Pit Bull Abuse Essay

Pit bulls may seem like aggressive dogs. Even the word â€Å"pit bull† may make people scared. Everything negative you hear about pit bulls is a big lie. Pit bulls are intelligent, super-loyal, very loving, and have high amounts of energy. But you’d be hard-pressed to find another breed with more raw athletic ability. They are the best dogs in the world with the proper training. Sadly, people mistreat pit bulls and use them as negative entertainment for their own selfish minds. Some people raise pit bulls to be fighting machines and killers. Many pit bulls are suffering indulgently because of this cruel human addiction. People are taking advantage of many pit bulls misunderstanding of civilization. We all know that pit bulls are animals, and they don’t understand our language or ways of life, but that does not mean we should take advantage of their misunderstanding. Pit bulls are innocent like babies, so we should give them the love and care they deserve. The dogs are taken from garages, abandoned apartments, and dark basements. Crowds are gathered around the dogs to watch them tear each other apart. The dogs have heavy chains on their necks and deep, untreated gashes on their legs and faces. If a pit bull were too weak to fight, people would just neglect it on the street. Police find dead decomposed pit bulls on the street or in dumpsters a few times a week. These poor animals are suffering in a living Hell and we are just watching it happen. People who do such a thing should be prosecuted and receive for life sentence in prison. We’re not the only ones who have a life just because we have so many psychological skills; pit bulls have a life too. The sad fact of abuse towards pit bulls is not just hurting pit bulls; it’s hurting everyone who cares. Those who care are working extra hard for injured pit bulls. Do we really need more depressed people in this world? We shouldn’t make the world a big entertainment scheme; we should treat it like a gift; including everything in it. Let’s take a walk back in History and even today. People would be cruel to each other, and demean others just because of their skin color or religion. There seemed to be only high and low class citizens. The lower class people would be treated like garbage. Now, we have laws so every man is equal. We have a Black president, Asian basketball players, Native American actors, and many more. They are our inspirations today. As a metaphor, right now, people are first class, and pit bulls are in the low class. We should all become equal. Some day in the future, they might become a miracle. As a result of being nice to every living creature in this world, the outcome would be beautiful. Pit bulls are waiting for answers that won’t come. They are battling for freedom, but won’t be freed. We need to do something about this, before it becomes too late. Many miracles can happen with a kind heart. Please give pit bulls the love and care they deserve today.

Language Processing and Production Essay

This experiment investigated hemispheric specialisation and dominance with regards to language functions. It used a computer program to measure the amount of key presses achieved by participants in a given time across four different trials (1 with the left hand, no talking, 2 with the left hand whilst being asked questions, and the same two trials again with the right hand). The participants were 2nd year psychology students from which a cohort of 20 was selected for data analysis. A significant difference was found for the effect of hemisphere and language processing task present or absent. However, the means for each trial did not support left hemispheric dominance for language functions: more key presses were recorded when talking and using the right hand than when talking and using the left. Handedness and some involvement of the right hemisphere in language processing and production were also shown as appearing to influence the results obtained. The main conclusion to be drawn is that hemispheric specialisation and language dominance is a subject that needs further investigation in order to clarify the generalisability of conclusions made about left hemisphere language specialisations. Our brain consists of two halves; the left hemisphere and the right hemisphere. The left hemisphere receives information from and controls muscles in the right side of the body, whilst the right hemisphere receives information from and controls muscles in the left side of the body. Research using brain imagery and studies of brain damaged and split brain patients, to name just a few examples, has shown that some of our functions are controlled more by one hemisphere than the other, i.e. are more specialised for that particular function. This experiment aims to investigate these differing specialisations of the hemispheres more deeply and with particular regard to language. Research into language differences between the two hemispheres is widespread and supports the view that the left hemisphere is the more dominant. Marc Dax was the first to notice hemispheric differences in his brain damaged patients, after having seen many patients suffering from loss of speech. Dax found what appeared to be an association between the loss of speech and the side of the brain where the damage occurred. ‘In more than 40 patients with aphasia, Dax noticed damage to the left hemisphere; he was unable to find a case that involved damage to the right hemisphere alone’ (Springer and Deutsch, 1998, p. 1-2). By 1870 further evidence also began to surface, when other investigators began to realise that ‘many types of language disorders could result from damage to the left hemisphere’ (Springer & Deutsch, 1998, p. 1). For example, Broca’s and Wernicke’s aphasia: Broca’s aphasia causes speech problems associated with comprehension, resulting from damage to Broca’s area (situated in the left frontal cortex), whilst Wernicke’s aphasia causes word salad (hard to understand, jumbled speech), resulting from damage to Wernicke’s area (situated in the left temporal lobe). Later research has also supported Dax’s original findings, one example of such research concluded ‘that the left hemisphere is responsible for language in almost all right-handed individuals’ (Butler, S. R. 1997, p. 187). This research also links the additional factor of handedness to investigations of hemispheric lateralisation, an idea which has been supported by others in the field. For example: ‘In right handers †¦ , it is almost always the case that the hemisphere that controls the dominant hand is also the hemisphere that controls speech’ (Springer and Deutsch, 1998, p. 2), therefore it is possible that for left handers, as their dominant hand is being controlled by the right hemisphere, the right hemisphere may be responsible for speech control and other language functions instead of the left hemisphere. Additional research looking at right hemisphere lesions has demonstrated that the right hemisphere is responsible for some linguistical functions: finding that patients with such lesions may be ‘impaired relative to normal controls on certain tests of language’ (Corballis, C. M. 1983, p. 33). One study by Lesser (1974) reported such an impairment ‘on a semantic test involving comprehension of spoken words but not on a phonological or syntactic test’ (Corballis, C. M. 1983, p. 33), suggesting a small role for the right hemisphere in language processing. Kinsbourne and McMurray carried out valuable research using healthy participants, using a procedure similar to the current study (cited in Kalat, 2004, pg. 427). They asked participants to tap with a pencil on a piece of paper as many times as they could in one minute, first with their right hand then with their left, then asked them to do the same again whilst talking, they found that ‘for most right-handers, talking decreases the tapping rate with the right hand more than with the left hand’. This further supports left hemispheric dominance for language, as well as supporting the current study’s methodology and informing its hypothesis. As has been demonstrated most research supports left hemispheric dominance of language functions, but also links hemispheric specialisation with other factors and accepts that the right hemisphere holds some language comprehension control. This experiment looks for further supportive evidence and also briefly looks at handedness as a possible affecting factor. The study uses a finger tapping and language processing task, with the notion that the speed at which keys are pressed will be relatively similar with both hands. If however, if it is the case that language is more associated with the left hemisphere, then on average when processing language, the speed of the right hand will be slower than the left hand, presumably because the left hemisphere then has to do two tasks at once (right hand finger tapping and language processing). This is only the case however if all participants in the experiment have left hemisphere dominance for language, and is thus the reason we have recorded the handedness of our participants. As a result of previous studies and research the hypothesis for this experiment is: there will be differences in the number of taps made from each of the two hands when language is or isn’t being processed. Method Design The experiment used a fully repeated measures within-subjects design: all participants took part in all conditions. There was one independent variable, consisting of four different levels: left hand, talking, no talking and right hand talking, no talking. The dependent variable was the number of key presses made within the time limit of 30 seconds per trial.

Coca-Cola Assignment Example | Topics and Well Written Essays - 750 words

Coca-Cola - Assignment Example Also, the millennials are more likely to frequent social media sites than other generations before them. Advertisements that hope to catch their interest have to use this medium, therefore, to a larger extent than other channels such as television or print media. This means that companies such as Coca Cola and Pepsi have to invest in these interests in order to create loyal consumers out of this demographic. The Coca Cola Corporation has shown great interest in engaging in environmental sustainability programs in developing nations. In Africa, the multinational corporation has joined with several charities, as well as non-governmental organizations to create and sustain programs that support the free provision of safe water for various communities. According to ‘Rain Water for Africa’, the Coca Cola Africa Foundation has entered into a partnership with the NGO ‘WaterAid’ to supply safe drinking water to the poorer areas of Ouagadougou, in Burkina Faso, as well as Ethiopia. This will involve sponsoring the construction of new pipelines which will aid in the provision of clean water to poor areas that have few road networks. According to ‘Rain Water for Africa’, the Coca Cola Corporation has also sponsored the creation of the ‘Replenish Africa Initiative’ which intends to see safe water provided for 2 million Africans by the year 2015. In the past, even though the Coca-Cola and Pepsi companies have had different advertising campaigns for their products, they are still perceived, especially in non-English speaking nations such as India, to be one singular company. In the first place, the advertisers of both companies should seek to understand the mental images that are associated with the two brands among citizens who have a tendency to make this mistake. Once they have discovered the current mental images that citizens have of

Journal Research Paper Example | Topics and Well Written Essays - 250 words

Journal - Research Paper Example Upon knowing this, the teacher would now know the customized approach he or she should take on such as the transitional bilingual education which is one that is most effective. This means that the teacher uses the child’s native language to introduce them to the context of a secondary language. Primary language of the student is now used as a bridge to develop literary comprehension with another language (Coonan, C. M., n.d.). Another way to develop linguistic competency through bilingual education would be the Dual Language Immersion. This means that teachers would practice a clear separation of two languages being used in each curriculum. What they do is that instead of translating each principle to another language which could sometimes not encompass the whole meaning or idea and cause confusion, they strengthen one’s understanding of a specific concept delivered in one language and when students already have a strong hold on it, they will then alter the language to further explicate a topic (Cook, Vivian, n.d.) Cook, Vivian (n.d.). Bilingual Cognition and Language Teaching. Virgin Media - Cable broadband, TV & phone plus mobile broadband & phone. Retrieved May 21, 2012, from http://homepage.ntlworld.com/vivian.c/Writings/Papers/BilCog&Teaching.htm Masters Degree Program - Bilingual Education - NYU Steinhardt. (n.d.). NYU Steinhardt School of Culture, Education, and Human Development. Retrieved May 21, 2012, from

