Financial Management Essay

Part A There are three main areas of decision making for the corporate financial manager: Investment: The choice of projects or assets in which to invest company funds. Competing alternatives have to be assessed using a number of techniques. This type of decision will also be of concern to the private individual when making choices about which shares to buy. Finance: How these investments should be financed. It is necessary to evaluate the possible sources, external and internal, and the effect they will have on the capital structure of the company. Dividend: Whether corporate earnings should be retained or paid out in the form of dividends, and if the latter, when the dividends should be paid. Otherwise, we will cover the risk management as well as the management of a company’s assets and liabilities in its working capital cycle. Assets must be managed effectively so that they generate income and profits, and so that funds are available to pay creditors and take up opportunities for investment. In summary ,therefore, we can say that financial management involves the following areas as investment decisions, funding decisions, including the capital structure of the company, dividend decisions, risk management. This implies that dividend payments and gains made when selling a shareholding are better indicators of shareholder wealth than profits. However, if the dividend payments are not consistent over a period of time, this will not increase confidence in the company shares, and their market price will reflect the variability of dividend payments. When the shareholder sells their investment, they may lose money. The prime objective of the company therefore needs to be adjusted slightly to the maximization of long-term shareholder wealth. This will be indicated by maximisation of dividends over time and reflected in the market value of the ordinary shares. If the share price reflects shareholder wealth, then we can say that any financial decision taken to increase the value of shares will be a decision that maximises shareholder wealth, and will be in keeping with the prime objective of the company, such a decision can involve are using appraisal techniques to assess investment projects and sourcing funding to provide for the company the most appropriate capital structure that can be serviced from available funds and paying dividends that the company can afford, while leaving sufficient retained earnings for investment and managing the risks associated with these decisions. This may leave you with the impression that the managers of a company will carry out its day to day functions efficiently and effectively on behalf of the owners, always asking themselves about the result of the decision maximise shareholder wealth, this is a realistic view because of the tension between ownership and control of company. That is limitations of shareholder wealth maximisation as concern to agency theory. Agency theory is based in the separation of ownership and control that distinguishes the limited liability company from the other two business entities of the sole trader and the partnership. The relationship between shareholders and management is the principal agent relationship, and has given reis to agency theory. Where an agent was defined as a person used to effect a contract between their principal and a third party. The agency problem is that managers may not always act in the best interest of the shareholders, to maximise the latter’s wealth. Offering incentives, such as share options, to managers may reduce this problem. Solving the agency problem When the agency problem exits, therefore, when managers or directors do not act in the best interest of the shareholders to maxmise the latter’s wealth. Management goals could include increasing their rewards. It was suggested in an earlier activity that two ways to ensure that management act in shareholders interests are to vote unacceptable directors off the board, or to offer share options. Shareholder could monitor the actions of managers using independently audited accounts, backed up by additional reporting requirements and external analysts. The managers may not act in the best interest of the shareholders, so they may be offering other such as share options. However, the share options also have some things to consider as the advantages is encourage managers to maximise shareholder wealth since the option may result in their being able to sell shares at a higher price. But the disadvantages is the price of shares is influenced by some factors outside the control of management, so the benefits may accrue despite management actions. Managers may also change accounting polices to improve the performance of the company and influence the share price deliberately. Otherwise, Capital structure refers to the way an entity finances its assets through a combination of equity and debt. An entity’s capital structure is then the composition or structure of its liabilities. Capital structure ratios show an entity’s capital structure and measure its ability to meet its long term obligations. If the entity appears unable to meet its long term obligations, it will be in serious danger of collapse or takeover. Further, long term financial position depends much on an entity’s profitability since, in the long run, the entity will not be able to repay its debts unless it is profitable. The capital gearing ratio is a measure of the financial risk of an entity because of the prior claim that debt capital has on the profits and assets of the entity in the event of liquidation. Also, if the profits are low, the entity may not have sufficient funds available to make dividend payments to the ordinary shareholders. Capital gearing ratio: (preference shares + long term loans) / (shareholder’s funds + long term loans) X 100 The difficulty is the inclusion of preference shares, since they take many different forms. If a company’s preference shares are of the standard type, that is, having no voting rights and conveying nothing but the right to a fixed rate of dividend, they should be included as debt funding. The higher the percentage, the higher the level of gearing. It is advisable to include short term debt such as overdraft if it is used to fund long term investments and is not, therefore, of a temporary nature and bears a financial risk. A highly geared company may also experience difficulties in attracting funds from investors, who are not attracted by the risks involved in a high geared company. In this event, the market price of the company’s shares will fall. The more debt, the more risk for ordinary shareholders and ultimately for everyone, if the company faces liquidation. However, the more debt, the lower the WACC because debt is cheaper than equity. At very high levels of debt, however, the WACC will rise because of the higher levels of risk involved. Reference: Notes of the University of Sunderland APC308 Financial Management Conclusion The areas of corporate financial management are the decisions concerning investment, funding, dividend and working capital. And the company will use the gearing ratio to express the debt funding as a percentage of the total funding, because the high gearing ratio also brings problems associated with the interest rates and the main objective in financial management is the maximisation of long term shareholder wealth that is the market value of the ordinary shares, because it is related to the how many dividends will pay to shareholders. However, the agency problem is a main problem on the managers may not act in the best interest of the shareholders, so they may be offering other such as share options. Part B In Part A, i have explored two of three main areas of decision making for corporate financial managers: the investment decision (NPV) and the finance, or funding, decision. In this part i am concerned with the third area, the dividend decision. The basis for the discussion in this part is the need for dividend policy and the relevance of dividend policies to investors. NPV is a net present value is the present value of the future recipts from a project less any investment made in the project. Modigliani and Miller’s theory: dividends are irrelevant but almost is not quite. MM’s theory of dividend irrelevancy refers not to the payment of the dividends but to the timing of their payment. According to MM, if a company has an investment opportunity giving a positive NPV, it should be taken up using retained earnings rather than paying out a dividend. The company’s value will go up, since share value is a function of the level of earnings, which reflect a company’s investment policy, rather than a function of dividend payments. Similarly, in their theory of dividend irrelevancy they say that shareholders can create their own dividend, if they want to, by selling some of their theory of dividend, if they want to, by selling some of their shares. In a perfect market, shareholders can create a dividend stream to suit themselves, so it works in reverse too: if the company does pay a dividend and the shareholder does not want one, they can reinvest by buying more shares. Otherwise, MM’s view is that it is not the company but the individual shareholder who should decide dividend policy. Therefore, there is no such thing as an optimal dividend policy for a company, only an optimal investment policy. This would be a policy of investing in all projects with a positive NPV. In a perfect capital market, a company with insufficient internal funds could raise the funds required for investment externally. If a company had surplus internal funds, there could be distributed as dividends.

Analysis of Family Guy Essay

Back in the eighth grade at the Pierce elementary school, a few of my friends and I sat around the circular lunch room tables, the same ones where we sat every day of the year. Our discussion shifted to our favorite TV. shows. At the time, I was a big Simpsons fan and I didn’t really watch too many other shows regularly. We would go around blurting out funny lines and quotes from our favorite episodes or recall hilarious incidents. This was when two of my friends were talking about this show Family Guy. Even though I had never seen it, I could tell from their impersonations that it was a funny show. It had the same general theme as The Simpson, but had even crazier and funnier plots and adventures. When I finally saw my first episode in ninth grade, it was an instant classic in my list of favorite shows. From then on I would watch it as mush as it was on and I even got a collection of DVD’s which I watch regularly. This show goes into the life of an average family in Rhode Island. The characters include a mother and father, three children including two awkward and socially challenged teenagers and a talking baby, as well as the talking family dog. It makes fun of things we do every day that may not seem stupid, but really they are unnecessary and pointless. This show is filled with hilarious flash backs to past events, and includes lots of sarcasm as well as some dumb comments and actions by the unintelligent father, Peter. One of my favorite episodes is â€Å"Pre-Retarded†, where Peter finds out he’s retarded and goes around doing stupid, but hilarious things. He wins a game of Trivial Pursuit because his wife gave him ridiculously easy questions from the children’s version including â€Å"What color are fire trucks?† Peter struggles, but eventually gets it right and wins the game, convincing himself that he’s a genius. When he takes the test, he finds out that not only is he not a genius, he’s actually mentally retarded so he bulldozes the house in celebration. This episode is similar, but better than the rest of the episodes, because the plot is typical, but it is filled with more funny comments and random instances. Although this show may seem just like a basic comedy, meant to entertain children, it is really targeted at teens and young adults. The comedy makes fun of other stereotypes and gets away with things that may be considered racist, sexist, anti-Semitic, and homophobic. It portrays these groups of people in the way they are supposed to be seen in society, but shows that the stereotypes aren’t true, by making the stereotypes seem stupid and exaggerated. In another episode when they are trying to get away from a bunch of southerners, the dog, Brian screams â€Å"Look, it’s a newly-married, interracial, gay couple burning the American flag†. It shows how ridiculous they look when they all scream, â€Å"Oh let’s get’em!†, and this way it makes fun of the stereotypes against southerners, and the group of people described in his remark, because the people would never actually do this. The reason I like Family Guy is because it is really one of the funniest, and most genius shows on television. The writers of the show are very intelligent, and smart about what they write. Although this show is hilariously funny, that is just one of its good qualities. It also sends an important ideas about how people are supposed to be seen, and tells us that stereotypes aren’t always true. It makes fun of average things and has long awkward pauses to show how funny our daily routines can be. Although this show may be offensive to some, I believe it is all in good humor. I am Jewish and in some episodes they do make fun of Jews reinforcing the stereotypes, that all Jews are rich accountants, lawyers, or doctors. This is just to make a point, and the writers do not really believe the things they show, because they exaggerate the stereotypes to make them look silly. In a way, this show is a lot like me. On the outside I really enjoy comedies, and basic entertainment that I can laugh about. There are also real issues that are important to me, and other things in my life that I care about besides just humor. This show is very provocative, but I believe it to be very funny as well as important, even if others may not share these same views. This program shows that I am a caring person and I am aware of the realities in life. Like Family Guy, I may be funny and joking on the outside, but we both go deeper on the inside.

