6 ms·

Save your Linux machine – Recovering your root password and more

93 points by MartinHeinz 6y ago

battery_cowboy 6y ago
I would guess most folks here use full disk encryption, which would generally preclude you from reading the filesystem if you don't have the password any longer. If not, this is a good article to convince you to do so since anyone could do something similar to your laptop with no encryption.
- chrisMyzel 6y ago
  encryption password ≠ root password , at least not for me :-)
  - organsnyder 6y ago
    The root password is pretty useless by itself if you can't decrypt the data.
    - chrisMyzel 6y ago
      Sure but you might have forgotten your root password and remembered your disk encryption pw
- johnchristopher 6y ago
  I am scared to use full disk encryption or $HOME encryption because of potential loss of speed, hardware failures because of fragmenting or SSD grinding, the inability to use file recovering tools and being locked out if anything goes wrong. I just read changing the password might lock me out if the key is encrypted (or something). Any tips?
  - organsnyder 6y ago
    Speed loss is unnoticeable with any recent hardware (less than a decade old) and typical workloads (even for developers). If concerns about losing data are a roadblock, then you need a good backup strategy. You're already rolling the dice that you'll never have a hardware failure, human error, natural disaster, theft... I can't speak to your SSD wear concern or potential issues during password changes.
  - yrro 6y ago
    Run 'cryptsetup luksHeaderBackup' and store it in a safe place. If you manage to corrupt your LUKS header, you can restore it from the backup. The master encryption key in the LUKS header is still encrypted by your passphrase, so don't use this as an alternative to remembering your passphrase!
  - boring_twenties 6y ago
    There is no loss of speed on any CPU that supports AES instructions, which is pretty much any CPU released after 2010.
sfj 6y ago
False advertising. The title says recovering your root password, but the article only talks about bypassing having to enter one.
- gerdesj 6y ago
  That is how you reset the root password on Linux. If you have physical access to any computer, then you can do what you like. If you need to recover administrator on a Windows box then you go in with a systemrescue CD and edit the SAM database. The choice is yours. You can deploy disc encryption, BIOS passwords etc but be prepared for being locked out.
  - hawaiian 6y ago
    RECOVERING your password usually means retrieving the plaintext representation. Not just "resetting" it.
    - zouhair 6y ago
      It could also mean recovering the access to root, this is just splitting hair anyway.
      - deleted 6y ago
        [deleted]
      - eitland 6y ago
        > It could also mean recovering the access to root, No! Even for me as a non native speaker this is obvious since I have worked in the field for a few years. A car is a vehicle but saying that "a vehicle means a car is wrong". In the same way recovering access to the root account might give you the same effect as recovering the password, but often not. This is a situation were correct wording isn't hard and a situation where it matters in my opinion. People come here to learn and we shouldn't mislead them especially when the cost of fixing it is trivial. If I recover the access to root, fine, I have access to that machine. If I recover the root password I have access to all that the root password gives me access to. On systems where for example home or certain configuration files are encrypted using the password as a key (yes, a bit simplified), this is the difference between getting access to the data or not. > this is just splitting hair anyway. No. This is trying to avoid potentially costly misunderstandings.
spicymaki 6y ago
This is a nice write up. I was not aware of the rd.break option. Very helpful when you have an kernel module that hangs boot trying to configure failing hardware.
bovermyer 6y ago
This is good, but why not just post the original URL? https://martinheinz.dev/blog/22 https://martinheinz.dev/blog/22
technofiend 6y ago
This must be something asked of RedHat support quite a bit because it was covered thoroughly in their UNIX sysadmin training material for Redhat 7 and there's a published solution on their site from years ago. [1] Redhat documentation is pretty decent and access is free via their developer program [2]. The program gives one free bare metal license for a system with up to 8 sockets that can host unlimited VMs. [3] I realize HN is all about open source and free software but for people looking to work in a corporate environment that uses RHEL, Redhat does try to make entry at least possible for those who can self study. [1] https://access.redhat.com/solutions/1192 https://access.redhat.com/solutions/1192 [2] https://developers.redhat.com/ https://developers.redhat.com/ [3] https://developers.redhat.com/articles/faqs-no-cost-red-hat-enterprise-linux/ https://developers.redhat.com/articles/faqs-no-cost-red-hat-...

