Construct A Script By Using Scapy Computer Science Essay

Construct A Script By Using Scapy Computer Science Essay Wireless network generally can be defined as a network which is set up by using radio signal frequency to communicate among computers and other network devices. Wireless networks known as WiFi network or WLAN. As a network grows and expands wireless networks are extremely popular and easy to setup feature and no cabling involved. There are two main components to access the wireless network which are wireless router or access point and wireless clients. Wireless network normally used in 802.11a, 802.11b, 802.11g, and 802.11n standards protocol. Wireless network needs highly security to carry all kinds of confidential data which means at least enabling Wired Equivalent Privacy (WEP) on the access point. Without proper implementation of security measures, any wireless network adapter coming within the range can access the internet without permission. So, it will results in congestion and some of the authorized client cannot access the internet. So, this research will do wireless network auditing by sniffing some of the information within the access point and detect possible intrusions in Faculty of Computer and Mathematical Sciences. 1.1 Background Wireless network is a network which is setup by using radio signal frequency to communicate among multiple stations at one time. In addition, wireless network referred as WiFi network or WLAN. Although we have enable WEP encryption on the access point, there are still some weaknesses which can be easily crack by the users with the right equipment to crack. The attacker can sniff easily with several tools to crack the password to break in as unauthorized person. In order to verify the correct access point settings and detect intrusions in terms of security in wireless network, we construct the complete script to audit wireless networks. 1.2 Problem Statement Nowadays wireless network become a trend in communication. Each wireless system or access point was setup with certain policies. It is hard to verify whether each wireless access point setup correctly or not. Plus, nowadays we need to use many tools to verify the wireless access point status. Furthermore, most of network admin does not check back each wireless access point after its configuration. Moreover, we need some tools to identify the intrusions that come where they are try to access the Internet. Besides that, some of attackers send spoofing frame to try access the wireless network. So, we cannot identify the attackers MAC address. 1.3 Research Objectives The main objective of this project is: To construct a script by using Scapy To sniff and to find possible intrusion on wireless network related with wireless security. 1.4 Scope of the Research This project focuses in Faculty of Computer and Mathematical Sciences that has multiple access points which will enables to sniff all the information on wireless networks. We focuses on Data Link layer 2 to sniff the broadcast frame and identify possible intrusion. The main platform to run the tools:- Ubuntu10.10 We are use two main tools to construct the script which are:- Python2.6 Scapy 1.5 Significance of the Research This project is important to gain knowledge to construct the complete script by using Python2.6 and Scapy script. We can learn the easiest way by using this script with the shorter line compared to other script. This project also helps to learn 802.11 frame structure including beacon frame that has transmitted by the access point. 1.6 Organization of Thesis This project divided into 5 main chapters: Chapter 1: In this chapter, we discussed on the introduction generally of this topic. It includes problem statement, objectives, scope and significance of the research. Chapter 2: This chapter reviewed literature that relate to the topic with previous researches. We include the similar of related studies to our research. Chapter 3: In third chapter, we identify materials and methods that are described in methodology phases in order to get the desired information for the accomplishment of this research. Chapter 4: In fourth chapter, we discusses on the findings of the research. Chapter 5: Finally, the last chapter is focuses on the recommendations and suggestions where it will summarize the conclusion of the research. 1.7 Conclusion This introduction of this chapter had clearly explained the problem statement, objectives, scope, and significances of the research. This chapter gives a clear view of the overall content of the research. CHAPTER 2 LITERATURE REVIEW 2.0 Introduction This chapter examines the previous work done by prior researcher in the field of auditing wireless network, security of wireless network and any other related works. Section 2.1 discuss on main platform to install the tools. Section 2.2 discuss on the tools to be use to construct and run the script. Section 2.3 discuss on standard protocol fro wireless Lan(WLAN), IEE 802.11. Then, sections 2.4 discuss on frame for 802.11, 2.5 Wireless LAN components, 2.6 Wireless Network Sniffing, 2.7 reviews for the related works and lastly 2.8 Summarizations of Literature Reviews. 