Should Graffiti Be Illegal Research Paper Example | Topics and Well Written Essays - 1000 words

Should Graffiti Be Illegal - Research Paper Example Why is it that people want to see masterpieces in museums and art galleries and not in the streets where they walk? It could be because people directly affiliate graffiti with gangs and their territories, it is seen as the work of punks and gangsters. Graffiti is actually an innovative form of expression for youngsters. Letting your creativity flow doesn’t mean that you’re a criminal or a thug. An online article seconds this: â€Å"The graffiti is their way of expressing what they think is art and what art may mean and represent to them. This art helps people express who they are and what they feel art should look like and isn't that what art is all about† (Graffiti good or bad?). ‘Bombing’ is one of the most popular styles of graffiti art. It can be described as a form of art in which a person writes up on canvas or a wall in their own unique style with colors and fancy lettering (Graffiti good or bad?). We usually see examples of bombing, as decora tive writing on walls with different letter formations and an explosion of color and creativity. It is used to write for fun, to poke fun or to make a bold statement against the wrong-doings in society. People often find such art intriguing and appreciate its uniqueness, but at the same time it is also seen as an expression of violence. Hence the mixed attitudes debate over the legality of such art. These artists should be provided with a platform to express their own selves and be recognized for their talents instead of being convicted and put into jail. Why don't we have art museums for street art? In modern times, there is no definition of what art is. There are no restrictions or limits to how art can be represented. Representations and expressions of modern-day art know no boundaries. An online article seconds this when it says, â€Å"Art can be created into anything; it can be created into different forms that both intrigue and stimulate our senses but who actually decides wh at art is? Who has the right to tell us what we can and cannot do with art† (Graffiti good or bad?). They are as free flowing as the creativity of modern-day artists themselves, including graffiti artists. According to Bomb, It the documentary by Jon Reiss, the idea of graffiti art sprung from the childish habit of writing your name whenever you had a pen in your hand or in this case, a can of spray-paint. Street artists love to leave their mark on the walls, and they do that by writing their names, aliases or nicknames in all sorts of styles and colors on the walls. â€Å"Bomb it† the documentary also explores the roots of graffiti art and traces it back to Philadelphia, Pennsylvania. A street artist named cornbread is widely acknowledged as the world’s first graffiti artist and not just by himself, but by other street artists as well. Moreover, the documentary also goes on to say that graffiti actually existed from the earlier times and had a quite appealing th eory to support their claim; they say that cave drawings found from the earliest of times are, in fact, a form of graffiti. This suggestion that graffiti art has primitive roots is  really  very  interesting and a rather viable theory considering the nature of cave drawings. Graffiti artists see themselves as revolutionaries trying to speak their mind out using the form of expression, they’re best at. In the documentary Bomb It, we see how one street artist claims that it is the society that has given them the

Teaching and Education Essay Example | Topics and Well Written Essays - 2000 words

Teaching and Education - Essay Example Therefore, more precisely put, reflective practice is an independent approach, which fosters critical thinking and in-depth understanding of concepts and ideas. Reflective practitioners derive their origin from learning proposed by Socrates that emphasizes the importance of asking questions and collecting feedback from one’s own self and others. It also stresses upon the fact that learning eventually comes from individual’s inner self and that no teacher can demonstrate the connections an individual mind makes out of a piece of knowledge and his/her own cognition better than the student him/herself. The notion of reflective practice in education is a product of studies and innovation in constructivist theories and cognitive psychology. According to this modern and much-regarded view, intelligence is a fluid, active thought process and reflection on one’s own learning and life experience proves to be an important landmark of intellectual growth. John Dewey, the pi oneer of this field, remarks that intellectual growth is a product of rebuilding the experience. One of the many proposed models for doing this is problem-solving model that comprises of four steps: the first is to analyze the situation and determine its difficulty level. Second is to come up with alternatives and choosing the best amongst the available ones. Lastly, the final touch comes by applying the solution and checking the results. Experts (Roffey-Barensten & Malthouse, 2008, 23-49) have indicated that most individuals reflect on their practice and actions naturally, while others may take reflection as extra work on top of what they have to do. Reflection helps teachers in not only their lessons but it also benefit... This paper approves that planning is just a phase in the entire process of effective teaching. Classroom management is another important step, invariably the most important one, for the development of an ideal learning setting. Several strategies have proven remarkably excellent in the past studies and they have been known to bring out the best in students. Some of the important ones include, conveying the fact that the teacher is in complete knowledge of students’ behavior. Another important way of eliciting high levels of work involvement by students is that the transition between the activities and classes be made less and less prominent for the students. Often, it happens that students do well till recess after which their energy levels fall drastically, or some kids who were brilliant in the art class sleep in the science class that follows. In this regard, the teacher should ensure that students are on the same page by employing warm-ups and ice-breaking activities. This essay makes a conclusion that training teachers to be reflective practitioners and aiding them with proper classrooms with tools for positive interaction and learning help in effective teaching and lead to better education systems. Conclusively, the paper has analyzed some of the significant aspects of teaching and education. The paper recognized and scrutinized different studies related to the topic; and it is expectation that the discussion will be beneficial for students, teachers, and professionals in comprehensive understanding of the topic.

Leonardo Da Vinci Contribution To Aviation History Research Paper - 2

Leonardo Da Vinci Contribution To Aviation History - Research Paper Example It is evidently clear from the discussion that one of the great achievement made by Leonardo Da Vinci was his most significant contribution to the industry of Aviation. Leonardo Da Vinci was fascinated by the concept of flying human beings and this promoted him to develop thousands of words as well as hundreds of sketches that focused on the subject of aviation. His ideas regarding the aviation have been presented in the form of several codexes and one of the codes that specifically focuses on the aviation industry is recognized as the Codex on the Flight of Birds. His interest in the concept of aviation seems to be guided by the huge amount of in-depth work he has performed on the subject of militia and technology for military purposes. Due to his focus on military based technological advancements, he was able to develop the concept of aerial reconnaissance. He was the one who came up with the idea that there should be a machine that can fly and help in attaining the objective of ae rial reconnaissance. Most of Leonardo Da Vinci’s ideas were based on nature and he applied the same basis to the idea of developing an airplane or an aircraft that can fly with the assistance of flapping wings. This idea led him to design an aircraft which is recognized as ornithopters. While developing this design he did not take into consideration that fact the human beings have limited amount of capacity to move their muscles. But the design of two arms or wings flapping can be said to have provided a direction to aircraft developers in realizing that an aircraft needs wings to fly. A much realistic design and thought provided by Leonardo Da Vinci was on various concepts of aviation in his Codex on the Flight Birds. In Codex on the Flight Birds, he focused on the importance of center of gravity and its use in lifting the weight.

CNC machines(Fundamentals and Applications) Essay

CNC machines(Fundamentals and Applications) - Essay Example Nowadays in order to provide better online data transfer, CNCs can be connected to the internet. Companies having multi operations are benefitted a lot from this so that they can transfer their programmes to other locations. Today’s CNCs provide a very high level of automation. Any skillful operator can use all the features to increase his/her own as well as company’s productivity. Their capacity to deliver extreme precision has given a great boost to innumerable new state-of-the-art technologies as a multiplier effect to produce thousands of products in the last 30-40 years. In the manufacturing and production sectors, automation using computers has become a common, if necessary trend. The application of Numerical Control (NC) and Computer Numerical Control (CNC) has seen production work become more effective in virtually all dimensions. With the three and five axis CNC machines, more complex shapes can be produced in real time, more accurately and without having to set and reset machines and workpieces over and over as I always the case with conventional machines. Having several structural components and coming in modular form, CNC machines are controlled using dedicated software and programs to automate and control its functions. Computer Numerical Control (CNC) is the automated control of the machine tools by a computer program and a computer; the machine is controlled by a computer rather than a person (Mattson 2009, p.9). On the other hand, Numerical Control (NC) can be defined as a type of programmable automation that involves the use of a program of instructions to control the mechanical actions of machines or equipment. The program has set of instructions that include positioning of the workhead and workpiece and other instructions that are necessary to operate the machine. A workhead is the cutting tool and the workpiece is the object being processed. The application of

