Static or Dynamic Checkpoint

* As a network administrator for a company, you want to configure an IP route between two routers. Of static and dynamic routing, which is more appropriate? A router is a device that connects two LANs or WANs together. It has the ability to determine the best known route to send packets to a destination. The factors used to determine the best known route include not only the fastest route, but the most efficient.By using routing tables the router can determine the route with the least amount of congestion or traffic, as well as the safest route for the packets to travel. It doesn’t always mean it’s the fastest route to the destination, but it is the most efficient. A router can be manually programmed by the network administrator to provide the most efficient route. This is called static routing. In this type of routing, the network administrator manually determines the best mappings to each destination before the routing begins.This is a finite form of routing. Once the network administrator programs the routers, there is no change in the routing pattern unless it is reprogrammed to a new route. If the pattern runs through a congested network area, a router in the pattern is not functioning properly, or part of the network is down, the router continues to try the same pattern because that is all it is programmed to remember. For today’s larger networks, an unforgiving router mapping is not necessarily the most efficient way of passing information within the network.When routing dynamically, software is used to program a router to be forgiving. This means that the router remembers the best or most efficient path, but if that path is not working, it will try the next most efficient route. The router is able to do this by remembering the routing tables most often used in the network. A dynamic router needs very little maintenance because it automatically remembers the network routing protocols as they are used. If a path is congested or a oute r is down, it uses the remembered routing tables to find the next best route without any manual programming. This type of dynamic routing is fault tolerant. It not only senses the usual route is not efficient, but it shares the information among routers on the internetwork so that all routers are aware of the new route. In the above scenario, as a network administrator in the present time, I would choose to configure an IP route between two routers dynamically.I believe it is more appropriate to route packets in the most efficient manner, and by routing dynamically this will happen automatically, and without any knowledge by the end user. The network administrator will only have to do the initial programming of the router, and the rest is done by the router itself. As a network administrator, not having to program each path a router will take, will free up time for other projects. In the given scenario, routing the network dynamically is the most appropriate choice.

Homeless research Essay

1.0 HYPOTHESIS The aim of this research is to define whether or not drug and or alcohol abuse are contributing factors to becoming homeless. It is not easy to establish a correlation between addiction, homelessness and substance abuse; however this research aims to determine the answer through the collection of  both qualitative and quantitative data in the form of a questionnaire. 2.0 Introduction 2.1 This research intends to discover whether there is a correlation between homelessness and drugs/alcohol abuse? In England homelessness has been accepted as a social norm, although ethically this should not be the case. In 2002 legislation such as The Homelessness Act was brought in for local authorities to prevent homelessness. My interest in the topic arose after attending a programme with Tenant Support a voluntary organisation, regarding an early intervention of alcohol abuse, which aimed to prevent people becoming homeless due to addictions, the question arose, does substance abuse contribute to becoming homeless, and what can be done to help prevent this? In addition to this can becoming homeless create an addiction or alcohol/drug dependency? 3.0 Homelessness 3.1 What is homelessness? Homelessness is viewed as individuals/families finding themselves in a situation where they have no secure accommodation to live in. According to Amore et al ‘How homelessness should be defined is a fundamental and persistent problem’(2011:2). 3.2 Under the 1996 Housing Act a person or persons are defined homeless if: There is no accommodation that they are entitled to occupy They have accommodation but it is not reasonable for them to continue to occupy this accommodation They have accommodation but cannot secure entry to it; They have accommodation but it consists of a moveable structure, vehicle or vessel designed or adapted for human habitation and there is no place where they are entitled or permitted both to place it and to reside in it. Any one meeting this definition and who has successfully applied to their local authority to be classified as such is officially recognised as being homeless’. Firth, (2010, :3) 3.3 The effects of homelessness The effects of homelessness can often include or lead to; loss of  self-esteem, discrimination, vulnerability, substance abuse, criminal activities, self neglect, sexual and psychical abuse. For example, ‘some homeless women act strangely and neglect personal hygiene as a way to protect themselves from attack’. Many homeless people are discriminated against due to the fact that some people just look down at them and presume that there in that situation due to there own doing. 4.0 Substance abuse. 4.1 What is substance abuse? The term substance abuse means the use of any substance such as; drug or alcohol, to a degree that is deemed hazardous. According to Firth (2008:1) ‘Some drugs, such as morphine, have medical purposes. If they are used for other reasons, or in unnecessarily large quantities, then the term ‘drug abuse’ is applied’. 4.2 The effects of drug abuse The effects alone can be devastating so in conjunction with homelessness can result in the devastation of lives. Some of the effects of drug abuse are: loss of job, social exclusion, increased criminal activity, family breakdowns, psychical and psychological effects. One example of social exclusion is that people tent to alienate others that used drugs due to the prejudice and stigma attached to them. People often over see the underlining contributing factors that first caused the drug abuse in the first place. 4.3 Possible prevention strategies Early intervention could be brought in at the very start of substance abuse i.e. an employee turns up for work on a number of occasions under the influence of alcohol or drugs and inevitably gets fired as a direct result of turning up for work under the influence, the employee does not see the employer again as in his opinion he has fulfilled his role. It is at this point a vital chance for early intervention has been missed. If the employer had perhaps signposted the employee to the correct services for some help and support with the high risk drinking, then this issue may have been recognised and steps could have be taken to help and perhaps prevent further misuse. 5.0 key debates 5.1 Despite attempts from the Government and local authorities, Homelessness remains a significant issue. From the homeless people interviewed for the primary research (see appendix three), a large percentage of them have the view that the Government does not do enough to help them. The department for Communities and local Government suggest ‘the most effective way of preventing a large rise in the numbers of repossessions is to address the public deficit and make sure that interest rates remain low funding for debt advice services’ therefore reducing the possible numbers of potential homeless. 5.1 Many of the questionnaire participants have no Intention of stopping the re-occurring drug/alcohol abuse or even have self realisation that there is a problem. The Government should perhaps put in place educational talks seminars in schools to do with drug/alcohols and the dangers of misusing them and what to do if an individual finds them self in a position of homelessness so they have some knowledge of what to do or where to go for help, guidance or assistance. 5.2 Perhaps the Government should review the content taught in schools today, According to Chabot 2012 ‘The current structure works for lots of students, who have lots of structure and high expectations at home. But society and families are not the same as 30 years ago. The school hasn’t changed we need to adapt. On the contrary is the role of education to socially engineer children? Graph A 5.3 Results of the distributed questionnaires clearly show that the main cause of homelessness is a break down in family relationship. According to Firth (2010: 40) ‘The breakdown of family relationships has been identified as the main cause of homelessness’ Additionally, 5.4 Graph B shows the results from the question ‘since becoming homeless have you used alcohol/drugs’? Clearly the results show that from the sample of the homeless community that filled out my questionnaires, once an individual finds them self in the position of being homeless then the use of  drugs/alcohol develops. ‘Some people may view drug and alcohol use as necessary to be accepted among the homeless community’ (Didenko and Pankratz, 2007). Graph B Analysis The Evaluation of my research has proved my hypothesis wrong, homelessness is not always primarily caused by drug/alcohol related abuse, my findings show that a breakdown in the family is a major contributing factor to homelessness. Furthermore once an individual finds themselves homeless a drug/alcohol issue arises for various reason; such as; to numb the pain, to forget, boredom and because they generally enjoy the use of substances. 6.0 Methodology 6.1 Initially I read around the topic using secondary sources (see literature review) but to secure a deeper understanding and obtain my own results I undertook a primary piece of research. I created a questionnaire which had a mix of open and closed questions, which I submitted 20 throughout the homeless community that attend YMCA Project in Warrington town centre. The reason for choosing the YMCA to submit my questionnaire was the fact that the YMCA run a night shelter for the homeless in Warrington, and provided other various services that work closely with the homeless community. 