Cloud Proxy PAC File Client Identification via NAT
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Solution Overview
Problem
Cloud-hosted proxies struggle to identify and manage client devices within private networks due to network address translation (NAT) hiding internal IP addresses, and existing proxy auto-configuration (PAC) methods are limited in scalability and customization, making it inefficient to control domain access and enforce policies.
Innovation Solution
A system that dynamically generates a PAC file embedding the client's private network identifier in the proxy hostname, allowing clients to query a PAC lookup service for proxy usage instructions, and uses encryption to secure the client identifier, enabling the cloud-hosted proxy to accurately attribute and authenticate client requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cloud-hosted proxy is used to protect private networks, then the proxy can be deployed flexibly and scaled easily, but the proxy cannot capture client IP addresses due to NAT hiding internal IP addresses
Solution Approach 1:
The system performs preliminary actions by embedding the client's private network identifier into the PAC file before the client makes requests. This identifier is inserted into the proxy hostname in advance, so when the cloud-hosted proxy receives requests, it can extract and identify the client without needing to capture IP addresses that are hidden by NAT. This resolves the contradiction by preparing the identification data beforehand, enabling both cloud deployment flexibility and accurate client identification.
Solution Approach 2:
The PAC file acts as an intermediary that carries the client's private network identifier from the client to the cloud-hosted proxy. Instead of relying on direct IP address transmission (which is blocked by NAT), the identifier is embedded in the PAC file that the client downloads and uses to configure proxy connections. This intermediary mechanism enables accurate client identification while maintaining the cloud-hosted proxy's deployment flexibility.
2Ease of operation
If traditional PAC files are used for proxy auto-configuration, then clients can be directed to use or bypass the proxy, but the system lacks scalability and customization for dynamic policy application
Solution Approach 1:
The system transforms static PAC files into dynamic configurations by embedding the client's private network identifier and enabling the proxy hostname to change based on the client identity. The PAC file now contains dynamic elements that allow the system to apply different policies to different clients dynamically, while maintaining the simplicity of automatic configuration. Clients continue to download and apply PAC files automatically, but the content is now customized and dynamic rather than static.
Solution Approach 2:
The system applies local quality by customizing the PAC file content for each specific client based on their private network identifier. Each client receives a PAC file tailored to their identity and access requirements, enabling localized policy application. This allows different clients to have different proxy configurations and policy applications while maintaining the overall simplicity of the auto-configuration mechanism.
3Measurement precision
If client identifiers are embedded in proxy hostnames for identification, then the proxy can attribute requests to specific clients, but the client identifier may be exposed in clear text over the network
Solution Approach 1:
The system applies color changes by encrypting the client's private network identifier before embedding it in the proxy hostname. The identifier is transformed from visible clear text into an encrypted form that appears as random data. This allows the proxy to accurately attribute requests to specific clients through decryption, while the encrypted identifier remains secure even if transmitted over the network in clear text portions of the hostname.
Data Source
AI summary
Among other things, this document describes systems, methods and devices for providing a cloud proxy auto-config (PAC) function for clients connected to a private network, such as an enterprise network. The teachings hereof are of particular use with cloud hosted proxy services provided by server deployments outside of the private network (e.g., external to the enterprise or other organizational network). This document also describes systems, methods and devices for providing a proxy auto-config (PAC) function for clients connected to a third party network, such as when the client moves outside of the enterprise network.