## 1 General Background  
Marine network protocols are communication standards that define the rules, syntax, and procedure of synchronization between marine vessels. Seafaring vessel communications have experienced major technological advances within the last century. Early in the twentieth century, radio was implemented to transmit signals in Morse code between vessels. By the 1980s, there were 154 radio operators translating over 20 million words per year [1]. The large demand of manpower and expense for radio communication lead to the increase of satellite broadcasting services by the end of the decade. Companies, such as INMARSAT and COSPAS-SARSAT, have been providing operational communications and safety services for decades with some of the most prominent partners/consumers, such as The U.S. Coast Guard, Boeing, and Comast [2, 3]. Satellite services cover the entire area of communications including voice calling, email and Internet access, navigation and fishing, and tracking vessels. With the variety of services for maritime communication, organizations, such as the National Marine Electronic Association (NMEA), were formed to create a uniform interface standard for digital data exchange between different marine electronic products. NMEA 0183 and NMEA 2000 are the main standards widely accepted by manufacturers and maritime agencies worldwide, and they receive frequent updates, such as NMEA 0183 version 4.11 [4] and NMEA 2000 version 2.000 [5]. However, although much of security research has focused on conventional network protocols (e.g., TCP/IPv6), limited work has been conducted for network marine protocols. Aside from a few security studies [6, 7], there is a lack of risk analysis for these types of protocols. In this communication paper, we highlight the current state of maritime communication and provide an exploratory analysis of security risks. We first highlight the usage and history of marine data transmission. Next, we discuss the requirements for these protocols, such as hardware, software, and manpower. We further identify the mechanisms (built-in or not) used to protect marine network protocols. We introduce our security analysis and identify strengths and weaknesses. The result of this is a classification of security risks associated with each protocol. Finally, we discuss the core challenges and opportunities for marine network protocols. Marine network protocols are often implemented in software, hardware, or a combination of both. Traditional radio communication utilizes hardware, such as VHF Radios, totransfer and receive messages. The biggest use of VHF Radio is to send distress signals to coast guards and other vessels within a certain vicinity. In addition, these can be set up as a full-duplex system, which allows both ends to simultaneously communicate with each other. This enables Marine VHF Radios to double up as a telephonic communicator by making calls through a marine operator. In many situations, a radio officer monitors and keeps track of ship communications. With the introduction of modern technology, radio officers have to work not only with radios but also with computers. For example, merchant marines (a civilian fleet of vessels) have radio officers that transmit regular reports about the weather in the oceanic and sea areas where the ship is positioned. When implementing radios, manufacturers must also consider the area of operation of a particular vessel. The Global Maritime Distress and Safety System (GMDSS) divides the world in four sub areas. Depending on where a ship operates, different systems are required to be carried on that ship [8]. In contrast with radio systems, modern day satellite communications generally require both hardware and software. Hardware is used to generate and receive signals relayed by satellites. Many satellite data services also provide internet access, email, and Voice over IP (VoIP) services, which use an interface software, like a secure website that facilitates user interaction.