English Law Position of the Hijab on Muslim Customary Laws Essay

English Law Position of the Hijab on Muslim Customary Laws - Essay Example Hijab comes from the Arabic word Hajaba, which means to hide or conceal from view. Generally, it refers to modest dressing for Islamic women. It is extended to mean privacy and modesty. Hijab is not just a piece of cloth on the head, but rather it is a way of life. Hijab requires much more than just covering the head. Hijab is the way you carry yourself, the way you talk, the way you walk. Hijab as a matter of fact is a whole way of life and hence an attitude in itself. For those who are non-Muslims, Hijab is mostly associated with a modest way of clothing that is worn by Muslim women. It is also called the headscarf and it is one of the most noticeable things of Muslim women. Hijab is a duty that is expected from all Muslims. Some Muslims see the concept of Hijab as being consistent and balanced with ideas of gender equality; others view the religious requirement on female covering as patriarchal, chauvinistic, and oppressive and an enforcement of women against their rights (Bahi, 2 008). The wearing of Hijab impacts on so many human rights issues both philosophical and practical and has much currency given recent events. The issue of Islamic dress is linked with immigration issues. The reasons given for prohibition vary but in most cases legal bans on face covering clothing are undertaken as an anti terrorism measure and is justified on security grounds. However there is public controversy which indicates the possibility of polarization between western European societies and the Muslims. In the year two thousand and six, the then British Prime Minister Mr. Tony Blair described it as a mark of separation (Werner, 2011). Terrorism is the criminal enactment or acts expected or ascertained to incite a state of fear in the overall population. It’s an aggregation of persons or specific persons for political purposes and such gestures are in any circumstances outlandish whatever the contemplations of a political, philosophical, ideological, ethnic, racial, religious or other nature that may be conjured to support them. In virtually every corner of the world we can say that the human cost of terrorism has been felt. Terrorism has a very direct and real impact on human rights. Its consequences are very devastating in regards to liberty, physical integrity of victims and enjoyment of the right to life. Terrorism has the ability to undermine civil society, threaten social and economic development, jeopardize peace and security and destabilize governments. An individual’s security is a basic human right and thus the protection of the individuals is considered a fundamental obligation of the government (Macmillan, 2010). States therefore are obligated to uphold human rights of their citizens and others by taking positive measures to keep them safe from terrorists and their threats and bring such perpetrators to justice. Lately however the measures to counter terrorist acts have by states have been challenging to the rule of law and human right s .The bedrock of fighting terrorism should be the respect for the rule of law and human rights. The development of national counter terrorism strategies whose aim is to prevent the acts of terror, prosecute the perpetrators and offer protection of human rights and the rule of law is a major requirement. This implies measures to address the drivers to motivation of terrorism. Terrorism threatens the security and dignity of human beings everywhere, takes innocent lives, endangers lives, and creates an environment that destroys the freedom since the people are in fear. Through acts of terror, fundamental freedom is jeopardized and there is destruction of human rights. It undermines the pluralistic civil society, affects the rule of law and its establishment and it has the ability to destabilize governments that are legitimately constituted. Research shows that terrorism has links with organized crime that is transnational, drug

Accounting Assignment Example | Topics and Well Written Essays - 250 words - 15

Accounting - Assignment Example Technological advancements improve appropriate investment leading to low-cost production of delicious bakery foods. Clients at the end receive extraordinary services with improved processes, quality enhancement, and resource conservation lead to smart baking. Team members are always encouraged and appreciated hence acquire the motivations in their line of duty. The automated bread line includes dough baking, ingredients, mixing, and transportation to the final collection stages. The automation helps to ensure quality and a standard sizing of bread. The size is at 215,000 square feet (Flowers Foods, 2014). Production lines fit the two one-bread line and a one-bun line, whereas the capacity set at 3 million pounds of breads. The buns produced per week owing a speed of 60,000 buns per hour or 10,000 loaves of bread per hour. The products maintained in the market include nature own breads and burns, Betsy Ross, Mary Jane and Bunny. Dough making, transportation, and delivery to the consumers are labor intensive. Human resource investment is essential in various areas of production and marketing. Massive human resource contributes a fundamental role in enhancing the delivery of baked cakes to

Franklin Pierce Essay Example for Free

Franklin Pierce Essay Franklin Pierce (November 23, 1804 – October 8, 1869) was the 14th President of the United States, serving from 1853 to 1857, an American politician and lawyer. To date, he is the only President from New Hampshire. Pierce was a Democrat and a doughface (a Northerner with Southern sympathies) who served in the U. S. House of Representatives and Senate. Later, Pierce took part in the Mexican-American War and became a brigadier general. His private law practice in his home state, New Hampshire, was so successful that he was offered several important positions, which he turned down. Later, he was nominated for president as a dark horse candidate on the 49th ballot at the 1852 Democratic National Convention. In the presidential election, Pierce and his running mate William R. King won by a landslide in the Electoral College, defeating the Whig Party ticket of Winfield Scott and William A. Graham by a 50% to 44% margin in the popular vote and 254 to 42 in the electoral vote. According to historian David Potter, Pierce was sometimes referred to as Baby Pierce, apparently referring to both his youthful appearance and his being the youngest president to take office to that point (although he was, in reality, only a year younger than James K. Polk when he took office). Pierce attended school at Hillsborough Center and moved to the Hancock Academy in Hancock at the age of 11; he was transferred to Francestown Academy in the spring of 1820. In fall 1820, he entered Bowdoin College in Brunswick, Maine, where he participated in literary, political, and debating clubs. There he met writer Nathaniel Hawthorne, with whom he formed a lasting friendship, and Henry Wadsworth Longfellow. He also met Calvin E. Stowe, Seargent S. Prentiss, and his future political rival, John P. Hale, when he joined the Athenian Society, a group of students with progressive political leanings. In his second year of college his grades were the lowest of his class, but he worked to improve them and upon graduation in 1824 ranked third among his classmates. In 1826 he entered a law school in Northampton, Massachusetts, studying under Governor Levi Woodbury, and later Judges Samuel Howe and Edmund Parker, in Amherst, New Hampshire. He was admitted to the bar and began a law practice in Concord, New Hampshire in 1827. Pierce served as President from March 4, 1853, to March 4, 1857. He began his presidency in a state of grief and nervous exhaustion. Two months before, on January 6, 1853, the President-elects family had boarded a train in Boston and shortly thereafter were trapped in their derailed car when it rolled down an embankment near Andover, Massachusetts. Pierce and his wife survived, merely shaken up, but saw their 11-year-old son Benjamin crushed to death. Jane Pierce viewed the train accident as a divine punishment for her husbands pursuit and acceptance of high office. Pierce chose to affirm his oath of office rather than swear it, becoming the first president to do so; he placed his hand on a law book rather than on a Bible while doing so. He was also the first president to recite his inaugural address from memory. In it Pierce hailed an era of peace and prosperity at home and urged a vigorous assertion of US interests in its foreign relations. The policy of my Administration, said the new president, will not be deterred by any timid forebodings of evil from expansion. Indeed, it is not to be disguised that our attitude as a nation and our position on the globe render the acquisition of certain possessions not within our jurisdiction eminently important for our protection. The nation was enjoying a period of economic growth and relative tranquility. The Compromise of 1850 seemed to have calmed the storm about the issue of slavery. When the issue flamed up early in his administration, though, Pierce did little to cool the passions it aroused, and sectional fissures reopened. The greatest challenge to the countrys equilibrium during the Pierce administration, though, was the passage of the Kansas-Nebraska Act in 1854. It repealed the Missouri Compromise and reopened the question of slavery in the West. This measure, sponsored by Senator Stephen A. Douglas, had its origins in the drive to facilitate the completion of a transcontinental railroad with a link from Chicago, Illinois to California through Nebraska.

Global Warming Essay Example for Free

Global Warming Essay Among The most profound environmental problems, Global Warming is one of the serious problem. Former vice president Al Gore takes his environmentally friendly political agenda to the big screen with the documentary ‘An Inconvenient Truth’. The film follows Gores platform of recognizing global warming as a worldwide problem. Gore says the truth must be revealed or there will be consequences to pay . Since the beginning of Industrial Revolution, atmospheric concentration of CO2 have increased by 30%, Methane concentration by 100% and Nitrous oxide concentration by about 15%. These increases have enhanced the heat trapping capability of the Earth’s atmosphere. The combustion of coal, oil and natural gas accounts for most of the heat trapping greenhouse gases emitted by human activities. Most of the best and brightest in the world scientific community, however, believe we are heading for the trouble. But coal and petroleum products are abundantly used for moving the life cycle of people. Asking such people to slow down or choose more expensive alternative energies is asking for trouble. Petroleum industry is very big industry In which there are millions of people employed and the millions of families thriving on this for their livelihood. To find out the solution of Global Warming merely alleging the petroleum industry and burning of fossil fuels then those millions of people who are depending on these industries are badly affected. There are so many other causes also which are responsible for the Global Warming like industrial revolution, nuclear radiations and emitting of green house gases. 98% of total global greenhouse gas emission are natural, mostly water vapour; the effect of water vapour is not well understood. Some of the critics of Al Gore’s ‘Inconvenient of Truth’ says â€Å" An Inconvenient Truth, Al Gore makes absurd remarks about global warming that stretch well beyond the IPCC claims. This clip demonstrates some of Gores various exaggerations on the subject of global warming†. There could be benefits in the wake of the planet’s warming. Increased rainfall, created by climatic fluctuations, in a semi arid region will raise agricultural productivity. Rising CO2 levels cause plants to grow faster and absorb more CO2, through photosynthesis. Longer growing seasons may boost yields in northern Canada and Europe. In fact, a vast majority of scientists now believe that even an immediate and dramatic cut in global greenhouse gas emissions would not fully prevent climate change impacts. Even USA, world’s largest emitter of greenhouse gases, is not willing to be subjected to any kind of restraint on their energy use. USA has not ratified the Kyoto Protocol. The country claimed that if it has to implement the provisions of the Protocol, the economic losses will be heavy and will drive 5 million Americans out of work. Policies to promote energy efficiency, in the long run, will improve economic performance, at the individual firm or country level. Global warming is a global problem calling for global solutions; no nation alone can defeat the problem. Industry must develop energy – efficient vehicles, consumer goods and production processes. â€Å" Most important, individual households must contribute to emissions reduction through their power of consumer choice and their personal lifestyle decision†. Reference: With inputs from â€Å" Is Apocalypse Near, Far or Never? † by G. Vijaya Raghavan V S M Nair.

