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Old 08-28-2006, 03:48 AM   #1
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Registered: Aug 2006
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su password problem

Hello all,

I just installed Gentoo and after that i came up with this problem:

login as root I have no problem.
login as user I have no problem.

su to user from root I have no problem.
su to root from user I have a password authentication problem:

su: Permission denied

My password is as simple as it gets, with no special characters.
I also read the previous thread about this problem and my etc/su file permitions are u+s.

I have PAM installed and its contents are:


auth required
auth sufficient likeauth nullok
auth required

account required

password required difok=2 minlen=8 dcredit=2 ocredit=2 retry=3
password sufficient nullok md5 shadow use_authtok
password required

session required
session required
/etc/pam.d/system-auth lines 1-14/14 (END)

Can anyone help me here? I am a newbie so any help would be really helpfull.

Thanks in advance

Joao Pinto
Old 08-28-2006, 04:01 AM   #2
Registered: Jun 2005
Distribution: Gentoo
Posts: 552

Rep: Reputation: 30
Is your user a part of the "wheel" group? To check run the command "groups" when you are logged in as the user to see the groups you are in. Then just run (I think): gpasswd -a wheel USERNAME.

Hopefully that helps.

Last edited by Centinul; 08-29-2006 at 04:02 AM.
Old 08-28-2006, 04:56 AM   #3
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Registered: Jun 2002
Location: UK .
Distribution: *buntu (usually Kubuntu)
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Originally Posted by Centinul
Is your user a part of the "wheel" group? To check run the command "groups" when you are logged in as the user to see the groups you are in. Then just run (I think): usermod -G wheel USERNAME.

Hopefully that helps.
From memory (of when I had gentoo installed), having the user in the wheel group just means that the user can issue the "su" command to change to root, surely it would be the other way round i.e. that root is also a member of the wheel group ??? because to "su" in root is attempting to su from root to root. Could that be why joaoPinto is being given the "permission denied" error ???

Or is it that joaoPinto is forgetting that when you are "su' ing" back from root to user, you would normally do su joaoPinto or whatever other username is used.

I may well be talking a load of bollocks. It's just that root has (or is supposed to have) overall control of the system. If the user wasn't in the wheel group, then the command su just responds with "command not known" (or it did when I last had gentoo installed).

So hence, I'm wondering if the command to switch back from root to user is being issued correctly
su username
as oppossed to just
which from root, well the system wouldn't know where to "su" too because it's already in root.
Old 08-28-2006, 05:21 AM   #4
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Registered: Aug 2006
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a thousands thanks you's

tha problem was the wheel groups that needed to be in my users' list.

i did

usermod -G wheel username

as root and everything went fine.

Thanks you both, specially Centinul

Old 08-28-2006, 10:46 AM   #5
Registered: Jun 2004
Distribution: Gentoo, LFS, Slackware
Posts: 203

Rep: Reputation: 30
A word of caution...using usermod -G makes the user a member of only the specified groups. If the user belonged to any other groups but you didn't include them then the user will no longer belong to them.

Next time use
gpasswd -a wheel <username>

Last edited by Baix; 08-28-2006 at 10:47 AM.


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