I will explain it in the instructions Essay Example | Topics and Well Written Essays - 500 words - 1

I will explain it in the instructions - Essay Example   Therefore, authorizing euthanasia results to doctor-assisted death of non-critical casualties1. Conservatives like in America wants a dominion on the world .Only if Americans synergetic ally work tough, and attain the potential, then they reign as the only cost-effective and martial superpower. Other countries will befriend them, work with us and trade with them but cannot manage to contest with them, whereas, liberals don’t want the nation to be much successful as such1. Liberals  consider the action of the state governance to provide opportunities fairly to all and equality.   It is upon the government to assuage the social ills to defend social independence, entity and human rights. The essential responsibility of government is to care for the general wellness and secretive civil rights which were considered inextricably associated if not similar people concur to restrictions on their conduct by conceding to government definite imperfect powers and only if the government policy represented in both public and private rights  while on the other hand, Conservatives  holds on individual accountability, partial government, liberal markets, character autonomy, traditional2.   Believe the task of government ought to endow people with the liberty required to practice the goals of their desire. Conventional policy commonly emphasizes on strengthening individuals to handle their own questions at hand1. The importance of ideology differences became a theoretical debate just after the assertion of the occurrence in political discourse2. This is due to the fact that main components of ideology cover political behavior and use of propaganda to obtain both within and global legitimacy to be recorded since in the past. A severe methodical investigation of the ideological mechanism in intercontinental associations turned out to be promising, subsequent to two situations that were realised. To

Project Management Review Essay Example | Topics and Well Written Essays - 1250 words

Project Management Review - Essay Example While the former deals with system, the latter is related to environment and culture. It is necessary to develop a clear project scope statement that connects the project and customer. In addition, it is necessary for planning and control. Thereafter, there is proper work breakdown that will enable proper planning and monitoring of the progress of the project. As a result, the project and its changes will be properly documented and traceable. On the other hand, as Larson, and Gray, point out, the sociocultural aspects deal with developing a social system that incorporates the talents of various people working together to complete a project (14). It is the sociocultural aspect that develops a project culture that enhances teamwork and ensures high level of motivation. In addition, it should ensure provisions to quickly solve problems. Also, the dimension takes into consideration the interaction between the project and external environment. In total, it is about developing conducive so cial network of skilled professionals. II The three main elements which are to be balanced continuously in a project are time, cost and performance. In fact, in a project, these three constraints are not independent. Instead, they interact each other. For example, if resources are added to shorten the time period, there will be a rise in the project cost. For example, every project is evaluated according to â€Å"accomplishment, cost, and time period† (Larson, and Gray, 5). So, it becomes the most important function of a project management to balance the tradeoffs between time, cost and performance as a way to satisfy the customer in the end. III There are three basic ways to organize a project team. They are functional organization, dedicated project teams, and matrix structure. In the functional organization, the project is managed within the traditional, functional departments of an organization. Some examples are the departments of R&D and IT. This form is usually selecte d when the number of functional departments in the project is just one or two. In addition, in this system, one department is mainly responsible for implementation and it is this department that plays the most important role in the project. However, this system many not be suitable when a project is complex that requires a lot of independent decision making. However, a dedicated project team is usually an independent organizational unit, and it has members who devote their full time effort on the project. This team is suitable when the project is complex and large which requires a considerable number of functional disciplines, often more than six. The last one is matrix structure of organization. For this team, multiple functional units within the company are incorporated for people to be team members as needed. This form is often adopted when the project size is medium; that is bigger for the traditional functional organization and smaller for a full time dedicated team. In other w ords, when there are four to six functional disciples in a project, the matrix system is favored. The advantages of the traditional functional organization are flexibility, in-depth expertise, easy project transition, and lack of changes. However, the issues associated with this form are lack of focus due to fewer obligations, poor interaction among functional units, slow speed, and lack of motivation

People and Organisation Management Essay Example | Topics and Well Written Essays - 1000 words

People and Organisation Management - Essay Example The researcher states that HRM can be considered as the base of all management activities but it certainly is not the base for all business activities. The anorexic nature of businesses has made HRM too vital to be restricted to recruitment and people management rather it now demands a balance between achieving business objectives of financial and strategic requirements and meeting the human ambitions. Purcell and Hutchinson specify that by incorporating the responsibilities of HRM with line managers has shown constructive results considering performance appraisal, team briefing, discipline, recruitment, dismissal, staffing, quality circles and employee empowerment. Hall and Torrington determine that the main reason for voluntary resignation in many organizations is the inequity of the supervisors leading to disappointment amongst the employees. HRM should integrate into line with line managers in order to reduce staff turnover. They further state that high employees’ turnover and poor performance is directly related to low motivation – i.e. employees are not satisfied due to many reasons, e.g. unfair HR policies or favoritism/discrimination/biases during the performance appraisal, etc. etc. Katzenbach and Santamaria point out that keeping front-line employees motivated is a crucial aspect for any organization in terms of the long-term success. Line Managers have the direct relationship with employees and customers and play a key role in the HR aspect of general management work by making certain that absence procedures work and a reduced level of the absentee is achieved. HR and Line managers’ interaction The essay basically investigates as a making reference to theoretical aspects whilst focusing on some organizations. It will shed light onto the front line environment of organizations in relation to the interaction between HR and Line manager and evaluate issues associated to the integration of line managers into HRM for the improved perf ormance of the staff and organizations. When investigating from the perspectives of line managers and HR, it is important to discuss how HR involves the functions of Human resource management (HRM) and human resource development (HRD). Line managers embrace HRD activities. Gibb indicates that the relationships connecting line managers to HRM and HRD are questionably changing – i.e. the inclusion of line managers’ has become mandatory in designing and implementing HRD and has now become more crucial than ever before. He further claims that the increased involvement of the line manager in HRD shall certainly demonstrate a more transparent use of HR resources. HRM in practice recruits people and manages employment relationships by involving the planning, acquisition, development, and utilization of manpower. HRM gives great importance to good people management and according to many like a set of specifications developed and customized HR practices quantifiably upgrade the level of performance.

Ethics Essay Example | Topics and Well Written Essays - 1500 words

Ethics - Essay Example This is particularly true when it comes to fellow professionals or protecting the reputation of our particular field. While â€Å"whistleblowers† are praised for their courage and integrity, the personal cost of â€Å"doing the right thing† can mean death to a career. Such behavior can also seriously affect the career of fellow professionals. A good example of the problems involved in balancing ones duty to fellow professionals and doing the right thing when one sees something wrong is clearly laid out by Michael Davis in Thinking Like an Engineer: Studies in the Ethics of a Profession. Davis outlines events leading up to the now infamous Challenger disaster brought on by certain engineering decisions regarding the questionable safety of ORings (4 Codes and Ethics of the Challenger, p 43-44). In reading the account the â€Å"blame† seems to fall upon one man, Robert Lund, vice president of engineering at Morton Thiokol, manufacturer of faulty ORings which were blamed for the tragedy. A team of engineers had recommended the flight be scraped, but Lund, with pressure from various people at the Space Center, was persuaded to allow the project to go forward. Space Center officials were â€Å"appalled at the evidence on which the no-launch recommendation was based.† (p44). Lund was in a professional bind. Should he take the advice of fellow engineers at Thiokol, or go with the recommendation of officials at the Space Center most of them engineers, to go forward. There was a lot of money at stake for Thiokol, and Lund knew it. The reputations of engineers were also at stake. He had to choose between duty to fellow professionals and pressure from outsiders to â€Å"think like a manager.† (p44) He chose the latter to disastrous results. It is easy as a professional to judge Lund’s decision in hindsight. Should he have blown the whistle then? Did he even think it necessary?

Correlations between prayer and evangelism Research Paper - 1

Correlations between prayer and evangelism - Research Paper Example Prayers are essential for spreading the gospel through evangelism. The paper will seek to discuss the correlation between the prayers and evangelism in relation to the teachings from the bible. The most essential tool for effective evangelism is said to be prayers. All the great awakening that has happened in the church history since the time of Apostles to the present gospel has been attributed to prayers. Even if great awakening has come as a result of great preaching, prayer has always been the center of breakthrough in these preaching messages. One of the best illustrations on prayer as a great tool in evangelism is found in Acts 1:14. During this time, Peter and other apostles were engaged in a prayer as they were preparing to spread the gospel to the world. Though the main focus of this prayer was to find a replacement for Judas, the prayer was also aimed at strengthening their faith towards evangelism which they were about to start. Through this prayer there were many people who converted to Christianity thus indicating that prayer led to effective evangelism. In Acts 2:4, the bible reports that the effect of the prayers led to conversion of more than 3,000 souls to the Christian community (Torrey, 2009). According to the Epistle of Timothy, Paul urges the church to engage in prayers of intercession and thanksgiving for all people and especially for those who have not been saved so that they can be transformed to the knowledge of truth and life of holiness. In the book of 1 Timothy 2:1-8, Paul convinces Timothy that through prayers, God would be pleased and since He cares for those who are not saved, and he want them to now the light. He outlines that he would want all men to engage in prayer through Jesus Christ who is the mediator between God and men. He states that one of the most important responsibilities of church is to commit to the work of God by praying for those that have not

Restaurant - Eating Essay Example for Free

Restaurant Eating Essay One of my favorite restaurants is Olive Garden. Without going to Italy to taste their traditional food just come in to Olive Garden and experience the Italian food. They offer wide varieties of Italians food. While the restaurants are similar in the type of food they prepare the difference in their atmosphere, menu and services will assist the customers in making the big decision on which one they like to satisfy their appetite. Olive Garden is the perfect place for a meal if you’re looking for both exquisite and casual dining. The atmosphere is very comforting and the mood is relaxed with the dà ©cor being contemporary but restrained. The tables are in a good distance apart so the diners are given their privacy, but at the same time do not feel isolated from others. When my first time walked in their restaurant, I said to my self that this is a place that I can bring my family to enjoy our dinner together. Even though, I have to spend time waiting to get the table, but it is worth to wait. While the atmosphere is a place to go so do their services. The staffs are friendly, welcoming and efficient. They are always willing to go to lengths to help make your dining experience as memorable as possible. My family and I were very new to the restaurant; the waitress came make us feel like home. She took us to the table and asked to order the drink. She greed us and told us that she will be your table service for tonight. The service was very knowledgeable of the menu and was very polite while taking order. Olive Garden offers wide varieties of Italian food. You can order from an exclusive range of starters, main courses and desserts. The dishes are quite reasonable price range from $10 to $25 including entrà ©e and dessert. I was order Chicken Alfredo which is my favorite. While we were waiting for our main course the entrà ©e came with the salad and breadsticks and also the wine are exclusively sold only at Olive Garden for their customer to taste; then our order came in a short time after. While we were eating the waitress came asked for drink refill or how did we enjoy the food. We were really enjoying our dinner at Olive Garden where we can enjoy good food, a place where we can relax and the staffs treat us as family. We brought friend and family their many time after and everything is treating us the same way even better. This is our favorite Italian restaurant of all time.

