A computação móvel emerge como uma tecnologia inovadora para aárea educacional. Neste trabalho é apresentado um framework para aconstrução de aplicações educacionais em dispositivos móveis com recursosde realidade virtual. Este framework tem como objetivo principal fornecer aodesenvolvedor uma arquitetura consistente para implementação de programasem dispositivos móveis, com foco na aprendizagem. Para validação doframework foi desenvolvido um protótipo que demonstra sua interatividade,usabilidade e portabilidade, além de permitir uma experimentação daintegração das tecnologias de realidade virtual e computação móvel.

Document viewer and browser applications have gained attention in the mobile scenario due to the improvement on accessibility and portability of different kinds of information. However, mobile devices are still limited in relation to memory size, processing capacity and battery. Due to these limitations, software engineers that develop mobile applications must find ways to adequate them to the available. In this paper, we describe a strategy to safely manage memory traffic for mobile applications that intensively use bitmap font files, such as a document viewer.

Denial-of-service (DoS) and distributed denial-of-service (DDoS) are two of the most severe attacks against computer networks, especially the Internet. Despite its destructive effect, planning these attacks is a feasible task. Given that most attackers usually spoof the source address in packet headers, countermeasures can be based on two steps. First of all, some information from the attack space of the offender must be gathered. Fortunately, packets that reach a victim carry important data that can be acquired by means of a data collection process. One possibility is to use the probabilistic packet marking (PPM) approach for data acquisition. Once this is achieved, the next step consists of reconstructing the attack path, which can be carried out by several methods available in the literature. However, none of them provides a precise solution. In this paper, a new theoretical tracking model for the identifi cation of DoS attackers is presented. The model unites the PPM approach and the concept of winding number, derived from the well-known Cauchy's integral theorem. The winding number is a hydraulic analogy of the amount of attacking packets growing from a router. A suitable transformation allows seeing the packet traffi c, in the attack environment, as a fl uid fl ux in the space of complex variables. The method of solving the tracking problem and identifying the sources of attack presents an additional motivation: the use of continuous techniques when approaching a problem that occurs in a discrete environment. Such association will contribute to the development of further solutions possibly more robust than the one dealt with here. This paper shows that the new model can correctly identify the IP address of the router from which the attack comes by using an integral equation derived from the winding number expression. A1 A2 A3 R5 R6 R7 R3 R4 R2 R1 V Figure 1. Topology of the DoS attack environment AN INNOVATIVE APPROACH TO IDENTIFY THE IP ADDRESS IN DoS ATTACKS 341The goal of the injective function Φ is to associate each router R k , of set A, to a complex number of the form z k = x k + i.y k , in U. The elements that constitute the real, R (z k ) = x k , and imaginary, S (z k ) = y k , parts of the complex number z k correspond to Cartesian coordinates. These coordinates can be obtained, for instance, by means of instruments that detect the geographic global positioning (e.g., GPS receptors).On the other hand, once each point in the virtual space corresponds to a router that is represented by an IP address, the injective function Φ : A → U determines actually the (univocal) association of a pair of Cartesian coordinates. In order to fi nd a practical meaning for such an association, it is necessary to represent the injective function Φ by means of some mathematical expression. In the next section, an expression for Φ is presented, among others that could be considered for this task. DEFINITION OF THE FUNCTION Φ342 M. M. VIANA ET AL.a modifi cation on the protocol. Moreover, care must be taken regarding spoo...

In the area of monitoring communication networks, GEDSystem is a tool for supporting the development of programs driven to the management of domains that may show up when networks are monitored by SNMP. This tool is supported by an automatic modeling of data and events and automates the grouping of MIB objects from several SNMP agents, producing data structures that represent Domains and Events. The structures are automatically transformed into Tables and Views of a relational database. The views implement the perception mechanisms of the Events defined in the tool. The GEDSystem also provides a Monitoring Agent that automatically recognizes, collects and stores information about the Domains.