Blocking by file extension

Steps

  1. On the File Blocking tab, click Add Extensions.
  2. Enter the extension you wish to block. You can enter groups of extensions, separated by commas.
    Note: If you include the period in the extension (for example, .jpg) it will be removed. Wildcards are not supported.
  3. Set the file blocking Rule State to Enabled.
  4. To configure blocking by file size:
    1. Under Blocking Options, select Block all files over... KB.
    2. Define whether you want to block all files with this extension over a particular size that you enter or block files with this extension over a particular size but only in specific categories. You also have the option to block files in specific categories without regard to size.
  5. To block files in specific categories:
    1. Select Category specific blocking.
    2. Optionally, to block files by size, select Block files in certain categories over... KB, then fill in the size in kilobytes.

      Only files of the selected type that are over this size will be blocked in the categories you choose.

      Note: Blocking by file size is not available for web traffic that has been handled by an appliance.
    3. By default, files with the selected extensions are blocked for all categories. To change this, use the category and action lists.

      You can select a category directly from the list, or enter text in the search box to locate the category you want. Click on the plus sign to the left of each category to view subcategories to which you can also apply blocking actions. If the parent and subcategory actions differ, an asterisk appears next to the parent category.

      To select multiple categories, use the Shift and/or Ctrl keys. You can also use the drop-down menu above the category list to select all Web 2.0 categories or privacy categories, or to select or deselect all categories.

  6. Optionally, enter or select the users and groups to whom the file blocking applies. You can also specify that the file blocking applies to all users and groups in the policy except the group you select.
  7. Select the block page that will be displayed when this file extension is detected and blocked.
  8. Click Save.
    Important: Archived/compressed files are inspected for malware but are not extracted to determine if the contents contain a file that should be blocked based on file extension. Archived and compressed files can be blocked, if needed, and access to all files contained in those archived files is blocked.