To cite the use of this formal theory, please use Achim D. Brucker, Lukas Brügger, and Burkhart Wolff. Formal Network Models and Their Application to Firewall Policies. In Archive of Formal Proofs, 2017. http://www.isa-afp.org/entries/UPF_Firewall.shtml, Formal proof development. A BibTeX entry for LaTeX users is @Article{ brucker.ea:upf-firewall:2017, abstract = {We present a formal model of network protocols and their application to modeling firewall policies. The formalization is based on the \emph{Unified Policy Framework} (UPF). The formalization was originally developed with for generating test cases for testing the security configuration actual firewall and router (middle-boxes) using HOL-TestGen. Our work focuses on modeling application level protocols on top of tcp/ip.}, author = {Achim D. Brucker and Lukas Br{\"u}gger and Burkhart Wolff}, date = {2017-01-08}, file = {https://www.brucker.ch/bibliography/download/2017/brucker.ea-upf-firewall-outline-2017.pdf}, filelabel = {Outline}, issn = {2150-914x}, journal = {Archive of Formal Proofs}, month = {jan}, note = {\url{http://www.isa-afp.org/entries/UPF_Firewall.shtml}, Formal proof development}, pdf = {https://www.brucker.ch/bibliography/download/2017/brucker.ea-upf-firewall-2017.pdf}, title = {Formal Network Models and Their Application to Firewall Policies}, url = {https://www.brucker.ch/bibliography/abstract/brucker.ea-upf-firewall-2017}, year = {2017}, } An overview of the formalization is given in: Achim D. Brucker, Lukas Brügger, and Burkhart Wolff. Formal Firewall Conformance Testing: An Application of Test and Proof Techniques. In Software Testing, Verification & Reliability (STVR), 25 (1), pages 34-71, 2015. https://www.brucker.ch/bibliography/abstract/brucker.ea-formal-fw-testing-2014 A BibTeX entry for LaTeX users is @Article{ brucker.ea:formal-fw-testing:2014, abstract = {Firewalls are an important means to secure critical ICT infrastructures. As configurable off-the-shelf prod\-ucts, the effectiveness of a firewall crucially depends on both the correctness of the implementation itself as well as the correct configuration. While testing the implementation can be done once by the manufacturer, the configuration needs to be tested for each application individually. This is particularly challenging as the configuration, implementing a firewall policy, is inherently complex, hard to understand, administrated by different stakeholders and thus difficult to validate. This paper presents a formal model of both stateless and stateful firewalls (packet filters), including NAT, to which a specification-based conformance test case gen\-eration approach is applied. Furthermore, a verified optimisation technique for this approach is presented: starting from a formal model for stateless firewalls, a collection of semantics-preserving policy transformation rules and an algorithm that optimizes the specification with respect of the number of test cases required for path coverage of the model are derived. We extend an existing approach that integrates verification and testing, that is, tests and proofs to support conformance testing of network policies. The presented approach is supported by a test framework that allows to test actual firewalls using the test cases generated on the basis of the formal model. Finally, a report on several larger case studies is presented.}, author = {Achim D. Brucker and Lukas Br{\"u}gger and Burkhart Wolff}, doi = {10.1002/stvr.1544}, journal = {Software Testing, Verification & Reliability (STVR)}, keywords= {model-based testing; conformance testing; security testing; firewall; specification-based testing; testing cloud infrastructure, transformation for testability; HOL-TestGen; test and proof; security configuration testing}, language= {USenglish}, number = {1}, pages = {34--71}, pdf = {https://www.brucker.ch/bibliography/download/2014/brucker.ea-formal-fw-testing-2014.pdf}, publisher= {John Wiley & Sons}, title = {Formal Firewall Conformance Testing: An Application of Test and Proof Techniques}, url = {https://www.brucker.ch/bibliography/abstract/brucker.ea-formal-fw-testing-2014}, volume = {25}, year = {2015}, }