Biblio

Underwater Acoustic Networks (UANs) have long been recognized as an instrumental technology in various fields, from ocean monitoring to defense settings. Their security, though, has been scarcely investigated despite the strategic areas involved and the intrinsic vulnerability due to the broadcast nature of the wireless medium. In this work, we focus on attacks for which the attacker has partial or total knowledge of the network protocol stack. Our strategy uses a watchdog layer that allows upper layers to gather knowledge of overheard packets. In addition, a reputation system that is able to label nodes as trustful or suspicious is analyzed and evaluated via simulations. The proposed security mechanism has been implemented in the DESERT Underwater framework and a simulation study is conducted to validate the effectiveness of the proposed solution against resource exhaustion and sinkhole attacks.

Underwater acoustic communications experiments often involve custom implementations of schemes and protocols for the physical and data link layers. However, most commercial modems focus on providing reliable or optimized communication links, rather than on allowing low-level reconfiguration or reprogramming of modulation and coding schemes. As a result, the physical layer is typically provided as a closed, non-reprogrammable black box, accessible by the user only through a specific interface. While software-defined modems would be the ultimate solution to overcome this issue, having access to the symbols transmitted by the modems using a proprietary modulation format already opens up a number of research opportunities, e.g., aimed at the cross-layer design and optimization of channel coding schemes and communication protocols. In this paper, we take the latter approach. We consider the commercial EvoLogics modem, driven by a custom firmware version that bypasses the channel coding methods applied by the modem, and allows the user to set the transmit bit rate to any desired value within a given set. This makes it possible to evaluate different coding schemes in the presence of different bit rates. Our results show that the custom firmware offers sufficient flexibility to test different configurations of the coding schemes and bit rates, by providing direct access both to correctly decoded and to corrupted symbols, which can be separated at the receiver for further processing. In addition, we show that the DESERT Underwater framework can also leverage the same flexibility by employing low-level physical layer access in more complex networking experiments.