Groups > linux.debian.user > #200426

Re: Why does Debian allow all incoming traffic by default

From	Pascal Hambourg <pascal@plouf.fr.eu.org>
Newsgroups	linux.debian.user
Subject	Re: Why does Debian allow all incoming traffic by default
Date	2018-09-22 13:00 +0200
Message-ID	<wANNL-3x4-1@gated-at.bofh.it> (permalink)
References	<wAjZo-39S-1@gated-at.bofh.it> <wAx6h-2p2-1@gated-at.bofh.it> <wAKGd-1MF-5@gated-at.bofh.it> <wAMeZ-2Mf-5@gated-at.bofh.it>
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Le 22/09/2018 à 11:12, Gene Heskett a écrit :
> On Saturday 22 September 2018 03:34:45 Pascal Hambourg wrote:
> 
>> Le 21/09/2018 à 19:09, Dan Ritter a écrit :
>>> Let's suppose Debian installs a basic firewall by default. How
>>> basic? Let's say:
>>>
>>>       - outbound: permit
>>>       - forward: deny
>>>       - inbound: accept NTP, DHCP, DNS, and any TCP packet which is a
>>>         response to an outbound packet
>>
>> Why should unsolicited NTP, DHCP and DNS inbound packets be allowed ?
>>
> Because you can set an ntp corrected machine as a broadcaster

Does the client NTP daemon accepts inbound broadcast messages from any 
source by default ? If so, this seems quite insecure to me and the 
firewall should not allow this by default. If not, it requires some 
configuration, and allowing inbound NTP broadcast from the broadcaster 
address only should be part of this configuration.

>> Why should only TCP inbound responses be allowed ? What about
>> UDP-based protocols, ping replies (ICMP echo reply), ICMP error
>> messages, and so on ?
> 
> I probably should have iptables running on all my machines, but in 15
> years, only one person as gotten thru dd-wrt to this machine, and I had
> to give him the login credentials, I needed help configuring something,
> on a long since replaced fedora install.  So there is no firewall
> enabled on any of the machines here. And because everytime Andrew
> Triggel sits down at a keyboard cifs dies, same for NFS, I've found that
> ssh and sshfs as local networking tools Just Work, so I don't have to
> putz near as much with access maintenance. No NFS shares, no sammba/cifs
> shares.  And life is so much simpler.
> 
> Computers should work for you, not the other way around, forcing you to
> remember how to push 17 buttons just to answer an incoming email.  This
> message only required 1 button click and all this typing. Everything
> else is handled automatically by scripts.

I do not see how all this replies to my question :

Why should only TCP inbound responses be allowed ? What about UDP-based 
protocols, ping replies (ICMP echo reply), ICMP error messages, and so on ?