6.2 After undertaking some research about the YMCA and talking to staff members it seemed the most effective way for the homeless to participate in the research was to be there in person offering a free cup of tea coffee to willing participants. The results will be analysed and put in to a table so a clear distinction of these results can be seen. I will then try to draw some comparisons to the secondary source data and information obtained from Firth (2010). 6.3 The aim of the questionnaire was to try and identify what help is already accessible for the homeless or substance misusers, what is readily available, and is it equally and easily accessible to everyone who needs it, should they want such services. . 6.4 The questionnaires created consisted of fourteen questions. The first question was to establish the age group the participant comes under. The next five questions are regarding homelessness and the details surrounding becoming homeless. There are two questions regarding the use/misuse of drugs and alcohol. The following four  questions are in relation to services regarding drug/alcohol and homelessness. Finally the last three questions ask whether the participant thinks ‘Do the Government do enough to help prevent homelessness?’, ‘What changes would you like to see for the homeless?’ and ‘any other comments’?. I chose not to administer my questionnaire directly as this would have a direct response on the answers the participant would give. I handed out the questionnaire and asked the participant to fill them in on their own thus ensuring that they could take their time and it would be more objective and the result more valid. However, because I was in the vicinity and had provided tea this may be considered as pressure and could have had an impact on the type of response they gave. After analysing all 20 completed questionnaires, I found that the main reason for the cause of homelessness was in fact due to a family breakdown. I compiled all the findings from question 3 ‘what are the reasons for becoming homeless’ and the results are shown in table A below. 6.5 The conclusion that was obtained from the questionnaire results, is that many homeless people believe the Government do not do enough to help them, but my figures show that a large percentage have been or are currently in the process of being re homed, which suggests that the Government is doing more than is perceived by the homeless community. This is not necessarily tackling the underling issues that caused the homelessness in the first place. So should the Government be contributing towards the underlining issues that primarily make that person homeless? This could include delivering a service to the homeless community, which identifies the problems and gives the knowledge to empower them to make informed decisions about substance use, in an attempt to eradicate the problem before it becomes one. 7.0 Reflective Accounts As a result of talking to the homeless participants I came to the conclusion that most of them were very uncomfortable filling out the questionnaires and only continued to do so for the free cup of tea/coffee that was provided, this could possibly make my research results subjective as they could have been giving me the answers that they thought I wanted. While this led to the statistics that was needed for the research, I over looked what the homeless community actually needed, this was for someone to get to know them  and sit down casually and listen to what they had to say and what they need and want in the form of support, while applying that the homeless need accommodation they also have individual needs too. 6.0 Bibliography Amore, K et a, 2011, The ETHOS Definition and Classification of Homelessness: An Analysis, [Online], Volume 5.2, article 1, :19, Available: http://eohw.horus.be/files/freshstart/European%20Journal%20of%20Homelessness/Volume%20Five/Volume%205.2/article-1.pdf , Access date 03/04/12 Communities and local Government, Homelessness and rough sleeping, 2011, [Online], Available: http://www.communities.gov.uk/housing/homelessness/ , [Accessed: 30/03/12] Firth, L. (2008), Drugs in the UK, volume 163, Cambridge, Great Briton, independence, MWL print group Ltd. Firth, L. (2010,:3), The Homeless Population, volume 189 Cambridge, Great Briton, independence MWL print group Ltd. Johnson KD et al, 2011, Substance Abuse Disorders among Homeless and Runaway Adolescent, [Online] Available: http://ht.ly/4KWan , [Accessed: 30/03/12] Published by the National Coalition for the Homeless, Substance Abuse and Homelessness, 2009, [Online], Available: http://www.nationalhomeless.org/factsheets/addiction.pdf , [Accessed:30/03/12] The Health of the Homeless, 2012, [Online], Available: http://www.libraryindex.com/pages/2321/Health-Homeless-MENTAL-HEALTH-HOMELESS-PEOPLE.html , [Accessed: 30/03/12] Washuk B, 2012, Lewiston Auburn, More programs, new teaching methods, requested for Lewiston Middle School, [Online] 1page long, Available: http://m.sunjournal.com/news/city/2012/03/13/more-programs-new-teaching-methods-requested-lewis/1167599 , Access date 03/04/12 Age (please circle) 16 or under 21 -25 26-3030-4040+ Did you become homeless in Warrington? How long have you been homeless? What are the reasons for becoming homeless? (was the reason for becoming homeless alcohol/ drugs related?) Since becoming homeless have you used alcohol /drugs? How often do you use drugs/alcohol (please circle) Dailyweeklymonthlyoccasionallynever Do you want to be re-homed? What services do you know about in Warrington that assist people that are homeless? Do you know of any services in Warrington for alcohol/drug abuse? Do you want to access services for alcohol/drug abuse? Is there any other services/ organisation that you would like help to access for anything else? Do you think the Government do enough in Warrington to help prevent homelessness? What changes would you like to see for the homeless? Any other comments? Research proposal By Claire Smith Intended proposal This research proposal intends to discover whether drugs and or alcohol contribute to homelessness, is it homelessness that exacerbates the problem of drug and alcohol abuse? , Reason for intended proposal The reason behind this proposal is the high need for early intervention regarding drug and alcohol abuse. Currently not all professional’s advise or signpost when necessary regarding this current matter. Only 18months ago in the UK professionals began training in Alcohol Identification and Advice so that early intervention could be established to prevent medium risk individuals becoming high risk or alcohol dependants. The problem of homelessness is an important issue especially if the common cause is drug / alcohol abuse. If my research can establish whether drug/alcohol abuse is the causes leading to homelessness then professionals could aim to put in place strategies to solve substance abuse, and then latter will become less of an issue. So in tackling alcohol and substance misuse Briton could be facing a population with less homeless. Research methodology I am going to create a questionnaire which I am going to submit to the YMCA for the homeless to fill out. After doing some research about the YMCA and talking to staff members it seems the most effective way for the homeless to participate is to be their in person offering a free cup of tea coffee to willing participants. I am going to put my finding into a table and present them to NSH Warrington Health Improvement Project Public Health. The questionnaires that are being drafted will try to determine what homeless people what in the way of tools to empower them to help themselves out of their situation. The questionnaires will try to identify; what help is already assessable for the homeless or substance misusers, is it readily available, is it equally and easily accessible to everyone who need it? This research proposal is aiming to identify whether homeless people try to access services provided to help substance and alcohol abuse and if so was it successful, of if the services ar e well publicised and easily accessible for the homeless. The research also intends to find out if there are organisations that are not well publicised to professionals that would be able to sign post potential people at risk. Literature review The Homeless Population by Lisa Firth (2010, may). Reading about and around the subject of homelessness in The Homeless Population by Lisa Firth, it becomes very clear to me that homelessness is a complex subject and does in fact have many different elements to what may cause it. Lisa Firth goes into depth about the different types of homelessness and the different possible reasons without going ‘around the houses’ so to say. I was able to learn a lot in a short space of time such as; hidden homeless and reasons for becoming homeless. Within the contents of this book are the many frequently asked questions such as; ‘surely there’s no harm in giving a few pence to the homeless’ Firth (2012). These questions have both sides of the argument with facts and figures which for me personally answered everything that I wanted to know about the homeless community. The ETHOS Definition and Classification of Homelessness: An Analysis by Kate Amore, Michael Baker and Philippa Howden-Chapman (2011) Upon discovering this pdf about the homeless population, it seems that this pdf was made with the intention of discovering a global definition for homelessness. This pdf suggests that certain criteria for being homeless that is applied in one place that would determine an individual homeless, does not necessarily apply to everyone globally. The ETHOS definition of homeless tries to establish what constitutes homelessness. As it is there was a great amount of information in this particular pdf however it was not easy to follow and seemed to repeat itself. It was not clear or concise. Skimming this information seemed to be the best way to get to the point of the basis of the pdf. The Health of the Homeless (2012) The Health of the Homeless is a very clear easy to follow online document which has lots of statistics on and are homelessness. This piece of short writing starts from 1960s and comes up to current date although it wasn’t necessarily about the exact topic that the report was based on it was interesting to read. It also ties in with the point that homeless people have a voice too and they should be included in the care package provided for homeless. It was very well presented and to the point.