2.1 Platform 2.1.1 Ubuntu10.10 Ubuntu is a free operating system, developed by small team developers who are established Linux Debian projects. This free operating system was developed to facilitate the use of desktop linux, Ubuntu. It developed based on the Debian GNU/Linux distribution and distributed as free and open source software. Most Ubuntu packages are based on package from Debian. Both distributions are using Debians deb package format and package management tools, Apt and Synaptic. However, sometimes .deb packages need to be rebuild from source to be used in Ubuntu. Ubuntu have variant edition such as GNOME desktop, KDE edition, Kubuntu and server edition. In this project, we use Ubuntu 10.10 as our platform to run all the tools in it. 2.2 Tools 2.2.1 Python Python is the one of the programming language that can interpret in developing the applications such as web applications and integrate the system more effectively. Python can run on Windows, Linux/Unix, Mac OS X. All the Python programs can be packaged into stand-alone executable code for many using various tools. In this project, we use the latest version, Python2.6 tool to construct and run the complete script after install all the Python package in Ubuntu10.10. We use Python as a programming language because it is most powerful language and shorter to write the code than other languages. Compared to other programming languages, Python are readable syntax, intuitive object orientation, very high level dynamic data types, full modularity, supporting hierarchical packages and many more. 2.2.2 Scapy According to Philippe Biondi (2009), Scapy is a powerful interactive packet manipulation program from Python program that be able to forge or decode packets of a wide number of protocols, send them on the wire, capture them, match requests and replies, and much more. It can easily handle most classical tasks like scanning, tracerouting, probing, unit tests, attacks or network discovery. For this project, we focused on 802.11 standard protocols. Scapy enable to sniff wireless network and generate the packet and can send it to the wireless network. 2.3 Wireless Protocol 2.3.1 IEEE 802.11 IEEE 802.11 is a standard protocol for wireless LAN (WLAN), which is uses RF technology to transmit and receive data over the air. Based on this standard protocol, it communicates between wireless client and a base stations or access point. There are several types of standard protocols which are 802.11a, 802.11b, 802.11g, and 802.11n. Here are briefly about types of standard protocols: 2.3.1.1 IEEE 802.11b IEEE 802.11b standard supports maximum bandwidth 11Mbps in 2.4 Ghz. The advantage of this protocol is lowest. Disadvantage using this protocol is lowest maximum speed because it may interfere if no determined the frequency band. 2.3.1.2 IEEE 802.11a 802.11a supports bandwidth up to 54 Mbps in 5 GHz. The advantage of this protocol is fast maximum speed. Disadvantage using this protocol is the cost is higher than IEE 802.11b 2.3.1.3 IEE 802.11g IEE 802.11g standard supports maximum bandwidth 54Mbps in the 2.4 GHz band in maximum range. The advantage is signal range is better with fastest maximum speed. Disadvantage using this protocol is higher cost than IEEE 802.11b. 2.3.1.4 IEEE 802.11n IEEE 802.11n is developed on previous IEEE 802.11 standards by adding MIMO. IEEE 802.11n offers high throughput wireless transmission at 100Mbps 200 Mbps. It is better performance compared with IEE 802.11g. 2.4 802.11 Frame 2.4.1 Frame header Each  frame  contains  a  standard  header  as  shown  in  Figure  2.1 Figure 2.1 Frame Header from http://technet.microsoft.com/en-us/library/cc757419(WS.10).aspx The  frame header  contains  all  the  information  needed  to  get  the  frame to  where  it  is  going  and  allow  the  receiver  to  understand  what message  the  frame  is  carrying. Frame Control FC contains control information used for defining the type of 802.11 MAC frame and providing information necessary. FC field as shown in Figure 2.2 Figure 2.2 Frame Control Field from http://technet.microsoft.com/en-us/library/cc757419(WS.10).aspx The details of frame control field as follows: Protocol Version Protocol Version provides the current version of the 802.11 protocol used. Type and Subtypes It is determines the function of the frame. There are three main different of type fields which are control, data and management and breaks into multiple subtypes. Three values of type field: 00 Management 01 Control 10 Data 11 Reserved/Unused Breaks into subtype field: 00/0000 Management/Association Request 00/1000 Management/Authentication 00/1100 Management/Deauthentication 01/1011 Control/Request To Send (RTS) 10/0000 Data/Data To DS and from DS Specify  the  addressing  type  of  the frame, either the frame is going to or exiting from the DS. More Fragments   Shows more fragments of the frame, either data or management type. Retry Retransmitted either data or management frame types. Power Management   shows whether the sending station is in active mode or power-save mode. More Data   shows to a station in power-save mode that the AP has more frames to send. It is also used for APs to show that additional broadcast/multicast frames are to follow. WEP   shows whether or not encryption and authentication are used in the frame. Order   Shows that all received data frames must be processed in order. Duration/ID Shows the remaining duration needed to receive the next frame transmission. Sequence Control (SEQ) SEQ used  for  fragmentation  and packet  reassembly. Frame body The frame body contains the data or information included in either management type or data type frames. Frame Check Sequence (FCS) The transmitting STA uses a cyclic redundancy check (CRC) over all the fields of the MAC header and the frame body field to generate the FCS value. 