DD file is a disk image file and replica of a hard disk drive. The file having extension .dd is usually created with an imaging tool called DD. The utility provides command line interface to create disk images in a system running UNIX & LINUX OS.

• DD file, sometimes referred as forensic dd image, is often used to investigate Linux hard disk data in Windows OS.
• In Linux, DD utility uses the following command to create a dd image file:
  • dd if=/dev/hdr of=mydisk.dd
    • if is an input file
    • /dev/hdr is a physical disk of linux
    • of is an output file
    • mydisk.dd is a name of the destination file
      
  • dd if=/dev/hdr of=mydisk.dd bs=64836 conv=noerror,sync
    • bs is block size
    • conv=noerror parameter makes the command continue to run even if any read error occurs from source drive.
    • sync If error occurs then null fill the rest of the block
• In Windows, DD utility uses the following command to create a dd disk image:
  • dd.exe if=\\.\PhysicalDrive0 of=d:\images\PhysicalDrive0.dd
    • This cmd will create a duplicate copy of a source drive

DD File can be opened using command line of following operating system

• Linux
• Microsoft Windows