A denial of service attacks are usually employed to interrupt the system's activity by getting a large number of fake requests, which leads to slowing down and stopping information system or network operations. This paper outlines the basic principles of DDoS attacks, explains how DDoS attack works. The paper presents an experimental using OPNET simulation tool in which traffic from three different applications VoIP, FTP, and HTTP is used to make the practical model with a firewall shield to model and simulate DDoS over Internet. However, three scenarios have been developed to illustrate different aspects of the DDoS over networks. The results clearly demonstrate how firewalls can be configured to mitigate DDoS attacks
Azeddien M. Sllame, Reema A. Saed, Mariam Abojella Msaad(5-2021)

DLFSR is promising for enhancing the security of stream ciphers. However, good inviolability and statistical properties of the DLFSR generator are only achievable when the parameters of the switching algorithm are properly selected. This paper describes a new experimental method for choosing suitable parameters for the algorithm of switching the polynomial in DLFSR. This method was used to enhance the Grain-128 stream cipher. The randomness of the modified Grain was evaluated using the NIST suite, and the results are encouraging. The modified Grain was also compared to the original, and the results indicated that the modified algorithm outperforms the original in several tests. arabic 12 English 82
Fayrouz Aljadi, Ibrahim Almerhag, Fardous Eljadi(3-2019)

This paper is presenting a discrete-event simulator written in C++ for modeling and simulating Fat tree network-on-chip systems based on MPLS technique. The simulator contains main component that construct butterfly Fat tree structure and other components that generate suitable number of switches and IP nodes (cores). The designed switch consists of input ports, output ports, input/output link controller, multi-buffers, crossbar switch, routing and arbitration components and MPLS unit. The correctness and the efficiency of the MPLS based Fat network-on-chip system is measured against well-known wormhole+ virtual channels technique. The produced results are clearly demonstrated the efficiency of the MPLS technique for future NoC designs. arabic 45 English 189
Azeddien M. Sllame, Nagwa Abobaker Salama(2-2018)