2.4.2 Beacon Frame Beacon frames are identified by the type field being set to 0 (Management Frame) and subtype of 8. Beacon frame are used by access point to advertise its presence and relay information, such as timestamp, SSID, and other parameters based on access point to radio NICs that are within range. Radio NICs continually scan all 802.11 radio channels and listen to beacons as the basis for choosing which access point is best to associate with. According to Robin Wood (2007), people  mostly believe that turning  off  beacons  will  hide  their  network  from  attacks  as  their SSID will no longer be broadcast. Unfortunately, SSID is transmitted in clear text in all management frames and when the network is hidden while there is no data being transmitted, attacker can collect a management frame they can find in network SSID. 2.5 Wireless LAN component 2.5.1 Access point Wireless access point (WAP) is a basically hardware equipment that allows wireless devices to connect to a wired network using Wi-Fi, Bluetooth or related standards. In a wireless network, an access point sends and receives signals to any number of other, local wireless devices. These are usually adapters and routers. The WAP is commonly use in offices, homes and educational institutions. WAP devices use in IEEE 802.11 standards. 2.6 Wireless Network Sniffing Wireless Sniffer is captures the data on wireless network without being detected. Wireless network sniffing works in 802.11, Ethernet as the physical and data link layers which is able of reporting raw packets (RFMON support), which include any prism2 based card (Linksys, D-Link, Rangelan, etc), Cisco Aironet cards, and Orinoco based cards. Moreover, sniffing can also help find the easy kill as in scanning for open access points that allow anyone to connect, or capturing the passwords used in a connection session that does not even use WEP, or in telnet, rlogin and ftp connections. Sniffing wireless network usually used by the attackers to capture the data and get the appropriate information from the beacon frame. There are several techniques used to sniff the wireless network. Some of them are as follows:- Passive Scanning Passive scanning is the first steps used to sniff the wireless networks. It is turn to mode RF into monitor mode that allows every frame appearing on a channel to be copied as the radio of the station tunes to various channels. A station in monitor mode can capture packets without associating with an AP or ad-hoc network. When the transmission of the data in the form of radio waves starts the attackers can scan the whole data passively and carry on the sniffing process. The so-called promiscuous mode allows the capture of all wireless packets of an associated network. In this mode, packets cannot be read until authentication and association are completed. With the help of this data sniffer can easily decodes the secret information of the wireless networks. SSID Detection After scan the data transmitted, it can detect the list of service set identifier (SSID) in the particular wireless network. The SSID shown in the Beacon frames is set to null in the hope of making the WLAN invisible unless a client already knows the correct SSID.  When the Beacon displays a null SSID, there are two possibilities.   Eventually, an Associate Request may appear from a legitimate station that already has a correct SSID.   To such a request, there will be an Associate Response frame from the AP.   Both frames will contain the SSID in the clear, and the attacker sniffs these.   If the station wishes to join any available AP, it sends Probe Requests on all channels, and listens for Probe Responses that contain the SSIDs of the APs.   The station considers all Probe Responses, just as it would have with the non-empty SSID Beacon frames, to select an AP. Normal association then begins.   The attacker usually waits to sniff these Probe Responses and extract the SSIDs. Otherwise, if the beacon transmission is disabled, the attacker has two choices.   The attacker can keep sniffing waiting for a voluntary Associate Request to appear from a legal station that already has a correct SSID and sniff that SSID.   Collection of MAC addresses After detecting the SSID, sniffer now take steps to sniff the wireless network by collecting the required MAC addresses with the help of passive scanning and also with the help of different types of software. The collected of MAC address used for constructing spoofed frame by using specific tool. In wireless sniffing, there are some reasons why attacker collects all the MAC address. Some of the reasons are the attacker used sniffing to hide his or her identity and their access points. The other reason, access points used in collecting the MAC would not be registered. 2.7 Review of Previous Related Works 2.7.1 Author: David Maynor Title of Paper: Beginners Guide to Wireless Auditing (2006) This paper is a study of how to find the vulnerabilities in wireless devices drivers with specific techniques. The researcher discuss on how to build auditing environment, how to construct tools and finally how to interpret the results. On this paper, although this was done on Dell Latitude D610, the internal wireless card of the machine was not used. The researcher was used wireless card, Netgear WPN511 to set up auditing environment that is supported with madwifi drivers. The combination with LORCON (Loss Of Radio CONnectivity) ability to craft the packet from scratch. Moreover, after setting up the good environment with patch madwifi and LORCON, the researcher construct the script with Scapy to generate a simple frame and inject it. The researcher use Wireshark to see the packets injected. 