Re: users ssh access

[Alan Peery <peery io com>]

Ed Wilts wrote:

> Here's the problem, and I'll let you suggest some solutions that are
> actually secure.
Sounds fun. :-)

> Allow hundreds of authenticated users scattered throughout the
> Internet to transfer files.  Restrict uploads to pre-determined
> directories and downloads to other pre-determined directories.  Allow
> automated processes to easily do this.  Trivial to do with wu-ftpd and
> the ftpaccess file, but I've never found a way to allow an scp to honor
> any sort of directory restrictions.  If any user has scp/sftp access, 
> then they can simply use this or remote command execution to grab my
> system password file, 
This sounds like a call for modifying the source of sshd.  After sshd 
authenicates a user, it should be able to look at the users home 
directory in /etc/passwd.  If  it contains the character pattern that 
indicates to ftpd that it should operate chroot'd (././dir IIRC), then 
disallow remote command execution, run a different command/function when 
the ssh stream contains file transfers that operates chroot'd, and 
disallow any attempt at port forwarding.

It seems a relatively simple set of mods for sshd, and I am surprised 
that the OpenSSH people aren't interested.  Perhaps there is something 
in the structure of the code that would make it unexpectedly difficult.

Alan
--
Alan Peery
peery io com