Simultaneous Implementation Of Ssl And Ipsec Protocols For Remote Vpn Connection

A Virtual Private Network is a wide spread technology for connecting remote users and locations to the main core network. It has number of benefits such as cost-efficiency and security. SSL and IPSec are the most popular VPN protocols employed by large number of organizations. Each protocol has its benefits and disadvantages. Simultaneous SSL and IPSec implementation delivers efficient and flexible solution for companies’ with heterogeneous remote connection needs. On the other hand, employing two different VPN technologies opens questions about compatibility, performance, and drawbacks especially if they are utilized by one network device. The study examines the behavior of the two VPN protocols implemented in one edge network device, ASA 5510 security appliance. It follows the configuration process as well as the effect of the VPN protocols on the ASA performance including routing functions, firewall access lists, and network address translation abilities. The paper also presents the cost effect and the maintenance requirements for utilizing SSL and IPSec in one edge network security devic

Exploring fundamental physics with gravitational waves

In this dissertation I explore several topics in the field of gravitational wave astronomy. By means of introduction, I review the historical evolution of humanity's understanding of the mechanics of gravity, and the events which eventually led to the first ever detection of gravitational waves in 2015. The first half of the thesis is dedicated to the effect which gravitational waves have on the apparent position of stars on the sky. The astrometric shift caused by a gravitational wave signal can be quantified, and precise astrometric measurements (from $\textit{Gaia}$) can provide a new method for searching for low-frequency GWs. This method is applied to searches for signals from individually resolvable supermassive black hole binaries. The main obstacle to performing efficient searches is the large size of the data sets, which consist of more than one billion stars. A near-lossless compression which reduces the size of the data set by a factor of $10^{6}$ is discussed and implemented. Mock data sets are generated to simulate detections of gravitational waves using this method, and the frequency and directional sensitivities of the full-term $\textit{Gaia}$ mission are calculated. Parallels are drawn with the field of pulsar timing searches for GWs. This knowledge of the astrometric response is used to address the problem of searching for low frequency gravitational wave backgrounds using astrometric measurements. The astrometric deflections due to a stochastic GW background form a correlated vector field on the sphere (sky). Using a convenient decomposition of the correlation matrix, the 2-point correlation functions are calculated and compared to the redshift correlation in pulsar timing literature (and the Hellings-Downs curve). The correlation between redshift and astrometric deflections is also considered. The second part of the dissertation focuses on the problem of resonances in extreme mass-ratio in-spirals (EMRIs). These events are prime candidates for GW detection in the millihertz band (by detectors like LISA), and involve a stellar mass black hole (or a similar compact object) merging with a supermassive black hole. Properties of the trajectory of the lighter body are well known, however little is known about the behaviour of such systems during resonance of the radial and polar motions. Two existing models for this behaviour are described: the instantaneous frequency approach (developed by Gair, Bender, and Yunes) and the two timescales approach (proposed by Flanagan and Hinderer). Both methods depend on exact treatment of the gravitational self-force, which is currently not available. The results of Gair, Bender, and Yunes are extended to higher-order in the on-resonance flux modification, and the instantaneous frequency approach is confirmed to be a valid treatment of this problem. The algorithm for finding higher-order solutions is described, and further directions for extending this research are proposed.STFC Funding 1032375

Astrometric Effects of Gravitational Wave Backgrounds with non-Luminal Propagation Speeds

A passing gravitational wave causes a deflection in the apparent astrometric positions of distant stars. The effect of the speed of the gravitational wave on this astrometric shift is discussed. A stochastic background of gravitational waves would result in a pattern of astrometric deflections which are correlated on large angular scales. These correlations are quantified and investigated for backgrounds of gravitational waves with sub- and super-luminal group velocities. The statistical properties of the correlations are depicted in two equivalent and related ways: as correlation curves and as angular power spectra. Sub-(super-)luminal gravitational wave backgrounds have the effect of enhancing (suppressing) the power in low-order angular modes. Analytical representations of the redshift-redshift and redshift-astrometry correlations are also derived. The potential for using this effect for constraining the speed of gravity is discussed.ER

pySEOBNR: a software package for the next generation of effective-one-body multipolar waveform models

We present pySEOBNR, a Python package for gravitational-wave (GW) modeling developed within the effective-one-body (EOB) formalism. The package contains an extensive framework to generate state-of-the-art inspiral-merger-ringdown waveform models for compact-object binaries composed of black holes and neutron stars. We document and demonstrate how to use the built-in quasi-circular precessing-spin model SEOBNRv5PHM, whose aligned-spin limit (SEOBNRv5HM) has been calibrated to numerical-relativity simulations and the nonspinning sector to gravitational self-force data using pySEOBNR. Furthermore, pySEOBNR contains the infrastructure necessary to construct, calibrate, test, and profile new waveform models in the EOB approach. The efficiency and flexibility of pySEOBNR will be crucial to overcome the data-analysis challenges posed by upcoming and next-generation GW detectors on the ground and in space, which will afford the possibility to observe all compact-object binaries in our Universe.Comment: 21 pages, 4 figure

Theoretical groundwork supporting the precessing-spin two-body dynamics of the effective-one-body waveform models SEOBNRv5

Waveform models are essential for gravitational-wave (GW) detection and parameter estimation of coalescing compact-object binaries. More accurate models are required for the increasing sensitivity of current and future GW detectors. The effective-one-body (EOB) formalism combines the post-Newtonian (PN) and small mass-ratio approximations with numerical-relativity results, and produces highly accurate inspiral-merger-ringdown waveforms. In this paper, we derive the analytical precessing-spin two-body dynamics for the \texttt{SEOBNRv5} waveform model, which has been developed for the upcoming LIGO-Virgo-KAGRA observing run. We obtain an EOB Hamiltonian that reduces to the exact Kerr Hamiltonian in the test-mass limit. It includes the full 4PN precessing-spin information, and is valid for generic compact objects (i.e., for black holes or neutron stars). We also build an efficient and accurate EOB Hamiltonian that includes partial precessional effects, notably orbit-averaged in-plane spin effects for circular orbits, and derive 4PN-expanded precessing-spin equations of motion, consistent with such an EOB Hamiltonian. The results were used to build the computationally-efficient precessing-spin multipolar \texttt{SEOBNRv5PHM} waveform model.Comment: 35 page

Astrometric Search Method for Individually Resolvable Gravitational Wave Sources with Gaia.

Gravitational waves (GWs) cause the apparent position of distant stars to oscillate with a characteristic pattern on the sky. Astrometric measurements (e.g., those made by Gaia) provide a new way to search for GWs. The main difficulty facing such a search is the large size of the data set; Gaia observes more than one billion stars. In this Letter the problem of searching for GWs from individually resolvable supermassive black hole binaries using astrometry is addressed for the first time; it is demonstrated how the data set can be compressed by a factor of more than 10^{6}, with a loss of sensitivity of less than 1%. This technique was successfully used to recover artificially injected GW signals from mock Gaia data and to assess the GW sensitivity of Gaia. Throughout the Letter the complementarity of Gaia and pulsar timing searches for GWs is highlighted