First Assignment Paper in English II Essay Example | Topics and Well Written Essays - 750 words

First Assignment Paper in English II - Essay Example However, one can expect twists and differences in the narration if the story were told by some other member of the family (her father, mother, or brothers), depending on the changes in their perspectives and points of view. There are many narrative techniques such as the first person narration, the third person narration, and techniques such as the interior monologue and the stream of consciousness. While the third person omniscient is referred to as â€Å"having unlimited knowledge† (Schakel & Ridl 104) regarding the events, all the other narrative techniques have their own advantages and disadvantages. The narrator, in the story, is constructed by the author herself and the fact that Cisneros also â€Å"shared Esperanza’s sense of dislocation and lack of permanence† tend many to consider Esperanza as the ‘persona’ (‘first person narrator who seems to speak directly for the author’) of the author herself (Schakel & Ridl 101). A clear understanding of the point of view of the story calls for special â€Å"attention to the person telling the story and the perspective from which it is told† (Schakel & Ridl 101). The power of the story lies in the art of narration-narrating the story through a child’s perspective who is unaware of the actual problems the household faces such as poverty, class distinctions, housing patterns and the power of landlords (Schakel & Ridl 108). It is important to understand the ‘vantage point’ from which the narrator tells the story and an effective reader should be able to grasp the inside and outside of the narrator’s perspective. Similarly, the past events narrated by the narrator also are significant to understand the central idea or theme of the story. The narrator is somewhat happy that the house on the mango street is theirs and that they â€Å"don’t have to pay rent to anybody,

Perception and attitude of British customers towards cruise travel Essay

Perception and attitude of British customers towards cruise travel - Essay Example This  «Perception and attitude of British customers towards cruise travel » essay, describes the impact of cruise travel on the economy, problems, and prospects, and compares this tourism sector with same one in other countries. The Mediterranean and Baltic are the two most prominent stamping grounds in Britain for cruise liners. There has been a growth in need for ‘turn round’ traffic at UK ports this has not caused a commotion as more tourists are ready to extend their stay so that they do not have to book flights in return due to the traffic. They have found this hectic especially because it may mean for them to book from a new embarkation port (Miller 94). The maritime weather and climate in Britain is not truly a setback when it the cruise ships involved in the travel are large vessels and especially since most of these vessels start their journey in the United Kingdom ports and still end them there. Summer time is when there is the majority of the cruising around the beautiful British Isles. A major concern over time has been the lending of the smaller vessels by Britain. This is a serious risk especially since the ports have shallow waters that are likely to be disrupted in case of any summer squall that may occur (Lingard 32). The passenger embarkations at UK that are the majority are mainly the residents of Britain themselves. The overseas guests that take the cruise ships from the ports enjoy an incomparable experience with access for just about every part they may wish to travel and tour. For fantastic pre and post cruise travel extension, London is close to Dover, Southampton and not forgetting Harwich. This is notable because it has played a vital role in job creations and generation of income for some people in the region. This works across a great spectrum of businesses that tourism related that not many would notice was a result of the cruise ship travel in the region (Markham 45). The weakness of sterling pound provides a greater incentive for cruise lines to consider London as an extension destination due to the position of the city (Moutinho 175). Since this is a condensed island with convenient transport infrastructure and a number of

Feminism Essay Example | Topics and Well Written Essays - 500 words

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Home alone part 1 - Essay Example It is on one morning he finds himself alone in the house, but the family did not leave him intentionally. His dream comes true, but, unfortunately, some thieves attempt to rob the house but they get arrested in the end. (Bettig, 145) In Home Alone movie, Kevin is struggling to get his freedom in this family full of bullies. He feels that he does not belong to the family and even he gets to a point whereby he wishes that he did not have a family at all. Kevin is left behind by the family after they are rushing to catch the aircraft to Paris for vacation. Kevin was left in his bedroom that is in the third floor because he quarrels with his brother. Unfortunately, he is forgotten and left him in the house alone. However, Kevin is very happy and feels free as he once wished. He feels very good to be alone, having all the pizzas for himself, messing around and also jumping and playing on his parent’s bed. Kevin family is seen to leave their home to Paris for Christmas holiday. As as result, he is left alone in the house unintentionally by his family that he wishes that he never had. Unfortunately, Kevin does not know the real importance of it, or he does not consider it important as the rest of the family members. It is because, even after he learns that he is alone, to him feels like an absolute relieves from his bullying family. Kevin finds his house a difficult place to leave because of his other siblings and cousins too. Kevin is bullied by almost in the house. For instance, he feels that his cousins are bullying him making him do things he does not want to do. On the other hand, Kevin was forced to stay in his bedroom because his brother and he had an argument. In this case he feels bullied. Another theme that evolves the entire movie is the aspect of injustice. For instance, Kevin is forced to go to his bedroom that is on the third floor. He feels that he is not treated equally as the other members of the

