Re: Updating files in /etc Remotely (and automated)
On Sun, Sep 12, 2010 at 02:35:00PM -0400, Hal Vaughan wrote:
>
> On Sep 12, 2010, at 12:37 PM, Rob Owens wrote:
> >>>> ...
> >>> When using ssh keys to log in, you can specify (in
> >>> ~/.ssh/authorized_keys) a command which will automatically run when that
> >>> key is used to log in. And that key will be useless to do anything
> >>> else. Simply using that key to conenct to the remote server will run
> >>> that command.
> >>>
> >>> The authorized_keys file would look something like this:
> >>>
> >>> command="/path/to/my/script" ssh-rsa AAAAB3NzaC1yc2EAAA.... me@myhost
> >>
> >> I see. That would make perfect sense and I see I can use -i to specify which key to use, so for normal situations, I just use "ssh host," and when I want this done, I do "ssh -i .ssh/special_key host" instead.
> >>
> >> I thought I knew about authorized keys, but didn't know you could specify a command to be run in that file.
> >>
> >>> You could use this to ssh into the remote server as root, or as a user
> >>> with very specify sudo privileges that will allow your script to run.
> >>> (The script would perform the file changes you need done, or simply
> >>> rsync them from your local machine).
> >>
> >> But if I'm not running as root, from what I can see, no matter what I do with sudo, I still have to type in a password, don't I? using the authorized_keys file and specifying what can be done at login does a lot to help with security, but if I don't log in as root, no matter what I do, I'll still have to type in a password to use either "su" or "sudo," right? Or is there a way around it? I was going through man pages, but it seems both require a password to be typed in no matter what.
> >>
> > In /etc/sudoers, you can specify "NOPASSWD", like this:
> >
> > someuser ALL=NOPASSWD: /path/to/some/command
> >
> > Then "someuser" can run the specified command as root without typing a
> > password.
>
> When I tested this with some simple scripts, I find if I create a batch file that runs a few commands, like "chown root:root filename" that those commands, which would normally need the sudo command don't need it.
>
> Is this because of the (usually) 5 minute time limit sudo uses? Can I trust this on all systems, or is there anything that could prevent this behavior? In other words, if I include, in the script, commands that also need sudo, am I right that I can count on them executing without further need of verification?
>
If you run "sudo somescript", then the script runs as root, so every
command inside it will run as root. I think it is generally considered
smarter, security-wise, to run "somescript" and then include "sudo"
inside the script as necessary. For instance, your script might look
like this:
#!/bin/bash
#
# myscript.sh
#
sudo ls /root/*
ls /home/* #doesn't need root privileges
sudo touch /usr/local/somefile
This script could be run as a regular user, but it would only run
properly if the user had the appropriate sudo rights.
-Rob
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