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DNS and Web Security

Updated Jan 30, 2024 ·

Domain Name System (DNS)​

The Domain Name System (DNS) is a hierarchical and decentralized naming system used to convert human-readable domain names (like www.google.com) into IP addresses (like 192.0.2.1) that computers use to identify each other on the network.

It functions like a phonebook for the internet, allowing users to access websites using domain names instead of memorizing numerical IP addresses.

For more information, please see Domain Name System (DNS).

DNSSEC​

DNS Security Extensions (DNSSEC) enhance the security of the Domain Name System (DNS) by ensuring the authenticity and integrity of DNS data. It helps protect against attacks like cache poisoning.

  • All DNS zones have certificates.
  • DNSSEC uses digital signatures to authenticate DNS data.
  • It ensures that DNS responses are unaltered and legitimate.
  • Helps prevent cache poisoning by validating DNS responses.
  • Introduces new DNS record types like RRSIG, DNSKEY, and DS.
  • Establishes a chain of trust from the DNS root zone to individual domains.
  • Increases the overall security and trustworthiness of the internet's DNS infrastructure.

DNS Filtering​

DNS filtering controls internet content access by blocking domains at the DNS resolution level, preventing users from accessing harmful or inappropriate websites.

  • Blocks access to known harmful websites before the connection is established.
  • Reduces the load on network resources by stopping threats early in the DNS resolution process.
  • Can be configured to block access to categories of sites, such as social media or gambling.
  • Provides a broad security layer by integrating with other security measures to protect users.

Web Filtering​

Web filtering involves controlling the content that users can access on the internet through an organization's network. This process is crucial for protecting users from harmful websites and maintaining productivity by blocking access to non-work-related content.

  • Blocks access to malicious and unsafe websites.
  • Prevents access to inappropriate or non-compliant content.
  • Helps enforce company policies and legal requirements.
  • Can be configured to allow or restrict access based on categories, keywords, or specific URLs.
  • Monitors user activity to provide insights and reporting on web usage.

Types:

  • Agent-Based Web Filtering
  • Centralized Proxies
  • URL Scanning
  • Content Categorization
  • Block Rules
  • Reputation-Based Filtering

Agent-Based Web Filtering​

Agent-based web filtering uses software agents installed on client devices to enforce web content policies directly on the user's computer.

  • Provides direct control over user activities on the device.
  • Particularly effective for organizations with remote or mobile workers.
  • Allows for personalized filtering settings based on user or group profiles.
  • Can block content at the endpoint level, reducing reliance on network-level controls.

Centralized Proxies​

Centralized proxies route all network requests through a single proxy server, where web content is filtered and monitored.

  • Centralizes control of internet access and content filtering.
  • Reduces the load on client devices by offloading filtering to the proxy server.
  • Enables consistent policy enforcement across all devices in the network.
  • If request does not conform with the policies, the request is blocked or denied.

URL Scanning​

URL scanning involves inspecting the URLs accessed by users to determine if they are safe or harmful.

  • Helps detect malicious websites before they can be accessed.
  • Requested URL is checked against a database of known malicious websites.
  • If URL is not found in the database, it is assumed safe to access.
  • Integrates with other security systems for comprehensive protection.

Content Categorization​

Content categorization involves classifying web content into categories to facilitate filtering based on predefined rules.

  • Simplifies the management of web content policies.
  • Allows for more granular control over internet usage by category.
  • Helps in compliance with industry standards and regulations.

Block Rules​

Block rules define specific criteria or conditions under which web access is restricted or blocked.

  • Enables precise control over which websites or content types are accessible.
  • Helps enforce company policies and prevent access to harmful or non-compliant content.
  • Can be customized based on organizational needs.

Reputation-Based Filtering​

Reputation-based filtering assesses the trustworthiness of websites based on their history and feedback from a global network of users. It also uses reputation score, which is typically determined by a third-party service.

  • Provides dynamic protection against emerging threats.
  • Utilizes global databases of known good and bad sites to filter content.
  • Enhances security by blocking access to potentially harmful sites in real-time.