Accounting Fraud in an Organization Research Paper

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Constitutional & Administrative Law Essay Example | Topics and Well Written Essays - 1500 words

Constitutional & Administrative Law - Essay Example he first being that the parliament may legislate upon any subject-matter; secondly that Parliament could not be restricted by a predecessor not restrict the powers of a future Parliament; and finally the validity of Acts of Parliament cannot be challenged. Under the legal theory Parliament is entitled to pass law on anything once it has been passed by the House of Commons, House of Lords and receives Royal Assent and such would be held to be legally valid. The limits that have been listed down are those that have been laid down by the democratic process. Thus theoretically the powers of the parliament are absolute and so an Act can extend beyond the territory of the United Kingdom. Furthermore, Parliament can legislate with the Act having retrospective effect. As far as international law is concerned it cannot have effect unless implemented by the Parliament by introduction of an Act. As far as Parliament being bound or being able to bind its successor is concerned importance has been placed on the Act of Union with Scotland 1707, whereby it was suggested that intention of the Act was that it cannot be repealed; however, it is important to mention that there have been amendments that have been made. In Attorney General for New South Wales v. Trethowan2 the Privy Council found the Parliament to be bound by a previous Act while citing the reason that the earlier Act had to be repealed first and so if it was not repealed then the Parliament was bound by it. As far as the new view of sovereignty is concerned Sir Ivor Jennings and Professors Heuston, Marshall, Mitchell and de Smith have stated that Parliament can bind its successor, by redefining itself or by setting out ‘ manner and form’ provisions which need to be followed. A recent example in respect of the procedural requirements is that of Northern Ireland Act 1998 whereby it stated that the Northern Ireland would remain a part of United Kingdom unless done to the contrary by means of a referendum by the

The Beginning of Civil Rights Movement in the U.S. Essay Example for Free

The Beginning of Civil Rights Movement in the U.S. Essay â€Å"Being a Negro in America means trying to smile when you want to cry. It means trying to hold on to physical life amid psychological death. It means the pain of watching your children grow up with clouds of inferiority in their mental skies. It means having their legs off, and then being condemned for being a cripple.1† These were the words of Martin Luther King Jr.. For nearly 80 years after being freed from slavery, African-Americans suffered under the discrimination and segregation of their fellow Americans. After World War II, African-Americans were ready for change and the nation could feel the inevitable Civil Rights Movement coming. With nonviolence and motivation the Civil Rights wheels were set in motion led by determined leaders and brave youth, which would have a permanent effect on American society. After the Civil War ended on June 22nd, 1865 and the Emancipation Proclamation was enforced in the last states that still had slaves. With the passing of the 13th, 14th, and 15th Amendments, African-Americans had for the first time in history the privileges of citizenship and the right to vote. Unfortunately, with the withdrawal of federal troops from the South, the situation for African-Americans, all across the nation, would only deteriorate until the Civil Rights Movement starting in 1954, keeping most African-Americans unable to vote making them â€Å"economically and politically powerless†.2 Many unsuccessful attempts for civil rights, unsupportive presidents, and violence from groups like the Ku Klux Klan made Civil Rights progress nearly impossible for nearly 80 years, even under the support from organizations such as the NAACP. African-Americans had to abide by Black Codes and Jim Crow laws in many parts of America and faced daily discrimination. Segregation under Black Codes and Jim Crow laws became a part of daily life for African-Americans all over America. The â€Å"separate but equal† reasoning was backed by the US Supreme court in the Plessy v. Ferguson case after a Louisiana Law stated that railroads must provide â€Å"equal but separate accomm odations for the white, and colored, race.†3 African-Americans tried to push Civil Rights on different occasions such as  World War II, where the idea of a â€Å"Double V† (spreading democracy abroad and at home for African Americans) began after James G. Thompson wrote a letter to the Pittsburgh Courier in 1942; â€Å"let colored Americans adopt the double VV for a double victory.†4 Though somewhat successful with the passing of the Fair Employment Act, most consider the Civil Rights Movement to begin after the Brown v. Board of Education case5 in 1954, ruling segregated schooling unconstitutional. The Brown v. Board of Education was a major step in the Civil Rights Movement. One of the first attempts to integrate a school in Little Rock, Arkansas received national attention after the nine black students who were selected to join a previously white high school were met by an angry mob. President Eisenhower had to send troops in just so that these students could go to school unharmed, a headliner that shocked the nation.6 This would not be the only violent reaction to the Civil Rights Movement. The majority of Civil Rights activists, though, believed in nonviolence.7 Martin Luther King Jr., a leader in the Civil Rights Movement who was a supporter of nonviolence, said, â€Å"Nonviolence is a powerful and just weapon. It is a sword that heals. (It) cuts without wounding and ennobles the man who wields it.†8 This nonviolent approach to Civil Rights could be seen in the way African-Americans used Buses to break down segregation; both in the Montgomery Bus Boycott of 1955 and the Freedom Rides in 1961. Claudette Colvin was 15 years old when she was arrested for refusing to move to the black section of a bus. Nine months later, a more famous bus arrest happened to Rosa Parks. Martin Luther King Jr. saw the opportunity to start a mass boycott coordinated the Montgomery Improvement Association (MIA), of which he was president of.9 The boycott lasted 13 months and was a major success, when bus segregation was abolished in Montgomery. This proved that peaceful methods could be used to successfully achieve change for Civil Rights. Another popular nonviolent method of civil disobedience were the â€Å"Sit-ins.† One famous â€Å"sit-in† was lead by the â€Å"Greensboro Four† a group of four African-American college students who sat at the lunch counter of a segregated store, sparking a wave of similar sit-ins around the country.10 The nonviolent mindset of many Civil Rights activists was often not reflected in the resistance they met, particularly in Southern states. The Freedom Rides of 1961 were originally led by thirteen college students, seven black and six white, who tr aveled with  interstate Greyhound buses from the North to the South to defy the segregated busing system and segregation at the interstate transportation facilities.11 As the movement grew in numbers and recognition, so did the violence that met them when the buses rolled into the South. Angry white mobs, mainly made up of KKK members, threw firebombs and beat and tortured the students as they stumbled out of the burning buses. As media caught wind of this and images began circulating, the nation was shocked. The eventual desegregation on the interstate buses was pushed in most part by the newly elected President John F. Kennedy and his brother, the Attorney General, Robert Kennedy.12 In the election of 1960, the two candidates were Richard Nixon for the Republican Party and John F. Kennedy for the Democratic Party, though he was part of a more liberal part of the Democratic party, causing much of the South to be somewhat hesitant in their support.13 The election ended up being one of the closest elections of US history, and Kennedy won mainly due to the first-ever televised presidential debate. Kennedy was good-looking, and charismatic whereas Nixon was nervous and sweating; unprepared for the media.14 He appointed his brother, Attorney General shortly thereafter. P resident Kennedy was a supporter of civil rights, but had to choose between the support of the South and his belief in civil rights, so he started taking only small steps towards progress. His brother was also a supporter of Civil Rights and helped by integrating the government. Many Civil Rights activists, who were hoping Kennedys would kick the Civil Rights Movement into motion were disappointed by the slow process. Kennedy changed his cautious approach after violence escalated in the town of Birmingham, Alabama as a result of a peaceful protest led by Martin Luther King Jr. The Birmingham Campaign of 1963 was located in Birmingham, Alabama, considered at the time to be â€Å"America’s most segregated city.† Martin Luther King Jr. took up the challenge of desegregating this town believing that if he could successfully desegregate the town of Birmingham, he could desegregate any town in America. A court order was obtained by the city against the protests, though Martin Luther King Jr., along with the other leaders of the movement decided to disobey the order and continue. King was arrested and kept in solitary confinement for eight days.15 The campaign leader came up with the idea to bring young people and even children into the protest, representing innocent and pure intentions of  young Civil Rights activists.16 On May 2nd, thousands of young people protested and hundreds were arrested. Images of policemen clubbing, shooting with high powered hoses, and releasing dogs on the youth flooded the media, causing once again, a very outraged nation. Pressure mounted on the government and President Kennedy. Kennedy, who had only been dipping his feet in the Civil Rights Movement until that moment, now cannonballed his way into full-fledged support of Civil Rights after giving a very clear message in his Civil Rights Address on June 11th, 1963, â€Å"The events in Birmingham and elsewhere have so increased the cries for equality that no city or State or legislative body can prudently choose to ignore them.†17 In this speech he also declared that he was going to propose an act allowing all Americans to use public facilities without facing discrimination or segregation, continuing the integration of schools, and other features, such as more protection for voters. This would be known as the Civil Rights Act, and would be passed by President Lyndon Johnson in 1964. Though the government had proved supportive in this case, many in the government tried to suppress the Civil Rights Movement, such as J. Edgar Hoover, the director of the FBI from 1924 to 1972. Many of the direct attacks on the Civil Rights Movement came from groups like the Ku Klux Klan and policemen, but the FBI under J. Edgar Hoover led a much more invasive attack on the movement and Dr. King in particular. J. Edgar Hoover was a white supremacist with no sympathy for Civil Rights and spent much of his time trying to discredit the movement and Dr. King. Even as the Red Scare died down in the 1950’s, being accused of communism or affiliations with communism was often a serious blow to a person’s career and reputation.18 The FBI and J. Edgar Hoover were also responsible for investigations against communist activities. Hoover used an allegation of communism to keep Martin Luther King Jr. and the movement under constant investigation and surveillance. He used tapes of Kennedy affairs as blackmail, so that President Kennedy would allow him to wiretap King’s phones in October 1963. What he found though, were not communist activities, but affairs King had. T he FBI then mailed the tapes to him, encouraging him to commit suicide to spare him public embarrassment.19 The FBI continued investigating King even after the Civil Rights Act of 1964 was passed, when the FBI’s responsibility of investigating crimes against civil rights greatly increased.20 After King spoke out against the Vietnam War in  1967, the FBI saw this as proof that he was being influenced by communist advisers. However when Martin Luther King Jr. was assassinated, the FBI launched a successful investigation finding his killer. Martin Luther King Jr.’s most famous speech, â€Å"I have a dream,† was given at the March on Washington on August 28th, 1963, the largest peaceful rally of the time with around 250,000 people of all ages, races, and walks of life. The march had been planned in 1941 by A. Philip Randolph for equality in the jobs market, but never happened after Randolph threatened the 100,000 strong march to President Roosevelt and Roosevelt passed the Fair Employment Act.21 The event was sponsored by numerous organizations and people. There were also a variety of speakers (among them a rabbi representing the overwhelming proportion of Jewish supporters of the civil rights movement22) and musicians including Bob Dylan.23 The most memorable moment, was of course, the speech of Martin Luther King Jr. towards the end of the event. This historical speech was not only on Civi l Rights, but also of the dream that King had of a nation where blacks and whites would live together in friendship and acceptance. 24 After the historical march, King and other Civil Rights leaders met with President Kennedy and Vice President Lyndon Johnson to discuss the necessity the complete support of Civil Rights.25 Some of the terms discussed in the aftermath of the March on Washington were reflected the the Civil Rights Act and the Voting Rights Act after Kennedy was assassinated. President Kennedy was the hope and inspiration of many young Americans of the Baby Boomer generation, especially African-Americans. In the midst of campaigning for his second term, Kennedy was assassinated in Dallas, Texas on November 22nd, 1963 by Lee Harvey Oswald. This stunned the American people and caused a wave confusion and grieving. The resulting mood was one of grief and apprehension of the future of the American government. Kennedy’s vice president was Lyndon B. Johnson, an avid supporter of Civil Rights and social justice, but also known for his â€Å"arm-twisting† methods of getting things through Cong ress and being a drunkard, was somewhat of a love-hate figure of American Politics. He used his questionable methods to push Kennedy’s proposed Civil Rights Act through Congress in 1964. The Act made it illegal for private businesses to discriminate, effectively destroying the Jim Crow system and making Civil Rights crimes a matter of the federal court, not the state court. The act was a huge step forward, but  did not address voting rights. Voting rights were passed in the Voting Rights Act of 1965 after a wave of violence in the town of Selma, Alabama when a nonviolent campaign to register African-American voters led by Martin Luther King Jr. and many Civil Rights leaders marched it’s way from Selma to Montgomery. Things began escalating about a month in on February 2nd, 1965 when a young African-American was shot to death by a state-trooper after trying to protect his mother from the police.26 This sparked the Selma to Montgomery March on March 7th, 1965. The march met a police blockade in Selma with clubs and tear gas and that day became known as â€Å"Bloody Sunday,† sparking national outrage. The march continued and was continually met by police and KKK brutality and added deaths. On August 6th, 1965, President Lyndon B. Johnson signed the Voting Rights Act; the events in Selma greatly impacting the act. This is considered the â₠¬Å"political and emotional peak of the American civil rights movement.†27 The movement began to stray from the nonviolent tradition in the late 1960’s and especially after Martin Luther King Jr. was assassinated on April 4th, 1968. Many African-Americans in the North felt left out from the successes of the Civil Rights. The suburb culture of the 1950’s and 60’s led to a flood of rich white Americans moving out of the cities, leaving the poor African-Americans in the North, stuck in a cycle of poverty and crime. The more militant movement challenging Martin Luther King Jr.’s ideas was led by Malcolm X, formally part of the Nation of Islam. He promoted the idea of black pride and that African-Americans should defend themselves against white aggression.28 Malcolm X was assassinated in 1965, but his ideas of black pride led to the Black Power movement, empowering African-Americans and instilling a sense of pride among them. Unfortunately it also promoted a very â€Å"macho† culture, which was not very women’s rights friendly. Many consider the Civil Rights Movement to have ended in 1968, and may believe that racism is a thing of the past and that this generation has learned, as Martin Luther King Jr. said, â€Å"not be judge by the color of their skin but by the conte nt of their character.†29 Unfortunately, discrimination for many minorities is a very real part of their life in America today. There is statistical data showing that problems like discrimination in the workplace30, wealth gaps between races31, and disproportionately high crime and incarceration rates for minorities exist. A study done in 2000 to 2002, showed that most employers called back  applicants with resumes with white-sounding names (versus black-sounding names) more often than not.32 Nonwhite families earned approx. 65% of what white families earned in 2012.33 This gap between whites and minorities is a battle still being fought today. Many believe that the minorities are also unrepresented in the government, thus hindering any major progress for minorities. The Civil Rights movement was a movement against hundreds of years of oppression and discrimination. It was a movement that swept the country and changed the culture and politics of America forever, led by determined, courageous leaders whose names will always be remembered. It opened the economic, political, and social doors that African-Ameri cans had never had the privilege to explore in the days of segregation and discrimination. Though racism will probably always be present in some form, the impact of the civil rights movement was a necessary and undeniable step for all of mankind.