Security for Insider Attacks in Mobile Ad Hoc Networks

Security for Insider Attacks in Mobile Ad Hoc Networks Abstract Mobile ad hoc networks are collection of wireless mobile nodes forming a temporary network without the aid of any established infrastructure. Security issues are more paramount in such networks even more so than in wired networks. Despite the existence of well-known security mechanisms, additional vulnerabilities and features pertinent to this new networking paradigm might render the traditional solutions inapplicable. In particular these networks are extremely under threat to insider attacks especially packet dropping attacks. It is very difficult to detect such attacks because they comes in the category of attacks in mobile ad hoc networks in which the attacker nodes becomes the part of the network. In this research work we have proposed a two folded approach, to detect and then to isolate such nodes which become the part of the network to cause packet dropping attacks. First approach will detect the misbehavior of nodes and will identify the malicious activity in network, and then upon identification of nodes misbehavior in network other approach will isolate the malicious node from network. OMNET++ simulator is used to simulate and verify the proposed solution. Experimental results shows that E-SAODV (Enhanced Secure Ad hoc On Demand Distance Vector protocol) performs much better than conventional SAODV (Secure Ad hoc On Demand Distance Vector Protocol) Chapter 1 Introduction Overview Mobile Ad-hoc networks are a new paradigm of wireless communication for mobile hosts. As there is no fixed infrastructure such as base stations for mobile switching. Nodes within each others range communicate directly via wireless links while those which are far apart rely on other nodes to transmit messages. Node mobility causes frequent changes in topology. The wireless nature of communication and lack of any security infrastructure raises several security problems. The following flowchart depicts the working of any general ad-hoc network. Features of Mobile Ad hoc Networks Based on the characteristics, Mobile Ad hoc Networks has following main features. Because of the limited energy supply for the wireless nodes and the mobility of the nodes, the wireless links between mobile nodes in the Ad hoc Network are not consistent for the communication participants. Due to the continuous motion of nodes, the topology of the mobile ad hoc network changes constantly, the nodes can continuously move into and out of the radio range of the other nodes in the ad hoc network, and the routing information will be changing all the time because of the movement of the nodes. Lack of incorporation of security features in statically configured wireless routing protocol not meant for Ad hoc environments. Because the topology of the Ad hoc Networks is changing constantly, it is necessary for each pair of adjacent nodes to incorporate in the routing issue so as to prevent some kind of potential attacks that try to make use of vulnerabilities in the statically configured routing protocol. Mobile Ad hoc Network Routing Protocols Routing in Mobile Ad hoc Networks faces additional challenges when compared to routing in traditional wired networks with fixed infrastructure. There are several well-known protocols that have been specifically developed to cope with the limitations imposed by Ad hoc networking environments. The problem of routing in such environments is aggravated by limiting factors such as rapidly changing topologies, high power consumption, low bandwidth and high error rates [1]. Most of the existing routing protocols follow two different design approaches to confront the inherent characteristics of Ad hoc networks namely Proactive Routing Protocols, Reactive Routing Protocols. Proactive Routing Protocols Proactive ad hoc routing protocols maintain at all times routing information regarding the connectivity of every node to all other nodes that participate in the network. These protocols are also known as Table-driven Ad hoc Routing Protocols. These protocols allow every node to have a clear and consistent view of the network topology by propagating periodic updates [1]. Therefore, all nodes are able to make immediate decisions regarding the forwarding of a specific packet. Two main protocols that fall into the category of proactive routing protocols are Destination-Sequenced Distance-Vector (DSDV) protocol [2] and the Optimized Link State Routing (OLSR) protocol [3]. Reactive Routing Protocols An alternative approach to the one followed by Proactive Routing Protocols also known as source-initiated on-demand routing, is Reactive Routing Protocols. According to this approach a route is created only when the source node requires one to a specific destination. A route is acquired by the initiation of a route discovery function by the source node. The data packets transmitted while a route discovery is in process are buffered and are sent when the path is established. An established route is maintained as long as it is required through a route maintenance procedure. The Ad hoc On-demand Distance Vector (AODV) routing protocol [4], Temporally Ordered Routing Algorithm (TORA) [5] and the Dynamic Source Routing protocol [6] are examples of this category of protocols. Security issues in Mobile Ad hoc Routing Protocols Any routing protocol must encapsulate an essential set of security mechanisms. These are mechanisms that help prevent, detect, and respond to security attacks. We can classify these major security goals into five main categories, which need to be addressed in order to maintain a reliable and secure ad-hoc network environment. Confidentiality Confidentiality is the protection of any information from being exposed to unintended entities. In ad-hoc networks this is more difficult to achieve because intermediates nodes receive the packets for other recipients, so they can easily eavesdrop the information being routed. Availability Availability means that a node should maintain its ability to provide all the designed services regardless of the security state of it . This security criterion is challenged mainly during the denial-of-service attacks, in which all the nodes in the network can be the attack target and thus some selfish nodes make some of the network services unavailable, such as the routing protocol or the key management service. Authentication Authentication assures that an entity of concern or the origin of a communication is what it claims to be or from. Without which an attacker would impersonate a node, thus gaining unauthorized access to resource and sensitive information and interfering with operation of other nodes. Integrity Integrity guarantees the identity of the messages when they are transmitted. Integrity can be compromised through malicious and accidental altering. A message can be dropped, replayed or revised by an adversary with malicious goal, which is regarded as malicious altering while if the message is lost or its content is changed due to some failures, which may be transmission errors or hardware errors such as hard disk failure, then it is categorized as accidental altering. Non-Repudiation Non-repudiation ensures that sending and receiving parties can never deny their sending or receiving the message. In order to achieve the overall goal of Mobile Ad hoc Network security, above five mechanisms must be implemented in any ad-hoc networks so as to ensure the security of the transmissions along that network. Secure Ad hoc Routing As discussed earlier over the past decade, many Ad hoc routing protocols have been proposed in literature. Among them the most widely used are AODV (Ad hoc On Demand Distance Vector) [4] and DSR (Dynamic Source Routing) [2] which comes in the category of re-active routing protocols of Ad hoc Networks. All of these protocols have been studied extensively. But as there were no security considerations in the original design of these protocols, these protocols remain under threat from the attackers. The main assumption of these protocols was that all participating nodes do so in good faith and without maliciously disrupting the operation of the protocol. However the existence of malicious entities can not be disregarded in the systems especially the environment used for Ad hoc Networks. To overcome the security vulnerabilities in existing routing protocols, many security enhancements in these protocols have been proposed but unfortunately these secure Ad hoc Routing Protocols were either designed for a particular protocol or to address a specific problem operation of the protocol. For example SAODV (Secure Ad hoc On Demand Distance Vector Protocol) [7] was proposed to secure AODV (Ad hoc On Demand Distance Vector) protocol, Ariadne [10] was proposed to protect DSR (Dynamic Source Routing) protocol, ARAN [7] was proposed to protect the Ad hoc Routing in general while SEAD [8] was proposed to protect the DSDV (Destination Sequence Distance Vector Routing) protocol. The purpose of SAR [9] (Security Aware Routing) was also to protect the Routing in Ad hoc Networks. Problem definition Thus ongoing studies on MANETs pose many challenging research areas including MANETs security. Since MANETs are made up entirely of wireless mobile nodes, they are inherently more susceptible to security threats compared to fixed networks [11]. Access to wireless links is virtually impossible to control thus adverse security events such as eavesdropping, spoofing and denial of service attacks are more easily accomplished. These security risks must be reduced to an acceptable level while maintaining an acceptable Quality of Service and network performance. However, in order to work properly, the routing protocols in MANETs need trusted working environments, which are not always available. There may be situations in which the environment may be adversarial. For example some nodes may be selfish, malicious, or compromised by attackers. Most of the work done regarding network security in MANETs focuses on preventing attackers from entering the network through secure key distribution and secure neighbor discovery [10],[12]. But these schemes become ineffective when the malicious nodes have entered the network, or some nodes in the network have been compromised. Therefore, threats from compromised nodes inside the network are far more dangerous than the attacks from outside the network. Since these attacks are initiated from inside the network by the participating malicious nodes which behave well before they are compromised, it is very hard to detect these attacks. Keeping in view the security threats faced by MANETs we focus on Packet Dropping Attack which is a serious threat to Mobile Ad hoc Networks. Although many research efforts have been put on secure routing protocols but the attacks like packet dropping is not adequately addressed. We study the packet dropping attack in which a malicious node intentionally drops the packets they received. Unlike all previous researches which attempt to tolerate Packet Dropping Attacks, our work makes the first effort to detect the malicious activity and then identify the malicious or compromised nodes in the network. Research Objective The fundamental objective of this research is to discuss the security attacks faced by Mobile Ad hoc Networks specially insider attacks and to review the security in existing routing protocols especially secure routing protocols in MANETs. We particularly focus on packet dropping attack which is a serious threat to Mobile Ad hoc Networks. A novel security enhancement scheme to address packet dropping attack has been proposed. Thesis Organization Chapter 2 provides a brief introduction of security threats faced by Mobile Ad hoc Networks and secure routing to address these attacks. Chapter 3 discusses about the related work and flaws identified in the related work. Chapter 4 presents the possible solutions to address the packet dropping attack in Mobile Ad hoc Networks. Chapter 5 includes the implementation of proposed mechanisms and Results of the proposed mechanism and the thesis is concluded in Chapter 6. Chapter 2 Security Threats and Secure Ad hoc Routing Protocols Introduction This chapter includes the threats and types of attacks faced by Mobile Ad hoc Networks. Secure Ad hoc routing protocols like SAODV [7] (Secure Ad hoc On Demand Distance Vector), SAR [16] (Security Aware Routing), and ARAN [9] (Authenticated Routing for Ad hoc Networks) etc and how these protocols are still vulnerable to attacks, are discussed in this chapter. Types of attacks in MANETs There