Two sociological theories and two psychological theories

Two sociological theories and two psychological theories The Johnson family Scenario In this assignment I will explore two sociological theories and two psychological theories impacting on the Johnson family. I shall begin by exploring sociological theories analysing and defining them and in the second half of this assignment will then explore psychological theories. I will also look at the professional interventions available in social work. I shall endeavour to indicate their strength and weaknesses incorporating their relationships to issues of class, race, culture gender and sexuality. I will then reflect on the influence of these theories on my own development to achieve social work professional status. Max Weber defined consensus as existing when expectations about the behaviour of others are realistic because the others will usually accept these expectations as valid for themselves, even without an explicit agreement. For Marxists, consensus is a highly ideological concept used to perpetuate class rule by attempting to disguise the extent of conflict within society. (Answers.com) Durkheim is known to have drawn an analogue of the functionalist perspective view in which he said that society is a system of interrelated parts each of which relies upon the other parts for efficient functioning.'(Cunningham, J Cunningham,S).These institutions are essential for maintaining that society works harmoniously and orderly. The view of the functionalist is that the use of power is acceptable and generally beneficial to society. They share norms and values which help them to determine the right from the wrong. There is an acceptance from the functionalists positions that conflicts will occur but will only be temporary and can quickly be resolved. Society should be adequately prepared to deal with instances of anti social behaviour so that society as a whole benefits. In the functionalist perspective schools first role is to emphasise proper behaviour and knowledge that is necessary to maintain a civilised society. According to the functionalist, the children in the Johnsons should therefore be sent to school to be equipped with this weapon and the fact that they are truanting could easily be viewed as anti social behaviour. Karl Marx did not at all agree with capitalisms theories of consensus and in his writing highlighted the conflict theory, although acknowledging structural integration of societys institutions such as political, legal or religious which he described as the superstructure. His view was that workers in the class system like Desmond a car mechanic and Mary a cook at a primary school were being exploited and that there should be equality on control, power, wealth and the best education. Marxists felt that it was those with the means of production that had the power and therefore significantly influenced the rest of the society. This causes a difference of interest among social groups which in turn causes conflict. As both Desmond and Mary are working this creates pressure on parenting skills and has probably forced Desmond to decide sending Eustace to a residential home. Marxists perceive functionalists as deceiving as they say the norms and values which they claim are the backbone of society are infect their norms and values that only help to strengthen their positions perpetuating the unequal social system. Marxists argued that the workers were being replaced by machines in their roles of employment and this resulted in them loosing their skills, assuming monotonous jobs, separated from each other by the noise and would return home dehumanised and physically exhausted. Marx believed the proletariat would realise the exploitation, join together and revolt overthrowing the system and establishing true systems . The Marxists view of social work is that it is an agent of the state and as such reinforces the interest of the ruling class. Their view is that the state in capitalists societies saves the interests of the ruling classes and do not treat their citizens equally even in cases of welfare services. They further state that the image of caring that they create is only a myth which serves to enhance the profits of the capitalists that the social workers serve through the state. The Marxists do not see the necessity of the social control role of social work but an agent of state bent on socially controlling those that are already marginalised and excluded. In this view social workers tend to be ignorant of the poverty they are meant to be addressing from the society by empowering service users to take action and bring about change. The Johnson family appears overcrowded in their residence and this is associated with poverty. Social workers have found themselves working with tied hands as th e system is tightly regulated and procedural thereby restricting social workers from exercising their knowledge. Functionalists viewed the institution of family to be the best organisational basis for society. Talcott Parsons (1955) insists that the family retains two basic and irreducible functions. These are the primary socialisation of children and the stabilisation of adult personalities. So this view will explain that for the family to maintain stability, it needs support to ensure normality. This perspective then explains that if there are signs of antisocial behaviour such as truanting then the family unit needs to be supported. According to Murdock (1949) family performs four important functions i.e. providing new members of the society by reproduction, providing stability for adults through sexual gratification, providing for the economic well being and educating the young to socialise into societys norms and values. Eustaces wondering and confusion could be viewed as hindering by the functionalists because it is affecting Mary who they expect to be participating in the society both as a mother and a worker as it is the institute that will influence good behaviour of children. Functionalists believed that the family is a positive institution, a view that meets well with the needs of an advanced industrial society. The functionalists would view Eustaces confusion as costing the society in terms of health care for Mary and himself. Eustaces problems must be rectified in order to get Mary functioning well again and become productive in the society. Functionalists highlight the ideal family type in a modern society, as the nuclear family. The view of the nuclear family comprises of a breadwinner husband ( in the scenario this would be Desmond) and dependant wife and children. Mary cannot be classified as dependant as she is also working and earning. The functionalist view of the family as ideological is criticised as a conservative stance. Some feminists criticise this view as being unrealistic as it does not recognise the oppression of women in families. However, they defend the claim that the functionalist view of family life is shared by many people, if not only as an aspiration. The nuclear family is seen as traditional and positive. Marxism states that the family is a product of capitalism and is therefore an exploitative institution. They argue that families are not built upon love but are founded from necessity. Women therefore become the property of men and all roles within families exist in order to maintain a capitalist state. There are two classes in the society according to Marxism. One is the ruling class and the other is the subject class. The Johnson family would be classified as a subject class and their employers like the garage owners where Desmond works would be the ruling class. This is opposed by functionalist who claims that there are many classes in society and points to a division of labour. Eustaces situation is also causing friction between Desmond (a father and mechanic) and Mary thereby threatening the institution of family. However a Marxist would hold a different view putting the blame on Mary being over worked and thereby causing her to be depressed. They highlight the lack of care from the employers who do not pay well enough keeping most of the profits to themselves prompting Mary to work long hours. Desmond is said to be impatient with Eustace who he sees as stressing his wife at home while trying to do her job. This appears a functionalist view where Desmond is concerned about Mary being disrupted in doing her job hence not able to contribute to the income. Mary and Desmond might have moved to the UK in response to the big drive for workforce after the world war. They were promised better lives with luxurious facilities only to realise when they arrived in the UK that it was not the case and they had to work extremely hard to earn a living. Desmonds role would be to provide and Mary also performing this role as she also works. Caring for Eustace could be seen by Desmond as preventing Mary from performing the task expected within her role, a view that the feminists would regard as oppressive. Whilst various sociological school of thought tries to explain family circumstances and possible interventions that may assist families it is not adequate in itself. In this context I will now turn to psychological perspectives. The essay will examine psychological theories of behavioural approach, which developed through the works of Thorndike (trial and error learning), Pavlov (classical conditioning) and Skinner (operant conditioning) who all believed that the environment controlled behaviour. Behavioural theory is based on a scientific method (Banks, 2001. p. 73) and on what can be observed, studied, measured and reliably changed (Feltham, 1995; cited in Adams R, Dominelli L Payne M, 2002. p.144). It argues that internal states such as thoughts, intentions and feeling are not observable and replicable, hence are not open to scientific analysis, it aims to eradicate or reduce behaviours that are deemed problematic while positive behaviours are encouraged, an agreement between the service user and the practitioner through the process of positively reinforcing and rewarding consequences that a service user consider valuable. Payne (1997) in his token economies (Payne, 1997. p.133) argues that this helps reinforce and strengthen the desirable behaviour. This theory sees the behaviourist assuming that most behaviour is learned as a result of our interactions with our environment, including emotional development, perceptions of the external world, social behaviour and personality. Milner and OByrne (1998 p112) describes Classical conditioning occurring when there is an association of conditioned and unconditioned stimulus such that the former stir up a response previously evoked only by the later. This was similar to Pavlovs (1911) conclusion in his famous Dog-Salivation-Experiment. If applied in this case study it would first try to identify the original stimulus, in this case, the loss of a loved one Susan, the response, Eustaces confusion and Marys anxiety and depression. Those associated with unpleasant or stressful feelings may become conditioned stimuli for feelings of anger and anxiety later on. (Birch A, 1997, p139). Another theory of behaviour Operant conditioning claims that learning occurs when voluntary behaviour arises from an individual and becomes more or less likely to be repeated depending on its results as demonstrated by Skinner (1953) in his Skinner-Box-Experiments with a cat and a pigeon. In the Johnson family scenario, Mary is a service user with depression and anxiety which Milner and OByrne argues ABC Approach (Milner and O Byrne, 1998. p.114) is necessary in identifying and analysing the behaviour that needs modification in agreement with the service user. Mary has gone to see the doctor on her own accord and therefore there is an agreement. This would involve establishing the Antecedent (caring for her father and the family), and the consequences (depression and anxiety). The consequences will either strengthen or weaken behaviour by reinforcement or punishment (Payne, 1997. p. 114). In Marys case it is the depression and anxiety that is undesirable. The distinctive characterist ic of operant conditioning relative to previous forms of behaviorism is that the organism ( Mary) can emit responses instead of only eliciting response due to an external stimulus (the practitioner). It is likely that Mary would respond positively if the right responses have been reinforced. Behaviourism models are advantageous due to their easy adaptability and practicability by inexperienced practitioners without extensive training than would be expected of a psychodynamic approach (Adams, R, Dominelli, L and Payne, M, 2002. p. 144) in facilitating an effective outcome. Payne (1997) also argues that the prescribed explicit, structured guidanceà ¢Ã¢â€š ¬Ã‚ ¦and assessment instruments employed (Payne, 1997. p. 134) gives unskilled practitioners the confidence to apply behavioural theory and procedures in interventions. My perception is that as behavioural intervention focuses on negative behaviour that needs modification, it is empowering the service user to choose and self determine the behaviours that need modification in partnership and therefore the practitioner is recognising and respecting individuality. The role of the practitioner is to facilitate and support the service user. Thus, labelling and making judgement on the service user is avoided and is then direct ed to the behaviour. Behavioural approaches have been criticised by some practitioners as being excessively mechanistic (Banks, 2001. p.73) and non-human (Payne, 1997. p.122) in some of its methods, conducts and terms used, as they do not take into account service user individuality and will to choose. It is true that Mary would be different from other service users who would have used the same theory. The behavioural approach overall intervention emphasis is on the need to change or modify the client behaviour rather than those around the client who may be the problem. In the case scenario it is probably Desmond who we need to convince that Mary and Eustace need his understanding and cooperation as well as dealing with the fact that the family were not offered support to grieve and move on with life after the death of a loved one. Milner and OByrne (1998) point out that social workers tend to do as they find easier to change an individual than challenge the status quo (Milner and OByrne, 1998. Attachment has been defined as an affectionate bond between two individuals that endures through space and time and serves to join them emotionally Kennell 1976. John Bowlby described attachment as a lasting psychological connectedness between human beings (Bowlby, 1969, p. 194). Bowlby believed that the earliest bonds formed by children with their caregivers had an impact lasting throughout their lives. Adult attachment theory helps Social Workers understand how people feel and act within close relationships, particularly in stressful situations.  Attachment is not different in adulthood and in childhood as they all will give and receive support. Attachment relationships can be secure or insecure.  Attachment is clearly influential in both professional and personal settings.   As a Social Worker knowing about the attachment theory can help to make the right steps in order to protect the child and the family. Mary Ainsworth expanded greatly on Bowlbys original work with behaviour experiment which she named Strange Situation. In the study children between 12 months and 18 months were left alone with a stranger with the mother returning a moment later. The study revealed three major styles of attachment: secure attachment, ambivalent-insecure attachment and avoidant insecure attachment. A fourth one was later added on by researchers Main and Solomon called disorganised insecure-attachment. It is clear that Mary has a bond with her father and hence his condition is affecting her psychologically. The fact that Mary and Desmonds relationship seemed to be strained by having Eustace living with them shows that they are experiencing lack of intimacy support for one another. The scenario mentions the death of Susan in the family and appears that Eustace, Mary and the Kids have been affected. Loss through death is a normal part of life experienced by everyone. The grief process varies in length and this also depends on the strength of the attachment. This period is usually very painful as the affected seek to adjust or cope without their loved one. Collin, Murray-parkes (1972) describes bereavement as an illness, thus in turn prompted Mary to see her doctor for help. The Johnson family appears not to have gone through the grieving process. Eustace is showing a lack of interest in normal life by wondering and could be his way of searching for his wife. The grieving process involves psychological suffering ( Birch, A ,1997 p251) Grief is defined as the process of psychological, social and somatic reactions to the perceptions of loss (Rando, 1984). This explains that the individual is affected mentally, physically as well as socially. Bereavement is defined as the state of having suffered a loss (Rando, 1984). According to Balwby excessive separation anxiety is usually the result of adverse family experiences, such as repeated threats of abandonment or rejections by parents, or to parents or siblings illnesses or death for which the child feels responsible. The truanting of the children could be a result of the feeling that they felt abandoned after the death of Susan who at one stage raised them for three years when their parents moved to the UK and could have bonded with the children. They have been living in the same house and this could have kept them close. A key principle of an attachment based practice is the acknowledgment that young children develop a range of adaptive strategies that are designed to help them cope with, survive and function in whatever situations they happen to find themselves, The children could be truanting as way of coping with the loss. As Eustace is wondering and possibly searching for his wife, it could be that he is thinking of joining her wife where ever she is. This brings Erikssons stages of development Integrity v Despair. Integrity is contentment with what you have achieved and Despair is the feeling that you have achieved nothing. As Eustace could be nearing the end of his life he will probably look back with integrity. He had his child who also got married and had her own family. He has lived for more than sixty years and although it does not look like he lived a porch life he was not homeless and up to this day still has a loving daughter taking care of him. Eustace will probably be looking forward to dying with contentment. Applying sociological and psychological theories as well as social work values has been a challenge for me considering my ethnic background of African origin as much as the Johnson family who travelled to settle in the UK, a country with different norms, cultures and values. I feel I empathise more with the Johnson family, in relation to the impact of new norms, culture and a new way of living. Studying social work has challenged some of my beliefs and prejudices and hence the toleration of others, provide recognition and ability to challenge discrimination. Adherence of work values have provided me with further understanding of being respectful of other peoples, views, religion, culture and preferences which is of paramount significance to become a social work practitioner. (GSCC 2002).  

