Blocking Google Image Search on the Symantec Web Gateway

book

Article ID: 158813

calendar_today

Updated On:

Products

Web Gateway

Issue/Introduction

You wish to block Google Image search results using the Symantec Web Gateway.

Cause

It is not possible to block embedded images in a Google Image search using an SWG content filtering rule. This is because the images are downloaded directly from Google and not the site itself. As the SWG content filtering engine blocks sites based on a database of known URL’s it has no reason to block this content. However, any attempt to connect to the website serving the images is blocked correctly. This applies to both HTTP and SSL traffic.

Resolution

Google suggest using Google SafeSearch functionality to block inappropriate embedded images from being displayed:

https://support.google.com/websearch/answer/186669?hl=en

Alternatively, the SWG can be configured to block the use of Google Image Search entirely. This requires that google searches be forced to use HTTP and not SSL:

Force Google Search to use HTTP only:

  1. Create a new forward lookup zone in DNS for “www.google.com” and any relevant google country addresses (www.google.co.uk etc.)
  2. In each new google DNS zone, create an A record. Leave the name blank (it will pick up the zone name), and enter IP address 216.239.32.20.

Block Google Image search:

  1. Create a new blacklist entry as follows:
  2. Name: google_image_search
  3. Block type: Block by URL
  4. Domain Name: www.google.com (and any relevant national sites)
  5. Keyword: imghp
  6. Description: Block_image_search
  7. Severity: Minor
  8. Category: Custom Restricted List 1

Block encrypted.google.com:

  1. Create a new blacklist entry as follows:
  2. Name: google_encypted_search
  3. Block type: Block by URL
  4. Domain Name: encrypted.google.com (and any relevant national sites)
  5. Keyword:
  6. Description: Block_encrypted_search
  7. Severity: Minor
  8. Category: Custom Restricted List 1