Thread

Why does Debian allow all incoming traffic by default Subhadip Ghosh <subhadip.sky@gmail.com> - 2018-09-21 05:10 +0200
  Re: Why does Debian allow all incoming traffic by default Roberto C. Sánchez <roberto@debian.org> - 2018-09-21 05:30 +0200
    Re: Why does Debian allow all incoming traffic by default Subhadip Ghosh <subhadip.sky@gmail.com> - 2018-09-21 05:40 +0200
      Re: Why does Debian allow all incoming traffic by default Roberto C. Sánchez <roberto@debian.org> - 2018-09-21 05:50 +0200
        Re: Why does Debian allow all incoming traffic by default deloptes <deloptes@gmail.com> - 2018-09-21 07:10 +0200
        Re: Why does Debian allow all incoming traffic by default Subhadip Ghosh <subhadip.sky@gmail.com> - 2018-09-21 19:40 +0200
      Re: Why does Debian allow all incoming traffic by default Dan Ritter <dsr@randomstring.org> - 2018-09-21 19:10 +0200
        Re: Why does Debian allow all incoming traffic by default Subhadip Ghosh <subhadip.sky@gmail.com> - 2018-09-21 19:40 +0200
          Re: Why does Debian allow all incoming traffic by default deloptes <deloptes@gmail.com> - 2018-09-21 20:00 +0200
            Re: Why does Debian allow all incoming traffic by default Subhadip Ghosh <subhadip.sky@gmail.com> - 2018-09-21 20:10 +0200
              Re: Why does Debian allow all incoming traffic by default Brian <ad44@cityscape.co.uk> - 2018-09-21 21:40 +0200
          Re: Why does Debian allow all incoming traffic by default David Wright <deblis@lionunicorn.co.uk> - 2018-09-21 21:50 +0200
          Re: Why does Debian allow all incoming traffic by default mick crane <mick.crane@gmail.com> - 2018-09-23 01:10 +0200
            Re: Why does Debian allow all incoming traffic by default Brian <ad44@cityscape.co.uk> - 2018-09-23 20:00 +0200
              Re: Why does Debian allow all incoming traffic by default Joe <joe@jretrading.com> - 2018-09-23 23:00 +0200
                Re: Why does Debian allow all incoming traffic by default Brian <ad44@cityscape.co.uk> - 2018-09-24 00:00 +0200
        Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-22 09:40 +0200
          Re: Why does Debian allow all incoming traffic by default Gene Heskett <gheskett@shentel.net> - 2018-09-22 11:20 +0200
            Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-22 13:00 +0200
              Re: Why does Debian allow all incoming traffic by default Dan Ritter <dsr@randomstring.org> - 2018-09-22 13:40 +0200
                Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-22 17:00 +0200
                Re: Why does Debian allow all incoming traffic by default Gene Heskett <gheskett@shentel.net> - 2018-09-22 20:20 +0200
                Re: Why does Debian allow all incoming traffic by default Richard Hector <richard@walnut.gen.nz> - 2018-09-24 05:20 +0200
                Re: Why does Debian allow all incoming traffic by default Gene Heskett <gheskett@shentel.net> - 2018-09-24 05:30 +0200
                Re: Why does Debian allow all incoming traffic by default <tomas@tuxteam.de> - 2018-09-24 09:10 +0200
                Re: Why does Debian allow all incoming traffic by default Gene Heskett <gheskett@shentel.net> - 2018-09-24 11:00 +0200
                Re: Why does Debian allow all incoming traffic by default <tomas@tuxteam.de> - 2018-09-24 11:40 +0200
                Re: Why does Debian allow all incoming traffic by default Gene Heskett <gheskett@shentel.net> - 2018-09-24 14:20 +0200
                Re: Why does Debian allow all incoming traffic by default Dan Ritter <dsr@randomstring.org> - 2018-09-22 20:30 +0200
                Re: Why does Debian allow all incoming traffic by default Gene Heskett <gheskett@shentel.net> - 2018-09-22 22:20 +0200
                Re: Why does Debian allow all incoming traffic by default <tomas@tuxteam.de> - 2018-09-22 22:40 +0200
                Re: Why does Debian allow all incoming traffic by default Gene Heskett <gheskett@shentel.net> - 2018-09-22 23:20 +0200
                Re: Why does Debian allow all incoming traffic by default Simon Kengelbacher <simon.kengelbacher@mail.ch> - 2018-09-22 23:50 +0200
                Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-23 00:00 +0200
                Re: Why does Debian allow all incoming traffic by default Simon Kengelbacher <simon.kengelbacher@mail.ch> - 2018-09-23 00:20 +0200
                SSH X forwarding going awry (Was: Why does Debian allow all incoming  traffic by default) Étienne Mollier <etienne.mollier@mailoo.org> - 2018-09-23 11:40 +0200
                Re: SSH X forwarding going awry FIXED (Was: Why does Debian allow all incoming traffic by default) Gene Heskett <gheskett@shentel.net> - 2018-09-23 16:10 +0200
                Re: SSH X forwarding going awry FIXED (Was: Why does Debian allow  all incoming traffic by default) Joe <joe@jretrading.com> - 2018-09-23 23:00 +0200
                Re: SSH X forwarding going awry FIXED (Was: Why does Debian allow all incoming traffic by default) Gene Heskett <gheskett@shentel.net> - 2018-09-24 04:50 +0200
                Re: Why does Debian allow all incoming traffic by default Jonathan Dowland <jmtd@debian.org> - 2018-09-24 21:00 +0200
                Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-23 00:00 +0200
            Re: Why does Debian allow all incoming traffic by default Jonathan Dowland <jmtd@debian.org> - 2018-09-24 21:00 +0200
              Re: Why does Debian allow all incoming traffic by default Joe <joe@jretrading.com> - 2018-09-24 21:30 +0200
                Re: Why does Debian allow all incoming traffic by default Jonathan Dowland <jmtd@debian.org> - 2018-09-26 15:50 +0200
                Re: Why does Debian allow all incoming traffic by default Joe <joe@jretrading.com> - 2018-09-26 17:10 +0200
                Re: Why does Debian allow all incoming traffic by default Jonathan Dowland <jmtd@debian.org> - 2018-09-26 19:30 +0200
          Re: Why does Debian allow all incoming traffic by default Dan Purgert <dan@djph.net> - 2018-09-22 15:50 +0200
            Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-22 16:50 +0200
        Re: Why does Debian allow all incoming traffic by default Jonathan Dowland <jmtd@debian.org> - 2018-09-24 20:50 +0200
  Re: Why does Debian allow all incoming traffic by default Henning Follmann <hfollmann@itcfollmann.com> - 2018-09-21 15:00 +0200
    Re: Why does Debian allow all incoming traffic by default Reco <recoverym4n@gmail.com> - 2018-09-21 18:30 +0200
      Re: Why does Debian allow all incoming traffic by default Brian <ad44@cityscape.co.uk> - 2018-09-21 20:20 +0200
        Re: Why does Debian allow all incoming traffic by default Reco <recoverym4n@gmail.com> - 2018-09-21 20:40 +0200
          Re: Why does Debian allow all incoming traffic by default Brian <ad44@cityscape.co.uk> - 2018-09-21 21:10 +0200
          Re: Why does Debian allow all incoming traffic by default deloptes <deloptes@gmail.com> - 2018-09-21 23:20 +0200
            Re: Why does Debian allow all incoming traffic by default Reco <recoverym4n@gmail.com> - 2018-09-21 23:40 +0200
              Re: Why does Debian allow all incoming traffic by default Dan Purgert <dan@djph.net> - 2018-09-22 00:10 +0200
                Re: Why does Debian allow all incoming traffic by default Reco <recoverym4n@gmail.com> - 2018-09-22 09:10 +0200
                Re: Why does Debian allow all incoming traffic by default Dan Purgert <dan@djph.net> - 2018-09-22 15:50 +0200
          Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-22 09:50 +0200
            Re: Why does Debian allow all incoming traffic by default Reco <recoverym4n@gmail.com> - 2018-09-22 12:00 +0200
              Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-22 13:00 +0200
                Re: Why does Debian allow all incoming traffic by default Reco <recoverym4n@gmail.com> - 2018-09-22 13:30 +0200
                Re: Why does Debian allow all incoming traffic by default <tomas@tuxteam.de> - 2018-09-22 22:00 +0200
                Re: Why does Debian allow all incoming traffic by default Stefan Monnier <monnier@iro.umontreal.ca> - 2018-09-22 22:20 +0200
                Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-22 23:40 +0200
          Re: Why does Debian allow all incoming traffic by default Henning Follmann <hfollmann@itcfollmann.com> - 2018-09-22 12:10 +0200
            Re: Why does Debian allow all incoming traffic by default Reco <recoverym4n@gmail.com> - 2018-09-22 12:40 +0200
            Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-22 13:10 +0200
    netstat (was: Re: Why does Debian allow all incoming traffic by default) rhkramer@gmail.com - 2018-09-21 20:00 +0200
      Re: netstat Reco <recoverym4n@gmail.com> - 2018-09-21 20:20 +0200
        Re: netstat rhkramer@gmail.com - 2018-09-22 20:50 +0200
    Re: Why does Debian allow all incoming traffic by default Jonathan Dowland <jmtd@debian.org> - 2018-09-24 20:50 +0200
      Re: Why does Debian allow all incoming traffic by default Henning Follmann <hfollmann@itcfollmann.com> - 2018-09-24 21:30 +0200
        Re: Why does Debian allow all incoming traffic by default Jonathan Dowland <jmtd@debian.org> - 2018-09-26 15:50 +0200
  Re: Why does Debian allow all incoming traffic by default Pablo Álvarez Córdoba <pabloalvarezcordoba@protonmail.ch> - 2018-09-21 18:30 +0200
    Re: Why does Debian allow all incoming traffic by default Subhadip Ghosh <subhadip.sky@gmail.com> - 2018-09-21 19:30 +0200
  Re: Why does Debian allow all incoming traffic by default songbird <songbird@anthive.com> - 2018-09-22 00:10 +0200
    Re: Why does Debian allow all incoming traffic by default Joe <joe@jretrading.com> - 2018-09-22 09:40 +0200
      Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-22 10:40 +0200
        Re: Why does Debian allow all incoming traffic by default Joe <joe@jretrading.com> - 2018-09-22 13:20 +0200
          Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-22 17:10 +0200
            Re: Why does Debian allow all incoming traffic by default Joe <joe@jretrading.com> - 2018-09-23 10:50 +0200
              Re: Why does Debian allow all incoming traffic by default Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-09-27 14:00 +0200
    Re: Why does Debian allow all incoming traffic by default Jonathan Dowland <jmtd@debian.org> - 2018-09-24 20:50 +0200

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