The Social Effects of Digital Technology :: Technology

Introduction: Digital technology was introduced thanks to numerous technological improvements, which have developed and changed society. As expected Postman (1992), â€Å"a new technology does not add or subtract something. It changes everything.† Digital technology is basically any software using or based on the binary code, a coding system using the binary digits 0 and 1 to represent a letter, digit, or character in a computer or any other electronic device. Both households and businesses use this technology for various purposes, such as entertainment, productivity, communication, etc. To define the actual benefits and negative impacts of digital technology, it first needs to be understood that this technology is mostly a platform, on which have grown numerous innovations. Digital technology is most known for providing society with personal computers and the Worldwide Web. President Clinton, in 1996 during his announcement of the initiative to take Internet to the Next Generation humorous ly said, â€Å"When I took office, only high energy physicists had ever heard of what is called the Worldwide Web†¦ Now, even my cat has its own page.† On the other hand, what was, until recent days, less advertised were the negative effects that digital technology has had on society and mankind since it’s massive implementation. What is induced by this technology, and most importantly, what are the real benefits and effects of digital technology? Negative Effect: A- A study done at the university of Maryland reports the addictive potential of new digitalized technologies (Ipods, cellphones, laptops). College students who gave up all form of technology for 24 hours reported feelings of â€Å"withdrawal and anxiety†, according to an editorial in the Seattle Times. Sociability issues as well as a tendency towards isolation were observed in the tested group. In addition, what is considered even more preoccupying is the â€Å"potential effect so much technology might have on how children develop† (Seattle Times). A study done by Commonsense Media, found that â€Å"52 percent of children ages 5 to 8 years old have had access to a mobile device, while 39 percent of 2 to 4-year-olds and 10 percent of zero to 1-year-olds have had access.† Another research, done by The Kaiser Family Foundation, reports that â€Å"children aged 8 to 18 spend in average 7 hours and 38 minutes using media devices†. An excessive use of modern digital medias is claimed to lead to a sedentary mode of life, less time for social interactions, and more and more within children, obesity.

The Benefits Of Laptops And Wireless Cards :: Technology Computers Papers

The Benefits Of Laptops And Wireless Cards The CEO of Viacom/Blockbuster was once quoted for saying, â€Å"The information superhighway is a dirt road that won’t be paved over until 2025† (The Freeman Institute). Obviously, this was an erroneous quote. The information age is currently at its peak. The use of technology and the Internet are an essential part of higher education. In the past few years, colleges have begun providing laptops to all students. A few colleges have even developed programs that use wireless network cards to access the Internet from anywhere on their campuses. Giving students a laptop and a wireless network card has increased the learning possibilities at schools nationwide. This is a very recent idea being practiced by hundreds of colleges around the United States. However, this idea is one of controversy. Despite the many benefits, these laptops have their flaws. They create problems such as maintenance efforts, depreciation value, classroom misuse, faculty training, and rai sed tuition (Beebe 2-8). Another issue is whether or not the laptops actually benefit the students or just distract them. There are many benefits of using laptops over conventional personal computers. Some of the benefits include portability, access, PowerPoint Presentations, slideshows, e-mail, using the Internet, and online notes. All of these advantages are put together to make a very economical and beneficial laptop (Shafer). One of the biggest advantages is portability. A Minnesota State student Timothy Huebsch says, â€Å"On a nice day, we don’t have to be cooped up† (Ojeda-Zapata). One can take his or her laptop to the library, cafeteria, or even to class. The students have all the advantages of a PC without having to sit at a desk working on assignments. Students at Buena Vista University have the capability of accessing the Internet from the residence halls, football stadium, and even the docks on the lake. In other words, it is a major convenience for all the students to have a laptop to write a paper rather than waiting in a line to use a computer lab (Dean). Rick Shafer, who is Buena Vista’s Director of Integrated Technology, summarizes the advantage of portability by saying, â€Å"The main purpose of the laptop program was so that student could have access to computers. Prior to this program students had to wait in line often to use a computer.

