Device Identification Behind NATs Using Packet Header Analysis
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Solution Overview
Problem
Network address translators (NATs) obscure device identities and communication patterns, making it difficult to monitor and differentiate communication from multiple devices using various networks, especially when they employ multiple NATs and networks simultaneously.
Innovation Solution
A system and method that aggregates packets from devices using network interface and processor, identifying unique device identifiers and device-usage characteristics to group packets into aggregations that correspond one-to-one with devices, even across multiple networks and NATs, using fields like TCP timestamps and IPIDs, and applying machine-learned models to compute expected offset ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Network Address Translators (NATs) are used to translate multiple private IP addresses to a single public IP address, then network address conservation is improved and security is enhanced, but device identification and communication pattern monitoring deteriorate
Solution Approach 1:
The patent segments the identification problem into multiple independent fields within packet headers (TCP timestamps, IP IDs, packet lengths, inter-arrival times). By analyzing each field separately and combining the results, the system can identify devices behind NAT without requiring additional public IP addresses.
Solution Approach 2:
The patent moves from traditional single-field identification (source IP address) to multi-dimensional identification by incorporating temporal dimensions (timestamps, inter-arrival times) and structural dimensions (packet lengths, header fields). This dimensional expansion enables device differentiation despite IP address masking.
2Reliability
If multiple NATs are deployed across different networks to enhance security and network management, then network security and flexibility are improved, but the ability to track device communication patterns across networks deteriorates
Solution Approach 1:
The patent creates a universal identification mechanism that works across multiple NATs and networks by using fields present in all standard packet headers (TCP timestamps, IP IDs). This multi-functional approach allows the same identification technique to track devices regardless of which NAT or network they pass through.
Solution Approach 2:
The system continuously monitors and analyzes packet characteristics, using feedback from observed patterns to refine device identification. By tracking temporal patterns and packet structures across multiple NATs, the system adapts to maintain accurate device identification even as networks and NAT configurations change.
3Measurement precision
If packet header fields such as TCP timestamps and IP IDs are analyzed to identify devices behind NAT, then device identification accuracy is improved, but processing complexity and computational requirements increase
Solution Approach 1:
The patent applies partial action by focusing on the most discriminative packet fields (prioritizing TCP timestamps and IP IDs) rather than analyzing every possible header field. This selective approach maintains high identification accuracy while reducing processing complexity compared to exhaustive analysis.
4Ease of manufacture
If traditional monitoring methods relying on application-layer information are used, then implementation simplicity is maintained, but effectiveness deteriorates due to encryption and NAT obfuscation
Solution Approach 1:
The patent extracts identification information from the network layer and transport layer (packet headers containing TCP timestamps, IP IDs) rather than relying on application-layer information. This extraction from lower layers bypasses encryption and NAT obfuscation that affect application data, maintaining both simplicity and effectiveness.
Data Source
AI summary
An apparatus for monitoring a plurality of devices that use a plurality of networks includes a network interface and a processor. The processor is configured to receive, via the network interface, a plurality of packets that were collectively communicated, from the devices, via all of the networks, to aggregate the packets, using at least one field that is included in respective packet headers of the packets, into a plurality of packet aggregations, such that all of the packets in each one of the packet aggregations were collectively communicated from no more than one of the devices, to group the packet aggregations into a plurality of groups, such that there is a one-to-one correspondence between the groups and the devices, in that all of the packets in each of the groups were collectively communicated from a different respective one of the devices, and to generate an output in response thereto.