2.7.2 Author: Shreeraj Shah Title of Paper: Secure Your Wireless Networks with Scapy Packet Manipulation (2007) According to Shreej Shah, Scapy is scriptable and easy to use compared with Kismet and Airodump-ng. This paper focused on intrusion detection by using proven techniques. There are two techniques can be employed which are passive sniffing and active packet injection. The researcher discussed only passive sniffing methodology. In this project, there are several steps are used in passive sniffing methodology as follows:- Set up a station for radio frequency (RF) monitor mode Sniff packets and discover network access points Discover hidden access points and SSID (service set identifier) Harvest MAC and IP addresses Perform ongoing intrusion detection with sniffing. 2.7.3 Author: Robin Wood, Robin and freedomsoftware.co.uk Title: Programming Wireless Security (2007) This paper discussed some programming techniques to build wireless security tools. The researchers construct the script by using Python and Ruby script. There are several techniques that are used by using both scripts including deauthentication attack, sniffing wireless traffic and automating a Four-Way- Handshake capture. All the techniques will be brought together to create an applications to automate capturing an EAPOL handshake which can used to crack the Pre-Shared Key. This paper required several tools including Lorcon, Pylorcon, ruby lorcon and Scruby. Moreover, it also discussed about several issues on Scruby which means Ruby scripts will not work properly as exactly required. 2.8 Summarizations of some Literature Reviews No Author Year Project Title Project Similarities and Differences 1. Peter Seebach 2005 Getting practical about wireless security, Part 1: Building a wireless sniffer with Perl In this paper, lightweight wireless sniffer was build that runs on open source software. This paper show to use open source software by getting information about on wireless network and identified the common security problem. 2. TJ OConnor 2010 Detecting and Responding to Data Link Layer Attacks In this paper, Scapy is used to examine network traffic for data link layer attacks with identifying signatures and anomalies on both wired and wireless networks. 3. Petter Clutterbuck, Terry Rowlands, Owen Seamons 2007 Auditing the Data Confidentiality of Wireless Local Area Networks This paper describes how the software auditing artefact uses on sampled data packets to product a very detailed evaluation of the level of data confidentiality in effect across the WLAN. 4. Mingzhe Li, Mark Claypool, and Robert Kinicki 2005 How to Build and Use an IEEE 802.11 Wireless Network Sniffer In this paper, wireless sniffer is built on computers with Linux operating systems and prism GT-based wireless interface cards. The operating systems tested are SUSE (Novell) Linux release 9.0/9.1/9.2/10.0 and Linux Fedora Core 3 where the kernel version can be either 2.4.x or 2.6.x. The wireless network interface cards, Netgear WG 511 version 1 PCMCIA card and Allnet ALL0271 54Mbit Wireless PCI adapter are used Table 2.1: Summarization of related Literature Review 2.9 Conclusion All the information gathered from this literature review is very useful in order to identify potential information that can make this research more relevant. By understanding the scenario of past implementation, it will give a better view on how to achieve these research objectives and also inspire new ideas to be implemented or added into this research. CHAPTER 3 METHODOLOGY 3.0 Introduction This chapter presents about the methodology being used as a guideline to ensure the project will operate successfully. Methodology consists of hardware, software and method that being used in this research. We need to choose proper hardware and software to meet the research requirement. Methodology is very important part to audit the wireless network with sequence of phases. We need to follow all this phases in order to accomplish the final project with achieving the objective. We divide the methodology of our project to several phases, where every phase will include the important activities and its significant to be done. 3.1 Methodology Phase In this project, there are four phases of method that followed properly. First phase is planning, second phase is development, third phase is testing, fourth phase is result and evaluation and the last phase is documentation. All the flow of the methodology phase will be implementing systematically and efficiently as its role is vital to ensure the process of finishing this project in time. These phases are illustrated in methodology overview in Figure 3.1(i) and Figure 3.1(ii). PLANNING DEVELOPMENT TESTING RESULT AND EVALUATION DOCUMENTATION Figure 3.1 Project Phase (i) Documentation Development Testing Result and Evaluation Planning Problem Assessment Preliminary study of Literature Install OS Install Python package Install Scapy package Construct script Run Scapy script Sniff a list of access point. Sniff Intrusion Detection Writing a report Project Scope Project Objective Project Planning Determine hardware and software used Scapy script completed Result finding Final report completed. Figure 3.1 Project Phase (ii) 3.2 Research Methodology 3.2.1 Planning For planning phase, the activity is to define the objective of project by identifying problem assessment and by preliminary study of literature review. The deliverable of this phase can identify research objective