Catcher in the Rye Synthesis Essay Essay

Holden confronts many issues throughout Catcher in the Rye that still pose a problem to teenagers: such as the need to succeed, the desire for friendship, and the need to mature. These issues are generally forced upon a teenager by a more authoritative figure with higher expectations in comparison to themselves. Although some may regard these as a eustress, they cause distress to many teenagers, and society still upholds such standards. The need to succeed was forced upon Holden by his parents when they set very high expectations and enlisted him in private schools. Holden did not like this pressure and revolted: â€Å"All of a sudden, I decided what I’d really do, I’d get the hell out of Pencey–right that same night and all† (Page 51). This proved that the need to succeed was a form of distress in Holden’s time because he decided to pack his bags and just leave Pencey. In addition, parents in Holden’s time did not understand that this issue caused stress to teenagers. In an article written by William Zinsser, children ask their parents, â€Å"But what if we fail?† (Zinsser). The parents respond, â€Å"Don’t† (Zinsser). The article shows how oblivious parents could be to the stress they were causing to their own children. But what kind of stress and to what extent is it a stressor today? Today, the need to succeed can causes eustress when used in moderation and in a positive manner. For example, my parents take me out to dinner wherever I choose if I finish a six week grading period with all A’s. To this day, the need to succeed is very much alive, but it has taken on a new form compared to back in Holden’s time. The desire for friendship was forced upon Holden by himself. He always tried to make a friend wherever he went. Holden even stooped so low as to hire a prostitute and ends up just talking to her, â€Å"I don’t know. Nothing special. I just thought perhaps you might care to chat for a while† (Page 95). This demonstrated Holden’s true desire for friendship because, without the prostitute, he has no one else to talk to. Even nowadays, the desire for friendship is very much evident among teenagers. For example, when my friend Moe moved to Buffalo Grove from Texas in 7th grade, he didn’t really fit in at first. Later, he began to make friends and now he has many friends, as most teenagers do. Thus, the desire for friendship has gone very much unchanged since Holden’s time in comparison to today. The need to mature was  forced upon Holden by the society in which he lived, â€Å"I ordered a Scotch and soda, and told him not to mix it—I said it fast as hell, because if you hem and haw, they think you’re under twenty-one and won’t sell you any intoxicating liquor† (Page 69). Throughout the whole novel, Holden attempted to act more mature in order to fit in with the adults around him during his time period. He smokes, drinks, and hangs around loose women. Holden’s desperation to fit in with the adult world around him is indicated when he goes to the bar and orders a drink which normally, only adults do. In addition, teenagers in Holden’s time were expected by the society in which they lived in to confront issues that only adults normally have to confront, â€Å"Teenagers now are expected to confront life and its challenges with the maturity once expected only of the middle-aged, without any time for preparation† (Elkind). The article, by David Elkind, adds to the fact that teenagers in Holden’s time were expected to mature at a more increasing rate. Nowadays, that expectation is still a burden to teenagers. For example, teenagers today see many celebrities, such as Miley Cyrus, rapidly changing from their innocent, childish ways to acting grown up and developing a stylized, adult personality. Therefore, it is safe to assume that the need to mature has gone rather unchanged from Holden’s time to this day. The need to succeed is still a pressure that many teenagers face, but it is more of a good stress today compared to Holden’s time when it was a negative stress. The desire for friendship is just as apparent today is it was back in Holden’s time because as long as there will be people, they will always need some form of companionship. Lastly, the need to mature is just as required by society today as it was in Holden’s time because teenagers were expected to take on more adult characteristics both then and now. Teenagers had set expectations to meet back in Holden’s era and many of these expectations have gone unchanged since then.