Eye Injury Risk from Water Stream Impact Essay Example for Free

Eye Injury Risk from Water Stream Impact Essay

Security Issues in Peer-to-peer Networking

Security Issues in Peer-to-peer Networking ACKNOWLEDGEMENTS: The interest in the field of networking, driven me to take the computer networking as my course in M.Sc. there are many different types of networks. Out of them the more popularized and upcoming trend of networks are peer-to-peer networks. This report of my final dissertation for the partial fulfilment of my M.Sc, computer networking, would not have been possible without the support of my supervisor, Mr. Harry Benetatos. He helped me a lot by guiding me and pin-pointing the key mistakes which I have done during my research. My course leader Mr. Nicholas Ioannides also helped me a lot to complete this dissertation. His advises and suggestions gave me a lot of encouragement and support which made me do this research and finish it in time. I am very thankful to my university, LONDON METROPOLITAN UNIVERSITY which provided me the free access to the IEEE library which helped me to find the key papers which are very useful for my research. I also thank my parents for their support given to me in all walks of my life. DEDICATION: I dedicate this report to my parents and my well wisher Sakshi for their constant support and encouragement throughout my education and life. CHAPTER 1 PROJECT INTRODUCTION 1.1 INTRODUCTION TO THE PROJECT: This dissertation is all about the security issues in the peer-to-peer networks. There are many security issues in peer-to-peer networks. I have chosen to do research on worm intrusions in peer-to-peer networks. In this document I have mentioned how the worm propagates in the network from one peer to another peer, how the worm can be detected and how the detected worm can be attacked and save the network from getting infected. 1.2 AIM: Security issue in Peer-to-peer networks: Securing the peer-to-peer network from worms.   1.3 OBJECTIVES: Ø To understand how the peers communicate with each other in the peer-to-peer network Ø To analyse the propagation of worms in the network. Ø To detect the worms near the nodes of the network Ø To defence the worms in the network. 1.4 RESEARCH QUESTION: This document briefly discusses about how the worms propagates in the network and how can it be detected and attacked in order to save the peer-to-peer network 1.5 APPROACH: My approach for this dissertation is as follows: Ø Understanding peer-to-peer networks Ø Defining the problem Ø Data collection and analysis Ø Study and understanding the existing solutions for the problem Ø Comparing different solutions Ø conclusion 1.6 METHODOLOGY: This section of my document contains what important steps to be followed in order to achieve the mentioned objectives. It also helps to schedule how to develop and complete different parts of the dissertation. In this dissertation firstly I will study and understand about the peer-to-peer networks and how the peers in the networks communicate and share information with the remaining peer in the network. Then I do research on how the worm propagates in the network, how can the worm be detected and how the detected worm can be attacked and restore the network.   In the pictorial form the different stages of my dissertation are 1.7 PREVIEW ABOUT THE COMING CHAPTERS IN THE REPORT: The rest of the report is organised as follows: in the chapter 2, there is brief discussion about the peer-to-peer networks, different types of peer-to-peer networks, advantages and disadvantages of the peer-to-peer networks. There is also some information about the worms, its nature and different types of worms. In chapter 3, there is a discussion about the methods given by the different person to detect the worm in the network by the method of matching the characteristic string of the worm. In section 4, there is a solution for this issue. That is mathematical method of detecting the worm in the network and defending it. Chapter 5 consists of a critical appraisal and suggestions for the further work. Finally, I concluded in chapter 6. CHAPTER 2 OVERVIEW OF THE GENERIC AREA AND IDENTIFICATION OF PROBLEM: 2.1 NETWORK: Network is a group of electronic devices which are connected to each other in order to communicate which each other.   The devices can be computers, laptops, printers etc. networks can be wired or wireless. Wired networks are networks in which the devices are connected with the help of wires. Wireless networks are the networks in which the devices are connected without the wires. There are many different types of networks and peer-to-peer is one of the important and special types of networks. 2.2 PEER-TO-PEER NETWORKS: Peer-to-peer networks are emerged in 1990 because of the development of the peer-to-peer file sharing like Napster [1].   Peer-to-peer networks abbreviated as p2p networks are the networks in which all the nodes or peers in the network acts as servers as well as clients on demand. This is unlike typical client server model, in which the clients requests the services and server supplies the resources. But in case of peer-to-peer networks every node in the networks requests services like a client and every node will supply the resources like server on demand. Peer-to-peer network doesn’t need any centralized server coordination.   Peer-to-peer network is scalable. Addition of new nodes to the network or removal of already existing nodes on the network doesn’t affect the network. That means addition or removal of nodes can be done dynamically. All the nodes connected in a peer-to-peer network run on the same network protocol and software. Resources available on a node in the network are available to the remaining nodes of the network and they can access this information easily. Peer-to-peer networks provide robustness and scalability. All the wired and wireless networks can be configured as peer-to-peer networks. Home networks and small enterprise networks are preferable to configure in a peer-to-peer networks. Most the networks are not pure peer-to-peer networks because of they use some network interface devices. In the beginning, the information is stored at all the nodes by making a copy of it. But this increases the flow of traffic in the network. But now, a centralised system is maintained by the network and the requests are directed to the nodes which contains the relevant information. This will save the time and the traffic flow in the network. 2.3 WIRELESS NETWORKS: Devices connected to each other without any wires can also be configured like peer-to-peer networks. In a case of small of number of devices it is preferable to configure the network in wireless peer-to-peer networks because it will be easy to share the data in both the directions. It is even cheaper to connect the networks in wireless peer-to-peer because we do not need to spend on the wires. Peer-to-peer networks are divided into three types. They are: Instant messaging networks Collaborative networks Affinity community networks[2] Instant messaging networks: In this type of peer-to-peer networks, the users can chat with each other in real time by installing some software such as MSN messenger, AOL instant messenger etc. Collaborative networks: This type of peer-to-peer networks are also called as distributed computing.   This is widely used in the field of science and biotechnology where the intense computer processing is needed. Affinity community peer-to-peer networks: It is a type of p2p network, where the group of devices are connected only for the purpose of sharing the data among them. Peer to peer networks are basically classified into two types. They are: Ø Structured peer-to-peer networks Ø Unstructured peer-to-peer networks 2.4 STRUCTURED PEER-TO-PEER NETWORKS: In the structured peer-to-peer nodes connected in the network are fixed. They use distributed hashing table (DHT) for indexing [4]. In DHT data is stored in the form of hash table like (key, value). Any node willing to retrieve the data can easily do that using the keys. The mapping of values to the keys are maintained by all the nodes present in the network such that there will be very less disruption in case of change in the set of participants DHT-based networks are very efficient in retrieving the resources. 2.5 UNSTRUCTURED PEER-TO-PEER NETWORKS: In unstructured p2p network nodes are established arbitrarily. There are three types of unstructured p2p networks. They are Pure peer-to-peer Hybrid peer-to-peer Centralized peer-to-peer In Pure p2p networks all the nodes in the network are equal. There won’t be any preferred node with special infrastructure function. In hybrid p2p networks there will be a special node called â€Å"supernodes† [3] . This supernode can be any node in the network depending on the momentary need of the network. Centralized p2p network is a type of hybrid network in which there will be one central system which manages the network. The network cannot be able to work without this centralized system Basically, all the nodes in the peer-to-peer networks contain the information of the neighbour in its routing table. The rate of propagation of worms in the peer-to-peer networks is larger than compared to the other networks. This is because the information of the neighbour peers can easily achieved from the routing table of the infected node. Different types of files are shared between the nodes in the peer-to-peer networks. These files can be the audio files, video files, music files, text documents, books; articles etc. there are a lot of peer-to-peer software available these days in the market for sharing the files. Some of them are bittorrent, limeware, shareaza, kazaa, Imesh, bearshare Lite, eMule, KCeasy, Ares Galaxy, Soulseek, WinMX, Piolet, Gnutella, Overnet, Azureus (vuze), FrostWire, uTorrent, Morpheus, Ants, Acquisition[5]. There are lot more file sharing softwares in the market but these are the top 20 file sharing softwares for peer-to-peer networks. Basically, all the nodes connected together in the network should configure with the same network protocol and the same software should be installed in all the nodes in order to communicate with each other. Else the nodes in the network cannot communicate if they are configured with the different software or protocol. 2.6 ADVANTAGES OF PEER-TO-PEER NETWORKS [6]: It is more useful for the small business network comprising of very small number of computer systems or devices. Computers in this network can be configured easily. Full time network administrator is not required for the p2p networks. Easy maintenance of the network. Only a single operating system and less number of cables needed to get connected Can be installed easily Users can control the shared resources Distributed nature of the network increases the robustness of the network. 2.7 DISADVANTAGES OF THE PEER-TO-PEER NETWORKS [12]: No centralised administration Back-up should be performed on the each computer individually. Peer-to-peer networks are not secure Every computer in the network behaves as server and client which can slow down the performance of the system Legal controversy with the copyrights. 2.8 WORM: Worm is a computer malware program or it can be called as a mischievous code which can multiple itself   into several replicas or it duplicate itself into several copies. Worm in simple can be called as â€Å"autonomous intrusion agent† [19] .It doesn’t actually alters the function of the system but it pass through i.e., worm is unlike virus.   It intrudes the network without the mediation of the user. This is first detected by Robert T Morris in 1988[18]. Today we have some billions of systems connected to internet. Bu during 1988 there were only 60,000 systems connected to the internet. During that period 10% of the internet systems i.e., 6000 of the systems are infected and almost clogged because of the worms [8]. Worms when enters the system it hides in the operating system where it cannot be noticeable [18] . It drastically slows down the system the effect the other programs in the system. In worst cases it could even effect the entire network and slow down the internet across whole world. As it is said earlier that it replicates itself into multiple copies and attach itself to the emails and corrupt them and sometimes deleting the file without the user interaction. If it enters our email, it can able to send itself to all the contacts in our email book and then to all the contacts of the emails of our email book and likewise it propagates, grow and spread at the higher rate. Worms will even create the â€Å"backdoor† into the computer [11]. This will make the attackers to send spam easily. Some famous worms discovered in 2003 and 2004 are â€Å"Mydoom†, â€Å" Sobig† and â€Å"Sasser†[7].   