Konosuke Kawashima

Controlling File Distribution in the Share Network Through Content Poisoning

Peer-to-Peer (P2P) file sharing applications have dramatically increased in popularity for the past few years. Although a P2P file sharing network shares many files, it does not usually have a management and control mechanism for the files exchanged. Consequently, copyright infringement and malware propagation in P2P file sharing networks have become prevalent. In order to prevent these file distribution, content poisoning has attracted much attention recently. Although content poisoning aims to obfuscate users by diffusing a lot of poisoned chunks in P2P networks, its effect to the networks have not been well studied yet. In this paper, we apply content poisoning to “Share”, one of the most popular P2P file sharing applications in Japan, to control its file distribution. Our evaluation includes how effective our proposed content poisoning method to a live Share network composed of over 100,000 active peers. The evaluation result shows that our content poisoning method decreases the number of peers that complete file download to less than 5% compared to the case without our control. Our content poisoning method also reduces additional traffic required for poisoning to 4%.

A Study on Traffic Characteristics Evaluation for a Pure P2P Application

Peer-to-peer (P2P) file sharing applications are widely used nowadays. In overlay networks, it is mainly music and video files that are transferred, and it is known that the traffic volume is much larger than that of classical client/server applications. However, the nature of current P2P application traffic is not well known because of the anonymous communication architectures used. To solve this problem, we have developed an identification method for pure P2P application traffic, especially for Winny, the most popular pure P2P file sharing application in Japan. Our method relies only on client/server relationships among the peers, without recourse to application header information. With using the method, we give an evaluation of the characteristics of the identified traffic collected in an ISP.

A Cross-Layer Retransmission Control for Improving TCP Performance in Wireless LAN

In this paper we propose a cross-layer retransmission control for TCP communication over a wireless link. With our proposed control, a retransmission delay for lost packet is reduced, packet losses in the wireless link are eliminated and all packets are delivered in the correct order. No change is required to TCP itself or to the sender. Our proposed method is implemented in a queue between the media access control (MAC) layer and logical link layer in a base station, and is designed to assist local retransmission control in the MAC layer. Computer simulations show that our proposed method can maximally use the bandwidth of the wireless link under high bit error rates conditions with conventional TCP control. The fairness problem of TCP communication between connections with different bit error rates in a wireless link is also improved, and MAC level fairness is also controllable.

A queue management method for improving TCP performance in wireless environments

We propose a queue management method for improving TCP performance over a wireless link. With our proposed control method, packet loss in the wireless link is completely eliminated and all packets are delivered in the correct order. No change is required to TCP itself or to the servers. Our proposed method is implemented between the media access control (MAC) layer and logical link layer in a base station, and is designed to help the local retransmission control in the MAC layer. Computer simulation experiments show that our proposed method can maximize the bandwidth use of the wireless link at high bit error rate conditions under conventional TCP controls. The fairness problem of TCP communication between connections with different bit error rate in wireless link is also improved.

A Measurement Study on Peer Behaviors for a Pure P2P Network

Dynamic peer behavior in P2P networks has a large impact on the performance because the peer acts simultaneously as the server and client of an overlay network. However, peer behavior in pure P2P networks is not well known because there is no management system and the size is large. We have proposed a measurement method to efficiently collect information of an entire network for Winny, which is the most popular P2P file sharing application in Japan. Especially, we analyze behaviors of the peer with/without files and identify long life peers in the network. The analysis results show that the network is composed of about 30 % of observed peers in 24 hours, and 50 % of peers contribute to the network as the files uploaders. Selfish peers, which leave the network after downloading, are observed especially in the morning. The file uploading peers and the joining peers after the midnight live long period in the network.