computability in this model is under way, and several results have been recently established. In these investigations, however, an agent is assumed to be capable to see through another agent.

An event-based platform for collaborative threats detection and monitoring

Organizations must protect their information systems from a variety of threats. Usually they employ isolated defenses such as firewalls, intrusion detection and fraud monitoring systems, without cooperating with the external world. Organizations belonging to the same markets (e.g., financial organizations, telco providers) typically suffer from the same cyber crimes. Sharing and correlating information could help them in early detecting those crimes and mitigating the damages. The paper discusses the Semantic Room (SR) abstraction which enables the development of collaborative event-based platforms, on the top of Internet, where data from different information systems are shared, in a controlled manner, and correlated to detect and timely react to coordinated Internet-based security threats (e.g., port scans, botnets) and frauds. In order to show the flexibility of the abstraction, the paper proposes the design, implementation and validation of two SRs: an SR that detects inter-domain port scan attacks and an SR that enables an online fraud monitoring over the Italian territory. In both cases, the SRs use real data traces for demonstrating the effectiveness of the proposed approach. In the first SR, high detection accuracy and small detection delays are achieved whereas in the second, new fraud evidence and investigation instruments are provided to law enforcement agencies.

Collaborative Detection of Coordinated Port Scans

In this paper we analyze the coordinated port scan attack where a single adversary coordinates a Group of Attackers (GoA) in order to obtain information on a set of target networks. Such orchestration aims at avoiding Local Intrusion Detection Systems checks allowing each host of the GoA to send a very few number of probes to hosts of the target network. In order to detect this complex attack we propose a collaborative architecture where each target network deploys local sensors that send alarms to a collaborative layer. This, in turn, correlates this data with the aim of (i) identifying coordinated attacks while (ii) reducing false positive alarms and (iii) correctly separating GoAs that act concurrently on overlapping targets. The soundness of our approach is tested on real network traces. Tests show that collaboration among networks domains is mandatory to achieve accurate detection of coordinated attacks and sharp separation between GoAs that execute concurrent attacks on the same targets.

Counting in Anonymous Dynamic Networks under Worst-Case Adversary

In this paper we investigate the problem of counting the size of a network where processes are anonymous (i.e, they share the same identifier) and the network topology constantly changes controlled by an adversary able to look internal process states and add and remove edges in order to contrast the convergence of the algorithm to the correct count. It is easy to show that, if the adversary can generate graphs without any constraint on the connectivity (i.e. it can generate topologies where there exist nodes not able to influence the others), counting is impossible. In this paper we consider a synchronous round based computation and the dynamicity is governed by a worst-case adversary that generates a sequence of graphs, one for each round, with the only constraint that each graph must be connected (1-interval connectivity property). It has been conjectured that counting in a finite time against such adversary is impossible and the existing solutions consider that each process has some knowledge about network topologies generated by the adversary, i.e. at each round, each node has a degree lesser than D. Along the path of proving the validity (or not) of the conjecture, this paper presents an algorithm that counts in a finite time against the worst-case adversary assuming each process is equipped with an oracle. The latter provides a process at each round r with an estimation of the process degree in the graph generated by the adversary at round r. To the best of our knowledge, this is the first counting algorithm (terminating in a finite time) where processes exploit the minimal knowledge about the behavior of the adversary. Interestingly, such oracle can be implemented in a wide range of real systems.

A collaborative event processing system for protection of critical infrastructures from cyber attacks

We describe an Internet-based collaborative environment that protects geographically dispersed organizations of a critical infrastructure (e.g., financial institutions, telco providers) from coordinated cyber attacks. A specific instance of a collaborative environment for detecting malicious inter-domain port scans is introduced. This instance uses the open source Complex Event Processing (CEP) engine ESPER to correlate massive amounts of network traffic data exhibiting the evidence of those scans. The paper presents two inter-domain SYN port scan detection algorithms we designed, implemented in ESPER, and deployed on the collaborative environment; namely, Rank-based SYN (R-SYN) and Line Fitting. The paper shows the usefulness of the collaboration in terms of detection accuracy. Finally, it shows how Line Fitting can both achieve a higher detection accuracy with a smaller number of participants than R-SYN, and exhibit better detection latencies than R-SYN in the presence of low link bandwidths (i.e., less than 3Mbit/s) connecting the organizations to Esper.

Stereoselectivity in the amination of chiral cyclohex-3-en-1-one ketals

Abstract Optically active cyclohex-3-en-1-one ketals by photolysis of N 3 CO 2 Et or N 3 C(OEt)NMs or by CaO induced α-elimination of NsONHCO 2 Et give diastereomeric aziridines (up to 72% yields, up to 60% d.e.). A simple HPLC separation allows to obtain practically pure aziridines. The conversion of the main product to the ketal of ( R )- N -(ethoxycarbonyl)- β -aminocyclohexanone is also reported and a further oxidation directly gives a derivative of ( R )-2-aminoadipic acid.

Counting in anonymous dynamic networks: An experimental perspective

Counting is a fundamental problem of every distributed system as it represents a basic building block to implement high level abstractions. In anonymous dynamic networks, counting is far from being trivial as nodes have no identity and the knowledge about the network is limited to the local perception of the process itself. Moreover, nodes have to cope with continuous changes of the topology imposed by an external adversary. A relevant example of such kind of networks is represented by wireless sensor networks characterized by the dynamicity of the communication links due to possible collisions or to the presence of duty-cycles aimed at battery preservation. In a companion paper [14], a leader-based algorithms to count the number of processes in an anonymous dynamic network, namely \(\mathcal {A}_{NoK}\), has been proposed. Such algorithm employs a technique that mimics an energy transfer from the anonymous nodes to the leader to converge to an exact count of the number of nodes having no knowledge on the dynamic network. Unfortunately \(\mathcal {A}_{NoK}\) is an unconscious counting algorithm, i.e., the algorithm eventually converges to the exact count but there is no node in the network that is able to detect when this happens. In this paper, we define a new algorithm, called \(\mathcal {A}^*_{NoK}\), by augmenting \(\mathcal {A}_{NoK}\) with a termination heuristic that allows the leader to decide when it should output the current count and we provide an experimental evaluation, for both \(\mathcal {A}_{NoK}\) and \(\mathcal {A}^*_{NoK}\), considering different types of dynamic graphs.

Brief Announcement: Investigating the Cost of Anonymity on Dynamic Networks

In this paper we study the problem of counting processes in a synchronous dynamic network where a distinguished leader is available and other nodes share the same identifier. The network topology may change at each synchronous round and each node communicates with its neighbors by broadcasting messages. In such networks it is well known that counting requires Ω(D) rounds where D is the network diameter. We identify a non-trivial subset of dynamic net- works where counting requires Ω(log |V|) rounds even when the dynamic diameter, D, is constant with respect to the network size and the bandwidth is unlimited.

Oblivious assignment with m slots

Preserving anonymity and privacy of customer actions within a complex software system, such as a cloud computing system, is one of the main issues that must be solved in order to boost private computation outsourcing. In this paper, we propose a coordination paradigm, namely oblivious assignment with m slots of a resource