Re: tramp and ssh-agent / ssh-add

[Michael Albinus <michael.albinus@gmx.de>]

Roland Winkler <Roland.Winkler@physik.uni-erlangen.de> writes:

Hi,

> Usually when I have emacs running on a remote machine, I do this as
> a subprocess of ssh-agent. Then when I establish ssh connections
> via tramp, I want to make sure that I type my password only once via
> ssh-add. What is the cleanest way to do that? Is there some support
> from tramp for that? Right now, my home-made solution uses a
> defadvice for tramp-open-connection-rsh, see the code below.
> However, if tramp-open-connection-rsh is the right entry point for
> what I want to do, it seems to me that a hook might be helpful. Or
> am I missing something else?

I wouldn't do it this way:

- You advice tramp-open-connection-rsh, a function of Tramp 2.0. It
  doesn't exist anymore in Tramp 2.1, so you solution isn't future safe.

- I believe that calling ssh-add on-the-fly is not the intended way. You
  should call it, before you run emacs "as a subprocess of ssh-agent" on
  the remote machine.

- Tramp supports password caching on its own. Install password.el in
  your own lisp directory. You could download it from <http://cvs.savannah.gnu.org/viewvc/*checkout*/tramp/contrib/password.el?revision=1.1.2.1&root=tramp&pathrev=branch-2-0-stable>.

  Then you add the following line to your .emacs, after loading Tramp:

  (setq password-cache-expiry nil)

> Thanks,
>
> Roland

Best regards, Michael.