Observing the Evolution of QUIC Implementations

The QUIC protocol combines features that were initially found inside the TCP, TLS and HTTP/2 protocols. The IETF is currently finalising a complete specification of this protocol. More than a dozen of independent implementations have been developed in parallel with these standardisation activities. We propose and implement a QUIC test suite that interacts with public QUIC servers to verify their conformance with key features of the IETF specification. Our measurements, gathered over a semester, provide a unique viewpoint on the evolution of a protocol and of its implementations. They highlight the arrival of new features and some regressions among the different implementations.Comment: 6 pages, 8 figure

The STRESS Method for Boundary-point Performance Analysis of End-to-end Multicast Timer-Suppression Mechanisms

Evaluation of Internet protocols usually uses random scenarios or scenarios based on designers' intuition. Such approach may be useful for average-case analysis but does not cover boundary-point (worst or best-case) scenarios. To synthesize boundary-point scenarios a more systematic approach is needed.In this paper, we present a method for automatic synthesis of worst and best case scenarios for protocol boundary-point evaluation. Our method uses a fault-oriented test generation (FOTG) algorithm for searching the protocol and system state space to synthesize these scenarios. The algorithm is based on a global finite state machine (FSM) model. We extend the algorithm with timing semantics to handle end-to-end delays and address performance criteria. We introduce the notion of a virtual LAN to represent delays of the underlying multicast distribution tree. The algorithms used in our method utilize implicit backward search using branch and bound techniques and start from given target events. This aims to reduce the search complexity drastically. As a case study, we use our method to evaluate variants of the timer suppression mechanism, used in various multicast protocols, with respect to two performance criteria: overhead of response messages and response time. Simulation results for reliable multicast protocols show that our method provides a scalable way for synthesizing worst-case scenarios automatically. Results obtained using stress scenarios differ dramatically from those obtained through average-case analyses. We hope for our method to serve as a model for applying systematic scenario generation to other multicast protocols.Comment: 24 pages, 10 figures, IEEE/ACM Transactions on Networking (ToN) [To appear

Traffic generator for firewall testing

Thesis (Master)--Izmir Institute of Technology, Computer Engineering, Izmir, 2009Includes bibliographical references (leaves: 52-56)Text in English; Abstract: Turkish and Englishix, 92 leavesFirewalls lead at the front line of a computer network to restrict unauthorized access. The desired security level is determined by a policy and implemented by a firewall which not only has to be effective but also stable and reliable service is expected. In order to verify the level of security of the system, testing is required. The objective of this thesis is to test a firewall with software testing techniques taking into consideration the nominated policy and the firewall. Iptables software was examined and tested by two different algorithms that were modified according to software testing techniques, and the results were observed. Packets sent through the Firewall Under Test (FUT) are compared to packets passed through the FUT and test results were observed. The security performance of the modified algorithms proved to be successful

Directed Security Policies: A Stateful Network Implementation

Large systems are commonly internetworked. A security policy describes the communication relationship between the networked entities. The security policy defines rules, for example that A can connect to B, which results in a directed graph. However, this policy is often implemented in the network, for example by firewalls, such that A can establish a connection to B and all packets belonging to established connections are allowed. This stateful implementation is usually required for the network's functionality, but it introduces the backflow from B to A, which might contradict the security policy. We derive compliance criteria for a policy and its stateful implementation. In particular, we provide a criterion to verify the lack of side effects in linear time. Algorithms to automatically construct a stateful implementation of security policy rules are presented, which narrows the gap between formalization and real-world implementation. The solution scales to large networks, which is confirmed by a large real-world case study. Its correctness is guaranteed by the Isabelle/HOL theorem prover.Comment: In Proceedings ESSS 2014, arXiv:1405.055