â€Å"Sasser† worm has recently affected the computers which are using Windows 2000 or Windows XP operating system. It restarts the system automatically and crashes it. It is spread to all the nodes in the network. There are some worms which are unlike the normal worms. These worms are very useful to the user some times. Hence, these are called the â€Å"helpful worms† [9]. Sometimes they help users without the interaction with the user. But most of the known worms are harmful and will always tries to infect the nodes in the network and affect the performance of the network. When the peer-to-peer networks are attacked by the worms, it slows down the efficiency of the network. So there is a need to save the networks from entering into the network and spreading itself all over the network. The worms should be detected and defended. If we delay in defending these worms, they replicate itself and makes many copies of itself and spread all through the network. This is very dangerous to the network as it affects the performance and efficiency of the network [10]. CHAPTER 3 RELEVANT WORK DONE BY OTHERS IN ORDER TO SOLVE THE PROBLEM: Many people proposed solutions to this problem. First Zhou L gave solution to p2p worm and he observed that propagation of worm in p2p network is very speed when compared to other networks[13] . Jayanthkumar performed some simulations on worm propagation from infected node to other node[10]. Wei yu researched on the behaviour of worms in p2p networks[14]. In my research I found one more interesting method of detecting the worms in the peer-to-peer network. This is indeed a special method of detecting the worms in network because the authors Yu Yao, Yong Li, Fu-xiang Gao, Ge Yu in their paper titled â€Å"A Signature-behaviour-based P2P worm detection approach† they proposed a mechanism of detecting the known worms in the peer-to-peer networks based on characteristic string matching. Worm make use of vulnerabilities in the network and +Spreads[15]. They also proposed the detection mechanism for the unknown worms based on their behaviour. They technique mainly consists of the te chnology of characteristic string matching, identifying the application and the unknown worm detection technology. They have given the algorithm for the matching the characteristics string of the worm called suffix-tree algorithm- suffix array algorithm. This is efficient and simple with very less time complexity. As peer-to-peer network follows fragment transfer technique there is chance of assigning the characteristics string of the worm to the other blocks of data. And again during the reorganisation process this characteristic string can identify the worm. These authors even validated their results by simulation. They proved that their method is also one of the efficient methods of p2p worm detection. As mentioned above this method detects the known worm and also the unknown worms based on characteristic string matching and their behaviour respectively. In this method they initially capture the network packets using the library function called â€Å"LibPcap†. â€Å"LibPcap† is the library function that captures the network packets in UNIX and Linux platforms. This function contains many functions that will be useful for capturing the network packets. After capturing the data packets with help of these functions the non-P2P packets are filtered out. So now the P2P packets are filtered. In these P2P packets the known worms are detected by using the characteristic string matching. This is implemented by the couple of algorithms. They are the â€Å"suffix array algorithm† and the â€Å"dichotomy algorithm†. These algorithms are very accurate and are capable of detecting the worms in very less time. As I mentioned above peer-to-peer networks follow fragment transfer mechanism. Hence the characteristic string of the worm can be assigned to the other blocks of data. So, in this situation it is difficult to detect the worm if the characteristic string of the worm is based on the single packet. But if the characteristic string is present in the block then there is a chance of detecting the worm because it will assign it to the two packets. At this time the worm characteristic string present in the two different data packets need to restructure. After restructuring, the worm can be detected by using the matching mechanism. In this way the known worm in the network is detected by using the characteristic string matching. The unknown worms in the p2p network can be detected with the help of the act characteristics of the worm at the initial stage of its propagation. This can be called as the behaviour based detection of the unknown p2p worms. Like this all the known and unknown worms in the network are detected. 3.1 P2P KNOWN WORM DETECTION: There are four steps in detecting the p2p known worms. They are: Deal flow Technology of identifying the application Characteristic string matching Reorganising the characteristic string 3.1.1 DEAL FLOW: In this step of deal flow the flow of data is divided into four steps[16]. Step 1: Extracting the p2p data stream from the original data stream. Step 2: check the extracted p2p data stream for worms using characteristic string matching with the worms already existing in the library function. Step 3: data is flow is reorganised. It now contains worm characteristic string as well. Go to step 2. Step 4: check the data flow for unknown worms using unknown worm detection techniques. After performing the four steps update the library function. All the four steps is represented   pictorially as in the next page. Figure 4: flow chart representing four steps to detect worms   yes    normal  Ã‚  Normal no  Ã‚  Ã‚  Ã‚   Abnormal abnormal 3.1.2 TECHNOLOGY OF IDENTIFYING THE APPLICATION: As said earlier, this paper uses the method of capturing the data packets and sca it for the worms which are known with the help of a function library called â€Å"LibPcap†[17] . For this there should be already some assigned rules in the network interface devices. So assigning these rules to those devices is done in stepwise procedure as: Identify the available network interface devices Open the network interface device Compile the rules that we are willing to attach to the devices Setup the rules of filtering to the device Now operate the equipment Start the process of capturing the packets There are some rules for identifying the p2p application. They are: Characteristic information of the known p2p is used Sometimes, if source-destination IP pairs don’t use the known P2P and they may use TCP and UDP at same time, then they are p2p. At a particular time source pairs {srcIP, srcport}[27] and the destination pairs {dstIP, dstport}[27] are checked Here we can identify whether it’s a p2p or not. If the number of connection port is equal to the number of connection IP, then we can say that it is a p2p. There are the situations where these rules have been used unruly. So the there were some amendments made to these rules. The amendments are rule (2) can identify even the mazes which are present and rule (3) is modified in such a way that in the detect cycle {srcIP, srcport}[27] pairs at the source and the {dstIP,   dstport }[27] pairs at the destination are checked. From this they derived that if the number of connection port is equal to the number of connection IP, the protocols which are used are same. If they are different then the protocols are different. 3.1.3 CHARACTERISTIC STRING MATCHING: This is the most important section of the paper. Here authors have given some definitions to the terms which we are going to use, the algorithms which we are going to use to detect the worm. Couple of algorithms are mentioned. They are suffix-array algorithm and the dichotomy algorithm. So the entire process of detecting the worm depends on the efficiency and the accuracy of these algorithms. First of all before using and understanding suffix-array algorithm we will try to understand some keywords and rules. Suffix: suffix is the part of a string or a substring which starts at a particular location to the end of the string. If a suffix in the string S starts at the location ‘i’ to the end of the string S, then the suffix can be represented as Suffix(i)=S[i,Len(S) ][27] . Let us understand how the strings can be compared. The comparison in this paper followed â€Å"dictionary comparison† If u and v are the two different strings. Comparing the strings u and v is same like comparing u[i] and v[i], where ‘i’ starts with the value 1. Ø Here string u is equal to string v i.e., u=v when u[i]=v[i] Ø String u is greater then string v i.e., u>v when u[i]>v[i] Ø String u is less than string v i.e., u But the results were still not obtained for i>len(u) or i>len(v) Also if len(u)>len(v) then u >v, if len(u) Suffix-array: suffix-array is denoted by SA. It is a one-dimensional array. It is an array of SA[1], S[2], SA[3],†¦. And so on. Here s[i] Rank-array: rank-array is nothing but SA-1. If SA[i]=j, then Rank[j]=i. we can say that the rank[i] saves the rank of Suffix(i) in an ascending order for all the suffixes. In this paper the author has taken the example of string â€Å"science† and explained everything clearly. The string â€Å"science† can generate seven suffixes. They are: Suffix(1): science Suffix(2): cience Suffix(3): ience Suffix(4): ence Suffix(5): nce Suffix(6): ce Suffix(7): e When we sort out everything in a dictionary order it will be in the order as follow Suffix(6)= ce Suffix(2)= cience Suffix(7)= e Suffix(4)= ence Suffix(3)= ience Suffix(5)= nce Suffix(1)= science Suffix-array algorithm follows multiplier ideas. Firstly get SA1 and Rank1 by comparing every character in the string. Comparing string is similar to comparing the every character sequentially. So by comparing every character, SA1 and Rank1 can derive SA2 and Rank2. And this SA2 and Rank2 will derive SA4 and Rank4. And this will again derive SA8 and Rank8. So finally suffix-array and rank-array are derived from this process. The main process of the suffix-array algorithm is Ø Calculating SA1 and Rank1. Firstly all the suffixes are arranged in the first letter order and then suffix-array (SA1) is generated by using quick sorry algorithm and then Rank1 is also generated. Ø Comparing 2k-prefix Suffix(i) and Suffix(j) using SAk and Rankk. 2k-Suffix(i) = 2k-Suffixes(j), this is equivalent to Rankk[SAk[i]] = Rankk[SAk[j]] and Rankk[SAk[i+k]] = Rankk[SAk[j+k]] 2k-Suffix(i) Suffix-array algorithm is a sorting algorithm which sorts out the characteristic string. So, this uses binary search algorithm. The algorithm follows Step 1: in the first step values are assigned like left=1, right=n and max_match=0 Step 2: the middle value i.e., mid= (left +right)/2. Step 3: comparing the characters corresponding to Suffix (SA[mid]) and P. the longest public prefix r can be helpful in implantation and comparison. If r > max_match, then max_match=r. Step 4: if Suffix(SA[mid])   If Suffix(SA[mid])>P, then right=mid-1   If Suffix(SA[mid])=P, then go to step 6 Step 5: if left Step 6: if max_match= m, then print â€Å"match is successful†. 3.1.4 REORGANISING THE CHARACTERISTIC STRING: In this step the characteristic string is reorganised. If the character string is divided into two different data blocks, then the data block with the partial characteristic string is stored. Basically, all the information about the data block like index, beginning offset, length of the block and so on are contained at the head of the each block. Here a structure piece is defined which consists of index of the block, beginning offset of the block offset, length of the character array head and the length of the character array end[18]. Initially each and every data packet is compared with the characteristic string for matching. If it is matched then the warning or an alert is sent to all the users about the worm. Here if the tail of the characteristic string of the worm matches with the head of the data block, then it will be stored in the character array end. And if the head of the characteristic string of the worm matches with the tail of the data block then it is stored in the corr esponding character array head. Suppose if the neighbouring data block contains a partial characteristic string of the worm then the neighbour string in the array head as well as in the end will be reorganised. Now this reorganised string will again perform the characteristic string matching and if any worm is detected then again the warning is sent to all users saying that the worm have found. If it is not matched then it won’t perform any operation. If in a case that the characteristic string is present in the block but is divided into two different data packets, then a special term called â€Å"character array† is introduced. First the matching mechanism is performed in both the data packet. If the matching characteristic string is found then the warning is sent to the users that there is a worm present. But if only part of the characteristic string is found then it will be enough if it meets some of the requirements like the head of the data packet should match wit h the tail of the characteristic string or the tail of the data packet should match with the head of the characteristic string. But if these conditions are not satisfied then no operation is performed. Now, if the tail of the data packet contains the partial characteristic string then the data packet is stored in the array. If the length of the characteristic string is m, then the Array[m] is set as ’’. And if the head of the data packet contains a part of the characteristic string then that data packet is stored in the n consecutive units of array. Finally, this array will be the characteristic string matching and if the worm is detected then the warning is sent to all the users. If it is not matched then nothing is done. 3.2 DETECTING UNKNOWN P2P WORM: In the above section we have seen how the known worm is detected. But that algorithm or mechanism are meant to detect the unknown p2p worms. So here in this section we will understand how the unknown worms can be detected and restrain the network. As we know in p2p networks a node can able to send the information to multiple hosts at a same time. Anyhow same protocol is used by all the nodes in the network[27]. These characteristics of the network helps worm to propagate easily. As we discussed above, only the known worms can be detected by using the characteristic string matching method. Here we will see how the unknown worms can be detected. The unknown worms are detected based on the behaviour of the node. Some of the detection rules are: same content files are transferred to multiple hosts in a very short time. Same protocol is used and the destination port is same. If these rules are satisfies by the source port then it allows the p2p worm to propagate. Now, it is necessary to e xtract the characteristics of worm near the worm propagation nodes. When these characteristics are extracted, they are added to the feature library. This data similarity comparison and extracting the characteristics are done using the LCSeq algorithm. But the LCSeq algorithm based on generalized suffix tree (GST) is the more efficient. The overall idea is that all the suffixes are represented as a tree. And this tree will have some characteristics like: Ø Every node in a tree is a string and root is the empty string Ø Every suffix can be represented as a path from the root. Ø Every substring can be considered as a prefix of a suffix. Ø To achieve the searching public sub sequence, every node should be set the information of its subordinate source string. 