## 4 Risk Analysis for Current Protocols  
There are several marine network protocols in use today that are used in commercial and civilian marine vessels. These include several specialized protocols, as well as generic communication protocols. For the purposes of an examination of the most relevant protocols in use today, we have also obtained the draft of the latest protocol (OneNet) that has been sent by NMEA to manufacturers for the development of the new generation of devices. Additionally, we have included the conventional TCP/IPv6 protocol standard in order to better contrast some of the similarities and differences between conventional and marine network protocols. We itemize a summary of the protocols described below:  
* TCP/IPv6: For data transmission via Internet.
* Controller Area Network (CAN) Bus/NMEA 2000: For vehicular and marine data transmission.
* NMEA 0183: For marine data transmission.
* Automated Identification System (AIS): For marine data transmission.
* NMEA OneNet: For marine data transmission.  
The list does not include some layer 2 and layer 3 protocols that have been implemented as communication technologies used for automation, such as autonomous navigation, collision avoidance, and early warning. Other protocol examples include 4G, ANT, and Bluetooth. 4G was not originally designed to be used in the maritime industry, but it can be used on boats. It is most commonly paired with a signal booster to make longer range calls. ANT has been used by Garmin in their GNX\({}^{\text{TM}}\) Wireless Wind Pack. Ant is designed and marketed by ANT wireless which is owned by Garmin [19]. Similar to ANT,Bluetooth is used for low power communication with a short range. Even though Bluetooth is not designed specifically for the maritime industry, it is used on boats (e.g., wireless speakers). Protocols that were not included in the study were omitted for either being too ubiquitous (i.e., they were used in a broader array of settings) or their use was limited.  
While these protocols continue to evolve, some are more vulnerable to attacks. We performed a theoretical analysis that contrasts these protocols against common attacks to demonstrate the current security state of these communication protocols. Our goal was to find deficiencies in the protocols that will allow for an attacker to exploit them. For example, protocols that lack authentication could be potentially vulnerability to spoofing attacks. The list of attacks are not meant to be comprehensive but rather representative of the most serious offenses that can be performed in such networks. As such, these attacks formed the basis of our research inquiry. Attacks include:  
* Denial of Service (DoS): Targets the availability of data.
* Spoofing: Targets the integrity of data.
* Packet sniffing: Targets the confidentiality of data.
* Replay/Man-in-the-Middle (MITM): Targets both confidentiality and integrity of data.  
Table 2 summarizes how each protocols hold up against these attacks. The values within each cell represent our own estimate based on our analysis of these protocols and their corresponding security risks. The relative scale (low, medium, and high) is used in order to highlight the differences between these protocols in a easily readable form and similar to other studies that analyzed similar protocols (e.g., Reference [20]). We further present our security analysis for these protocols and elaborate more on the table in the following subsections.