and scope and also project planning. It consists of: 3.2.1.1 Preliminary study of literature review The purpose is to understanding the similar or related project to be done. We need to review and get the idea on how it can be implemented and find the objective, scope and others benefit can get for the project requirement. This preliminary study can review by journals, online resource (internet), articles or book. USER ACCESS POINT USER SNIFF3.2.2 Development Diagram 3.1: Structure of research project 3.2.2 [a] Install operating system We install Ubuntu 10.10 with interactive Graphical User Interface (GUI) on the laptop. It is easier to update the latest package. All the latest package including Python will updated on Ubuntu10.10 [emailprotected]:~# sudo apt-get update 3.2.2 [b] Install tools We install Scapy in Python program where the Scapy is interactive manipulation program that can construct with the shorter script compared to the other script. We install Python program as a main programming language and resides the entire package in it. a. Install Python 2.6 package [emailprotected]:~# sudo apt-get install python [emailprotected]:~# cd /tmp [emailprotected]: /tmp# fetch http://www.secdev.org/projects/scapy/files/scapy-latest.tar.gz [emailprotected]: /tmp# tar xvzf scapy-latest.tar.gz [emailprotected]: /tmp# cd scapy-2.1.0 [emailprotected]: /tmp/scapy-2.1.0 # python setup.py install b. Install python-scapy package [emailprotected]:~# sudo apt-get install python-libpcap c. Install libpcap and libdnet and their Python wrappers. [emailprotected]:~# sudo apt-get install python-libdnet d. Install additional software for special features. [emailprotected]:~# sudo apt-get install tcpdump graphviz imagemagick python-gnuplot python-crypto python-pyx 3.2.2 [c] Construct the script We construct the script with Python program for sniffing and detect possible vulnerabilities. The script will run on Ubuntu 10.10 in root terminal. 3.2.3 Testing Testing phase, the action is to test by sniffing wireless network in an area by running the completed script. Before we run the script, we need to setting up the station for radio frequency (FR) in monitor mode. We illustrates the steps in Figure 3.2 Construct the script Setting up the station for Radio Frequency (RF) to monitor mode Script run Enter the command Get the data from acces point including:- Name of access point SSID channel Radio Type Security Type Signal Collect the data: Intrusion Detection including:- Discovering Rogue Access Point Discovering Dummy Access Point Figures 3.2 Steps for testing 3.2.4 Result and Evaluation In this phase, we come out with the result by running the script. We collect all the information about SSID, MAC address, channel, radio type, security type, signal from broadcast frame that send by multiple access point. Next, we can detect possible intrusion by running other script using a same scripting language. 3.2.5 Documentation In this final phase, all the results and findings will be included in one report. From the documentation, the researcher can determine whether the project achieve the objectives or not. 3.3 Hardware and Software Required To execute this project successfully, some requirement need to be accomplish. Some of the requirement will be involving hardware and software. Hardwares that will be required are: 3.3.1 Hardware This project will used laptop. Processor at least 1 Gigahertz of CPU speed. 3GB of RAM 250 Gigabyte of hard disk space Intel WiFi Link 5100 wireless network interface card Motherboard that support the processor Monitor Network cable 3.3.2 Software This project will be running on LINUX platform: Ubuntu 10.10 3.3.3 Tools Python2.6 Scapy 3.4 Conclusion As a conclusion, this chapter is very important to gather all related and relevant information required. All the information will be used in order to achieve the objectives of this research. CHAPTER 4 RESULTS AND DISCUSSIONS 4.0 Introduction This chapter discusses on the results gathered from this research, which is obtained by implementing the methods in Chapter 3. The result based on running completed script on Ubuntu10.10. It will display all the available information of access point actively in an area after sniffing it. Moreover we can detect all the possible intrusion with display the list of rogue access point and dummy access point. 4.1 Sniff the wireless network First of all we set up Radio Frequency (RF) into monitor mode which is in wlan0 interface. Next, we run the completed script that is already saved in root on Ubuntu 10.10 with the name of file, sniffap.py. Then, we open the root terminal by enter ./sniffap.py wlan0. The result has shown in Figure 4.1 Figure 4.1 Sniff Wireless Networks sniffap.py name of saved file wlan0 monitor mode interface CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS 5.0 Introduction This final chapter discuss about the conclusion of this research. It also discusses the suggestions and recommendations that will help those who want to upgrade or refers to this project in the future. 5.1 Conclusion As you can see, having an effective wireless access policy is critical to the security of any organization that operates a wireless networks. Without appropriate policy, the attacker easily gain access the wireless networks. 5.2 Recommendation This project is hopefully can only use the fully script to get the data from the access point without purchase the tools. Moreover, the admin take the action to get access point more securely and get a better signal for client to access the Internet.

