I am using Amazon's AWS insances running CentOS. I was trying to create a user with SUDO privilege and then disable the Root login to secure the systems. I have already done the required to bring this into effect but am now stuck with a problem I failed to understand.

When I created a User (say ABC) I did not set a password for it. Instead I use RSA Keys for authentication purpose.

Then I used visudo command and added ABC ALL=(ALL) ALL to the bottom of the file to give sudo privilege to this user.

Then I opened /etc/ssh/sshd_config in vi and turned PermitRootLogin to no and restart sshd. this is to disable root access.

I was expecting this to be it, i.e. disabling root login and having ABC do all the required administrative task. But am badly stuck now.

My Problem is when I login a ABC and try to sudo any command, it is asking for user passsword. This user does not have a password but a RSA Key with it, which i dont think can be used with SUDO.

I tried setting a password for this user using passwd command. Thats does not work either. Am getting following error.

$ passwd
Changing password for user kagzisa.
Changing password for kagzisa
(current) UNIX password:
passwd: Authentication token manipulation error

I am just pressing enter key when it prompts for current password as there is no current password specified.

Now I am stuck as I have got the Root login disabled and am not able to sudo any commands from ABC. I cant loose this system as there are some important process running on it.

Is there a way through which I can fix this. Either by reactivating root or by able to sudo commands?

  • I believe this question is for superuser.com – 4e6 Oct 24 '11 at 8:18

You should probably use NOPASSWORD tag in visudo so it won't ask you for any password. ABC ALL = NOPASSWD: ALL

| improve this answer | |

First of all become root.

As root you don't need to know any password to change it:

# passwd kagzisa
Enter new UNIX password: 
| improve this answer | |

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