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Tuesday, 14 January 2014


Cain & Abel is a password recovery tool for Microsoft Operating Systems. It allows easy recovery of various kind of passwords by sniffing the network, cracking encrypted passwords using Dictionary, Brute-Force and Cryptanalysis attacks, recording VoIP conversations, decoding scrambled passwords, recovering wireless network keys, revealing password boxes, uncovering cached passwords and analyzing routing protocols. The program does not exploit any software vulnerabilities or bugs that could not be fixed with little effort. It covers some security aspects/weakness present in protocol's standards, authentication methods and caching mechanisms; its main purpose is the simplified recovery of passwords and credentials from various sources, however it also ships some "non standard" utilities for Microsoft Windows users.
Cain & Abel has been developed in the hope that it will be useful for network administrators, teachers, security consultants/professionals, forensic staff, security software vendors, professional penetration tester and everyone else that plans to use it for ethical reasons. The author will not help or support any illegal activity done with this program. Be warned that there is the possibility that you will cause damages and/or loss of data using this software and that in no events shall the author be liable for such damages or loss of data. Please carefully read the License Agreement included in the program before using it.
The latest version is faster and contains a lot of new features like APR (Arp Poison Routing) which enables sniffing on switched LANs and Man-in-the-Middle attacks. The sniffer in this version can also analyze encrypted protocols such as SSH-1 and HTTPS, and contains filters to capture credentials from a wide range of authentication mechanisms. The new version also ships routing protocols authentication monitors and routes extractors, dictionary and brute-force crackers for all common hashing algorithms and for several specific authentications, password/hash calculators, cryptanalysis attacks, password decoders and  some not so common utilities related to network and system security.

Download Cain & Abel v2.0 for Windows 9x (discontinued and not supported anymore)
MD5 - A14185FAFC1A0A433752A75C0B8CE15D
SHA1 - 8F310D3BECC4D18803AF31575E8035B44FE37418
Download Cain & Abel v4.9.51 for Windows NT/2000/XP
MD5 - 9C627850434B8C5A24CF37B45ACAEA42
SHA1 - 552E633635AF426EC4173785862D9767118B874B


  • Cisco PIX Firewall password calculator for Windows 9x/NT/2000/XP

  • IRS v2.0 for Windows NT/2000/XP

  • ArpWorks v1.0 for Windows 95/98

Thursday, 5 December 2013

Mobile Network

Q1-How Does a Mobile Network Work?
A mobile network, also referred to as a cellular network, employs the use of radio frequencies that can be used simultaneously by several callers at one and the same time. Cell-sites and mobile devices manipulate the frequency, so that they can make use of low-power transmitters to supply their services with the least possible interference.
Mobile carriers use these mobile networks to offer wide network coverage to their subscribers. Larger regions are split up into smaller cells, all of which are connected to telephone switches or telephone exchanges, which again help in public telecommunication while on the move.
Different types of mobile technologies are used to provide mobile network services to users. Most common among them are GSM (Global System for Mobile Communication), GPRS (General Packet Radio Service), CDMA (Code Division Multiple Access), EDGE (Enhanced Data Rates for GSM Evolution), iDEN (Integrated Digital Enhanced Network) and EV-DO (Evolution-Data Optimized).
The signal reception and/or call service quality may be subject to change, depending upon the current location and region of the user. Some of the leading mobile network providers in the United States of America are Verizon Wireless, AT&T, T-Mobile and Sprint Nextel.

Q2-Functions of bts and bsc in a gsm architecture
Base Station Subsystem
The BSS provides the interface between the ME and the NSS. It is in charge of the transmission and reception. It may be divided into two parts:
  • Base Station Controller (BSC): It controls a group of BTSs and manages their radio ressources. A BSC is principally in charge of handoffs, frequency hopping, exchange functions and power control over each managed BTSs.
  • Base Transceiver Station (BTS) or Base Station: it maps to transceivers and antennas used in each cell of the network. It is usually placed in the center of a cell. Its transmitting power defines the size of a cell. Each BTS has between 1-16 transceivers depending on the density of users in the cell.

