Re: [gentoo-user] {OT} Are "push" backups flawed?

[Michael Mol]

On Fri, Nov 11, 2011 at 12:55 PM, Grant <emailgrant@×××××.com> wrote:

[snip]

> The problem with my current push-style layout is that if one of the 3
> machines is compromised, the attacker can delete or alter the backup
> of the compromised machine on the backup server.  I can rsync the
> backups from the backup server to another machine, but if the backups
> are deleted or altered on the backup server, the rsync'ed copy on the
> next machine will also be deleted or altered.

As a final stage in your backup, could you trigger a 'pull'-style
backup copying the data image to a more secure area? How about setting
your backup target on top of lvm, and snapshotting? Some mechanism
could be employed so that the snapshot command is run by a more
restricted user, and done so after, e.g. a certain amount of idle time
in the backup target directory

>
> If I run a pull-style layout and the backup server is compromised, the
> attacker would have root read access to each of the 3 machines, but
> the attacker would already have access to backups from each of the 3
> machines stored on the backup server itself so that's not really an
> issue.  I would also have the added inconvenience of using openvpn or
> ssh -R for my laptop so the backup server can pull from it through any
> router.

Check out freenet6. I use it so that my laptop has a static, global IP
address whether it's on my home network or not. It's quite nice. IPv6
in various applications also solves my other direct-access needs.

>
> What do you think guys?  Are push-style backups flawed and unacceptable?

I imagine you might still want to 'pull' from your backup server; if
someone gets a key that allows them to manipulate the behavior of a
local process that shouldn't normally be manipulated, your
vulnerability surface goes up.

-- 
:wq