Ubuntu – Recover sudo password of server over ssh

password-resetsshsudoUbuntuubuntu-12.04

I am working on an ubuntu 12.04 server and i was not provided a sudo password. Now i need to recover it. I found out that we need to reboot into recovery mode to do so but we don't know how to get into recovery mode through ssh.

Any idea of how is this possible or any other ideas for recovering the sudo password?
I have root access through ssh.

Update:

I've tried to do this:

su -

But without success:

su: Authentication failure

Best Answer

You cannot change your password due to the filesystem being mounted in read-only mode when booted into Ubuntu's recovery system.

See this AskUbuntu answer for more detail, but you will need to run the following command to re-mount the filesystem as read/write:

mount -rw -o remount /

After remounting, the output of the mount command should look similar to this for the root filesystem:

/dev/sda1 on / type ext4 (rw,errors=remount-ro)

As an aside, running su - as root will not give you any higher access - root is the highest possible on a Linux system.

Related Solutions

Ssh – How to automate SSH login with password

Don't use a password. Generate a passphrase-less SSH key and push it to your VM.

If you already have an SSH key, you can skip this step… Just hit Enter for the key and both passphrases:

$ ssh-keygen -t rsa -b 2048
Generating public/private rsa key pair.
Enter file in which to save the key (/home/username/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/username/.ssh/id_rsa.
Your public key has been saved in /home/username/.ssh/id_rsa.pub.

Copy your keys to the target server:

$ ssh-copy-id id@server
id@server's password:

Now try logging into the machine, with ssh 'id@server', and check-in:

.ssh/authorized_keys

Note: If you don't have .ssh dir and authorized_keys file, you need to create it first

to make sure we haven’t added extra keys that you weren’t expecting.

Finally, check to log in…

$ ssh id@server

id@server:~$

You may also want to look into using ssh-agent if you want to try keeping your keys protected with a passphrase.

Ubuntu – Key authentication not working when using ssh or rsync as sudo

You need to tell it to use the correct public key. I suspect ssh is still using user1's key, not user2. Use this command:

sudo -u user2 ssh -i ~user2/.ssh/id_rsa remoteserver

I tested this on my machine and it worked.

Best Answer

Related Solutions

Ssh – How to automate SSH login with password

Ubuntu – Key authentication not working when using ssh or rsync as sudo

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