Difference between revisions of "Forgotten Passwords"

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(added section re physical security)
Line 6: Line 6:
 
#<nowiki># su fred</nowiki>
 
#<nowiki># su fred</nowiki>
 
#execute password command to change password for user "fred"
 
#execute password command to change password for user "fred"
<nowiki>$ passwd</nowiki>
+
#<nowiki>$ passwd</nowiki>
  +
#'''logout''' from root account
  +
#<nowiki>$ exit</nowiki>
  +
#<nowiki># exit</nowiki>
  +
#<nowiki>$</nowiki>
   
 
== Root Password ==
 
== Root Password ==

Revision as of 09:47, 13 September 2016

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


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