How to use ssh -i with a key from ssh-agent rather than from a file?

[Danishka Navin]

On Wed, Sep 30, 2020 at 1:40 PM raf <ssh at raf.org> wrote:

> On Wed, Sep 30, 2020 at 03:35:43PM +1000, Damien Miller <djm at mindrot.org>
> wrote:
>
> > On Wed, 30 Sep 2020, raf wrote:
> >
> > > Hi,
> > >
> > > I have a VM with a git repository whose origin is on
> > > github. I have several keys known to github, so I needed
> > > to set git's core.sshcommand config parameter in the
> > > repository to something like this:
> > >
> > >   ssh -i ~/.ssh/id_ed25519_github2
> > >
> > > But it meant that I needed to copy that key to the VM.
> > > The same key is available via my forwarded ssh-agent
> > > connection. Is it possible to tell ssh to use that
> > > instead of the key in a file? The documentation for the
> > > -i option only mentions files.
> >
> > ssh will read the public key (id_ed25519_github2.pub) to identify the key
> > before it tries to use the private key (id_ed25519_github2). If the
> private
> > key is available in the agent then it will never try to use the private
> key
> > file.
> >
> > Summary: copy id_ed25519_github2.pub to your VM and the above command
> will
> > work.
> >
> > -d
>
> Hi Damien,
>
> Thanks. That's brilliant.
> It should get a mention in the manpage.
> I've attached a patch for ssh.1.
>
> However, I've just tried it and it didn't work for me. :-(
>
>   $ git config core.sshcommand
>   ssh -i ~/.ssh/id_ed25519_github2
>
>   $ ls -l ~/.ssh/id*
>   -rw-r--r-- 1 raf raf 110 Dec 19  2019
> /home/raf/.ssh/id_ed25519_github2.pub
>
>   $ cat ~/.ssh/id_ed25519_github2.pub
>   ssh-ed25519
> AAAAC3NzaC1lZDI1NTE5AAAAIHrmJ0gYTmZlilDBB/BsyOHqOT354aDLWgULmMPXRkJK
> user at domain.com
>
>   $ ssh-add -L
>   ssh-ed25519
> AAAAC3NzaC1lZDI1NTE5AAAAIHrmJ0gYTmZlilDBB/BsyOHqOT354aDLWgULmMPXRkJK
> user at domain.com
>   [...]
>
>   $ git pull
>   Warning: Identity file /home/raf/.ssh/id_ed25519_aps_github not
> accessible: No such file or directory.
>   ERROR: Repository not found.
>

>From where this id_ed25519_*aps*_githubfile coming?


>
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-- 
Danishka Navin