openssh unix dev - Apr 2014 - How can I have the same ssh key for dual boot (ssh-keygen)

I use:
ssh-keygen -t rsa
to generate a key file (id_rsa.pub) which I copy into authorized_keys2 on
other machines in order to permit ssh to these machines without being
asked for a password.

The thing is that I have dual boot on this machine: one for fedora and
one for ubuntu. The two key files which were generated on these machine
are different.

Is there a way so that I will have the same key file for both these fedora
and
ubuntu ?

regards,
Kevin

On Tue, 1 Apr 2014, Kevin Wilson wrote:
> I use:
> ssh-keygen -t rsa
> to generate a key file (id_rsa.pub) which I copy into authorized_keys2 on
> other machines in order to permit ssh to these machines without being
> asked for a password.
> 
> The thing is that I have dual boot on this machine: one for fedora and
> one for ubuntu. The two key files which were generated on these machine
> are different.
> 
> Is there a way so that I will have the same key file for both these fedora
> and
> ubuntu ?
Copy it from one to the other.

Hi Kevin,

  2 possible solutions:

1) put the same private key (id_rsa, not id_rsa.pub) on a shared medium
(usb stick comes to mind) and use that, by mounting it on ~/.ssh, or such.
2) copy the same private key to both environments.

Sincerely,

Jan.


On Tue, Apr 1, 2014 at 9:05 AM, Kevin Wilson <wkevils at gmail.com> wrote:
> I use:
> ssh-keygen -t rsa
> to generate a key file (id_rsa.pub) which I copy into authorized_keys2 on
> other machines in order to permit ssh to these machines without being
> asked for a password.
>
> The thing is that I have dual boot on this machine: one for fedora and
> one for ubuntu. The two key files which were generated on these machine
> are different.
>
> Is there a way so that I will have the same key file for both these fedora
> and
> ubuntu ?
>
> regards,
> Kevin
> _______________________________________________
> openssh-unix-dev mailing list
> openssh-unix-dev at mindrot.org
> https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
>


-- 
"Piracy is simply demand where supply does not exist."

one thing not yet mentioned by others:
You should not only synchronize the keys in ~/.ssh/ but, more important,
in order to avoid that all other clients complain about a suspeced man
in the middle attack, you should copy the host keys located in /etc/ssh/
(e.g. by temporarily putting them on an usb medium during reboot, or by
mounting the root partition of the other linux e.g. somewhere below /mnt
- just once for copying the files). Then, clean up the
~/.ssh/known_hosts files on the other machines.


On 04/01/2014 09:05 AM, Kevin Wilson wrote:
> I use:
> ssh-keygen -t rsa
> to generate a key file (id_rsa.pub) which I copy into authorized_keys2 on
> other machines in order to permit ssh to these machines without being
> asked for a password.
>
> The thing is that I have dual boot on this machine: one for fedora and
> one for ubuntu. The two key files which were generated on these machine
> are different.
>
> Is there a way so that I will have the same key file for both these fedora
> and
> ubuntu ?
>
> regards,
> Kevin
> _______________________________________________
> openssh-unix-dev mailing list
> openssh-unix-dev at mindrot.org
> https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev

Kevin Wilson <wkevils at gmail.com> writes:
> I use:
> ssh-keygen -t rsa
> to generate a key file (id_rsa.pub) which I copy into authorized_keys2 on
> other machines in order to permit ssh to these machines without being
> asked for a password.
>
> The thing is that I have dual boot on this machine: one for fedora and
> one for ubuntu. The two key files which were generated on these machine
> are different.
>
> Is there a way so that I will have the same key file for both these fedora
> and
> ubuntu ?
As mentioned by others, there is a way to do this, but I'd suggest that
you shouldn't want to.

What's wrong with having an additional key in the authorized_keys file?

If the thing you're trying to avoid is the pain of installing the keys
twice, well if you're using ssh-copy-id just add the public key for the
other machine into the id_*.pub file on each, then whichever you install
From will authorise both.  If you've got a more structured way of
installing the keys (i.e. chengine, puppet etc. etc.) then just add both
keys to your config and you're done.

This seems preferable both on the basis that you're not having to fiddle
with the host keys in possibly assumption-breaking ways, but also
because it may come to pass that one of the keys is somehow compromised
while the other remains secure, in which case you'll be able to boot the
secure system and fix things.

Cheers, Phil.
-- 
|)|  Philip Hands [+44 (0)20 8530 9560]    http://www.hands.com/
|-|  HANDS.COM Ltd.                    http://ftp.uk.debian.org/
|(|  10 Onslow Gardens, South Woodford, London  E18 1NE  ENGLAND
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