There is nowadays a wide range of TCP/IP stack identification tools that allow to easily recognize the operating system of foreseen targets. The object of this article is to show that fingerprint concealment and spoofing are uniformly possible against different known fingerprinting tools. We present IpMorph, counter-recognition software implemented as a user-mode TCP/IP stack, ensuring session monitoring and on the fly packets re-writing. We detail its operation and use against tools like Nmap, Xprobe2, Ring2, SinFP and p0f, and we evaluate its efficiency thanks to a first technical implementation that already covers most of our objectives.

Purpose – The purpose of this paper is to study a gas bubble flowing in a micro-channel filled with liquid and to quantify the compressibility effects induced in the bubble by a heat supply at the walls of the channel. Design/methodology/approach – The paper presents a model and its numerical implementation. A hybrid method combining front-tracking techniques and a Heaviside step function is introduced to ensure an accurate satisfaction of the mass and energy conservation laws. Findings – Compressibility effects in the bubble are quantified. Test cases for numerical simulations of two-phase flows involving heat transfer are proposed. Originality/value – The authors present original test cases in which expansion or compression of a gas bubble flowing in a liquid are induced by heat transfer at the wall.

Numerical simulations of an air bubble flowing in a micro-channel filled with liquid water and heated on the walls are presented. Due to the small channel size, pressure changes may be induced by a heat supply on the walls. The aim is to quantify these pressure changes. A numerical model, allowing for the description of an incompressible liquid and a compressible gas bubble is presented. Air in the bubble is modeled as a perfect gas, under the low Mach approximation while the liquid is modeled as an incompressible fluid. The Navier Stokes equations and the energy equation are solved. The interface description is performed combining front tracking techniques and a Heaviside step function. A first validation test-case is presented. Then, various heating conditions are examined including uniform and non uniform heating conditions, constant and time dependent heating conditions. It is shown that pressure oscillations in the bubble may be induced by an appropriate thermal actuation.