should I firewall an open port which isn't used? (was ... Re: Guide(s?) to backup philosophies)

From	cbannister@slingshot.co.nz
Newsgroups	linux.debian.user
Subject	should I firewall an open port which isn't used? (was ... Re: Guide(s?) to backup philosophies)
Date	2017-03-31 14:10 +0200
Message-ID	<tr3xn-4rg-3@gated-at.bofh.it> (permalink)
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On Mon, Mar 13, 2017 at 08:58:15PM -0700, David Christensen wrote:
> On 03/13/2017 05:38 AM, Dan Purgert wrote:
> >Currently, the system here is
> >
> > - every PC has a cronjob backing up $HOME to a central "server" (read -
> >   repurposed PC with decent WD drives), just an rsync script that runs
> >   daily.
> 
> Don't forget security:
> 
> 1.  With a "push" arrangement (e.g. each workstation backs up itself to the
> server) -- if a workstation gets compromised, the backups are at risk.
> 
> 2.  With a "pull" arrangement (e.g. the server backs up all the
> workstations) -- if a workstation gets compromised, the backups should be
> safe (and might have clues about the intrusion).  Additionally, the backup
> server can be completely firewalled (e.g. no open ports).

My understanding is that if there are no services listening on a port then
it cannot be accessed.

e.g.

http://serverfault.com/questions/733633/if-no-service-is-listening-on-a-port-can-a-system-still-be-accessed-using-that-p

An I missing something? 

-- 
The media's the most powerful entity on earth. 
They have the power to make the innocent guilty 
and to make the guilty innocent, and that's power.
 -- Malcolm X