93 points by MartinHeinz 6y ago

I would guess most folks here use full disk encryption, which would generally preclude you from reading the filesystem if you don't have the password any longer. If not, this is a good article to convince you to do so since anyone could do something similar to your laptop with no encryption.

chrisMyzel 6y ago
encryption password ≠ root password , at least not for me :-)
- organsnyder 6y ago
  The root password is pretty useless by itself if you can't decrypt the data.
  - chrisMyzel 6y ago
    Sure but you might have forgotten your root password and remembered your disk encryption pw
johnchristopher 6y ago
I am scared to use full disk encryption or $HOME encryption because of potential loss of speed, hardware failures because of fragmenting or SSD grinding, the inability to use file recovering tools and being locked out if anything goes wrong. I just read changing the password might lock me out if the key is encrypted (or something). Any tips?
- organsnyder 6y ago
  Speed loss is unnoticeable with any recent hardware (less than a decade old) and typical workloads (even for developers). If concerns about losing data are a roadblock, then you need a good backup strategy. You're already rolling the dice that you'll never have a hardware failure, human error, natural disaster, theft... I can't speak to your SSD wear concern or potential issues during password changes.
- yrro 6y ago
  Run 'cryptsetup luksHeaderBackup' and store it in a safe place. If you manage to corrupt your LUKS header, you can restore it from the backup. The master encryption key in the LUKS header is still encrypted by your passphrase, so don't use this as an alternative to remembering your passphrase!
- boring_twenties 6y ago
  There is no loss of speed on any CPU that supports AES instructions, which is pretty much any CPU released after 2010.

sfj 6y ago

False advertising. The title says recovering your root password, but the article only talks about bypassing having to enter one.

gerdesj 6y ago
That is how you reset the root password on Linux. If you have physical access to any computer, then you can do what you like. If you need to recover administrator on a Windows box then you go in with a systemrescue CD and edit the SAM database. The choice is yours. You can deploy disc encryption, BIOS passwords etc but be prepared for being locked out.
- hawaiian 6y ago
  RECOVERING your password usually means retrieving the plaintext representation. Not just "resetting" it.
  - zouhair 6y ago
    It could also mean recovering the access to root, this is just splitting hair anyway.
    - deleted 6y ago
      [deleted]
    - eitland 6y ago
      > It could also mean recovering the access to root, No! Even for me as a non native speaker this is obvious since I have worked in the field for a few years. A car is a vehicle but saying that "a vehicle means a car is wrong". In the same way recovering access to the root account might give you the same effect as recovering the password, but often not. This is a situation were correct wording isn't hard and a situation where it matters in my opinion. People come here to learn and we shouldn't mislead them especially when the cost of fixing it is trivial. If I recover the access to root, fine, I have access to that machine. If I recover the root password I have access to all that the root password gives me access to. On systems where for example home or certain configuration files are encrypted using the password as a key (yes, a bit simplified), this is the difference between getting access to the data or not. > this is just splitting hair anyway. No. This is trying to avoid potentially costly misunderstandings.

spicymaki 6y ago

This is a nice write up. I was not aware of the rd.break option. Very helpful when you have an kernel module that hangs boot trying to configure failing hardware.

bovermyer 6y ago

This is good, but why not just post the original URL? https://martinheinz.dev/blog/22 https://martinheinz.dev/blog/22

technofiend 6y ago

This must be something asked of RedHat support quite a bit because it was covered thoroughly in their UNIX sysadmin training material for Redhat 7 and there's a published solution on their site from years ago. [1] Redhat documentation is pretty decent and access is free via their developer program [2]. The program gives one free bare metal license for a system with up to 8 sockets that can host unlimited VMs. [3] I realize HN is all about open source and free software but for people looking to work in a corporate environment that uses RHEL, Redhat does try to make entry at least possible for those who can self study. [1] https://access.redhat.com/solutions/1192 https://access.redhat.com/solutions/1192 [2] https://developers.redhat.com/ https://developers.redhat.com/ [3] https://developers.redhat.com/articles/faqs-no-cost-red-hat-enterprise-linux/ https://developers.redhat.com/articles/faqs-no-cost-red-hat-...