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Re: [OCLUG-Tech] how to set up "passwordless" ssh login?

  • Subject: Re: [OCLUG-Tech] how to set up "passwordless" ssh login?
  • From: Rob Echlin <rob [ at ] echlin [ dot ] ca>
  • Date: Tue, 19 Mar 2013 14:18:57 -0700 (PDT)
Hi Rob,
1)
I believe that the location where the SSH server looks for keys can be configured in /etc in its config fiile.
Is that on a read-only location, too?

2)
Given what you do every day, I think there is some possibility that you are going to burn the file system on the remote system yourself.
<g>

If that is the case, create the .ssh folder with 1 or more public keys in it before you burn it.
Copy the private key to whatever system(s) you are working from.
Don't use the passwordless option for your private key. <g>

Probably don't try this with a production system, but test systems would be fine.


Captain Obvious strikes again!!
<g>





>________________________________
> From: Robert P. J. Day <rpjday [ at ] crashcourse [ dot ] ca>
>To: Ottawa Linux Users Group <linux [ at ] lists [ dot ] oclug [ dot ] on [ dot ] ca> 
>Sent: Tuesday, March 19, 2013 4:43:21 PM
>Subject: [OCLUG-Tech] how to set up "passwordless" ssh login?
> 
>
>  before i start digging through the docs for something subtle that i
>missed, i want to make sure i understand the recipe for setting up
>passwordless ssh login, and what it *requires* to be possible on both
>ends. (i think i already know the answer to this, i just want to be
>absolutely sure.)
>
>  so, i'm on system A, and i know an account and its password on
>system B -- that part is kind of essential to start with. with that
>alone, i can of course:
>
>  $ ssh nameb@systemb
>
>but i will be prompted for the password -- ssh is very particular
>about that.  so far, so good, right?
>
>  now i want to extend this so i don't have to type in the password
>every time.  AFAIK, this involves being able to do the following:
>
>1) on system A, i need to run "ssh-keygen" to generate my own pair of
>keys
>
>2) i need to then run "ssh-copy-id" to copy my *public* key to the
>remote system, into the home directory of the target account --
>specifically, into ~/.ssh/authorized_keys
>
>  again, all of this is pretty standard but here's where i run into
>trouble. turns out that the target system is a small embedded linux
>system where there is only one account -- root -- which has its home
>directory in a read-only filesystem. as best i know, i'm pretty well
>screwed here, right?
>
>  for the above to work, the home directory of the target account
>*must* be writable in order for me to stash my public key in
>~/.ssh/authorized_keys, correct? if even the remote account can't
>write into its own home directory, i don't see how to get around that.
>thoughts?
>
>  a couple other questions while i'm here. again, i think this is
>pretty obvious but if a whole bunch of different accounts want to
>passwordless ssh into the same remote account, each one of them has to
>run the recipe above, yes? so the remote account better be prepared to
>stash a lot of public keys in .ssh.
>
>  finally, if i'm unable to change the configuration of the remote
>system, the only option i see that's completely client side-based is
>"sshpass":
>
>  http://linux.die.net/man/1/sshpass
>
>am i missing anything? given the read-only nature of the target
>system, i don't see any easy workaround.
>
>rday
>
>-- 
>
>========================================================================
>Robert P. J. Day                                 Ottawa, Ontario, CANADA
>                        http://crashcourse.ca
>
>Twitter:                                      http://twitter.com/rpjday
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