Thread

Guide(s?) to backup philosophies Richard Owlett <rowlett@cloud85.net> - 2017-03-11 16:20 +0100
  Re: Guide(s?) to backup philosophies David Christensen <dpchrist@holgerdanske.com> - 2017-03-11 22:10 +0100
    Re: Guide(s?) to backup philosophies Dan Purgert <dan@djph.net> - 2017-03-13 14:00 +0100
      Re: Guide(s?) to backup philosophies David Christensen <dpchrist@holgerdanske.com> - 2017-03-14 05:00 +0100
        Re: Guide(s?) to backup philosophies Dan Purgert <dan@djph.net> - 2017-03-17 11:50 +0100
          Re: Guide(s?) to backup philosophies Glenn English <ghe2001@gmail.com> - 2017-03-17 19:50 +0100
          Re: Guide(s?) to backup philosophies David Christensen <dpchrist@holgerdanske.com> - 2017-03-18 06:20 +0100
            Re: Guide(s?) to backup philosophies Dan Purgert <dan@djph.net> - 2017-03-22 11:50 +0100
              Re: Guide(s?) to backup philosophies <tomas@tuxteam.de> - 2017-03-22 11:50 +0100
                Re: Guide(s?) to backup philosophies Dan Purgert <dan@djph.net> - 2017-03-22 13:20 +0100
                Re: Guide(s?) to backup philosophies <tomas@tuxteam.de> - 2017-03-22 13:30 +0100
                Re: Guide(s?) to backup philosophies Dan Purgert <dan@djph.net> - 2017-03-23 10:30 +0100
                Re: Guide(s?) to backup philosophies <tomas@tuxteam.de> - 2017-03-23 11:10 +0100
                Re: Guide(s?) to backup philosophies Dan Purgert <dan@djph.net> - 2017-03-23 13:10 +0100
              Re: Guide(s?) to backup philosophies David Christensen <dpchrist@holgerdanske.com> - 2017-03-23 04:00 +0100
                Re: Guide(s?) to backup philosophies Dan Purgert <dan@djph.net> - 2017-03-23 10:40 +0100
                Re: Guide(s?) to backup philosophies David Christensen <dpchrist@holgerdanske.com> - 2017-03-23 20:10 +0100
        Re: should I firewall an open port which isn't used? (was ... Re: Guide(s?) to backup philosophies) Dominik George <nik@naturalnet.de> - 2017-03-31 14:10 +0200
          Re: should I firewall an open port which isn't used? (was ... Re:  Guide(s?) to backup philosophies) Dominik George <nik@naturalnet.de> - 2017-03-31 23:20 +0200
          Re: should I firewall an open port which isn't used? (was ... Re:  Guide(s?) to backup philosophies) Nathan Dorfman <ndorf@rtfm.net> - 2017-04-01 11:00 +0200
        should I firewall an open port which isn't used? (was ... Re:  Guide(s?) to backup philosophies) cbannister@slingshot.co.nz - 2017-03-31 14:10 +0200
          Re: should I firewall an open port which isn't used? (was ... Re:  Guide(s?) to backup philosophies) <tomas@tuxteam.de> - 2017-03-31 14:20 +0200
            Re: should I firewall an open port which isn't used? (was ... Re:  Guide(s?) to backup philosophies) Brian <ad44@cityscape.co.uk> - 2017-03-31 15:20 +0200
              Re: should I firewall an open port which isn't used? (was ... Re:  Guide(s?) to backup philosophies) <tomas@tuxteam.de> - 2017-03-31 15:30 +0200
              Re: should I firewall an open port which isn't used? (was ... Re: Guide(s?) to backup philosophies) Dominik George <nik@naturalnet.de> - 2017-03-31 15:30 +0200
                Re: should I firewall an open port which isn't used? (was ... Re: Guide(s?) to backup philosophies) Dominik George <nik@naturalnet.de> - 2017-03-31 15:50 +0200
      Re: Guide(s?) to backup philosophies Glenn English <ghe2001@gmail.com> - 2017-03-14 19:00 +0100
        Re: Guide(s?) to backup philosophies Dan Ritter <dsr@randomstring.org> - 2017-03-14 19:20 +0100
          Re: Guide(s?) to backup philosophies Miles Fidelman <mfidelman@meetinghouse.net> - 2017-03-14 20:20 +0100
            Re: Guide(s?) to backup philosophies Dan Ritter <dsr@randomstring.org> - 2017-03-14 21:40 +0100
              Re: Guide(s?) to backup philosophies Stefan Monnier <monnier@iro.umontreal.ca> - 2017-03-15 13:30 +0100
                Re: Guide(s?) to backup philosophies Dan Ritter <dsr@randomstring.org> - 2017-03-15 14:10 +0100
                Re: Guide(s?) to backup philosophies "Martin McCormick" <martin.m@suddenlink.net> - 2017-03-15 14:30 +0100
                Re: Guide(s?) to backup philosophies Jonathan Dowland <jmtd@debian.org> - 2017-03-15 16:40 +0100
                Re: Guide(s?) to backup philosophies Jonathan Dowland <jmtd@debian.org> - 2017-03-15 16:40 +0100
                Re: Guide(s?) to backup philosophies Stefan Monnier <monnier@iro.umontreal.ca> - 2017-03-15 21:50 +0100
                Re: Guide(s?) to backup philosophies songbird <songbird@anthive.com> - 2017-03-16 23:50 +0100
        Re: Guide(s?) to backup philosophies Miles Fidelman <mfidelman@meetinghouse.net> - 2017-03-14 20:10 +0100
  Re: Guide(s?) to backup philosophies Joe <joe@jretrading.com> - 2017-03-11 23:30 +0100
    Re: Guide(s?) to backup philosophies Jonathan Dowland <jmtd@debian.org> - 2017-03-15 13:30 +0100
  Re: Guide(s?) to backup philosophies Dan Ritter <dsr@randomstring.org> - 2017-03-13 15:20 +0100
    Re: Guide(s?) to backup philosophies David Christensen <dpchrist@holgerdanske.com> - 2017-03-14 05:10 +0100
    Re: Guide(s?) to backup philosophies Richard Owlett <rowlett@cloud85.net> - 2017-03-14 15:50 +0100
  Re: Guide(s?) to backup philosophies Merlin Büge <toni@bluenox07.de> - 2017-03-14 19:50 +0100
  Re: Guide(s?) to backup philosophies DdB <debianlist@potentially-spam.de-bruyn.de> - 2017-03-19 11:40 +0100

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