Hostname-Based Firewall Policy Configuration via DNS Interception
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Solution Overview
Problem
Current firewall systems do not effectively support configuration of firewall policies using hostnames, leading to issues such as stale IP address mappings and blocked connections due to the lack of hostname-based configuration and IP address updates, especially in environments with load balancing and dynamic DNS resolutions.
Innovation Solution
A computer-implemented method and system that utilizes a hostname-based access configuration system (HNACS) to define and implement firewall policies referencing hostnames by intercepting DNS queries, resolving hostname to IP address mappings, and storing these mappings with time-to-live values in a local cache, ensuring accurate and dynamic IP address updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If firewall policies are configured using IP addresses, then the firewall can effectively filter network traffic, but the policies become difficult to maintain when IP addresses change or are assigned dynamically
Solution Approach 1:
The system performs preliminary DNS resolution to obtain IP addresses before applying firewall rules. By resolving hostnames to IP addresses in advance and caching the mappings, the firewall can be configured with hostnames while maintaining IP-based filtering capability, thus improving ease of operation without compromising connection reliability
Solution Approach 2:
The patent introduces a hostname-to-IP-address mapping mechanism as an intermediary between the hostname-based configuration and the IP-based firewall filtering. This mapping layer allows users to configure policies using human-readable hostnames while the underlying firewall continues to use IP addresses for actual packet filtering, resolving the contradiction between configuration ease and connection stability
2Ease of manufacture
If the firewall resolves hostname to IP address immediately at the time of applying the firewall rule, then the configuration is simple, but the IP address may become stale and block connections when DNS resolution changes
Solution Approach 1:
The system implements dynamic IP address updates by periodically re-resolving hostnames to IP addresses and updating the firewall rules accordingly. Instead of using static IP addresses captured at configuration time, the firewall dynamically refreshes its IP address mappings, ensuring that hostname-based policies remain effective even when DNS records change, thus maintaining both configuration simplicity and connection reliability
Solution Approach 2:
The patent implements a feedback mechanism where the system monitors DNS resolution results and automatically updates firewall rules when IP addresses change. By continuously checking for updated IP addresses associated with configured hostnames and refreshing the firewall rules, the system ensures that the firewall remains synchronized with current DNS information, preventing connection blocks due to stale IP addresses
3Device complexity
If the firewall does not track the expiry time of IP address mappings, then the configuration management is simpler, but connections are blocked when DNS mappings expire or change
Solution Approach 1:
The system implements periodic expiration checking of IP address mappings by associating each mapped IP address with an expiry time based on DNS TTL (Time To Live) values. The firewall periodically checks whether cached IP addresses have expired and automatically refreshes or removes expired mappings, ensuring that hostname-based firewall rules continue to resolve to valid IP addresses without requiring complex real-time tracking mechanisms
Data Source
AI summary
A hostname based access configuration system (HNACS) is provided for configuring a host-based firewall to implement firewall policies referencing hostnames. The HNACS defines a hostname based firewall policy (HNFP) referencing a host server using a corresponding hostname instead of an internet protocol (IP) address. The HNACS incorporates the HNFP onto the host-based firewall but renders the HNFP non-implementable on the computing device until a domain name system (DNS) query is generated. If the DNS query includes the hostname in the HNFP, the HNACS determines a mapping between the hostname specified in the DNS query and an IP address corresponding to the hostname (obtained via a DNS response corresponding to the DNS query). Based on the mapping, the HNFP is transformed via an implicit replacement of the hostname in the HNFP with the IP address of the host server, thereby rendering the HNFP executable on the host-based firewall.