BYZANTINE ATTACK SIMULATION IN NS 2

In order to simulate most of the Byzantine attacks, we developed a protocol-independent Byzantine attack simulation module for ns2. This module provides the capability to simulate the black hole, Byzantine wormhole, and Byzantine overlay network wormhole attacks without modifying the routing protocol. It was not possible to simulate the flood rushing attack using this technique because it requires timing changes in the routing protocol code. Because this attack simulation module is potentially useful to the secure routing community, we make it publicly available below.

The module is implemented as part of the ns2 Link Layer (LL) object which lies directly below the Routing Agent and directly above the MAC layer. The modified LL has several commands that allow it to be configured from the simulation TCL setup script. The first command enables the black hole attack, which is executed by checking the packet type of any packet sent down by the routing agent, and silently dropping any packet which has an application data type (as opposed to a routing protocol type). The second command is used to setup the various wormhole configurations, and creates a back channel connection from one node to another wormhole peer node. The attack module manages any number of these wormhole peer connections, thus allowing the setup TCL script to create either a simple point to point wormhole or the more complicated overlay network wormhole. As a packet is sent down from the routing protocol, its next hop address is used to determine the correct action. In addition to being sent down to the interface queue for transmission by the MAC, copies of any broadcast packets are sent to every configured wormhole peer. If the next hop address of a unicast packet matches a wormhole peer address, the packet is sent directly to that peer. Otherwise, it is sent down the stack normally.

The module was developed for version 2.27 of ns2. The archive contains a directory with the original ns2 files (orig-ns-2.27) and a directory with the modified files for the attack module (odsbr-ns-2.27).

Related Papers:

[1] Baruch Awerbuch, Reza Curtmola, David Holmer, Cristina Nita-Rotaru and Herbert Rubens. On the Survivability of Routing Protocols in Ad Hoc Wireless Networks. In Proc. of IEEE First International Conference on Security and Privacy for Emerging Areas in Communications Networks (SECURECOMM '05), 2005.

[2] Baruch Awerbuch, Reza Curtmola, David Holmer, Cristina Nita-Rotaru and Herbert Rubens. ODSBR: An On-Demand Secure Byzantine Resilient Routing Protocol for Wireless Ad Hoc Networks. In ACM Transactions on Information and System Security (TISSEC), Volume 10, Issue 4, 2007.

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INTERNET BASED EFFICIENT CONTENT DISTRIBUTION PROTOCOL FOR MANET

Torrent is one of the Internet's most efficient content distribution protocols. It is known to perform very well over the wired Internet where end-to-end performance is almost guaranteed. However, in wireless ad hoc networks many constraints appear as the scarcity of resources and their shared nature, which make running BitTorrent with its default configuration not lead to best performances. To these constraints it adds the fact that peers are both routers and end-users and that TCP-performance drops seriously with the number of hops. We show in this work that the neighbor selection mechanism in BitTorrent plays an important role in determining the performance of the protocol when deployed over a wireless ad hoc network. It is no longer efficient to choose and treat with peers independently of their location. A first solution is to limit the scope of the neighborhood. In this case, TCP connections are fast but there is no more diversity of pieces in the network: pieces propagate in a unique direction from the seed to distant peers. This prohibits peers from reciprocating data and leads to low sharing ratios and sub optimal utilization of network resources. To recover from these impairments, we propose an enhancement to torrent which aims to minimize the time to download the content and at the same time to enforce cooperation among peers. Our solution considers a restricted neighborhood to reduce routing overhead and to improve throughput, while establishing few connections to remote peers to improve diversity of pieces. With the help of extensive NS-2 simulations, we show that these enhancements to Torrent significantly improve the file completion time while fully profiting from the incentives implemented in Torrent to enforce fair sharing.

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