Base transceiver station

A base transceiver station (BTS) is a piece of equipment that facilitates wireless communication between user equipment (UE) and a network. UEs are devices like mobile phones (handsets), WLL phones, computers with wireless Internet connectivity. The network can be that of any of the wireless communication technologies like GSM, CDMA, wireless local loop, Wi-Fi, WiMAX or other wide area network (WAN) technology.
BTS is also referred to as the radio base station (RBS), node B (in 3G Networks) or, simply, the base station (BS). For discussion of the LTE standard the abbreviation eNB for evolved node B is widely used.
Though the term BTS can be applicable to any of the wireless communication standards, it is generally associated with mobile communication technologies like GSM and CDMA. In this regard, a BTS forms part of the base station subsystem (BSS) developments for system management. It may also have equipment for encrypting and decrypting communications, spectrum filtering tools (band pass filters), etc. antennas may also be considered as components of BTS in general sense as they facilitate the functioning of BTS. Typically a BTS will have several transceivers (TRXs) which allow it to serve several different frequencies and different sectors of the cell (in the case of sectorised base stations). A BTS is controlled by a parent base station controller via the base station control function (BCF). The BCF is implemented as a discrete unit or even incorporated in a TRX in compact base stations. The BCF provides an operations and maintenance (O&M) connection to the network management system (NMS), and manages operational states of each TRX, as well as software handling and alarm collection. The basic structure and functions of the BTS remains the same regardless of the wireless technologies


In cellular telecommunications, the term handover or handoff refers to the process of transferring an ongoing call or data session from one channel connected to the core network to another channel. In satellite communications it is the process of transferring satellite control responsibility from one earth station to another without loss or interruption of service.
Handover is the mechanism that transfers an ongoing call from one cell to another as a user moves through the coverage area of a cellular system. The number of cell boundary crossings increases because smaller cells are deployed in order to meet the demands for increased capacity.
If we minimize the expected number of handovers the switching load minimizes as well, because each handover requires network resources to reroute the call to the new base station. In GSM, measurement reports, which are transmitted periodically from MS to BS on the SACCH assigned to each communication, are available for each connection. The repetition duration of the SACCH produces a fixed time grid of 480 ms in which the measurement reports occur.
In above Figure the measured RXLEVs from the serving BTS and from a neighborone (NC1), according to the measurement reports submitted during a call, are shown. The horizontal axis represents the number of measurement reports.
Obviously the handover procedure consider a set of parameters in such a way to avoid shortcomings. On the other hand, it is not possible to have a safe handover execution in cases like the one shown in Figure above, since the location and direction of user as well as the area characteristics are not known. In many cases the execution takes place and after a couple of measurement reports the handover procedure is triggered again.
There are several different reasons for a handover. Each mobile terminal attempts to use the radio channel that will provide the best connection quality, i.e., the best C/I (carrier-to interference ratio). Co-channel interference is unavoidable because of multiple use of the same time and frequency channels due to existing cell layouts, and consequently quality can be poor (i.e., bit-error ratio high) despite a high signal level.
The connection of a mobile terminal to the base stations can be the cause of interference to other mobile stations, even if it is a high-quality one. The interference can be minimized if the interfered station changes to a different radio channel. It is also possible for mobile users to have the same good receive quality from more than one cell. The service quality of the network can then be optimized if mobile users are equally distributed over the available cells.
The following pie-chart summarizes the handover causes, showing the percentage of the different reasons for handover:
In order to measure the handover performance in a cellular network several counters are used. As far as the procedure is concerned, each counter is triggered when a Handover Required message, containing the respective cause, is routed from the BSC to the MSC (inter-BSC handover). When the handover is internal (intra-cell or inter-cell, intra-BSC handover), the procedure (decision and execution, respective cause counted) is undertaken by the responsible BSC and the MSC is informed by a Handover Performed message.
An in-depth statistical evaluation shows that, there are several shortcomings in the normal handover procedure. The major ones are the following:
·         High failure of handovers, due to an insufficient planning in certain areas.
·         “Far-away-cell”, where subscribers are served from a BTS that is far away from the cell where the user is located
·         “Ping-pong” effect, the repeated handover between two base stations caused by rapid fluctuations in the received signal strengths from both base stations.
·         Unnecessary handover often leads to increased signaling traffic, which can result in traffic congestion in the call-setup procedure of other subscribers intending to set up calls.

