NAT Port Detection via Bubble Packets
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Solution Overview
Problem
Existing communication systems face challenges in securely establishing peer-to-peer communications between information processors traversing Network Address Translators (NATs), particularly when combinations of NATs, such as Sa NAT or Sc NAT, are involved, as they require knowledge of port number differentials and the position of the latest port on the receiving side NAT to facilitate communication.
Innovation Solution
A communication system that includes a reference port receiver, bubble packet transmitter, detection packet transmitter, and reply packet receiver to detect and establish the range of ports allowing bubble packets to pass through NATs, enabling secure communication by transmitting bubble packets based on reference port information and detecting the position of the bubble packet transmitting port using port detection packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If peer-to-peer communication is established between information processors traversing NATs, then communication capability is improved, but security and reliability deteriorate due to inability to detect port positions
Solution Approach 1:
The patent applies preliminary action by sending detection packets before establishing peer-to-peer communication to detect the port position on the NAT in advance. The detection packet is transmitted through the NAT to identify which port will be used for the bubble packet, allowing the system to prepare the correct receiving port beforehand. This preliminary detection ensures secure communication setup without compromising reliability.
Solution Approach 2:
The patent uses an intermediary approach by introducing a detection packet as a probe that mediates between the information processor and the NAT. This detection packet acts as a messenger to query the NAT's port assignment behavior without establishing actual communication, enabling the system to gather necessary port information securely before peer-to-peer connection.
2Measurement precision
If port detection packets are transmitted to detect bubble packet transmitting port, then measurement precision is improved, but loss of time increases due to additional detection steps
Solution Approach 1:
The patent applies partial action by sending only one or a few detection packets instead of exhaustively testing all possible ports. The detection packet is sent to a reference port, and based on the NAT's response (whether it returns the packet or assigns a different port), the system infers the port position information. This partial testing approach achieves sufficient measurement precision without excessive time consumption.
Solution Approach 2:
The detection packet transmission is performed as a preliminary step before actual data communication. By detecting the port position in advance through this single detection action, the system avoids time-consuming port scanning during actual communication establishment, thus minimizing time loss while maintaining high measurement precision.
3Reliability
If bubble packets are sent to leave transmission records in NAT, then communication reliability is improved, but device complexity increases due to multiple packet types and detection mechanisms
Solution Approach 1:
The patent segments the communication process into distinct phases: detection packet transmission phase and bubble packet transmission phase. Each phase has a specific purpose - the detection packet phase gathers port information, while the bubble packet phase establishes communication records. This segmentation allows the system to manage complexity by handling one function at a time rather than combining all functions simultaneously.
Solution Approach 2:
The detection packet serves as an intermediary that simplifies the overall system complexity. Instead of requiring complex port scanning or trial-and-error communication establishment, the detection packet mediates the information gathering process, providing clear feedback from the NAT about port assignment. This intermediary mechanism reduces the complexity of establishing reliable peer-to-peer communication through NATs.
Data Source
AI summary
A first information processor (1) transmits a bubble packet to a port assigned after assignment of specified port from reference port in a second communication control unit (4), a server (6) detects the position of the bubble packet transmitting port in a first communication control unit (3) used in transmission of this bubble packet, and a second information processor (2) transmits a reply packet to the detected bubble port transmitting port. In this configuration, the invention presents a communication system capable of establishing more securely communication between plural information processors for communicating by way of communication control unit (NAT). In this configuration, the invention presents a communication system capable of establishing more securely communication between plural information processors for communicating by way of communication control unit (NAT).