how do I login as root user in Ubuntu 6.10?

I opened the terminal

typed: su

and then I typed in my user password,

but I got an authentication failed message.

I dont know what other password I have to use because whenever I installed ubuntu I was only prompted to create one password which was for the user.

What should I do?

for ubuntu-based distros i think you have to use sudo to do something as root: 'sudo commandName' then your user password. there is no root user installed.

The root user account is installed, but is disabled by default.

to enable the root account, at the command, type
Then, type your new root account password.

Cheers

Ok thanks your advice worked,
I got a root password now,

There's no need to set a root password in Ubuntu.

will log you in as root (even without having set a root password). Just use your user password (as long as you're in the admin group).

Read more here:
https://help.ubuntu.com/community/RootSudo
http://www.psychocats.net/ubuntu/permissions

Sometimes it is nice to have a root user. I have always decided, that if a user doesn't want sudo, it doesn't hurt to let him. As long as you don't abuse root's privileges, you are fine.

You can't log in from a VT with "sudo -i", you need a root password, and it is useful to have a root password many times.

And I've always decided it's a good idea for people to try to use Ubuntu the way it was meant to be used before the user decides she "doesn't want sudo." Informed choice is the only real choice.

Yes, you can set up a root account in Ubuntu, but it's often unnecessary, and sudo can be more convenient. It's at least worth an honest try.

Coming from Mepis, I was also disoriented by the lack of root user login in Ubuntu, but I gave it a fair shot, got used to it, and now I prefer it. But I gave it a fair shot. I have no idea what a VT is.

VT = Virtual Terminal (AKA a TTY).
And yes you can login on a VT/TTY to get a root shell, you login as your normal user, then do "sudo -i"
You say "it is useful to have a root password many times.", really? what times? I've never needed one. Give some examples here.

If you want a root shell from the get-go, just login to single user mode, the root session starts then.

For all the people that say "Yeah, but I want to be able to login as root, without using sudo." can you explain why? I've never needed to. Every operation I've needed to do as root sudo has let me do just fine.

Thanks for the clarification, binrary_y2k2.

I had no idea what a VT was, but I also have never found a need to enable a root login (other than "recovery mode"). It's one thing to say, "Yeah, I've tried sudo extensively, but I just prefer to log in as root." It's quite another to make it sound as if sudo is some nonsensical system and that getting a root login is just putting things back to normal from some screwed up approach Ubuntu implemented.

The truth is that most people don't give sudo a chance. It's quite convenient.

I think I would be siding with the side that is saying that you dont really NEED a root password, and that sudo would suffice.

I mean, really, how many mistakes can you make as root that would screw everything up? by using sudo, it semi-elminates this problem by FORCING you to type in an extra "parameter" into the command to make it run (as root)
This sort of eliminates a huge F* up in my eyes for the fact that you are then thinking "hey, if i run this, I am running it as root"

The other reason for this is that in the unlikley event you get hacked, it will save you for the fact that you are not logged in as root, therefore, do not have root permissions, and cannot run some programs that can be quite destructive.