Q4-What is cdma2000
CDMA2000 (also known as C2K or IMT Multi‑Carrier (IMT‑MC)) is a family of 3G mobile technology standards, which use CDMA channel access, to send voice, data, and signaling data between mobile phones and cell sites. The name CDMA2000 actually denotes a family of standards that represent the successive, evolutionary stages of the underlying technology. These are, in order of evolution:
·         CDMA2000 1xRTT
·         CDMA2000 1xEV-DO: Release 0, Revision A, Revision B
·         CDMA2000 1xEV-DO Revision C or Ultra Mobile Broadband (UMB)
·         CDMA2000 1xEVDV
All are approved radio interfaces for the ITU's IMT-2000. CDMA2000 has a relatively long technical history and is backward-compatible with its previous2G iteration IS-95 (cdmaOne). In the United States, CDMA2000 is a registered trademark of the Telecommunications Industry Association (TIA-USA)
CDMA2000 is a code-division multiple access (CDMA) version of the IMT-2000 standard developed by the International Telecommunication Union (ITU). The CDMA2000 standard is a 3G mobile technology.
The CDMA2000 family of standards includes 1xRTT, EV-DO Rev 0, EV-DO Rev A and EV-DO Rev B (now called Ultra Mobile Broadband -- UMB). The CDMA2000 family of standards is deployed by Verizon Wireless and Sprint in the U.S. and uses CDMA technology as the underlying multiplexing scheme. CDMA2000 is often confused with CDMA technology itself.
CDMA2000 has several advantages:
Stronger signal: CDMA2000 has the ability to use signals that arrive in the receivers with different time delays -- known as multipath. It uses the multipath signals and combines them to make the cellular signal stronger.
Drop-offs and breakups: Drop-offs occur only when the mobile device is two times further from the cellular base station. CDMA networks use a scheme called soft handoff, which minimizes signal breakup as a handset passes from one cell to another.
Analog capabilities: In rural areas of the U.S., CDMA2000 offers analog capabilities that GSM does not.
Capacity: CDMA2000 has a very high spectral capacity, so it can accommodate more users per MHz of bandwidth.
Noise reduction: CDMA2000 uses an exclusive technology called vocoder EVRC which reduces background noise.
CDMA2000 has a few disadvantages:
Channel pollution: One major problem with CDMA2000 is channel pollution, where there are too many signals from cell sites in the subscriber's phone, but none is dominant -- degrading call quality.
International roaming: Another disadvantage of this technology is the lack of international roaming capabilities and the only CDMA2000 devices that can be used internationally must also have a GSM radio. If you have mobile users who travel overseas you may want to consider a dual-mode mobile device, because it offers the most flexible solution for international mobile users.
Remote activation: CDMA2000 devices are activated remotely, by the carrier, using the phone's electronic serial number (ESN). Since each carrier has a database of all the ESNs that are approved for its network, this lets most CDMA carriers refuse to activate phones not originally intended for their network.
In the U.S., CDMA2000 and GSM are currently the competing cellular phone standards. They are about equal in the U.S. in terms of users; but, internationally, 85% of the mobile users employ GSM. The future battle in cellular communications will be between WiMAX and Long Term Evolution (a GSM technology).
It is important for mobile managers to realize that -- in the long term -- the CDMA2000 family will be phased out. Verizon is abandoning CDMA2000 and moving to the GSM family for its 4G LTE network, and Sprint is using WiMAX for its 4G rollout.
Mobile managers need to consider such factors as coverage, performance, international roaming, mobile device selection and price when planning or modifying their mobile strategy. This is a major consideration for enterprises with distributed offices, employees and international business travelers when planning their mobile communications strategy.
Q5-Diversity techniques
In telecommunications, a diversity scheme refers to a method for improving the reliability of a message signal by using two or more communication channels with different characteristics. Diversity plays an important role in combatting fading and co-channel interference and avoiding error bursts. It is based on the fact that individual channels experience different levels of fading and interference. Multiple versions of the same signal may be transmitted and/or received and combined in the receiver. Alternatively, a redundant forward error correction code may be added and different parts of the message transmitted over different channels. Diversity techniques may exploit the multipath propagation, resulting in a diversity gain, often measured in decibels.
The following classes of diversity schemes can be identified:
·         Time diversity: Multiple versions of the same signal are transmitted at different time instants. Alternatively, a redundant forward error correction code is added and the message is spread in time by means of bit-interleaving before it is transmitted. Thus, error bursts are avoided, which simplifies the error correction.
·         Frequency diversity: The signal is transmitted using several frequency channels or spread over a wide spectrum that is affected by frequency-selective fading. Middle-late 20th century microwave radio relay lines often used several regular wideband radio channels, and one protection channel for automatic use by any faded channel. Later examples include:
·         OFDM modulation in combination with subcarrier interleaving and forward error correction
·         Spread spectrum, for example frequency hopping or DS-CDMA.
·         Space diversity: The signal is transmitted over several different propagation paths. In the case of wired transmission, this can be achieved by transmitting via multiple wires. In the case of wireless transmission, it can be achieved by antenna diversity using multiple transmitter antennas (transmit diversity) and/or multiple receiving antennas (reception diversity). In the latter case, a diversity combining technique is applied before further signal processing takes place. If the antennas are far apart, for example at different cellular base station sites or WLAN access points, this is called macrodiversity or site diversity. If the antennas are at a distance in the order of one wavelength, this is called microdiversity. A special case is phased antenna arrays, which also can be used for beamformingMIMO channels andspace–time coding (STC).
·         Polarization diversity: Multiple versions of a signal are transmitted and received via antennas with different polarization. A diversity combining technique is applied on the receiver side.
·         Multiuser diversity: Multiuser diversity is obtained by opportunistic user scheduling at either the transmitter or the receiver. Opportunistic user scheduling is as follows: at any given time, the transmitter selects the best user among candidate receivers according to the qualities of each channel between the transmitter and each receiver. A receiver must feed back the channel quality information to the transmitter using limited levels of resolution, in order for the transmitter to implement Multiuser diversity.
·         Cooperative diversity: Achieves antenna diversity gain by using the cooperation of distributed antennas belonging to each node.
There are several types of receiver diversity methods
Time Diversity
Frequency Diversity
Multiuser Diversity
Space Diversity

