Marine Protocol Guides
Strategic Protocol Intelligence & Security Research
A comprehensive technical guide to legacy and modern maritime communication protocols. Understand the inherent security gaps in NMEA, Modbus, and IEC standards to better implement segmentation and hardening across the vessel's OT infrastructure.
Intelligence Level: Technical
Framework: IEC 61162 / NMEA Standards
NMEA 0183 / IEC 61162-1
Architecture
Serial / Text-based
Common Maritime Usage
GPS, Heading, AIS (Serial), Wind sensors, Depth sounders.
The Security Gap
Plain-text communication with no authentication. Data is transmitted in ASCII sentences ($GP...) that can be spoofed or modified by any device on the serial line.
NMEA 2000 / IEC 61162-3
Architecture
CAN Bus / Binary
Common Maritime Usage
Modern bridge integration, Engine monitoring, Autopilot systems.
The Security Gap
Broadcast-based protocol. There is no source verification (Source Address can be claimed by any device). If one node is compromised, it can flood the bus or spoof PGNs.
Modbus TCP
Architecture
Ethernet / IP
Common Maritime Usage
Ballast control, Power Management Systems (PMS), Cargo pumps, HVAC.
The Security Gap
Designed in 1979. No encryption, no passwords. Any device on the network can issue "Write Single Register" commands to open valves or trip breakers.
Modbus RTU
Architecture
Serial (RS-485)
Common Maritime Usage
Generator controllers, Tank gauging, Battery monitoring.
The Security Gap
Similar to Modbus TCP but relies on physical serial access. Vulnerable to "Man-in-the-Middle" attacks if an attacker gains access to junction boxes or serial-to-ethernet gateways.
AIS (Automatic Identification System)
Architecture
RF / VHF Protocol
Common Maritime Usage
Vessel tracking, Collision avoidance, Search and Rescue (SART).
The Security Gap
Unauthenticated radio broadcast. Vulnerable to "Ghost Ship" injection via Software Defined Radio (SDR). No verification that the ship at the coordinates actually exists.
Bridge/VSAT Terminal
Architecture
Admin Interface / Web
Common Maritime Usage
Primary ship-to-shore connectivity (Cobham, Intellian, Thrane).
The Security Gap
The "Front Door" of the ship. Often left with default admin credentials or unpatched firmware, allowing remote access to the entire OT network from the internet.