[Freeipa-users] Allow IPA users to create SSH tunnel with no shell

[Simo Sorce]

On Mon, 2012-12-17 at 09:07 -0500, Albert Adams wrote:
> Thank you for the responses.  I was initially attempting to set this
> value via the web UI and if I entered anything other than the hash
> value of the user's public key it would get rejected.  After thinking
> about your response I realize that I really need to determine a method
> of doing this via a HBAC rule.  If I accomplish this with
> authorized_keys then the user is restricted across the board and would
> not be able to gain a shell on any system whereas HBAC would allow me
> to restrict thier access as needed.  We currently require users to
> tunnel over SSH to gain access to certain sensitive web apps (like
> Nessus) but those same users have shell access on a few boxes.
> Thoughts??

One thing you could do is to use the override_shell parameter in sssd.
However this one would override the shell for all users so just
putting /sbin/nologin there would not work if you need some users to be
able to log in (if you care only for root logins it would be enough).

However you can still manage to use it to point to a script that would
test something like whether the user belongs to a group or not, and if
so run either /bin/bash or /bin/nologin

This seem like a nice feature request for FreeIPA though, maybe we can
extend HBAC to allow a special option to define a shell, maybe creating
a special 'shell' service that sssd can properly interpret as a hint to
set nologin vs the actual shell.

Dmitri, should we open a RFE on this ?


Simo.

-- 
Simo Sorce * Red Hat, Inc * New York