On 02/22/2018 05:39 PM, Spyros Stathopoulos wrote:
> Greetings,
> I am facing what I initially thought to be a simple matter however it is
> now troubling me more than it should.
> I have setup shorewall to a pretty much standard Two-Interface
> configuration [0]. My LAN is As per the guide I have
> defined three zones, net, loc and fw and as it is packets flow freely
> within the LAN. Now, I have a specific device within my network (for
> instance to which I would like to restrict access. The idea
> is to limit access to only from a specific computer within my
> LAN ideally identified by MAC address. As there is no access control
> from the device itself I can only limit the connection from shorewall.
> Initially I intuitively added a simple DROP loc loc: rule to
> /etc/shorewall/rules to gauge whether the connection to is
> actually dropped. Perhaps slightly to my surprise I found out that this
> is not working as I thought and is accessible from all hosts
> from within the LAN.
> Then I tried to follow this guide [1] to define a "subzone" (the
> specific requirements bit) including only So I added (eth1
> is the LAN-facing interface)
> "dev  eth1:  broadcast" to /etc/shorewall/hosts,
> "dev:loc ipv4" to /etc/shorewall/zones and
> dev  loc  NONE
> loc  dev  NONE
> to /etc/shorewall/policy.
> Then I added the same DROP rule to /etc/shorewall/rules yet once again
> remains accessible from all hosts from within the LAN. Same
> were the results when defaulting the dev<->loc policy to DROP.
> At this point I'm out of ideas so I turned to the mailing list for help.
> It is indeed entirely possible that my question is trivial and I'm
> missing something fundamental so in that case I apologise in advance.
> I am using shorewall{,6,-core} v5.1.8 on Alpine Linux (kernel 4.9.65).
> [0]: http://shorewall.org/two-interface.htm
> [1]: http://shorewall.org/Multiple_Zones.html

The value in defining multiple zones within a LAN is to define different
rules/policies to/from the LAN. Because intra-LAN traffic within a
subnet does not pass through the Shorewall system, rules and policies on
that system are ineffective in controlling intra-LAN traffic. If
different disjoint subnets are defined, traffic between the subnets does
go through the Shorewall system, but such a setup is easily bypassed by
LAN users who have administrative privileges on their systems. The best
way to accomplish what you want is via firewall rules on itself.

Tom Eastep        \   Q: What do you get when you cross a mobster with
Shoreline,         \     an international standard?
Washington, USA     \ A: Someone who makes you an offer you can't
http://shorewall.org \   understand

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