Educational Principles Essay

Jean Piaget’s theories continue to have a major impact on both teacher training and classroom practices. This essay will discuss the three educational principles derived from his theory and also discuss the limitations of preoperational thought from his point of view. The first educational principle is discovery learning. In this principle, children are encouraged to discover things for themselves by interacting with the environment (Berk, 2010). Teachers provide them with things that will promote development thru their imagination and exploration. By providing a variety of materials like art supplies, books, building blocks, musical instruments and more, teachers are offering opportunities to widen their creativity and enhance their learning (Berk, 2010). Through their exploring and thinking students are taking on an active role in their learning and knowledge building. According to Castronova (n. d), â€Å"Piaget was the first to show that children were not â€Å"empty vessels† to be filled with knowledge, but active builders of knowledge. With our current access to so much on the internet and through technology, there are many more opportunities for teachers to introduce children to discovery learning. Another principle is sensitivity to children’s readiness to learn. In this theory, teachers introduce new activities that build on their current skills while challenging their incorrect ways and allowing them to practice those new skills. They do not push them before they are ready (Berk, 2010). It is ok to allow children to experiment and search out answers for themselves. Teachers should assess and identify a child’s strengths and weaknesses. This is where Piaget saw the teachers as facilitators and there to guide the students (Ginn, n. d). Children need to make mistakes and be able to learn from them. The third educational principle is the acceptance of individual differences. Piaget’s theory assumes that children develop at different rates, but in the same sequence, so teachers must plan activities for small groups and individuals (Berk, 2010). This theory’s implication is that instruction should be adapted to the development level of the learner and that the content is consistent with that level of learning (Piaget, n. . ). A child needs to be compared to their own previous level of development. The limitations of preoperational thought from Piaget’s point of view are described by him as what they can’t understand (Berk, 2010). The term preoperational suggests that he compared them to older, more competent children (Berk, 2010). One of these limitations is egocentrism. Piaget assumes that the egocentric child assumes that other people see, feel, and hear exactly the same way that they do (Berk, 2010). This is responsible for animistic thinking that inanimate objects have lifelike qualities (Berk, 2010). Children also have the inability to conserve. That is, something stays the same in quantity even though it’s appearance changes. For example, two children have identical boxes of raisins, but when child 1 spreads their raisins on the table, child 2 is convinced that they have more (Berk, 2010). Preoperational children also have the inability to reverse steps. They can’t mentally go through steps in a problem and reverse direction to the starting point (Berk, 2010). Lastly, they have difficulty with hierarchical classification. This is the inability to organize objects into classes and subclasses based on their differences and similarities (Berk, 2010). In conclusion, according to McLeod (2010), Piaget drew a number of conclusions about the limitations of preoperational thought: (1) Understanding of these situations is ‘perception bound’. Child is drawn by changes in the appearance of the materials to conclude that a change has occurred. (2) Thinking is ‘centered’ on one aspect of the situation.  Child notices change in level of water or in length of clay without noticing that other aspects of the situation have changed simultaneously. (3) Thinking is focused on states rather than on transformations. Child fails to track what has happened to the materials and simply makes an intuitive judgment based on how they appear ‘now’. (4) Thinking is ‘irreversible’ in that the child cannot appreciate that a reverse transformation would return the material to its original state. Reversibility is a crucial aspect of the logical (operational) thought of later stages.

