root@nas:~# cat /dev/sdp > cat_tikku.img
root@nas:~# dd if=/dev/sdp of=dd_tikku.img bs=1M
495+1 records in
495+1 records out
519569408 bytes (520 MB, 496 MiB) copied, 15.7777 s, 32.9 MB/s
root@nas:~# sha256sum *.img
19156cc717647811559bbae378897986b72c4fad03bf14dbcc74817704e68e4a cat_tikku.img
19156cc717647811559bbae378897986b72c4fad03bf14dbcc74817704e68e4a dd_tikku.img
root@nas:~# file *.img
cat_tikku.img: DOS/MBR boot sector MS-MBR Windows 7 english at offset 0x163 "Invalid partition table" at offset 0x17b "Error loading operating system" at offset 0x19a "Missing operating system", disk signature 0x57f83bb; partition 1 : ID=0xe, active, start-CHS (0x0,32,33), end-CHS (0x3e,254,63), startsector 2048, 1012736 sectors
dd_tikku.img: DOS/MBR boot sector MS-MBR Windows 7 english at offset 0x163 "Invalid partition table" at offset 0x17b "Error loading operating system" at offset 0x19a "Missing operating system", disk signature 0x57f83bb; partition 1 : ID=0xe, active, start-CHS (0x0,32,33), end-CHS (0x3e,254,63), startsector 2048, 1012736 sectors