Hybrid Network Security

ACCEPTED FROM OPEN CALL SECURITY ISSUES IN HYBRID NETWORKS WITH A SATELLITE COMPONENT AYAN ROY-CHOWDHURY, JOHN S. BARAS, MICHAEL HADJITHEODOSIOU, AND SPYRO PAPADEMETRIOU, UNIVERSITY OF MARYLAND AT COLLEGE PARK ABSTRACT Satellites are expected to play an increasingly important role in providing broadband Internet services over long distances in an efficient manner. Most future networks will be hybrid in nature — having terrestrial nodes interconnected by satellite links. Security is an imporSSSL tant concern in such networks, since the session 2 Proxy satellite segment is susceptible to a host of attacks, including eavesdropping, session hijacking and data corruption. In this article we address the issue of securing communication in satellite networks. We discuss various security attacks that are possible in hybrid SSSL session 1 SSSL handshaking and satellite translation at client proxy (RPA) networks, and survey the different solutions proposed to secure data communications in these networks. We look at the perforMost future networks mance problems arising in hybrid networks due to security additions like Internet Security Prowill be hybrid in tocol (IPSec) or Secure Socket Layer (SSL), and suggest solutions to performance-related nature — having problems. We also point out important drawbacks in the proposed solutions, and suggest a terrestrial nodes hierarchical key-management approach for interconnected by adding data security to group communication in hybrid networks. satellite links. Security is an important concern in such networks, since the satellite segment is susceptible to a host of attacks, including eavesdropping, session hijacking and data corruption. INTRODUCTION With the rapid growth of the Internet, satellite networks are increasingly being used to deliver Internet services to large numbers of geographically dispersed users. The primary advantage of satellite networks is their wide broadcast reach — a satellite can reach users in remote areas where terrestrial connectivity is not available. Satellite networks are also easily and quickly deployed, and can be a more cost-effective solution in areas where laying ground fiber networks would be too expensive. Although satellite networks offer great potential, they also present significant challenges that need to be addressed. Security is becoming an increasingly important aspect of all network. In this article we focus on the challenges that need to be addressed in order to make satellite networks more secure while maintaining seamless interoperability with terrestrial networks. These security-related challenges include the following considerations: †¢ Satellite channels are wireless broadcast media, which makes it possible for an unauthorized user to receive the signal and eavesdrop on the communication, if it is not encrypted. †¢ Without proper security mechanisms, any sufficiently well-equipped adversary can send spurious commands to the satellite and jam or disrupt the communication. †¢ Satellite channels can occasionally have high bursty errors (for example, during heavy rain) that result in packet loss. Satellite networks also suffer from long propagation delays (for example, 0. 5 seconds for geostationary satellites). Therefore, security systems should add minimal delays to the communication and have mechanisms to recover from loss in security information. Incorporating security solutions originally designed for terrestrial networks, such as Internet Security Protocol (IPSec) or Secure Socket Layer (SSL), into satellite networks can cause severe performance penalties. In this article we consider some of these issues. We focus on data security for IP-based commercial networks, and discuss the performance problems that arise due to the encryption of the Transmission Control Protocol (TCP) header and payload when popular unicast security protocols like IPSec or SSL, originally designed for terrestrial connections, are applied to satellite networks without incorporating changes necessitated by the unique characteristics of satellite networks. We also look at the protocols proposed for secure group communication in hybrid satellite networks, and describe a hierarchical approach to group key management that is robust, scalable, and suitable for the characteristic topology of hybrid networks. The rest of the article is organized as follows. We describe the hybrid satellite-network topology and features that make it different from terrestrial networks. We discuss security needs for the hybrid network. We discuss the current approach to provide end-to-end unicast security in hybrid networks, and describe the performance problems arising as a result. We survey 50 1536-1284/05/$20. 00  © 2005 IEEE IEEE Wireless Communications †¢ December 2005 NOC Internet Gateway Proxy Client Proxy NOC (a) Internet Web server Web server (b) n Figure 1. Commercial direct-to-home network topology: a) case 1; b) case 2. the proposals for key management for secure group communication in satellite networks. We describe a possible solution to secure unicast communication without sacrificing performance and highlight our key-management approach to security for group communication in satellite networks. We conclude the article by pointing to future research directions. highly susceptible to the delay-bandwidth product and exhibits very poor performance in satellite channels. Satellite TCP connections need large transmit windows to fully utilize the available bandwidth. However, due to the TCP slowstart algorithm and large propagation delay in the satellite channel, it takes much longer for satellite TCP connections to reach the target window size, in comparison to terrestrial TCP connections. Also, the window is very vulnerable to congestion due to the multiplicative decrease strategy of TCP. The problem is compounded by the fact that TCP misinterprets link-layer corruption (which is the prevalent source of loss in satellite links) as congestion (which is rare) and consequently reduces the window. The PEP provides an efficient solution to the above problem. In satellite networks, a PEP agent is installed at the satellite gateway between the satellite network and the Internet. The PEP agent inspects every TCP packet that flows through the network. For data packets, the PEP sends back premature acknowledgments to the TCP senders, without waiting for the TCP segments to be actually delivered to the receivers. These premature acknowledgments are specially formatted to be indistinguishable from real acknowledgments and they considerably shorten the perceived round-trip delay. Studies have shown that this technique is critical for the performance improvement of satellite networks [2–4]. Hence, TCP PEPs have been widely deployed in satellite networks today. Commercial networks also employ HTTP proxy servers to improve the speed of responses to Web-browser requests. When a user browses through content on the Internet, the application layer protocol in use is HTTP. A typical HTTP exchange involves a request by the browser for a Web page (â€Å"GET†), and a response from the Web server, which contains the hypertext markup language (HTML) text of the requested Web page. A typical HTML page would also contain multiple embedded â€Å"objects† such as images, embedded media or scripts, and so forth. Each embedded object has to be retrieved with a separate HTTP request-and-response exchange. Therefore, a Web page that contains n – 1 embedded objects takes n * RTT time to load fully, where RTT is one round-trip time. This can be extremely costly in a satellite network, where the RTT is usually high. COMMERCIAL HYBRID SATELLITE NETWORK ARCHITECTURE The network topologies we consider are illustrated in Fig. 1. In both topologies, we assume that there is one geostationary satellite with multiple spot-beams covering a large geographical area. Each spot-beam covers a subset of the total user set. We assume that future satellites will have an IP stack, be capable of onboard processing, and switch the data between supported spotbeams. The satellite therefore acts as an IP router-in-thesky. The Network Operations/Control Center (commonly known as NOC or NCC) connects to the satellite through the hub satellite gateway. The NOC is also connected to the Internet through high-speed terrestrial links. Terrestrial users can be either standalone machines (Fig. 1a), or a cluster of machines at each location, such as a local area network (LAN) (Fig. 1b). Terrestrial LANs can be either wired or wireless. Each user or LAN is connected to a local satellite terminal. The users receive traffic from the satellite via the forward channel (satellite downlink). The users can also communicate with the satellite via the return channel (uplink). There is no terrestrial connectivity between the users or the LANs. Usually, in commercial satellite networks that transfer Internet traffic, a split-connection Transmission Control Protocol (TCP) Performance Enhancing Proxy (PEP) is implemented to reduce the negative effects of the satellite link on the Internet connection [1]. Satellite channels provide large bandwidth (which can be as high as 90 Mb/s in the downlink), but also suffer from long propagation delay in comparison to terrestrial links. The delay can be as high as 500 ms (round-trip) for a geostationary satellite link. The propagation delay can have a severe adverse impact on the delivery of Internet traffic. Most of the Internet traffic uses the TCP, which is IEEE Wireless Communications †¢ December 2005 51 SSSL encryption New IP header ESP Original TCP header IP header header TCP payload (SSL record) IPSEC encryption ESP trailer proxy (user side). There is a hub proxy server located at the NOC with the hub satellite gateway — this proxy server represents the gateway proxy for both TCP and HTTP performance enhancements. SECURITY THREATS Similar security attacks can be launched against different hybrid satellite network topologies, but the impact of attacks would differ depending on the type of network and the applications supported by the network scenario. In the following, we list some of the important security threats in the hybrid network described above, and highlight the importance of the threats for the different network scenarios. Confidentiality of information: For networks that require information privacy, a primary threat is unauthorized access to confidential data or eavesdropping. Since the satellite is a broadcast medium, any entity on the ground with the right equipment can receive the satellite transmission. If the data is broadcast in the clear, then adversaries can be privy to the information that is flowing in the network. Data confidentiality can be achieved by message encryption. This requires that the senders and receivers are concurrently aware of the correct cryptographic keys used in the encryption/ decryption operations. This is a twofold problem: the problem of selecting suitable cryptographic algorithms for doing encryption so that overall network performance is not affected, and the problem of coordinating keys between users, that is, key management. Sending spurious commands: An adversary with the right equipment can send spurious control and command messages to the spacecraft, thus making the spacecraft perform operations different from their intended use. This can disrupt legitimate operations and communication in the network. This attack can be prevented if the sources of the messages are properly authenticated by every receiver. This would require suitable mechanisms for authentication, such as digital signatures [5]. The level of security required would dictate the authentication policy, for example, whether only the end users should authenticate each other, or whether authentication should happen on a per-hop basis. The latter might be necessary for scenarios where the satellite should not broadcast spurious information. If the satellite authenticates the source of every message it receives, it will transmit only those messages for which source authentication occurs correctly. Message modification attack: When the traffic goes over open networks, an adversary who is listening on the path can intercept both control and data messages. The adversary can modify the messages and send them to the destination, which can be the spacecraft, the ground terminals, or the end users. When the message reaches the intended destination, it would think that the corrupt message is coming from the true source, but the message content might be different from that expected or required for normal network operation. Message modification can be prevented by SSL record HTML page n Figure 2. IPSec and SSL encryption on a packet. The HTTP proxy server (also known by various other names, depending on the vendor) is implemented in satellite networks to overcome this problem. In a typical implementation, this requires a local Web proxy server at each user location, and a remote proxy server at the central hub facility of the satellite network (i. e. , the NOC). The Web browser at the user location should be able to recognize the local proxy (which can be either software on the client machine, or a separate hardware connected inbetween the client machine and the local satellite terminal). When the browser makes a request for a Web page, the HTTP GET request is sent to the local Web proxy, which forwards the request to the destination Web server. The Web server responds with the requested base HTML page. This page is intercepted by the proxy server at the network hub facility. The hub proxy server reads the base HTML page and sends multiple GET requests to the destination Web server for all the embedded objects in the base HTML page. This exchange occurs over a high-speed terrestrial connection between the hub and the Internet, thereby saving the time each request would have needed for a round trip over the satellite link. As the objects of the Web page are retrieved by the hub, they are immediately forwarded to the proxy at the user location. As the user browser receives the base HTML documents, it generates appropriate GET requests to fetch the objects corresponding to the links embedded in the document. The browser GET requests are terminated at the Web proxy server, which forwards the prefetched documents to the user browser immediately. The net result is that only a single â€Å"GET† request from the user browser traverses the satellite link, while a set of rapid responses quickly deliver the requested Web page and associated elements to the browser. The need for satellite capacity is also reduced, which is the most costly element of a satellite network. In terms of the user’s experience, the user sees a brief pause after the original Web-page request (corresponding to the round-trip time it takes for the request to the forwarded to the destination server, and the response to be received by the browser, over the satellite link), followed by near-instantaneous delivery of all content residing on the requested page. The trade-off is additional hardware at the user location and the central-hub facility. In Fig. 1a, the proxy server at the user