Biography of Rafael Carrera - Rafael Carrera Profile

Guatemalas Catholic Strongman: Josà © Rafael Carrera y Turcios (1815-1865) was the first President of Guatemala, serving during the turbulent years of 1838 to 1865. Carrera was an illiterate pig farmer and bandit who rose to the presidency, where he proved himself a Catholic zealot and iron-fisted tyrant. He frequently meddled in the politics of neighboring countries, bringing war and misery to most of Central America. He also stabilized the nation and is today considered the founder of the Republic of Guatemala. The Union Falls Apart: Central America achieved its independence from Spain on September 15, 1821 without a fight: Spanish forces were more desperately needed elsewhere. Central America briefly joined with Mexico under Agustà ­n Iturbide, but when Iturbide fell in 1823 they abandoned Mexico. Leaders (mostly in Guatemala) then attempted to create and rule a republic they named the United Provinces of Central America (UPCA). Infighting between liberals (who wanted the Catholic Church out of politics) and conservatives (who wanted it to play a role) got the best of the young republic, and by 1837 it was falling apart. Death of the Republic: The UPCA (also known as the Federal Republic of Central America) was ruled from 1830 by Honduran Francisco Morazà ¡n, a liberal. His administration outlawed religious orders and ended state connections with the church: this enraged the conservatives, many of whom were wealthy landowners. The republic was mostly ruled by wealthy creoles: most Central Americans were poor Indians who did not care much for politics. In 1838, however, mixed-blooded Rafael Carrera appeared on the scene, leading a small army of poorly armed Indians in a march on Guatemala City to remove Morazà ¡n. Rafael Carrera: Carrera’s exact date of birth is unknown, but he was in his early to mid-twenties in 1837 when he first appeared on the scene. An illiterate pig farmer and fervent Catholic, he despised the liberal Morazà ¡n government. He took up arms and persuaded his neighbors to join him: he would later tell a visiting writer that he had started out with thirteen men who had to use cigars to fire their muskets. In retaliation, government forces burned down his house and (allegedly) raped and killed his wife. Carrera kept fighting, drawing more and more to his side. The Guatemalan Indians supported him, seeing him as a savior. Uncontrollable: By 1837 the situation had spiraled out of control. Morazà ¡n was fighting two fronts: against Carrera in Guatemala and against a union of conservative governments in Nicaragua, Honduras and Costa Rica elsewhere in Central America. For a while he was able to hold them off, but when his two opponents joined forces he was doomed. By 1838 the Republic had crumbled and by 1840 the last of the forces loyal to Morazà ¡n were defeated. The republic sundered, the nations of Central America went down their own paths. Carrera set himself up as president of Guatemala with the support of the Creole landowners. Conservative Presidency: Carrera was a fervent Catholic and ruled accordingly, much like Ecuador’s Gabriel Garcà ­a Moreno. He repealed all of Morazà ¡n’s anti-clerical legislation, invited the religious orders back, put priests in charge of education and even signed a concordat with the Vatican in 1852, making Guatemala the first breakaway republic in Spanish America to have official diplomatic ties to Rome. The wealthy Creole landowners supported him because he protected their properties, was friendly to the church and controlled the Indian masses. International Policies: Guatemala was the most populous of the Central American Republics, and therefore the strongest and wealthiest. Carrera often meddled in the internal politics of his neighbors, especially when they tried to elect liberal leaders. In Honduras, he installed and supported the conservative regimes of General Francisco Ferrara(1839-1847) and Santos Guardiolo (1856-1862), and in El Salvador he was a huge supporter of Francisco Malespà ­n (1840-1846). In 1863 he invaded El Salvador, which had dared to elect liberal General Gerardo Barrios. Legacy: Rafael Carrera was the greatest of the republican era caudillos, or strongmen. He was rewarded for his staunch conservatism: the Pope awarded him the Order of St. Gregory in 1854, and in 1866 (a year after his death) his face was put on coins with the title: â€Å"Founder of the Republic of Guatemala.† Carrera had a mixed record as President. His greatest achievement was stabilizing the country for decades at a time when chaos and mayhem were the norm in the nations surrounding his. Education improved under the religious orders, roads were built, the national debt was reduced and corruption was (surprisingly) kept to a minimum. Still, like most republican-era dictators, he was a tyrant and despot, who ruled mainly by decree. Freedoms were unknown. Although it is true that Guatemala was stable under his rule, it is also true that he postponed the inevitable growing pains of a young nation and did not allow Guatemala to learn to rule itself. Sources: Herring, Hubert. A History of Latin America From the Beginnings to the Present. New York: Alfred A. Knopf, 1962. Foster, Lynn V. New York: Checkmark Books, 2007.

