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I'm using an Alestic image which disables root SSH logins, but provides a user "ubuntu" with NOPASSWD sudo privileges. See here.

In the course of trying to add a new user to the sudoers file I inadvertantly created another line for the "ubuntu" user, this time without NOPASSWD. I have now apparently lost root access to this machine.

Is there some way to mount the EBS root volume on a different instance (fixing the sudoers file) and then re-launch the server?

Or am I totally screwed?

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2 Answers 2

up vote 5 down vote accepted

You can mount the EBS volume to another instance.

  1. Set the problematic instance to "Stop"
  2. Identify the EBS volume mounted to the problematic instance via the instance-id it should be listed like any other EBS volume on the web console.
  3. Detach the drive and mount it to a working instance
  4. Modify it
  5. Detach it from the working instance
  6. Re-attach the drive back to your original problematic instance and set to "Start"
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Haven't had the opportunity to test this, but marked as answered since I assume it will work. Thanks. –  jberryman Feb 15 '11 at 18:03

If the ubuntu user has no password and the problem is that sudo requires a password have you tried giving the ubuntu user a password ?

ubuntu@host$ passwd
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

Edit - I've just had an opportunity to test this and can confirm that setting a password for the ubuntu user will let you regain access to sudo.

Having a password on the account is a Good Thing tm anyway.

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Thanks for the answer. I hadn't considered that maybe there would be no password set. Unfortunately passwd asks for my current password. I think the 'ubuntu' account may have been created with $ adduser --disabled-password ubuntu. Any other ideas? –  jberryman Feb 10 '11 at 22:01
    
I only tested it with a user that had no password rather than a --disabled-password user. I've set this up but can't find a way around it atm. –  Iain Feb 10 '11 at 23:12

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