represents both the PEP (user side) and the HTTP 2 IEEE Wireless Communications †¢ December 2005 appending message-integrity check mechanisms to every message, for example, message authentication codes (MACs) [6] or digital signatures. Security requirements and policies can dictate whether message authentication should happen only at the communication end points, or whether interme diate nodes should also verify the integrity of every message. Denial-of-service attack: Some attacks on security can be facilitated if strong security mechanisms are put in place for performing message-integrity checks or authenticating users. Consider the case where the satellite does authentication and integrity checks on all messages before broadcasting. An adversary can send a large number of spurious messages to the satellite, thus making the satellite spend significant computational cycles processing the spurious messages, which could be better spent broadcasting legitimate messages. Since the satellite has limited processing power, such an attack can be very effective, especially if strong cryptographic mechanisms like digital signatures are used for authentication and message integrity. This is a denial-of-service (DOS) attack. Although this DOS attack can be launched against any node in a network, a satellite network can be particularly susceptible to such an attack, since the satellite is a single point of failure and can be easily overwhelmed if made to perform too much computation. New IP header ESP Original IP TCP header header header TCP payload ESP trailer Encryption with K1 Original IPSEC ESP tunnel mode encryption New IP header ESP Original IP TCP header header header TCP payload ESP trailer Encryption with K2 Encryption with K1 Layered IPSEC ESP tunnel mode incryption n Figure 3. IPSec and layered IPSec encryption. Key K1 is shared between endpoints only. Key K2 is shared between endpoints and TCP PEPs. 1 embedded objects takes n * RTT to be loaded, an increase in delay by a factor of n. IPSEC FOR SECURITY AT THE NETWORK LAYER Several proposals for data confidentiality and authentication in satellite networks call for use of IPSec, which has been widely adopted by the Internet Engineering Task Force (IETF) for security at the network layer. IPSec and SSL are used independently of each other. IPSec creates an end-to-end tunnel at the network layer for the secure transfer of traffic. The two end-points in the communication negotiate security parameters known as the security association (SA) before traffic can be encrypted. Once the SA has been established in the handshake phase, the IP packets are encrypted using the algorithms and the keys specified in the SA. This is done when the IP-encrypted security payload (IPSec ESP) [9] is used. The IPSec ESP provides for both data encryption and authentication. IPSec provides strong security for data confidentiality and authentication, but it has a heavy byte overhead — in the ESP mode, IPSec adds 10 bytes of overhead to the header and trailer. In addition, if authentication is used, ESP adds 16 bytes or more for the integrity check value, and another 8 bytes or more of initialization vector (IV) if the encryption algorithm uses an IV. Also, IPSec has been designed primarily to secure point-to-point communication; it s not well suited for group communication, due to the lack of the dynamic key-establishment procedure necessary to for secure communication in groups where the membership changes with time. In addition, IPSec does not allow for authentication at intermediate nodes, but this might be useful in some security situations. A widely researched problem when using IPSec in satellite networks is its inability to coexist with PEPs. The keys used for encryption in the IPSec ESP are known only to the two endpoints and therefore any intermediate node in the network cannot decrypt the traffic. IPSec ESP has two modes of operation — tunnel mode and transport mode. In tunnel mode, the entire IP packet is encrypted and a new IP header and ESP header are generated and attached to the encrypted packet (Fig. 3), which adds an extra SECURING END-TO-END UNICAST COMMUNICATION USING IPSEC OR SSL Research on satellite security has focused on using the existing standardized technology, originally designed for terrestrial networks, to fix well-known security holes in satellite networks. Two such protocols that are widely used for secure unicast communication are IPSec [7] and SSL [8]. Figure 2 illustrates the encryption regions of SSL and IPSec. SECURE SOCKET LAYER FOR SECURE WEB TRAFFIC The SSL protocol secures the Web-browsing connection on an as-needed basis. When the client requests a secure connection or the server demands one, SSL is activated to secure the HTTP connection. The resulting connection is popularly known as secure HTTP (or HTTPS) and it encrypts the application-layer HTTP data end-to-end between the client and the server. In the protocol stack, the SSL layer sits between the application and the transport layers. Therefore, SSL encryption hides the TCP payload from all nodes in the network, except the client and the server. SSL encryption does not allow the HTTP proxy to function correctly. The HTML Web page encrypted into the SSL records is readable only by the client and the server who have the decryption keys. The keys are not available to the proxy, and therefore the proxy cannot read the HTML Web page. Consequently, the hub proxy server cannot send requests to the Web server for the embedded objects in the page and, therefore, HTML object prefetching cannot take place. The net result is that a Web page with n – IEEE Wireless Communications †¢ December 2005 53 The HTTP proxy also cannot function when the IPSec ESP is used. Since the HTML page is encrypted end-toend, the HTTP proxy cannot read the Web page in order to prefetch the embedded objects. Therefore, use of IPSec leads to a severe degradation in performance for both the TCP PEP and HTTP proxy. SSSL translation at hub proxy (HPA) SSSL session 2 SSL session 3 Proxy Client Internet Gateway NOC SSSL session 1 SSSL handshaking and translation at client proxy (RPA) Proxy Web server Figure 4. The SSL Internet Page Accelerator concept for efficient HTTPS over satellite. 20 bytes of overhead in addition to the overhead mentioned above. Encrypting the original IP header provides very strong security by disabling attacks (such as traffic analysis, etc. ). In transport mode, the payload portion of the IP packet is encrypted and a new ESP header is attached to the packet after the original IP header, which is in the clear. In either mode, the IP packet payload, which includes the TCP header, is encrypted with keys known only to the end points. Therefore, a TCP PEP, which is an intermediate node in the communication path, cannot read or modify the TCP header, since the PEP does not know the keys. Consequently, the PEP cannot function, thus leading to degradation in the performance of the TCP protocol. The HTTP proxy also cannot function when the IPSec ESP is used. Since the HTML page is encrypted end-to-end, the HTTP proxy cannot read the Web page in order to prefetch the embedded objects. Therefore, use of IPSec leads to a severe degradation in performance for both the TCP PEP and HTTP proxy. It is important to note that the problems that arise from the use of the SSL protocol or the IPSec ESP are independent of one another. It is conceivable that both protocols are used simultaneously, for example, when a secure Web page is accessed via a secure VPN tunnel. However, in such cases the performance issues do not change and the effect would be equivalent to using the IPSec ESP alone. On the other hand, if SSL alone is used, then the performance would be better, since the TCP PEP can function correctly in this scenario. [10] and layered IPSec [11], the idea is to encrypt different regions of the IP packet using different keys (Fig. ). The TCP payload is encrypted with key K1, which is shared only between the endpoints. The original IP header and the TCP header are encrypted with key K2, which is shared between the end points and also with intermediate authorized nodes such as the TCP PEP. Therefore, the TCP PEP can decrypt the header portion of the ESP packet with K2 and read the TCP header to do its performance optimizations. But the PEP cannot read the TCP payload and thus cannot access the actual data, since it does not posses the key K1. The layered IPSec approach allows TCP PEPs to function effectively. However, the method does not solve the problem of HTTP proxy servers. The HTML page is encrypted with key K1 as part of the TCP payload, and K1 is not shared with any intermediate node. Therefore, the Web page is not accessible to the HTTP proxy and no object prefetching can be accomplished. Olechna et al. [12] have suggested two solutions to the IPSec problem. In the first approach, the paper proposes moving the TCP PEP gateways to the endpoints. The TCP optimizations are done on the traffic in the clear, and then the traffic is encrypted using IPSec. There is no TCP PEP at the satellite hub. This approach improves the performance, but when a packet is lost or received in error TCP goes into congestionavoidance phase and the transmission is reduced by half. The second proposed approach, which deals effectively with this problem, is to split the secure connection into two at the satellite gateway. One connection is between the client and the gateway, and the second connection is between the gateway and the Internet server. This allows the gateway to decrypt the IPSec packet and read the headers and thereby do performance optimizations. This requires trust in the satellite gateway, which can now read all the traffic. This might be unacceptable to users who require strong end-to-end security. Several modified TCP protocols have been proposed that perform better than the original specification in the event of channel errors or delay, or when IPSec is used. A discussion of PROPOSED SOLUTIONS TO MITIGATE PERFORMANCE PROBLEMS WITH SSL OR IPSEC Several proposals have been made in academia and industry to deal with performance problems that arise from using IPSec and SSL in satellite networks. The concept of breaking up IPSec encryption into multiple encryption regions or zones on a single packet has been proposed independently in [10, 11]. Although the finer details in the two approaches are different, the basic idea is the same. Known as multilayer IPSec (ML-IPSec) 54 IEEE Wireless Communications †¢ December 2005 Group keys (TEK) K1,8 Internal keys (KEK) K1,4 K5,8 Path of keys for M8 K1,2 K3,4 K5,6 K7,8 Leaf keys Members Group key K2 K1,12 Group key K1 K1,8 K9,12 K1 K2 K3 K4 K5 K6 K7 K8 M1 M2 M3 M4 M5 M6 M7 M8 (a) K1K2 K3 K4K5 K6 K7K8 K9 K10K11K12 M1M2M3M4M5M6M7M8 G1 G2 G3 G4 Members Gateways (b) Figure 5. Logical key hierarchy and its extension to satellite networks: a) with eight members; b) ML-IPSec integrated LKH tree with users and gateways. these TCP enhancements can be found in [13]. The problem of HTTP proxy performance when SSL is used has been addressed within the industry by breaking up the end-to-end single SSL connection between client and server into m ultiple SSL connections [14]. In this solution, the client browser creates a secure HTTP connection with the remote page accelerator (RPA) at the client satellite terminal, a second connection is created between the RPA and the hub page accelerator (HPA), and a third connection is between the HPA and the server (Fig. 4). The RPA performs all necessary handshaking with the client browser. The HPA can decrypt the SSL traffic from the server and perform the desired object prefetching. Taken together, this allows delivery of secure Web content with little performance degradation and with little change to the standard protocols. The major drawback to this scheme is that it requires a high level of trust in the intermediate nodes. The HPA, which is a third-party entity, can read all the sensitive Web traffic that passes between the client and the server. This might be unacceptable when absolute end-to-end security is desired. is O(logN) (where N is the number of members in the group), which is less than the O(N) keys required if the GC arranged the members in a flat topology. To allow PEPs to function correctly when network-layer security is used, [15] proposes the use of ML-IPSec. The paper proposes using a single LKH tree to manage the group key K2, used to encrypt the transport layer header (known to end users and trusted gateways), and the group key K1, known only to the end users and used for encrypting the transport layer data. As shown in Fig. b, users M 1 †¦M 8 are leaf nodes in a subtree of degree three, and gateways G 1 †¦G 4 are leaf nodes in a subtree of degree two. The root key of the member node subtree, K 1,8 , is used to encrypt the transport payload. The root of the overall key tree, K1,12, is used to encrypt the transport header. All member nodes know both K1,8 and K1,12, but the gateways know K 1,12 only (apart from the internal keys in the gateway subtree). How the LKH tree would be managed is not stated in [15]. This is important, since the users and the gateways might not be in the same administrative or security domain. The paper also considers all users and gateways as a â€Å"flat† network for key distribution purposes, rather than taking into account the hierarchical nature of the network topology. The use of LKH for key management in satellite links has also been proposed in [18], which suggests algorithms for dynamically managing the LKH tree in case of member joins and leaves. Duquerroy et al. [19] proposed â€Å"SatIPSec,† for key distribution and secure communication for both unicast and multicast in a satellite network. The solution is based on IPSec, with the addition of flat multicast key exchange (FMKE) to support key management for secure group communication. Management of SAs for both unicast and multicast communication is integrated into the FMKE protocol. FMKE also incorporates reliability mechanisms so as to guarantee reliable key distribution in the lossy satellite setting. However, FMKE manages SAs between the satellite terminals or gateways only and does not extend to the end users. Therefore, end-to-end security is not provided when using SatIPSec. The RPA performs all necessary handshaking with the client browser. The HPA can decrypt the SSL traffic from the server and perform the desired object prefetching. Taken together, this allows delivery of secure Web content with little performance degradation and with little change to the standard protocols. KEY MANAGEMENT PROPOSALS FOR SECURE GROUP COMMUNICATION IN HYBRID NETWORKS Some research has been done with individual algorithms that serve as tools in building keymanagement protocols in order to facilitate secure group communication in hybrid satellite networks. Howarth et al. [15] have proposed the use of logical key hierarchy (LKH) [16, 17] for efficient key management for multicast groups in a satellite network. LKH makes use of a centralized key manager or group controller (GC), which constructs a logical key tree with the group members