are numerous kinds of attacks in the mobile ad hoc networks, almost all of which can be classified into two types, External Attacks and Insider Attacks. External Attacks External Attacks are those attacks, in which the attacker aims to cause congestion, propagate fake routing information or disturb nodes from providing services. External attacks are similar to the normal attacks in the traditional wired networks such that the adversary is in the proximity but not a trusted node in the network, therefore, this type of attack can be prevented and detected by the security methods such as authentication or firewall, which are relatively conventional security solutions. Internal or Insider Attacks Due to the invasive nature and open network media in the mobile ad hoc network, internal also known as insider attacks are more dangerous than the external attacks because the compromised or malicious nodes are originally the legitimate users of the Ad hoc network, they can easily pass the authentication and get protection from the security mechanisms. As a result, the adversaries can make use of them to gain normal access to the services that should only be available to the authorized users in the network, and they can use the legal identity provided by the compromised nodes to conceal their malicious behaviors. Therefore, more attention should be paid to the internal attacks initiated by the malicious insider nodes when we consider the security issues in the mobile ad hoc networks. Internal or insider nodes when become part of the network can misuse the network in the following ways Packet Dropping A malicious node can attack at its level or at lower levels. Particularly in the context of Packet Dropping Attack, within a trust level, a malicious node or any other node which aims at saving its resources or intentionally launching a attack can successfully drop packets without being noticed and can get services from other nodes for forwarding its own packets. Node Isolation An internal malicious node can prevent nodes from communicating with any other node. Route Disruption A malicious node can break down an existing route or prevent a new route from being established. Route Invasion An inside attacker adds itself between two endpoints of a communication channel. Attacks based on modification A very simplest way for a malicious node to disturb the operations of an ad-hoc network is to perform an attack based on modification. The only task the malicious or compromised node needs to perform is to announce better routes than the ones presently existing. This kind of attack is based on the modification of the metric value for a route or by altering control message fields. There are various ways to perform this type of attacks; some of them are discussed below Altering the Hop Count This attack is more specific to the AODV [4] protocol wherein the optimum path is chosen by the hop count metric. A malicious node can disturb the network by announcing the smallest hop count value to reach the compromised node. In general, an attacker would use a value zero to ensure to the smallest hop count. Changing the Route Sequence Number When a node decides the optimum path to take through a network, the node always relies on a metric of values, such as hop count delays etc. The smaller that value, the more optimum the path. Hence, a simple way to attack a network is to change this value with a smaller number than the last better value. Altering Routing Information This type of attack leads network toward Denial of Service (DoS) attack. For example in a situation where a node M wants to communicate with node S. At node M the routing path in the header would be M-N-O-P-Q-R-S. If N is a compromised node, it can alter this routing detail to M-N-O-P. But since there exists no direct route from O to P, P will drop the packet. Thus, A will never be able to access any service from P. This situation leads the network towards a DoS attack. Impersonation Attacks Impersonation is also known as spoofing. In this type of attack the malicious node hides its IP address or MAC address and uses the addresses of other nodes present in the network. Since current ad-hoc routing protocols like AODV [4] and DSR [6] do not authenticate source IP address. By exploiting this situation a malicious node can launch variety of attacks using spoofing. For example in a situation where an attacker creates loops in the network to isolate a node from the remainder of the network, the attacker needs to spoof the IP address of the node he wants to isolate from the network and then announce new route to the others nodes. By doing this, he can easily modify the network topology as he wants. Fabrication Attacks Fabrication attacks can be classified into three main categories. Detection is very difficult in all of these three cases. Routing table poisoning Routing protocols maintain tables which hold information regarding routes of the network. In routing table poisoning attacks the malicious nodes generate and send fabricated signaling traffic, or modify legitimate messages from other nodes, in order to create false entries in the tables of the participating nodes. For example, an attacker can send routing updates that do not correspond to actual changes in the topology of the ad hoc network. Routing table poisoning attacks can result in selection of non-optimal routes, creation of routing loops and bottlenecks. Route Cache Poisoning This type of attack falls in the category of passive attacks that can occur especially in DSR [6] due to the promiscuous mode of updating routing tables. This type of situation arises when information stored in routing tables is deleted, altered or injected with false information. A node overhearing any packet may add the routing information contained in that packets header to its own route cache, even if that node is not on the path from source to destination. The vulnerability of this system is that an attacker could easily exploit this method of learning routes and poison route caches by broadcast a message with a spoofed IP address to other nodes. When they receive this message, the nodes would add this new route to their cache and would now communicate using the route to reach the malicious node. Rote Error Messages fabrication This attack is very common in AODV [4] and DSR [6], because when nodes move these two protocols use path maintenance to recover the optimum path. The weakness of this architecture is that whenever a node moves, the closest node sends an error message to the other nodes so as to inform them that a route is no longer accessible. If an attacker can cause a DoS attack by spoofing any node and sending error messages to the all other nodes. As a result malicious node can separate any node quite easily. Eavesdropping Eavesdropping is another kind of attack that usually happens in the mobile ad hoc networks. The goal of eavesdropping is to obtain some confidential information that should be kept secret during the communication. This information may include the location, public key, private key or even passwords of the nodes. Because such data are very important to the security state of the nodes, they should be kept away from the unauthorized access. Secure Ad hoc Routing Protocols Many solutions have been proposed for secure routing in ad hoc networks, in order to offer protection against the attacks discussed earlier. These proposed solutions are either completely new stand-alone protocols, or in some cases incorporations of security mechanisms into existing ones (like DSR [6] and AODV [4]). In order to analyze the proposed solutions and how they are still vulnerable to attacks we classified them into two main categories based on asymmetric cryptography and symmetric cryptography. Asymmetric Cryptographic Solution Protocols that use asymmetric cryptography to secure routing in mobile ad hoc networks require the existence of a universally trusted third party. This trusted third party can be either online or offline. The trusted third party issues certificates that bind a nodes public key with a nodes persistent identifier. Authenticated Routing for Ad hoc Networks ARAN [9] falls in this category of secure Ad hoc routing protocols; many of the other protocols presented in other categories that use asymmetric cryptography operate in a similar manner and have similar requirements. Authenticated Routing for Ad hoc Networks ARAN The Authenticated Routing for Ad hoc Networks (ARAN) proposed in [9] is a standalone solution for secure routing in ad hoc networking environments. ARAN use digital certificates and can successfully operate in the managed open scenario where no infrastructure is pre-deployed. The basic mechanism used in ARAN is certification that is achieved through the existence of a trusted certification authority (CA). All nodes are supposed to know their public key from the certification authority and also the public key of server. Prior to entering into the network, each node has to apply for a certificate that is signed by the certificate server. ARAN accomplishes the discovery of routes by a broadcast message from source node which is replied in a unicast manner. This route discovery of the ARAN protocol begins with a node broadcasting to its neighbors a route discovery packet (RDP). The RDP includes the certificate of the initiating node, a nonce, a timestamp and the address of the destinatio n node. Furthermore, the initiating node signs the RDP. Each node validates the signature with the certificate, updates its routing table with the neighbor from which it received the RDP, signs it, and forwards it to its neighbors after removing the certificate and the signature of the previous node (but not the initiators signature and certificate). The signature prevents malicious nodes from injecting arbitrary route discovery packets that alter routes or form loops [13]. The destination node eventually receives the RDP and replies with a reply packet (REP). The REP contains the address of the source node, the destinations certificate, a nonce, and the associated timestamp. The destination node signs the REP before transmitting it. The REP is forwarded back to the initiating node by a process similar to the one described for the route discovery, except that the REP is unicasted along the reverse path. The source node is able to verify that the destination node sent the REP by chec king the nonce and the signature. Figure 2 illustrates the process of route discovery in ARAN. All messages are authenticated at each hop from source to destination as well as on the reverse path. Due to heavy computation involved with the certificates, ARAN is vulnerable to many attacks e.g. DOS attacks. In situation when there are no malicious nodes in the network the load involved in the routing process force the legitimate nodes to drop the packets in order to save their resources. Symmetric Cryptography Solutions Symmetric cryptographic solutions rely solely on symmetric cryptography to secure the function of routing in wireless ad hoc networks. The mechanisms utilized is hash functions and hash chains. A one-way hash function is a function that takes an input of arbitrary length and returns an output of fixed length [14]. As hash functions are especially lightweight when compared to other symmetric and asymmetric cryptographic operations, they have been extensively used in the context of securing ad hoc routing. Secure Ad hoc On-demand Distance Vector Protocol (SAODV) The Secure Ad hoc On Demand Distance Vector (SAODV) [7] addresses the problem of securing a MANET network. SAODV is an extension of AODV[4] routing protocol that can be used to protect the route discovery mechanism by providing security features like authentication, integrity and non-repudiation. It uses digital signatures to authenticate the non-mutable fields of the message, and hash chains to secure the hop count information (the only mutable field in message) in both RREQ and RREP messages. The SAODV scheme is based on the assumption that each node possesses certified public keys of all network nodes . In order to facilitate the transmission of the information required for the security mechanisms, SAODV defines extensions to the standard AODV message format. These SAODV extensions consist of the following fields. The hash function field identifies the one-way hash function that is used. The field max hop count is a counter that specifies the maximum number of nodes a packet is al lowed to go through. The top hash field is the result of the application of the hash function max hop count times to a randomly generated