(***************************************************************************** * Copyright (c) 2005-2010 ETH Zurich, Switzerland * 2008-2015 Achim D. Brucker, Germany * 2009-2016 Université Paris-Sud, France * 2015-2016 The University of Sheffield, UK * * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * * Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following * disclaimer in the documentation and/or other materials provided * with the distribution. * * * Neither the name of the copyright holders nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. *****************************************************************************) subsection ‹Personal Firewall IPv4› theory PersonalFirewallIpv4 imports "../../UPF-Firewall" begin text‹ The most basic firewall scenario; there is a personal PC on one side and the Internet on the other. There are two policies: the first one allows all traffic from the PC to the Internet and denies all coming into the PC. The second policy only allows specific ports from the PC. This scenario comes in three variants: the first one specifies the allowed protocols directly, the second together with their respective port numbers, the third one only with the port numbers. › text‹ Definitions of the subnets › definition PC :: "(ipv4 net)" where "PC = {{((a,b,c,d),e). a = 1 ∧ b = 3 ∧ c = 5 ∧ d = 2}}" definition Internet :: "ipv4 net" where "Internet = {{((a,b,c,d),e). ¬ (a = 1 ∧ b = 3 ∧ c = 5 ∧ d = 2)}}" definition not_in_same_net :: "(ipv4,DummyContent) packet ⇒ bool" where "not_in_same_net x = ((src x ⊏ PC ⟶ dest x ⊏ Internet) ∧ (src x ⊏ Internet ⟶ dest x ⊏ PC))" text ‹ Definitions of the policies › definition strictPolicy :: "(ipv4,DummyContent) FWPolicy" where "strictPolicy = deny_all ++ allow_all_from_to PC Internet" definition PortPolicy :: "(ipv4,DummyContent) FWPolicy" where "PortPolicy = deny_all ++ allow_from_ports_to {80::port,24,21} PC Internet" definition PortPolicyBig :: "(ipv4,DummyContent) FWPolicy" where "PortPolicyBig = deny_all ++ allow_from_port_to (80::port) PC Internet++ allow_from_port_to (24::port) PC Internet++ allow_from_port_to (21::port) PC Internet" lemmas policyLemmas = strictPolicy_def PortPolicy_def PC_def Internet_def PortPolicyBig_def src_def dest_def IPv4.src_port IPv4.dest_port PolicyCombinators PortCombinators in_subnet_def PortPolicyBig_def end