Forgotten Passwords

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Revision as of 22:44, 12 September 2016 by Rpeters (talk | contribs) (added section re physical security)
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User Passwords

User passwords can be reset as follows:

  1. log in as "root"
  2. switch to user account, eg for user "fred"
  3. # su fred
  4. execute password command to change password for user "fred"

$ passwd

Root Password

Root password can be reset only via booting another Linux on the same computer - either:

  • another installed Linux
  • a utility USB/CD booted on the computer - these generally run from the root account
  1. mount the partition containing the root filesystem of the installation for which password reset is required - eg for /dev/sda10
  2. # mount /dev/sda10 /mnt
  3. change to the mounted partition
  4. # chroot /mnt
  5. execute password command to change password for user "fred"
  6. $ passwd


Physical Security

It will be seen from the above that any password could be changed on a computer to which physical access is obtained. Any unencrypted data could then be retrieved from such computer. It is therefore essential to:

  • prevent unwanted physical access to working computers
  • securely erase SSD/HDD storage on computers sent for disposal
  • physically destroy or securely erase unwanted removable media such as floppies, USB, SD, CD/DVD