Re: ssh connection via a proxy

[Andreas Schneider <asn@xxxxxxxxxxxxxx>]

On Tuesday, August 3, 2021 9:16:15 AM CEST Jeremy Fix wrote:
> On 03/08/2021 08:52, Andreas Schneider wrote:
> > On Monday, August 2, 2021 11:28:10 PM CEST Jeremy Fix wrote:
> >> Hello,
> > 
> > Hi,
> > 
> >> I would like to use libssh for connecting to a remote host via a
> >> gateway, executing a command on the remote host and parsing its standard
> >> outputs/errors; So the picture is  localhost -> gateway -> remote
> >> 
> >> I'm pretty new with libssh. I used to do that with command line ssh by
> >> specifying
> >> 
> >>     ssh -o ProxyCommand='ssh -W %h:%p mylogin@gateway' mylogin@remote
> >> 
> >> mycommand
> >> 
> >> It is not obvious to me how to do that with libssh; One track I have in
> >> 
> >> mind is a variant of the above with :
> >>     ssh -L 9999:remote:22 mylogin@gateway
> >>     
> >>     ssh -p 9999 mylogin@localhost mycommand
> >> 
> >> therefore I would establish a tunnel then create a new libssh session on
> >> localhost and execute the command in a channel on this new session.
> > 
> > Which part to do you want to implement with libssh exactly. The client
> > side or the proxy or both?
> 
> I think I need to implement the whole chain. To specify the constraints;
> I need my program to run on Linux/Windows/MacOS and I thought, but I may
> be wrong, that I need to handle everything related to ssh with libssh.
> 
> > libssh supports the proxy command see the options:
> > https://api.libssh.org/stable/
> > group__libssh__session.html#ga7a801b85800baa3f4e16f5b47db0a73d
> > 
> > SSH_OPTIONS_PROXYCOMMAND: Set the command to be executed in order to
> > connect to server (const char *).
> 
> I agree but what puzzles me is that my proxy command "ProxyCommand='ssh
> -W %h:%p mylogin@gateway'" does involve ssh which I should also handle
> with libssh I believe.  If I want my program to be cross platform,
> shouldn't I also code the  'ssh -W %h:%p mylogin@gateway' with libssh ? 

You don't need a proxy command if you implement the proxy yourself ...

https://git.libssh.org/projects/libssh.git/tree/examples/proxy.c


-- 
Andreas Schneider                 asn@xxxxxxxxxxxxxx
GPG-ID:     8DFF53E18F2ABC8D8F3C92237EE0FC4DCC014E3D