number, and finally the field hash is this random number. When a node transmits a route request or a route reply AODV packet it sets the max hop count field equal to the time to live (TTL) field from the IP header, generates a random number and sets the hash field equal to it, and applies the hash function specified by the corresponding field max hop count times to the random number, storing the calculated result to the top hash field. Moreover, the node digitally signs all fields of the message, except the hop count field from the AODV header and the hash field from the SAODV extension header. An intermediate node that receives a route request or a route reply must verify the integrity of the message and the hop count AODV [4] field. The integrity requirement is accomplished by verifying the digital signature. The hop count field is verified by comparing the result of the application of the hash function max hop count minus hop count times to the hash field with the value of the top hash field. Before the packet is re-broadcasted by the in termediate node the value of the hash field is replaced by the result of the calculation of the one-way hash of the field itself in order to account for the new hop. In SAODV route error messages (RERR) that are generated by nodes that inform their neighbors that they are not going to be able to route messages to specific destinations are secured using digital signatures. A node that generates or forwards a route error message cryptographically signs the whole message, except the destination sequence numbers. Although SAODV provides reasonable security to MANETs routing, but it is still vulnerable to distance fraud attack [15] in which the forwarding node fails to increment the route metric because in SAODV there is no enforcement to do so. Further there is no method to detect the malicious nodes and DOS attacks because in SAODV it is assumed that DOS attacks are restricted to physical layer, but this assumption failed when colluding malicious nodes drop packets during the route discovery process. Security Aware Routing (SAR) SAR [16] (Security Aware Routing) is an extension to existing on demand routing protocols and used where nodes are grouped on the basis of trust level. In SAR each node has different security level which assigns them different trust levels. Two nodes can only communicate with each other if they have equal or greater trust values. If a node has lower security level it simply discards the packet. In case there is no node in the network with the desired level then communication cannot take place or we can say that, that particular packet cant be forwarded unless its security level is lowered. By exploiting this condition a malicious node can attack at its level or at lower levels. Particularly in the context of Packet Dropping Attack, within a trust level, a malicious node or any other node which aims at saving its resources or intentionally launching a attack can successfully drop packets without being noticed and can get services from other nodes for forwarding its own packets. SAR al so fails in the situations of secure routing in general because it only focuses on the situations in which certain groups are assumed to be trustworthy. Conclusion From the above discussion, we observe that all Secure Ad hoc routing protocols are still vulnerable to many attacks. Although proposed techniques provide security against external attacks, insider attacks are still an open issue in MANETs. Chapter 3 Literature Review Introduction Many solutions have been proposed to prevent selfishness in MANETs. The main goal of all the schemes proposed in the literature is to make decisions regarding trustworthy entities and to encourage behavior that leads to increasing trust. In this section we discuss some of the solutions presented in the literature in order to detect the malicious nodes in the network in context of packet dropping attack. Watchdog and Pathrater In [17] Marti el al, proposed a mechanism called as watchdog and pathrater on DSR[6] to detect the misbehavior of nodes in MANETs. Nodes in this scheme operate in a promiscuous mode. The watchdog monitors one hop neighbor by overhearing the medium to check whether the next neighbor forwards the packet or not. It also maintains a buffer of recently sent packets. If a data packet remains in the buffer too long, the watchdog declares the next hop neighbor to be misbehaving. Every node that participates in the ad hoc network employs the watchdog functionality in order to verify that its neighbors correctly forward packets. When a node transmits a packet to the next node in the path, it tries to promiscuously listen if the next node will also transmit it. Furthermore, if there is no link encryption utilized in the network, the listening node can also verify that the next node did not modify the packet before transmitting it . The watchdog of a node maintains copies of recently forwarded p ackets and compares them with the packet transmissions overheard by the neighboring nodes. Positive comparisons result in the deletion of the buffered packet and the freeing of the related memory. If a node that was supposed to forward a packet fails to do so within a certain timeout period, the watchdog of an overhearing node increments a failure rating for the specific node. This effectively means that every node in the ad hoc network maintains a rating assessing the reliability of every other node that it can overhear packet transmissions from. A node is identified as misbehaving when the failure rating exceeds a certain threshold bandwidth. The source node of the route that contains the offending node is notified by a message send by the identifying watchdog. As the authors of the scheme note, the main problem with this approach is its vulnerability to blackmail attacks. The pathrater selects the path with the highest metric when there are multiple paths for the same destination node. The algorithm followed by the pathrater mechanism initially assigns a rating of 1.0 to itself and 0.5 to each node that it knows through the route discovery function. The nodes that participate on the active paths have their ratings increased by 0.01 at periodic intervals of 200 milliseconds to a maximum rating of 0.8. A rating is decremented by 0.05 when a link breakage is Security for Insider Attacks in Mobile Ad Hoc Networks Security for Insider Attacks in Mobile Ad Hoc Networks Abstract Mobile ad hoc networks are collection of wireless mobile nodes forming a temporary network without the aid of any established infrastructure. Security issues are more paramount in such networks even more so than in wired networks. Despite the existence of well-known security mechanisms, additional vulnerabilities and features pertinent to this new networking paradigm might render the traditional solutions inapplicable. In particular these networks are extremely under threat to insider attacks especially packet dropping attacks. It is very difficult to detect such attacks because they comes in the category of attacks in mobile ad hoc networks in which the attacker nodes becomes the part of the network. In this research work we have proposed a two folded approach, to detect and then to isolate such nodes which become the part of the network to cause packet dropping attacks. First approach will detect the misbehavior of nodes and will identify the malicious activity in network, and then upon identification of nodes misbehavior in network other approach will isolate the malicious node from network. OMNET++ simulator is used to simulate and verify the proposed solution. Experimental results shows that E-SAODV (Enhanced Secure Ad hoc On Demand Distance Vector protocol) performs much better than conventional SAODV (Secure Ad hoc On Demand Distance Vector Protocol) Chapter 1 Introduction Overview Mobile Ad-hoc networks are a new paradigm of wireless communication for mobile hosts. As there is no fixed infrastructure such as base stations for mobile switching. Nodes within each others range communicate directly via wireless links while those which are far apart rely on other nodes to transmit messages. Node mobility causes frequent changes in topology. The wireless nature of communication and lack of any security infrastructure raises several security problems. The following flowchart depicts the working of any general ad-hoc network. Features of Mobile Ad hoc Networks Based on the characteristics, Mobile Ad hoc Networks has following main features. Because of the limited energy supply for the wireless nodes and the mobility of the nodes, the wireless links between mobile nodes in the Ad hoc Network are not consistent for the communication participants. Due to the continuous motion of nodes, the topology of the mobile ad hoc network changes constantly, the nodes can continuously move into and out of the radio range of the other nodes in the ad hoc network, and the routing information will be changing all the time because of the movement of the nodes. Lack of incorporation of security features in statically configured wireless routing protocol not meant for Ad hoc environments. Because the topology of the Ad hoc Networks is changing constantly, it is necessary for each pair of adjacent nodes to incorporate in the routing issue so as to prevent some kind of potential attacks that try to make use of vulnerabilities in the statically configured routing protocol. Mobile Ad hoc Network Routing Protocols Routing in Mobile Ad hoc Networks faces additional challenges when compared to routing in traditional wired networks with fixed infrastructure. There are several well-known protocols that have been specifically developed to cope with the limitations imposed by Ad hoc networking environments. The problem of routing in such environments is aggravated by limiting factors such as rapidly changing topologies, high power consumption, low bandwidth and high error rates [1]. Most of the existing routing protocols follow two different design approaches to confront the inherent characteristics of Ad hoc networks namely Proactive Routing Protocols, Reactive Routing Protocols. Proactive Routing Protocols Proactive ad hoc routing protocols maintain at all times routing information regarding the connectivity of every node to all other nodes that participate in the network. These protocols are also known as Table-driven Ad hoc Routing Protocols. These protocols allow every node to have a clear and consistent view of the network topology by propagating periodic updates [1]. Therefore, all nodes are able to make immediate decisions regarding the forwarding of a specific packet. Two main protocols that fall into the category of proactive routing protocols are Destination-Sequenced Distance-Vector (DSDV) protocol [2] and the Optimized Link State Routing (OLSR) protocol [3]. Reactive Routing Protocols An alternative approach to the one followed by Proactive Routing Protocols also known as source-initiated on-demand routing, is Reactive Routing Protocols. According to this approach a route is created only when the source node requires one to a specific destination. A route is acquired by the initiation of a route discovery function by the source node. The data packets transmitted while a route discovery is in process are buffered and are sent when the path is established. An established route is maintained as long as it is required through a route maintenance procedure. The Ad hoc On-demand Distance Vector (AODV) routing protocol [4], Temporally Ordered Routing Algorithm (TORA) [5] and the Dynamic Source Routing protocol [6] are examples of this category of protocols. Security issues in Mobile Ad hoc Routing Protocols Any routing protocol must encapsulate an essential set of security mechanisms. These are mechanisms that help prevent, detect, and respond to security attacks. We can classify these major security goals into five main categories, which need to be addressed in order to maintain a reliable and secure ad-hoc network environment. Confidentiality Confidentiality is the protection of any information from being exposed to unintended entities. In ad-hoc networks this is more difficult to achieve because intermediates nodes receive the packets for other recipients, so they can easily eavesdrop the information being routed. Availability Availability means that a node should maintain its ability to provide all the designed services regardless of the security state of it . This security criterion is challenged mainly during the denial-of-service attacks, in which all the nodes in the network can be the attack target and thus some selfish nodes