Bruteforce Attacks Blocking Solution on Embedded SIP Communication Server

This article deals with embedded SIP communication server with an easy integration into the computer network based on open source solutions and its effective defense against the most frequent attack in the present - Denial of Service. The article contains brief introduction into the Bright Embedded Solution for IP Telephony - BESIP and describes the most common types of DoS attacks, which are applied on SIP elements of the VoIP infrastructure including the results of defensive mechanism that has been designed

Evolution of the small ball-like structures in the plasma focus discharge

The experiments were carried out in the PF-1000 plasma-focus device at the maximum current reaching about 2 MA, at the deuterium or neon filling and with deuterium injected from a gas-puff nozzle placed on the axis of the anode face. Ball-like structures of diameters of 1-12 mm were identified in interferometric and XUV pinhole camera frames. We made the statistical description of their parameters. A lifetime of the ball-like structures was in the range from 30 to 210 ns, and in some cases even more. These structures appeared mostly at the surface of the imploding plasma shell and they did not change their position in relation to the anode end. During the evolution of these structures, interferometric fringes were observed near the surfaces of the structures only, and their internal parts were initially chaotic (without noticeable) fringes. Subsequently the number of interferometric fringes increased (the internal ‘chaotic’ area was filled with fringes too) and later on it decreased. The radii of the ball-like structures were mostly increasing during their existence. The maximum electron density reached the value of 1024 to 1025 m-3. The ball-like structures decayed by absorption inside the expanded pinch column and/or gradually expired in rare plasma outside of the dense plasma column

Generation of Secondary Particles from Subnanosecond Laser Irradiation of Targets at Intensities of 10^16 W/cm^-2

none15J.Krasa; D.Margarone; D.Klir; A.Velyhan; A.Picciotto; E.Krousky; K.Jungwirth; J. Skala; M.Pfeifer; J. Ullschmied; J.Kravarik; K.Rezac; P.Kubes; P.Parys; and L.RycJ., Krasa; D., Margarone; D., Klir; A., Velyhan; Picciotto, Antonino; E., Krousky; K., Jungwirth; J., Skala; M., Pfeifer; J., Ullschmied; J., Kravarik; K., Rezac; P., Kubes; P., Parys; L., Ry

Plastic plasma as a compressor of aluminum plasma at the PALS experiment

abstractEN: In our earlier papers, we demonstrated that plasma pressure decreases with the growing atomic number of the target material. That experimentally confirmed fact brought about a question whether it would be possible to collimate the Al plasma outflow by using plastic plasma as a compressor. To prove that idea we used in our next experiments a plastic target with an Al cylindrical insert of 400 µm in diameter. The measurements were carried out at the Prague Asterix Laser System iodine laser facility. The laser provided a 250 ps (full width at half maximum (FWHM)) pulse with energy of 130 J at the third harmonic frequency (λ3 = 0.438 µm). The focal spot diameters (ΦL) 800, 1000, and 1200 µm ensured predominance of the plastic plasma amount high enough for the effective Al plasma compression. To study the Al plasma stream propagation and its interaction with plastic plasma a three-frame interferometric system and an X-ray camera were used. The experiment provided a proof that creation of the collimated Al plasma jet by action of outer plastic plasma is feasible. In order to discuss of the experimental results a thorough theoretical analysis was carried out.score: 35collation: 1-