Q6-what is wmax
WiMAX is a wireless technology put forth by the WiMAX Forum that is one of the technologies that is being used for 4G networks. It can be used in both point to point and the typical WAN type configurations that are also used by 2G and 3G mobile network carriers. Its formal name is IEEE standard 802.16. Sprint owns a WiMAX based network that is marketed under the name XOHM, though that will eventually be merged with Clearwire's network and sold under the Clearwire name. LTE is a competing technology that has the support of far more carriers worldwide.

Architecture of wimax
The IEEE 802.16e-2005 standard provides the air interface for WiMAX but does not define the full end-to-end WiMAX network. The WiMAX Forum's Network Working Group (NWG) is responsible for developing the end-to-end network requirements, architecture, and protocols for WiMAX, using IEEE 802.16e-2005 as the air interface.
The WiMAX NWG has developed a network reference model to serve as an architecture framework for WiMAX deployments and to ensure interoperability among various WiMAX equipment and operators.
The network reference model envisions a unified network architecture for supporting fixed, nomadic, and mobile deployments and is based on an IP service model. Below is simplified illustration of an IP-based WiMAX network architecture. The overall network may be logically divided into three parts:
  1. Mobile Stations (MS) used by the end user to access the network.
  2. The access service network (ASN), which comprises one or more base stations and one or more ASN gateways that form the radio access network at the edge.
  3. Connectivity service network (CSN), which provides IP connectivity and all the IP core network functions.
The network reference model developed by the WiMAX Forum NWG defines a number of functional entities and interfaces between those entities. Fig below shows some of the more important functional entities.
  • Base station (BS): The BS is responsible for providing the air interface to the MS. Additional functions that may be part of the BS are micromobility management functions, such as handoff triggering and tunnel establishment, radio resource management, QoS policy enforcement, traffic classification, DHCP (Dynamic Host Control Protocol) proxy, key management, session management, and multicast group management.
  • Access service network gateway (ASN-GW): The ASN gateway typically acts as a layer 2 traffic aggregation point within an ASN. Additional functions that may be part of the ASN gateway include intra-ASN location management and paging, radio resource management, and admission control, caching of subscriber profiles, and encryption keys, AAA client functionality, establishment, and management of mobility tunnel with base stations, QoS and policy enforcement, foreign agent functionality for mobile IP, and routing to the selected CSN.
  • Connectivity service network (CSN): The CSN provides connectivity to the Internet, ASP, other public networks, and corporate networks. The CSN is owned by the NSP and includes AAA servers that support authentication for the devices, users, and specific services. The CSN also provides per user policy management of QoS and security. The CSN is also responsible for IP address management, support for roaming between different NSPs, location management between ASNs, and mobility and roaming between ASNs.

The WiMAX architecture framework allows for the flexible decomposition and/or combination of functional entities when building the physical entities. For example, the ASN may be decomposed into base station transceivers (BST), base station controllers (BSC), and an ASNGW analogous to the GSM model of BTS, BSC, and Serving GPRS Support Node (SGSN).

Saturday, 5 October 2013



How your email server works


How the DNS works


How the Internet Works


Internet Structure Educational Video


How the internet works


Animated CompTIA Network+ Video Course at PowerCert.com


Installation And Configuration of MS Exchange Server 2010


Windows Server 2012: Installation process and basic configuration