Forgotten Passwords

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"
5. $ passwd
6. logout from root account
7. $ exit
8. # exit
9. $

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
7. return to booted environment
8. # exit
9. safely unmount installed system
10. # umount /mnt
11. if running from installed OS, then logout from root account

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