The Invention of Radio Technology

Radio owes its development to two other inventions: the telegraph and the telephone.  All three technologies are closely related, and radio technology actually began as wireless telegraphy. The term radio can refer to either the electronic appliance that we listen with or to the content that plays from it. In any case, it all started with the discovery of radio waves—electromagnetic waves that have the capacity to transmit music, speech, pictures, and other data invisibly through the air. Many devices work by using electromagnetic waves, including radios, microwaves, cordless phones, remote controlled toys, televisions, and more. The Roots of Radio Scottish physicist  James Clerk Maxwell first predicted the existence of radio waves in the 1860s. In 1886, German physicist  Heinrich Rudolph Hertz demonstrated that rapid variations of electric current could be projected into space in the form of radio waves, similar to light waves and heat waves. In 1866, Mahlon Loomis, an American dentist, successfully demonstrated wireless telegraphy. Loomis was able to make a meter connected to a kite cause a meter connected to another nearby kite to move. This  marked the first known instance of wireless aerial communication. But it was Guglielmo Marconi, an Italian inventor, who proved the feasibility of radio communication. He sent and received his first radio signal in Italy in 1895. In 1899, he flashed the first wireless signal across the English Channel, and two years later received the letter S, which was telegraphed from England to Newfoundland (now part of Canada). This was the first successful transatlantic radiotelegraph message. In addition to Marconi, two of his contemporaries,  Nikola Tesla and Nathan Stubblefield, took out patents for wireless radio transmitters. Nikola Tesla is now credited with being the first person to patent radio technology. The Supreme Court overturned Marconis patent in 1943 in favor of Teslas. The Invention of Radiotelegraphy Radiotelegraphy is the sending by radio waves of the same dot-dash message (Morse code) used by telegraphs. Transmitters, at the turn of the century, were known as spark-gap machines. They were developed mainly for ship-to-shore and ship-to-ship communication. This form of radiotelegraphy allowed for simple communication between two points. However, it was not public radio broadcasting as we know it today. The use of wireless signaling increased after it was proved to be effective in communication for rescue work at sea. Soon a number of ocean liners even installed wireless equipment. In 1899, the United States Army established wireless communications with a lightship off Fire Island, New York. Two years later, the Navy adopted a wireless system. Up until  then, the Navy had been using visual signaling and homing pigeons for communication. In 1901, radiotelegraph service was established between five Hawaiian Islands. In 1903, a Marconi station located in Wellfleet, Massachusetts,  carried an exchange between President Theodore Roosevelt and King Edward VII. In 1905, the naval battle of Port Arthur in the Russo-Japanese war was reported by wireless. And in 1906, the U.S. Weather Bureau experimented with radiotelegraphy to speed up notice of weather conditions. Robert E. Peary, an arctic explorer, radiotelegraphed  I found the Pole in 1909. A year later, Marconi established regular American-European radiotelegraph service, which several months later enabled an escaped British murderer to be apprehended on the high seas. In 1912, the first transpacific radiotelegraph service was established,  linking San Francisco with Hawaii. Meanwhile, overseas radiotelegraph service developed slowly, primarily because the initial radiotelegraph transmitter was unstable and caused a high amount of interference. The Alexanderson high-frequency alternator and the De Forest tube eventually resolved many of these early technical problems. The Advent of Space Telegraphy Lee de Forest was the inventor of space telegraphy, the triode amplifier, and the Audion, an amplifying vacuum tube. In the early 1900s, the development of radio was hampered by the lack of an efficient detector of electromagnetic radiation. It was De Forest who provided that detector. His invention made it possible to amplify the radio frequency signal picked up by antennae. This allowed for the use of much weaker signals than had previously been possible. De Forest was also the first person to use the word radio. The result of Lee de Forests work was the invention of amplitude-modulated or AM radio, which allowed for a multitude of radio stations. It was a huge improvement over the earlier spark-gap transmitters. True Broadcasting Begins In 1915, speech was first transmitted by radio across the continent from New York City to San Francisco and across the Atlantic Ocean. Five years later, Westinghouses KDKA-Pittsburgh broadcasted  the Harding-Cox election returns and began a daily schedule of radio programs. In 1927, commercial radiotelephony  service linking North America and Europe was opened.  In 1935, the first telephone call was made around the world using a combination of wire and radio circuits. Edwin Howard Armstrong  invented frequency-modulated or FM radio in 1933. FM improved the audio signal of radio by controlling the noise static caused by electrical equipment and the earths atmosphere. Until 1936, all American transatlantic telephone communication had to be routed through England. That year, a direct radiotelephone circuit was opened to Paris. In 1965, the first Master  FM Antenna system  in the world, designed to allow individual FM stations to broadcast simultaneously from one source, was erected on the Empire State Building in New York City.