DNS-Based VoIP Device Discovery Bypassing Firewalls
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Solution Overview
Problem
Current methods for detecting Voice-over Internet Protocol (VoIP) devices on a computer network are inefficient, requiring special IP addresses and port configurations, and are often frustrated by firewalls and filters, consuming valuable device resources.
Innovation Solution
The method involves using Domain Name System (DNS) requests to discover VoIP devices on a local area network, filtering and responding to DNS requests to provide local network addresses, and forwarding requests to ensure device detection without requiring specific IP addresses or port configurations, thus bypassing network filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If broadcast and multicast techniques are used for device detection, then device discovery capability is improved, but device complexity and resource consumption increase
Solution Approach 1:
The patent introduces a DNS server as an intermediary to facilitate device discovery. Instead of devices directly broadcasting or multicasting their presence, they register with the DNS server which then provides their addresses on demand. This mediator approach enables versatile device discovery while keeping individual devices simple and resource-efficient.
Solution Approach 2:
The patent creates a virtual copy of the device address book through DNS records. Rather than requiring devices to maintain and exchange complex presence information directly, each device's address information is copied into DNS records on the server, allowing any device to query this centralized copy without direct interaction with the target device.
2Reliability
If firewalls and filters are implemented for security, then network security is improved, but device detection capability deteriorates
Solution Approach 1:
The DNS server acts as a trusted intermediary that sits between devices and the network. Devices query the DNS server for address information rather than directly probing other devices. This intermediary approach maintains security by preventing direct device-to-device scanning while still enabling legitimate device discovery through authorized DNS queries.
Solution Approach 2:
Devices perform self-service by registering their own address information with the DNS server and querying the server themselves for discovery. This eliminates the need for intrusive scanning or probing that would trigger firewalls, as each device independently obtains information through authorized DNS protocol operations that are permitted through security filters.
3Measurement precision
If special IP addresses and port configurations are required for detection, then device detection accuracy is improved, but ease of operation deteriorates
Solution Approach 1:
The patent makes the DNS protocol universal for device discovery purposes. Instead of requiring special detection protocols or configurations, the system uses the existing, universally-supported DNS protocol that all network devices already implement. This multi-functional approach allows DNS to serve both its traditional address resolution function and the additional function of device discovery, eliminating the need for special configurations.
Solution Approach 2:
The patent changes the approach from requiring special address parameters (multicast addresses, special ports) to using standard unicast DNS queries to well-known DNS server addresses. This parameter change simplifies operation because devices use ordinary DNS query parameters rather than specialized detection parameters, making the process as simple as any standard DNS lookup while maintaining accurate device detection.
Data Source
AI summary
A method, apparatus, and system for discovering devices on a local area network. The method comprises sending a DNS request from a host networking element, receiving the DNS request at one or more devices, and responding to the host networking element with one or more DNS responses. The DNS request comprises one or more particular domain names. The one or more DNS responses comprise local network address information for the one or more VoIP devices. The apparatus comprises means for filtering a set of network traffic for a DNS request, means for responding to a DNS request with a local network address, and means for forwarding the DNS request to another device. The system comprises a computer for generating a DNS request for a particular domain, and one or more VoIP devices for receiving the DNS request and sending a DNS response to the computer with a local network address for the VoIP device.