Re: [Qemu-block] [Qemu-devel] [PATCH v2] ssh: switch from libssh2 to libssh

[Pino Toscano]

On Friday, 21 October 2016 12:25:40 CEST Daniel P. Berrange wrote:
> On Fri, Oct 21, 2016 at 01:16:11PM +0200, Pino Toscano wrote:
> > Rewrite the implementation of the ssh block driver to use libssh instead
> > of libssh2.  The libssh library has various advantages over libssh2:
> > - easier API for authentication (for example for using ssh-agent)
> > - easier API for known_hosts handling
> > - supports newer types of keys in known_hosts
> > 
> > Kerberos authentication can be enabled once the libssh bug for it [1] is
> > fixed.
> 
> IIUC from the code this relies on QEMU being able to talk to an ssh
> agent to do public key auth. Is there a way to directly provide the
> passphase for the private key (avoiding need for an agent), or to
> provide a plani password to libssh ?

Yes, both are supported by libssh.

> If so, you could use the QEMU 'secret' object type to provide these
> passphrases & passwords to QEMU, which can in turn pass them to
> libssh.
> 
> Avoiding the need for ssh agent in this way would make it possible
> to use this driver with libvirt in more circumstances.
> 
> eg for plain passwords you could do
> 
>   $QEMU -object secret,id=sec0,data=mypassword
>         -drive driver=ssh,....,password-secret=sec0
> 
> while for private key passphrases
> 
>   $QEMU -object secret,id=sec0,data=mypassphrase
>         -drive driver=ssh,....,key-passphrase-secret=sec0
> 
> 
> No need to do this all as part of this patch though - it'd be cleaner to
> do this as a separate patch

Right, good idea.

Thanks,
-- 
Pino Toscano

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