make some of the network services unavailable, such as the routing protocol or the key management service. Authentication Authentication assures that an entity of concern or the origin of a communication is what it claims to be or from. Without which an attacker would impersonate a node, thus gaining unauthorized access to resource and sensitive information and interfering with operation of other nodes. Integrity Integrity guarantees the identity of the messages when they are transmitted. Integrity can be compromised through malicious and accidental altering. A message can be dropped, replayed or revised by an adversary with malicious goal, which is regarded as malicious altering while if the message is lost or its content is changed due to some failures, which may be transmission errors or hardware errors such as hard disk failure, then it is categorized as accidental altering. Non-Repudiation Non-repudiation ensures that sending and receiving parties can never deny their sending or receiving the message. In order to achieve the overall goal of Mobile Ad hoc Network security, above five mechanisms must be implemented in any ad-hoc networks so as to ensure the security of the transmissions along that network. Secure Ad hoc Routing As discussed earlier over the past decade, many Ad hoc routing protocols have been proposed in literature. Among them the most widely used are AODV (Ad hoc On Demand Distance Vector) [4] and DSR (Dynamic Source Routing) [2] which comes in the category of re-active routing protocols of Ad hoc Networks. All of these protocols have been studied extensively. But as there were no security considerations in the original design of these protocols, these protocols remain under threat from the attackers. The main assumption of these protocols was that all participating nodes do so in good faith and without maliciously disrupting the operation of the protocol. However the existence of malicious entities can not be disregarded in the systems especially the environment used for Ad hoc Networks. To overcome the security vulnerabilities in existing routing protocols, many security enhancements in these protocols have been proposed but unfortunately these secure Ad hoc Routing Protocols were either designed for a particular protocol or to address a specific problem operation of the protocol. For example SAODV (Secure Ad hoc On Demand Distance Vector Protocol) [7] was proposed to secure AODV (Ad hoc On Demand Distance Vector) protocol, Ariadne [10] was proposed to protect DSR (Dynamic Source Routing) protocol, ARAN [7] was proposed to protect the Ad hoc Routing in general while SEAD [8] was proposed to protect the DSDV (Destination Sequence Distance Vector Routing) protocol. The purpose of SAR [9] (Security Aware Routing) was also to protect the Routing in Ad hoc Networks. Problem definition Thus ongoing studies on MANETs pose many challenging research areas including MANETs security. Since MANETs are made up entirely of wireless mobile nodes, they are inherently more susceptible to security threats compared to fixed networks [11]. Access to wireless links is virtually impossible to control thus adverse security events such as eavesdropping, spoofing and denial of service attacks are more easily accomplished. These security risks must be reduced to an acceptable level while maintaining an acceptable Quality of Service and network performance. However, in order to work properly, the routing protocols in MANETs need trusted working environments, which are not always available. There may be situations in which the environment may be adversarial. For example some nodes may be selfish, malicious, or compromised by attackers. Most of the work done regarding network security in MANETs focuses on preventing attackers from entering the network through secure key distribution and secure neighbor discovery [10],[12]. But these schemes become ineffective when the malicious nodes have entered the network, or some nodes in the network have been compromised. Therefore, threats from compromised nodes inside the network are far more dangerous than the attacks from outside the network. Since these attacks are initiated from inside the network by the participating malicious nodes which behave well before they are compromised, it is very hard to detect these attacks. Keeping in view the security threats faced by MANETs we focus on Packet Dropping Attack which is a serious threat to Mobile Ad hoc Networks. Although many research efforts have been put on secure routing protocols but the attacks like packet dropping is not adequately addressed. We study the packet dropping attack in which a malicious node intentionally drops the packets they received. Unlike all previous researches which attempt to tolerate Packet Dropping Attacks, our work makes the first effort to detect the malicious activity and then identify the malicious or compromised nodes in the network. Research Objective The fundamental objective of this research is to discuss the security attacks faced by Mobile Ad hoc Networks specially insider attacks and to review the security in existing routing protocols especially secure routing protocols in MANETs. We particularly focus on packet dropping attack which is a serious threat to Mobile Ad hoc Networks. A novel security enhancement scheme to address packet dropping attack has been proposed. Thesis Organization Chapter 2 provides a brief introduction of security threats faced by Mobile Ad hoc Networks and secure routing to address these attacks. Chapter 3 discusses about the related work and flaws identified in the related work. Chapter 4 presents the possible solutions to address the packet dropping attack in Mobile Ad hoc Networks. Chapter 5 includes the implementation of proposed mechanisms and Results of the proposed mechanism and the thesis is concluded in Chapter 6. Chapter 2 Security Threats and Secure Ad hoc Routing Protocols Introduction This chapter includes the threats and types of attacks faced by Mobile Ad hoc Networks. Secure Ad hoc routing protocols like SAODV [7] (Secure Ad hoc On Demand Distance Vector), SAR [16] (Security Aware Routing), and ARAN [9] (Authenticated Routing for Ad hoc Networks) etc and how these protocols are still vulnerable to attacks, are discussed in this chapter. Types of attacks in MANETs There are numerous kinds of attacks in the mobile ad hoc networks, almost all of which can be classified into two types, External Attacks and Insider Attacks. External Attacks External Attacks are those attacks, in which the attacker aims to cause congestion, propagate fake routing information or disturb nodes from providing services. External attacks are similar to the normal attacks in the traditional wired networks such that the adversary is in the proximity but not a trusted node in the network, therefore, this type of attack can be prevented and detected by the security methods such as authentication or firewall, which are relatively conventional security solutions. Internal or Insider Attacks Due to the invasive nature and open network media in the mobile ad hoc network, internal also known as insider attacks are more dangerous than the external attacks because the compromised or malicious nodes are originally the legitimate users of the Ad hoc network, they can easily pass the authentication and get protection from the security mechanisms. As a result, the adversaries can make use of them to gain normal access to the services that should only be available to the authorized users in the network, and they can use the legal identity provided by the compromised nodes to conceal their malicious behaviors. Therefore, more attention should be paid to the internal attacks initiated by the malicious insider nodes when we consider the security issues in the mobile ad hoc networks. Internal or insider nodes when become part of the network can misuse the network in the following ways Packet Dropping A malicious node can attack at its level or at lower levels. Particularly in the context of Packet Dropping Attack, within a trust level, a malicious node or any other node which aims at saving its resources or intentionally launching a attack can successfully drop packets without being noticed and can get services from other nodes for forwarding its own packets. Node Isolation An internal malicious node can prevent nodes from communicating with any other node. Route Disruption A malicious node can break down an existing route or prevent a new route from being established. Route Invasion An inside attacker adds itself between two endpoints of a communication channel. Attacks based on modification A very simplest way for a malicious node to disturb the operations of an ad-hoc network is to perform an attack based on modification. The only task the malicious or compromised node needs to perform is to announce better routes than the ones presently existing. This kind of attack is based on the modification of the metric value for a route or by altering control message fields. There are various ways to perform this type of attacks; some of them are discussed below Altering the Hop Count This attack is more specific to the AODV [4] protocol wherein the optimum path is chosen by the hop count metric. A malicious node can disturb the network by announcing the smallest hop count value to reach the compromised node. In general, an attacker would use a value zero to ensure to the smallest hop count. Changing the Route Sequence Number When a node decides the optimum path to take through a network, the node always relies on a metric of values, such as hop count delays etc. The smaller that value, the more optimum the path. Hence, a simple way to attack a network is to change this value with a smaller number than the last better value. Altering Routing Information This type of attack leads network toward Denial of Service (DoS) attack. For example in a situation where a node M wants to communicate with node S. At node M the routing path in the header would be M-N-O-P-Q-R-S. If N is a compromised node, it can alter this routing detail to M-N-O-P. But since there exists no direct route from O to P, P will drop the packet. Thus, A will never be able to access any service from P. This situation leads the network towards a DoS attack. Impersonation Attacks Impersonation is also known as spoofing. In this type of attack the malicious node hides its IP address or MAC address and uses the addresses of other nodes present in the network. Since current ad-hoc routing protocols like AODV [4] and DSR [6] do not authenticate source IP address. By exploiting this situation a malicious node can launch variety of attacks using spoofing. For example in a situation where an attacker creates loops in the network to isolate a node from the remainder of the network, the attacker needs to spoof the IP address of the node he wants to isolate from the network and then announce new route to the others nodes. By doing this, he can easily modify the network topology as he wants. Fabrication Attacks Fabrication attacks can be classified into three main categories. Detection is very difficult in all of these three cases. Routing table poisoning Routing protocols maintain tables which hold information regarding routes of the network. In routing table poisoning attacks the malicious nodes generate and send fabricated signaling traffic, or modify legitimate messages from other nodes, in order to create false entries in the tables of the participating nodes. For example, an attacker can send routing updates that do not correspond to actual changes in the topology of the ad hoc network. Routing table poisoning attacks can result in selection of non-optimal routes, creation of routing loops and bottlenecks. Route Cache Poisoning This type of attack falls in the category of passive attacks that can occur especially in DSR [6] due to the promiscuous mode of updating routing tables. This type of situation arises when information stored in routing tables is deleted, altered or injected with false information. A node overhearing any packet may add the routing information contained in that packets header to its own route cache, even if that node is not on the path from source to destination. The vulnerability of this system is that an attacker could easily exploit this method of learning routes and poison route caches by broadcast a message with a spoofed IP address to other nodes. When they receive this message, the nodes would add this new route to their cache and would now communicate using the route to reach the malicious node. Rote Error Messages fabrication This attack is very common in AODV [4] and DSR [6], because when nodes move these two protocols use path maintenance to recover the optimum path. The weakness of this architecture is that whenever a node moves, the closest node sends an error message to the other nodes so as to inform them that a route is no longer accessible. If an attacker can cause a DoS attack by spoofing any node and sending error messages to the all other nodes. As a result malicious node can separate any node quite easily. Eavesdropping Eavesdropping is another kind of attack that usually happens in the mobile ad hoc networks. The goal of eavesdropping is to obtain some confidential information that should be kept secret during the communication. This information may include the location, public key, private key or even passwords of the nodes. Because such data are very important to the security state of the nodes, they should be kept away from the unauthorized access. Secure Ad hoc Routing Protocols Many solutions have been proposed for secure routing in ad hoc networks, in order to offer protection against the attacks discussed earlier. These proposed solutions are either completely new stand-alone protocols, or in some cases incorporations of security mechanisms into existing ones (like DSR [6] and AODV [4]). In order to analyze the proposed solutions and how they are still vulnerable to attacks we classified them into two main categories based on asymmetric cryptography and symmetric cryptography. Asymmetric Cryptographic Solution Protocols that use asymmetric cryptography to secure routing in mobile ad hoc networks require the existence of a universally trusted third party. This trusted third party can be either online or offline. The trusted third party issues certificates that bind a nodes public key with a nodes persistent identifier. Authenticated Routing for Ad hoc Networks ARAN [9] falls in this category of secure Ad hoc routing protocols; many of the other protocols presented in other categories that use asymmetric cryptography operate in a similar manner and have similar requirements. Authenticated Routing for Ad hoc Networks ARAN The Authenticated Routing for Ad hoc Networks (ARAN) proposed in [9] is a standalone solution for secure routing in ad hoc networking environments. ARAN use digital certificates and can successfully operate in the managed open scenario where no infrastructure is pre-deployed. The basic mechanism used in ARAN is certification that is achieved through the existence of a trusted certification authority (CA). All nodes are supposed to know their public key from the certification authority and also the public key of server. Prior to entering into the network, each node has to apply for a certificate that is signed by the certificate server. ARAN accomplishes the discovery of routes by a broadcast message from source node which is replied in a unicast manner. This route discovery of the ARAN protocol begins with a node broadcasting to its neighbors a route discovery packet (RDP). The RDP includes the certificate of the initiating node, a nonce, a timestamp and the address of the destinatio n node. Furthermore, the initiating node signs the RDP. Each node validates the signature with the certificate, updates its routing table with the neighbor from which it received the RDP, signs it, and forwards it to its neighbors after removing the certificate and the signature of the previous node (but not the initiators signature and certificate). The signature prevents malicious nodes from injecting arbitrary route discovery packets that alter routes or form loops [13]. The destination node eventually receives the RDP and replies with a reply packet (REP). The REP contains the address of the source node, the destinations certificate, a nonce, and the associated timestamp. The destination node signs the REP before transmitting it. The REP is forwarded back to the initiating node by a process similar to the one described for the route discovery, except that the REP is unicasted along the reverse path. The source node is able to verify that the destination node sent the REP by chec king the nonce and the signature. Figure 2 illustrates the process of route discovery in ARAN. All messages are authenticated at each hop from source to destination as well as on the reverse path. Due to heavy computation involved with the certificates, ARAN is vulnerable to many attacks e.g. DOS attacks. In situation when there are no malicious nodes in the network the load involved in the routing process force the legitimate nodes to drop the packets in order to save their resources. Symmetric Cryptography Solutions Symmetric cryptographic solutions rely solely on symmetric cryptography to secure the function of routing in wireless ad hoc networks. The mechanisms utilized is hash functions and hash chains. A one-way hash function is a function that takes an input of arbitrary length and returns an output of fixed length [14]. As hash functions are especially lightweight when compared to other symmetric and asymmetric cryptographic operations, they have been extensively used in the context of securing ad hoc routing. Secure Ad hoc On-demand Distance Vector Protocol (SAODV) The Secure Ad hoc On Demand Distance Vector (SAODV) [7] addresses the problem of securing a MANET network. SAODV is an extension of AODV[4] routing protocol that can be used to protect the route discovery mechanism by providing security features like authentication, integrity and non-repudiation. It uses digital signatures to authenticate the non-mutable fields of the message, and hash chains to secure the hop count information (the only mutable field in message) in both RREQ and RREP messages. The SAODV scheme is based on the assumption that each node possesses certified public keys of all network nodes . In order to facilitate the transmission of the information required for the security mechanisms, SAODV defines extensions to the standard AODV message format. These SAODV extensions consist of the following fields. The hash function field identifies the one-way hash function that is used. The field max hop count is a counter that specifies the maximum number of nodes a packet is al lowed to go through. The top hash field is the result of the application of the hash function max hop count times to a randomly generated number, and finally the field hash is this random number. When a node transmits a route request or a route reply AODV packet it sets the max hop count field equal to the time to live (TTL) field from the IP header, generates a random number and sets the hash field equal to it, and applies the hash function specified by the corresponding field max hop count times to the random number, storing the calculated result to the top hash field. Moreover, the node digitally signs all fields of the message, except the hop count field from the AODV header and the hash field from the SAODV extension header. An intermediate node that receives a route request or a route reply must verify the integrity of the message and the hop count AODV [4] field. The integrity requirement is accomplished by verifying the digital signature. The hop count field is verified by comparing the result of the application of the hash function max hop count minus hop count times to the hash field with the value of the top hash field. Before the packet is re-broadcasted by the in termediate node the value of the hash field is replaced by the result of the calculation of the one-way hash of the field itself in order to account for the new hop. In SAODV route error messages (RERR) that are generated by nodes that inform their neighbors that they are not going to be able to route messages to specific destinations are secured using digital signatures. A node that generates or forwards a route error message cryptographically signs the whole message, except the destination sequence numbers. Although SAODV provides reasonable security to MANETs routing, but it is still vulnerable to distance fraud attack [15] in which the forwarding node fails to increment the route metric because in SAODV there is no enforcement to do so. Further there is no method to detect the malicious nodes and DOS attacks because in SAODV it is assumed that DOS attacks are restricted to physical layer, but this assumption failed when colluding malicious nodes drop packets during the route discovery process. Security Aware Routing (SAR) SAR [16] (Security Aware Routing) is an extension to existing on demand routing protocols and used where nodes are grouped on the basis of trust level. In SAR each node has different security level which assigns them different trust levels. Two nodes can only communicate with each other if they have equal or greater trust values. If a node has lower security level it simply discards the packet. In case there is no node in the network with the desired level then communication cannot take place or we can say that, that particular packet cant be forwarded unless its security level is lowered. By exploiting this condition a malicious node can attack at its level or at lower levels. Particularly in the context of Packet Dropping Attack, within a trust level, a malicious node or any other node which aims at saving its resources or intentionally launching a attack can successfully drop packets without being noticed and can get services from other nodes for forwarding its own packets. SAR al so fails in the situations of secure routing in general because it only focuses on the situations in which certain groups are assumed to be trustworthy. Conclusion From the above discussion, we observe that all Secure Ad hoc routing protocols are still vulnerable to many attacks. Although proposed techniques provide security against external attacks, insider attacks are still an open issue in MANETs. Chapter 3 Literature Review Introduction Many solutions have been proposed to prevent selfishness in MANETs. The main goal of all the schemes proposed in the literature is to make decisions regarding trustworthy entities and to encourage behavior that leads to increasing trust. In this section we discuss some of the solutions presented in the literature in order to detect the malicious nodes in the network in context of packet dropping attack. Watchdog and Pathrater In [17] Marti el al, proposed a mechanism called as watchdog and pathrater on DSR[6] to detect the misbehavior of nodes in MANETs. Nodes in this scheme operate in a promiscuous mode. The watchdog monitors one hop neighbor by overhearing the medium to check whether the next neighbor forwards the packet or not. It also maintains a buffer of recently sent packets. If a data packet remains in the buffer too long, the watchdog declares the next hop neighbor to be misbehaving. Every node that participates in the ad hoc network employs the watchdog functionality in order to verify that its neighbors correctly forward packets. When a node transmits a packet to the next node in the path, it tries to promiscuously listen if the next node will also transmit it. Furthermore, if there is no link encryption utilized in the network, the listening node can also verify that the next node did not modify the packet before transmitting it . The watchdog of a node maintains copies of recently forwarded p ackets and compares them with the packet transmissions overheard by the neighboring nodes. Positive comparisons result in the deletion of the buffered packet and the freeing of the related memory. If a node that was supposed to forward a packet fails to do so within a certain timeout period, the watchdog of an overhearing node increments a failure rating for the specific node. This effectively means that every node in the ad hoc network maintains a rating assessing the reliability of every other node that it can overhear packet transmissions from. A node is identified as misbehaving when the failure rating exceeds a certain threshold bandwidth. The source node of the route that contains the offending node is notified by a message send by the identifying watchdog. As the authors of the scheme note, the main problem with this approach is its vulnerability to blackmail attacks. The pathrater selects the path with the highest metric when there are multiple paths for the same destination node. The algorithm followed by the pathrater mechanism initially assigns a rating of 1.0 to itself and 0.5 to each node that it knows through the route discovery function. The nodes that participate on the active paths have their ratings increased by 0.01 at periodic intervals of 200 milliseconds to a maximum rating of 0.8. A rating is decremented by 0.05 when a link breakage is