SonicOS 7.0 Rules and Policies for Classic Mode

Hex Editor

You can use a hexadecimal (hex) editor to view the hex representation of a file or a graphic image. One such hex editor is XVI32, developed by Christian Maas and available at no cost at the following URL:

http://www.chmaas.handshake.de/delphi/freeware/xvi32/xvi32.htm

For example, if there is a certain graphic contained within all confidential company documents, you could use the hex editor to obtain a unique identifier for the graphic, and then use the identifying hex string to create a match object. You could reference the match object in a policy that blocks the transfer of files with content matching that graphic.

To create a match object for a graphic using the SonicWall graphic as an example

  1. Start XVI32 and click File > Open to open the graphic image GIF file.

  2. In the left pane, mark the first 50 hex character block by selecting Edit > Block <n> chars… and then select the decimal option and type 50 in the space provided. This will mark the first 50 characters in the file, which is sufficient to generate a unique thumbprint for use in a custom match object.

    Alternatively you can mark the block by using the following sequence:

    • Click on the first character (#0).
    • Press Ctrl+B.
    • Click on the character in position #49.
    • Press Ctrl+B.

    To locate the character in position #49, click on a character in the right pane (the text pane) and then look at the bottom left corner for the decimal address. Try different characters until it shows Adr. dec: 49.

    You must click on the corresponding location in the left pane before you press Ctrl+B to mark the block.

    When the block is marked, it changes to red font. To unmark a block of characters, press Ctrl+U.

  3. After you mark the block, click Edit > Clipboard > Copy As Hex String.

  4. In a multi-featured text editor, press Ctrl+V to paste the selection and then press Enter to end the line.

    This intermediary step is necessary to allow you to remove spaces from the hex string.

  5. In the text editor, click Search > Replace to bring up the Replace dialog box. In the Replace dialog box, type a space into the Find text box and leave the Replace text box empty. Click Replace All.

    The hex string now has 50 hex characters with no spaces between them.

  6. Double-click the hex string to select it, then press Ctrl+C to copy it to the clipboard.

  7. In the SonicOS user interface, navigate to Objects > Match Objects and click Add Match Object.

  8. In the Match Object Settings dialog, type a descriptive name into the Object Name field.

  9. In the Match Object Type drop-down menu, select Custom Object.

  10. For Input Representation, click Hexadecimal.

  11. In the Content field, press Ctrl+V to paste the contents of the clipboard.

  12. Click Add.

  13. Click OK.

    You now have a Match Object containing a unique identifier for the image. You can create an App Rules policy to block or log traffic that contains the image matched by this Match Object. For information about creating a policy, see Configuring an App Rules Policy.

Was This Article Helpful?

Help us to improve our support portal

Techdocs Article Helpful form

  • Hidden
  • Hidden

Techdocs Article NOT Helpful form

  • Still can't find what you're looking for? Try our knowledge base or ask our community for more help.
  • Hidden
  • Hidden