3.3 EXPERIMENT: We know that the worm body tries to infect the other nodes in the network by sending the worm to the specific ports of p2p node. So here the author tried to prove the efficiency of his method by performing an experiment. In this experiment he prepared a multiple group worm body and sent it repeatedly at regular intervals of time. Then he captured these packets and extracted their characteristics and compared it with the one that already exist in the feature library. P2p worm is detected separately using different algorithms like BF algorithm, KMP algorithm and suffix-array algorithm and compared their results doing three experiments. In the experiment 1, worm characteristics are in the same packet.. in the experiment Security Issues in Peer-to-peer Networking Security Issues in Peer-to-peer Networking ACKNOWLEDGEMENTS: The interest in the field of networking, driven me to take the computer networking as my course in M.Sc. there are many different types of networks. Out of them the more popularized and upcoming trend of networks are peer-to-peer networks. This report of my final dissertation for the partial fulfilment of my M.Sc, computer networking, would not have been possible without the support of my supervisor, Mr. Harry Benetatos. He helped me a lot by guiding me and pin-pointing the key mistakes which I have done during my research. My course leader Mr. Nicholas Ioannides also helped me a lot to complete this dissertation. His advises and suggestions gave me a lot of encouragement and support which made me do this research and finish it in time. I am very thankful to my university, LONDON METROPOLITAN UNIVERSITY which provided me the free access to the IEEE library which helped me to find the key papers which are very useful for my research. I also thank my parents for their support given to me in all walks of my life. DEDICATION: I dedicate this report to my parents and my well wisher Sakshi for their constant support and encouragement throughout my education and life. CHAPTER 1 PROJECT INTRODUCTION 1.1 INTRODUCTION TO THE PROJECT: This dissertation is all about the security issues in the peer-to-peer networks. There are many security issues in peer-to-peer networks. I have chosen to do research on worm intrusions in peer-to-peer networks. In this document I have mentioned how the worm propagates in the network from one peer to another peer, how the worm can be detected and how the detected worm can be attacked and save the network from getting infected. 1.2 AIM: Security issue in Peer-to-peer networks: Securing the peer-to-peer network from worms.   1.3 OBJECTIVES: Ø To understand how the peers communicate with each other in the peer-to-peer network Ø To analyse the propagation of worms in the network. Ø To detect the worms near the nodes of the network Ø To defence the worms in the network. 1.4 RESEARCH QUESTION: This document briefly discusses about how the worms propagates in the network and how can it be detected and attacked in order to save the peer-to-peer network 1.5 APPROACH: My approach for this dissertation is as follows: Ø Understanding peer-to-peer networks Ø Defining the problem Ø Data collection and analysis Ø Study and understanding the existing solutions for the problem Ø Comparing different solutions Ø conclusion 1.6 METHODOLOGY: This section of my document contains what important steps to be followed in order to achieve the mentioned objectives. It also helps to schedule how to develop and complete different parts of the dissertation. In this dissertation firstly I will study and understand about the peer-to-peer networks and how the peers in the networks communicate and share information with the remaining peer in the network. Then I do research on how the worm propagates in the network, how can the worm be detected and how the detected worm can be attacked and restore the network.   In the pictorial form the different stages of my dissertation are 1.7 PREVIEW ABOUT THE COMING CHAPTERS IN THE REPORT: The rest of the report is organised as follows: in the chapter 2, there is brief discussion about the peer-to-peer networks, different types of peer-to-peer networks, advantages and disadvantages of the peer-to-peer networks. There is also some information about the worms, its nature and different types of worms. In chapter 3, there is a discussion about the methods given by the different person to detect the worm in the network by the method of matching the characteristic string of the worm. In section 4, there is a solution for this issue. That is mathematical method of detecting the worm in the network and defending it. Chapter 5 consists of a critical appraisal and suggestions for the further work. Finally, I concluded in chapter 6. CHAPTER 2 OVERVIEW OF THE GENERIC AREA AND IDENTIFICATION OF PROBLEM: 2.1 NETWORK: Network is a group of electronic devices which are connected to each other in order to communicate which each other.   The devices can be computers, laptops, printers etc. networks can be wired or wireless. Wired networks are networks in which the devices are connected with the help of wires. Wireless networks are the networks in which the devices are connected without the wires. There are many different types of networks and peer-to-peer is one of the important and special types of networks. 2.2 PEER-TO-PEER NETWORKS: Peer-to-peer networks are emerged in 1990 because of the development of the peer-to-peer file sharing like Napster [1].   Peer-to-peer networks abbreviated as p2p networks are the networks in which all the nodes or peers in the network acts as servers as well as clients on demand. This is unlike typical client server model, in which the clients requests the services and server supplies the resources. But in case of peer-to-peer networks every node in the networks requests services like a client and every node will supply the resources like server on demand. Peer-to-peer network doesn’t need any centralized server coordination.   Peer-to-peer network is scalable. Addition of new nodes to the network or removal of already existing nodes on the network doesn’t affect the network. That means addition or removal of nodes can be done dynamically. All the nodes connected in a peer-to-peer network run on the same network protocol and software. Resources available on a node in the network are available to the remaining nodes of the network and they can access this information easily. Peer-to-peer networks provide robustness and scalability. All the wired and wireless networks can be configured as peer-to-peer networks. Home networks and small enterprise networks are preferable to configure in a peer-to-peer networks. Most the networks are not pure peer-to-peer networks because of they use some network interface devices. In the beginning, the information is stored at all the nodes by making a copy of it. But this increases the flow of traffic in the network. But now, a centralised system is maintained by the network and the requests are directed to the nodes which contains the relevant information. This will save the time and the traffic flow in the network. 2.3 WIRELESS NETWORKS: Devices connected to each other without any wires can also be configured like peer-to-peer networks. In a case of small of number of devices it is preferable to configure the network in wireless peer-to-peer networks because it will be easy to share the data in both the directions. It is even cheaper to connect the networks in wireless peer-to-peer because we do not need to spend on the wires. Peer-to-peer networks are divided into three types. They are: Instant messaging networks Collaborative networks Affinity community networks[2] Instant messaging networks: In this type of peer-to-peer networks, the users can chat with each other in real time by installing some software such as MSN messenger, AOL instant messenger etc. Collaborative networks: This type of peer-to-peer networks are also called as distributed computing.   This is widely used in the field of science and biotechnology where the intense computer processing is needed. Affinity community peer-to-peer networks: It is a type of p2p network, where the group of devices are connected only for the purpose of sharing the data among them. Peer to peer networks are basically classified into two types. They are: Ø Structured peer-to-peer networks Ø Unstructured peer-to-peer networks 2.4 STRUCTURED PEER-TO-PEER NETWORKS: In the structured peer-to-peer nodes connected in the network are fixed. They use distributed hashing table (DHT) for indexing [4]. In DHT data is stored in the form of hash table like (key, value). Any node willing to retrieve the data can easily do that using the keys. The mapping of values to the keys are maintained by all the nodes present in the network such that there will be very less disruption in case of change in the set of participants DHT-based networks are very efficient in retrieving the resources. 2.5 UNSTRUCTURED PEER-TO-PEER NETWORKS: In unstructured p2p network nodes are established arbitrarily. There are three types of unstructured p2p networks. They are Pure peer-to-peer Hybrid peer-to-peer Centralized peer-to-peer In Pure p2p networks all the nodes in the network are equal. There won’t be any preferred node with special infrastructure function. In hybrid p2p networks there will be a special node called â€Å"supernodes† [3] . This supernode can be any node in the network depending on the momentary need of the network. Centralized p2p network is a type of hybrid network in which there will be one central system which manages the network. The network cannot be able to work without this centralized system Basically, all the nodes in the peer-to-peer networks contain the information of the neighbour in its routing table. The rate of propagation of worms in the peer-to-peer networks is larger than compared to the other networks. This is because the information of the neighbour peers can easily achieved from the routing table of the infected node. Different types of files are shared between the nodes in the peer-to-peer networks. These files can be the audio files, video files, music files, text documents, books; articles etc. there are a lot of peer-to-peer software available these days in the market for sharing the files. Some of them are bittorrent, limeware, shareaza, kazaa, Imesh, bearshare Lite, eMule, KCeasy, Ares Galaxy, Soulseek, WinMX, Piolet, Gnutella, Overnet, Azureus (vuze), FrostWire, uTorrent, Morpheus, Ants, Acquisition[5]. There are lot more file sharing softwares in the market but these are the top 20 file sharing softwares for peer-to-peer networks. Basically, all the nodes connected together in the network should configure with the same network protocol and the same software should be installed in all the nodes in order to communicate with each other. Else the nodes in the network cannot communicate if they are configured with the different software or protocol. 2.6 ADVANTAGES OF PEER-TO-PEER NETWORKS [6]: It is more useful for the small business network comprising of very small number of computer systems or devices. Computers in this network can be configured easily. Full time network administrator is not required for the p2p networks. Easy maintenance of the network. Only a single operating system and less number of cables needed to get connected Can be installed easily Users can control the shared resources Distributed nature of the network increases the robustness of the network. 2.7 DISADVANTAGES OF THE PEER-TO-PEER NETWORKS [12]: No centralised administration Back-up should be performed on the each computer individually. Peer-to-peer networks are not secure Every computer in the network behaves as server and client which can slow down the performance of the system Legal controversy with the copyrights. 2.8 WORM: Worm is a computer malware program or it can be called as a mischievous code which can multiple itself   into several replicas or it duplicate itself into several copies. Worm in simple can be called as â€Å"autonomous intrusion agent† [19] .It doesn’t actually alters the function of the system but it pass through i.e., worm is unlike virus.   It intrudes the network without the mediation of the user. This is first detected by Robert T Morris in 1988[18]. Today we have some billions of systems connected to internet. Bu during 1988 there were only 60,000 systems connected to the internet. During that period 10% of the internet systems i.e., 6000 of the systems are infected and almost clogged because of the worms [8]. Worms when enters the system it hides in the operating system where it cannot be noticeable [18] . It drastically slows down the system the effect the other programs in the system. In worst cases it could even effect the entire network and slow down the internet across whole world. As it is said earlier that it replicates itself into multiple copies and attach itself to the emails and corrupt them and sometimes deleting the file without the user interaction. If it enters our email, it can able to send itself to all the contacts in our email book and then to all the contacts of the emails of our email book and likewise it propagates, grow and spread at the higher rate. Worms will even create the â€Å"backdoor† into the computer [11]. This will make the attackers to send spam easily. Some famous worms discovered in 2003 and 2004 are â€Å"Mydoom†, â€Å" Sobig† and â€Å"Sasser†[7].   