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let root login using ssh-keys and disable all other users onlinux

Posted on 2010-09-01
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Last Modified: 2012-05-10
Is it possible?

Thanks.
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Question by:sminfo
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fosiul01 earned 1000 total points
ID: 33577732
yes that possible

you just need to add   /sbin/nologin word with each users in /etc/passwd file .  ( there is a command which you can use instead of editing /etc/passwd file)

example :

nobody:x:99:99:Nobody:/:/sbin/nologin


and in sshd_config file

insert this line

PermitRootLogin without-password


then reboot the sshd daemon

it will allow root to use key only and

by editing /etc/passwd file ( sbin/nologin) it will prevent to user to login to the server.


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by:woolmilkporc
woolmilkporc earned 1000 total points
ID: 33577870
You could also add to sshd_config
AllowUsers root
PermitRootLogin without-password

and disable all remote access like telnet, rsh and the like.
Remains only the phyical system console - is this a concern for you?

 
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by:simoesp
ID: 33578201
you can  always block an account by doing

passwd -l

then generate an ssh key to login without password

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by:fernandomerces
ID: 33583469
I don't know the /sbin/nologin program. I use /bin/false instead.

BUT I really recommends that you use a normal account to login via SSH and then elevate your privileges to root (su/sudo). Believe, you don't need root logged all time and you'll increase security.

Regards,

Fernando
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Expert Comment

by:mccracky
ID: 33632679
I would concur with fernandomerces AND woolmilkporc.

Use the sshd_config with allowusers and don't log in directly as root.
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Author Closing Comment

by:sminfo
ID: 33796700
The answers are fine and solved my question.
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