â€Å"Sasser† worm has recently affected the computers which are using Windows 2000 or Windows XP operating system. It restarts the system automatically and crashes it. It is spread to all the nodes in the network. There are some worms which are unlike the normal worms. These worms are very useful to the user some times. Hence, these are called the â€Å"helpful worms† [9]. Sometimes they help users without the interaction with the user. But most of the known worms are harmful and will always tries to infect the nodes in the network and affect the performance of the network. When the peer-to-peer networks are attacked by the worms, it slows down the efficiency of the network. So there is a need to save the networks from entering into the network and spreading itself all over the network. The worms should be detected and defended. If we delay in defending these worms, they replicate itself and makes many copies of itself and spread all through the network. This is very dangerous to the network as it affects the performance and efficiency of the network [10]. CHAPTER 3 RELEVANT WORK DONE BY OTHERS IN ORDER TO SOLVE THE PROBLEM: Many people proposed solutions to this problem. First Zhou L gave solution to p2p worm and he observed that propagation of worm in p2p network is very speed when compared to other networks[13] . Jayanthkumar performed some simulations on worm propagation from infected node to other node[10]. Wei yu researched on the behaviour of worms in p2p networks[14]. In my research I found one more interesting method of detecting the worms in the peer-to-peer network. This is indeed a special method of detecting the worms in network because the authors Yu Yao, Yong Li, Fu-xiang Gao, Ge Yu in their paper titled â€Å"A Signature-behaviour-based P2P worm detection approach† they proposed a mechanism of detecting the known worms in the peer-to-peer networks based on characteristic string matching. Worm make use of vulnerabilities in the network and +Spreads[15]. They also proposed the detection mechanism for the unknown worms based on their behaviour. They technique mainly consists of the te chnology of characteristic string matching, identifying the application and the unknown worm detection technology. They have given the algorithm for the matching the characteristics string of the worm called suffix-tree algorithm- suffix array algorithm. This is efficient and simple with very less time complexity. As peer-to-peer network follows fragment transfer technique there is chance of assigning the characteristics string of the worm to the other blocks of data. And again during the reorganisation process this characteristic string can identify the worm. These authors even validated their results by simulation. They proved that their method is also one of the efficient methods of p2p worm detection. As mentioned above this method detects the known worm and also the unknown worms based on characteristic string matching and their behaviour respectively. In this method they initially capture the network packets using the library function called â€Å"LibPcap†. â€Å"LibPcap† is the library function that captures the network packets in UNIX and Linux platforms. This function contains many functions that will be useful for capturing the network packets. After capturing the data packets with help of these functions the non-P2P packets are filtered out. So now the P2P packets are filtered. In these P2P packets the known worms are detected by using the characteristic string matching. This is implemented by the couple of algorithms. They are the â€Å"suffix array algorithm† and the â€Å"dichotomy algorithm†. These algorithms are very accurate and are capable of detecting the worms in very less time. As I mentioned above peer-to-peer networks follow fragment transfer mechanism. Hence the characteristic string of the worm can be assigned to the other blocks of data. So, in this situation it is difficult to detect the worm if the characteristic string of the worm is based on the single packet. But if the characteristic string is present in the block then there is a chance of detecting the worm because it will assign it to the two packets. At this time the worm characteristic string present in the two different data packets need to restructure. After restructuring, the worm can be detected by using the matching mechanism. In this way the known worm in the network is detected by using the characteristic string matching. The unknown worms in the p2p network can be detected with the help of the act characteristics of the worm at the initial stage of its propagation. This can be called as the behaviour based detection of the unknown p2p worms. Like this all the known and unknown worms in the network are detected. 3.1 P2P KNOWN WORM DETECTION: There are four steps in detecting the p2p known worms. They are: Deal flow Technology of identifying the application Characteristic string matching Reorganising the characteristic string 3.1.1 DEAL FLOW: In this step of deal flow the flow of data is divided into four steps[16]. Step 1: Extracting the p2p data stream from the original data stream. Step 2: check the extracted p2p data stream for worms using characteristic string matching with the worms already existing in the library function. Step 3: data is flow is reorganised. It now contains worm characteristic string as well. Go to step 2. Step 4: check the data flow for unknown worms using unknown worm detection techniques. After performing the four steps update the library function. All the four steps is represented   pictorially as in the next page. Figure 4: flow chart representing four steps to detect worms   yes    normal  Ã‚  Normal no  Ã‚  Ã‚  Ã‚   Abnormal abnormal 3.1.2 TECHNOLOGY OF IDENTIFYING THE APPLICATION: As said earlier, this paper uses the method of capturing the data packets and sca it for the worms which are known with the help of a function library called â€Å"LibPcap†[17] . For this there should be already some assigned rules in the network interface devices. So assigning these rules to those devices is done in stepwise procedure as: Identify the available network interface devices Open the network interface device Compile the rules that we are willing to attach to the devices Setup the rules of filtering to the device Now operate the equipment Start the process of capturing the packets There are some rules for identifying the p2p application. They are: Characteristic information of the known p2p is used Sometimes, if source-destination IP pairs don’t use the known P2P and they may use TCP and UDP at same time, then they are p2p. At a particular time source pairs {srcIP, srcport}[27] and the destination pairs {dstIP, dstport}[27] are checked Here we can identify whether it’s a p2p or not. If the number of connection port is equal to the number of connection IP, then we can say that it is a p2p. There are the situations where these rules have been used unruly. So the there were some amendments made to these rules. The amendments are rule (2) can identify even the mazes which are present and rule (3) is modified in such a way that in the detect cycle {srcIP, srcport}[27] pairs at the source and the {dstIP,   dstport }[27] pairs at the destination are checked. From this they derived that if the number of connection port is equal to the number of connection IP, the protocols which are used are same. If they are different then the protocols are different. 3.1.3 CHARACTERISTIC STRING MATCHING: This is the most important section of the paper. Here authors have given some definitions to the terms which we are going to use, the algorithms which we are going to use to detect the worm. Couple of algorithms are mentioned. They are suffix-array algorithm and the dichotomy algorithm. So the entire process of detecting the worm depends on the efficiency and the accuracy of these algorithms. First of all before using and understanding suffix-array algorithm we will try to understand some keywords and rules. Suffix: suffix is the part of a string or a substring which starts at a particular location to the end of the string. If a suffix in the string S starts at the location ‘i’ to the end of the string S, then the suffix can be represented as Suffix(i)=S[i,Len(S) ][27] . Let us understand how the strings can be compared. The comparison in this paper followed â€Å"dictionary comparison† If u and v are the two different strings. Comparing the strings u and v is same like comparing u[i] and v[i], where ‘i’ starts with the value 1. Ø Here string u is equal to string v i.e., u=v when u[i]=v[i] Ø String u is greater then string v i.e., u>v when u[i]>v[i] Ø String u is less than string v i.e., u But the results were still not obtained for i>len(u) or i>len(v) Also if len(u)>len(v) then u >v, if len(u) Suffix-array: suffix-array is denoted by SA. It is a one-dimensional array. It is an array of SA[1], S[2], SA[3],†¦. And so on. Here s[i] Rank-array: rank-array is nothing but SA-1. If SA[i]=j, then Rank[j]=i. we can say that the rank[i] saves the rank of Suffix(i) in an ascending order for all the suffixes. In this paper the author has taken the example of string â€Å"science† and explained everything clearly. The string â€Å"science† can generate seven suffixes. They are: Suffix(1): science Suffix(2): cience Suffix(3): ience Suffix(4): ence Suffix(5): nce Suffix(6): ce Suffix(7): e When we sort out everything in a dictionary order it will be in the order as follow Suffix(6)= ce Suffix(2)= cience Suffix(7)= e Suffix(4)= ence Suffix(3)= ience Suffix(5)= nce Suffix(1)= science Suffix-array algorithm follows multiplier ideas. Firstly get SA1 and Rank1 by comparing every character in the string. Comparing string is similar to comparing the every character sequentially. So by comparing every character, SA1 and Rank1 can derive SA2 and Rank2. And this SA2 and Rank2 will derive SA4 and Rank4. And this will again derive SA8 and Rank8. So finally suffix-array and rank-array are derived from this process. The main process of the suffix-array algorithm is Ø Calculating SA1 and Rank1. Firstly all the suffixes are arranged in the first letter order and then suffix-array (SA1) is generated by using quick sorry algorithm and then Rank1 is also generated. Ø Comparing 2k-prefix Suffix(i) and Suffix(j) using SAk and Rankk. 2k-Suffix(i) = 2k-Suffixes(j), this is equivalent to Rankk[SAk[i]] = Rankk[SAk[j]] and Rankk[SAk[i+k]] = Rankk[SAk[j+k]] 2k-Suffix(i) Suffix-array algorithm is a sorting algorithm which sorts out the characteristic string. So, this uses binary search algorithm. The algorithm follows Step 1: in the first step values are assigned like left=1, right=n and max_match=0 Step 2: the middle value i.e., mid= (left +right)/2. Step 3: comparing the characters corresponding to Suffix (SA[mid]) and P. the longest public prefix r can be helpful in implantation and comparison. If r > max_match, then max_match=r. Step 4: if Suffix(SA[mid])   If Suffix(SA[mid])>P, then right=mid-1   If Suffix(SA[mid])=P, then go to step 6 Step 5: if left Step 6: if max_match= m, then print â€Å"match is successful†. 3.1.4 REORGANISING THE CHARACTERISTIC STRING: In this step the characteristic string is reorganised. If the character string is divided into two different data blocks, then the data block with the partial characteristic string is stored. Basically, all the information about the data block like index, beginning offset, length of the block and so on are contained at the head of the each block. Here a structure piece is defined which consists of index of the block, beginning offset of the block offset, length of the character array head and the length of the character array end[18]. Initially each and every data packet is compared with the characteristic string for matching. If it is matched then the warning or an alert is sent to all the users about the worm. Here if the tail of the characteristic string of the worm matches with the head of the data block, then it will be stored in the character array end. And if the head of the characteristic string of the worm matches with the tail of the data block then it is stored in the corr esponding character array head. Suppose if the neighbouring data block contains a partial characteristic string of the worm then the neighbour string in the array head as well as in the end will be reorganised. Now this reorganised string will again perform the characteristic string matching and if any worm is detected then again the warning is sent to all users saying that the worm have found. If it is not matched then it won’t perform any operation. If in a case that the characteristic string is present in the block but is divided into two different data packets, then a special term called â€Å"character array† is introduced. First the matching mechanism is performed in both the data packet. If the matching characteristic string is found then the warning is sent to the users that there is a worm present. But if only part of the characteristic string is found then it will be enough if it meets some of the requirements like the head of the data packet should match wit h the tail of the characteristic string or the tail of the data packet should match with the head of the characteristic string. But if these conditions are not satisfied then no operation is performed. Now, if the tail of the data packet contains the partial characteristic string then the data packet is stored in the array. If the length of the characteristic string is m, then the Array[m] is set as ’’. And if the head of the data packet contains a part of the characteristic string then that data packet is stored in the n consecutive units of array. Finally, this array will be the characteristic string matching and if the worm is detected then the warning is sent to all the users. If it is not matched then nothing is done. 3.2 DETECTING UNKNOWN P2P WORM: In the above section we have seen how the known worm is detected. But that algorithm or mechanism are meant to detect the unknown p2p worms. So here in this section we will understand how the unknown worms can be detected and restrain the network. As we know in p2p networks a node can able to send the information to multiple hosts at a same time. Anyhow same protocol is used by all the nodes in the network[27]. These characteristics of the network helps worm to propagate easily. As we discussed above, only the known worms can be detected by using the characteristic string matching method. Here we will see how the unknown worms can be detected. The unknown worms are detected based on the behaviour of the node. Some of the detection rules are: same content files are transferred to multiple hosts in a very short time. Same protocol is used and the destination port is same. If these rules are satisfies by the source port then it allows the p2p worm to propagate. Now, it is necessary to e xtract the characteristics of worm near the worm propagation nodes. When these characteristics are extracted, they are added to the feature library. This data similarity comparison and extracting the characteristics are done using the LCSeq algorithm. But the LCSeq algorithm based on generalized suffix tree (GST) is the more efficient. The overall idea is that all the suffixes are represented as a tree. And this tree will have some characteristics like: Ø Every node in a tree is a string and root is the empty string Ø Every suffix can be represented as a path from the root. Ø Every substring can be considered as a prefix of a suffix. Ø To achieve the searching public sub sequence, every node should be set the information of its subordinate source string. 3.3 EXPERIMENT: We know that the worm body tries to infect the other nodes in the network by sending the worm to the specific ports of p2p node. So here the author tried to prove the efficiency of his method by performing an experiment. In this experiment he prepared a multiple group worm body and sent it repeatedly at regular intervals of time. Then he captured these packets and extracted their characteristics and compared it with the one that already exist in the feature library. P2p worm is detected separately using different algorithms like BF algorithm, KMP algorithm and suffix-array algorithm and compared their results doing three experiments. In the experiment 1, worm characteristics are in the same packet.. in the experiment