as the leaves of the tree (Fig. 5a). The internal nodes of the tree are the key encrypting keys (KEK), which are used to securely transport key updates to the group. The root of the tree is the session key or traffic-encrypting key (TEK), which is used to encrypt the session traffic. The number of keys that need to be updated when a member node joins or leaves the group IEEE Wireless Communications †¢ December 2005 55 New IP header ESP Original TCP HTML header IP header header object links Base HTML page Encryption with K2 ESP trailer Encryption with K1 n Figure 6. Layered IPSec with modifications for HTTP optimization. Also, FMKE treats all the satellite terminals it services (which are called SatIPSec clients) in a â€Å"flat† topology, and establishes separate secure channels to all SatIPSec clients. This will not scale when there are a large number of clients. Also, SatIPSec does not consider the dynamic joins and leaves of members in the group communication setting; a client needs to be preauthorized for all the groups it wants to take part in. The protocol also requires complete trust in the group controller and key server (GCKS), which is a third party that is responsible for managing the SAs between the clients. All clients need to have preshared secrets with the GCKS. IPSEC AND SSL IN HYBRID NETWORKS: OUR APPROACH We look at separate solutions to the performance problem arising out of using SSL and IPSec in hybrid networks, and also consider how the two approaches can be combined. HTTP OVER IPSEC TUNNEL One viable method is to break up the end-to-end IPSec tunnel into multiple connections. This is similar to the solution proposed in [12]. But while their approach looks at only the TCP enhancements, we add the use of the HTTP proxy as well. In our approach, the IPSec connection from the client is terminated at the client proxy. The proxy creates its own IPSec connection to the gateway TCP proxy. A third IPSec connection is created from the gateway TCP proxy to the Web server. Schematically, this is similar to Fig. , with IPSec connections replacing the SSL connections in the figure. The IPSec handshaking between the client and the server is spoofed by the client proxy on the client end, and by the TCP hub proxy on the server end. In this model, the Web traffic can be read completely by the client proxy and the hub proxy. The two proxies are able to perform the TCP enhancements because they can read the TCP header. In addition, the hub HTTP proxy can perform HTM L object prefetching from the server because it can read the base HTML page as it is returned to the client on a HTTP request. When the client browser generates staggered requests for the embedded objects upon receiving the base HTML page, the client proxy is responsible for returning local acknowledgments to the requests, and sending all the objects to the client browser at one time. The design is therefore fully able to maintain the functionality of the TCP and HTTP proxies. It also encrypts the traffic so that it can be seen only by the client, the server, and the two intermediate proxy servers. The design also makes minimal changes to existing standard protocols. However, the design also requires that there be full trust in the proxy servers. Also, there is additional overhead in setting up three IPSec connections, as opposed to one (as in the end-to-end case). The overhead in encryption/decryption also increases by a factor of three for every IP packet, since the intermediate proxies need to decrypt the TCP header and the HTML content. When the security requirement is that the traffic be unreadable to intermediate nodes, the above approach will not work. In this situation, we propose extending the layered IPSec approach in order to allow portions of the HTML content to be also accessible to the proxy servers. Assume for layered IPSec that the keys are K1 and K2. K1 is known only to the client and the server, while K2 is known to the client, the Web server, and the intermediate proxy servers at the client and the gateway. When the client makes HTTP requests, the requests are encrypted using K2, so that the client proxy server can read the requests and send local acknowledgments. Additional software at the Web server parses the requested HTML page so as to obtain all the embedded object links. These object links are collated into a new HTML page that contains only the object links, and this new page is encrypted with K2. The base HTML page that contains all the information and the object links is encrypted with K1. Both the encrypted base HTML page and the encrypted object links HTML page are sent in reply. Therefore, the encrypted ESP packet looks as it is depicted in Fig. 6. Upon receiving the IPSec packet from the Web server, the hub proxy is able to read the object links (since it has K2) and therefore do prefetching for the embedded links. In addition, the hub proxy can also read the TCP header and perform TCP enhancements. However, the HTML base-page data cannot be read by the hub proxy, since it does not have K1. The encrypted base HTML page can only be read by the client when the IPSec packet reaches the destination. This design allows the TCP and HTTP proxies to perform effectively while maintaining a high level of end-to-end security. However, the security is not as strong as in traditional IPSec, since the intermediate proxies do get some information insofar as they can read the links of the embedded objects, even though they cannot read the application data. This is the major trade-off necessary to achieve acceptable performance in this design. In addition, the model requires changes to be made to the IPSec protocol so that layered IPSec is supported with the HTTP performance additions. A major issue in the above model is the handshaking mechanism required to set up the layered IPSec connection. To maintain a high level of security, we propose that the connection be set up primarily between the client and the server, who negotiate both K1 and K2, apart from other parameters of the security association. The handshaking mechanism then provides K2 securely to both the client and the hub proxy servers. The client and the hub proxy servers are required to authenticate themselves correctly before they can receive the secondary key or access the IPSec traffic. 56 IEEE Wireless Communications †¢ December 2005 DSSL main mode (K1) DSSL main mode (K2) Internet Gateway Proxy (K2) Client (K1, K2) NOC DSSL primary and secondary modes Original TCP IP header header Proxy SSL record Primary SSL record Proxy (K2) Web server (K1,K2) Encryption with K2 Encryption with K1 IP packet format for DSSL n Figure 7. Dual-mode SSL for HTTP optimization. HTTP OVER SSL When the HTTP traffic is secured using SSL only, and there is no IPSec tunnel in use, several approaches are possible to ensure acceptable performance. If the security requirement of the client and the Web server allow for trusted intermediate nodes, then the SSL accelerator concept of [14] can be a viable solution. This would require no change to the protocols at the expense of higher overhead in order to set up multiple SSL connections between the client, proxy, and Web server. When the security policy does not allow for trusted third parties, a different approach is needed. We propose the use of a modified SSL protocol, which we term dual-mode SSL (DSSL). As shown in Fig. 7, the secure connection in DSSL has two modes — an end-to-end main mode connection between the client and the Web server, and a secondary mode connection that has the hub HTTP proxy as an intermediate node. When secure HTTP traffic is requested, the DSSL main mode connection is first negotiated between the client and the server. As part of the handshake for the main mode, the client and the Web server also negotiate the parameters for the secondary mode. Let K1 be the encryption key for the main mode, and K2 be the encryption key for the secondary mode. The client transfers the parameters of the secondary mode to the client and hub HTTP proxy servers only after the proxy servers authenticate themselves to the client. When the client makes an HTTP request, the client proxy sends local replies to the client browser, as discussed previously. The Web server, on receiving the request, parses the requested HTML page to obtain the embedded object links, which are collated into a new HTML page. The object links HTML page is then encrypted by DSSL using K2 to create the proxy SSL record. DSSL encrypts the base HTML page using K1 to create the primary SSL record. The two records are appended together and sent to the client in an IP packet (Fig. 7). The hub proxy intercepts the IP packet, extracts the object links from the proxy SSL record using K2, and prefetches the embedded objects. The Web server always encrypts the actual objects using K1, so that the hub proxy cannot read the base HTML page data. The hub proxy transfers all the embedded objects together to the client at one time. Therefore, the HTTP proxy functionality is preserved in DSSL while maintaining the end-to-end security of the HTML page contents. However, the security is less than in the end-to-end SSL connection case, since the HTTP proxy can read the object links. In standard SSL, the proxy servers can read no part of the base HTML page, not even the object links. We believe this slight reduction in security is acceptable, given the considerable improvement in performance using this method. The DSSL design is more complex in comparison to SSL since it requires the creation of an additional connection, and therefore involves a higher overhead. There is also the added overhead of multiple encryptions and decryptions with two different keys, and the complexity of parsing the HTML page for the object links. All these require changes to the base SSL protocol. The DSSL concept is similar to the multiplechannel SSL concept proposed in [20]. However, the authors do not differentiate encryption in primary and secondary SSL records but instead suggest that HTTP traffic with lower security requirements be encrypted entirely with keys known to intermediate nodes. For our security requirements, that approach would not be acceptable. Differential Encryption in Single SSL Record — The use of a proxy SSL record is not necessary if various parts of the HTML page can be encrypted with The DSSL design is more complex in comparison to SSL since it requires the creation of an additional connection, and therefore involves a higher overhead. There is also the added overhead of multiple encryptions and decryptions with two different keys. IEEE Wireless Communications †¢ December 2005 57 Secondary SSL encryption Primary SSL encryption New IP header ESP Original TCP Proxy SSL header IP header header record Secondary IPSec encryption Primary SSL record ESP trailer Primary IPSec encryption n Figure 8. Packet format for dual-mode SSL with IPSec. different keys. In that case, the Web server can encrypt the object links in the HTML page with key K2 and the rest of the HTML page contents with key K1, thus creating a single SSL record with different encryption. The hub proxy server can parse the SSL record and decrypt only the object links with key K2, before forwarding the IP packet to the client proxy. We assume that the primary and secondary encryption keys K1 and K2 have been set up and distributed as described in the previous sections, with K1 known to the client and the Web server only, while K2 is known to the client, the Web server, and the intermediate proxy servers. A similar technique can be applied when IPSec encryption is used instead of SSL encryption. The advantage here is that the size of the packet does not increase, although there is the overhead of distributing key K2 to the proxy servers to be considered. HTTPS OVER IPSEC For the sake of completeness, we consider the situation where a secure Web page is requested over an IPSec tunnel. This method involves redundancy of resources, since use of SSL when IPSec is being used does not provide any substantially added security. However, our approach can take care of the performance in this scenario as well. In this situation, we propose integrating DSSL with layered IPSec. Then the secondary keys for both the layered IPSec connection and the DSSL connection are shared with the proxy servers. The secondary key for layered IPSec is shared with both the TCP proxy and the HTTP proxy. When layered IPSec encrypts the packet, the secondary key encryption extends up to the proxy SSL record. The TCP proxy servers can therefore decrypt the TCP header of the ESP packet, and the HTTP proxy server can decrypt the proxy SSL record. Consequently, performance optimizations for both TCP and HTTP are allowed without letting the intermediate servers read the HTML page. A schematic of the IPSec packet in this setting is shown in Fig. 8. A HIERARCHICAL APPROACH TO KEY MANAGEMENT FOR DATA SECURITY IN HYBRID NETWORKS In [21], we have proposed a key-management framework for distributing cryptographic keys securely and in a scalable manner to users taking part in group communication in a hybrid satellite network. The objective is to ensure data confidentiality, by encrypting the data traffic with group keys known to all the group members. The key-management framework is built on top of the multicast routing architecture. We have considered the hybrid network topology shown in Fig. 1b and designed a multicast routing architecture to allow users to communicate seamlessly between multiple terrestrial LANs (also referred to as subnetworks) [22]. Our routing design makes specific use of asynchronous transfer mode (ATM) point-to-multipoint routing [23] over the satellite links, and Protocol-Independent Multicast Sparse-Mode (PIM-SM) multicast routing [24] in terrestrial LANs. We have extended PIM-SM to allow multiple rendezvous points (RPs) in each multicast group. The satellite gateway in each LAN acts as the local RP for the LAN and creates the local multicast trees for group members within the LAN. The local multicast trees are connected together over the satellite links by using the ATM point-to-multipoint virtual connection, thereby creating one end-to-end multicast tree for each group, encompassing all the LANs with group members in them. The multicast routing architecture is thus adapted closely to the hierarchical network topology, and allows for building efficient multicast trees with low control and data overhead. The design of the key-management protocol is independent of the routing algorithm, although it is based on the same underlying principle, that is, a hierarchical breakup of the network based on the topology. We divide the network into two levels — the lower level, comprised of terrestrial LANs where the users are located, and a higher level consisting of the satellite, the NOC, and the satellite gateways or RPs in each LAN, which together form an overlay (Fig. 9a) interconnecting terrestrial LANs. The RPs act as the â€Å"bridge† between the two levels. Key management is done separately in the two levels. In each LAN we introduce a local group controller (called the â€Å"subnetwork key controller† or SKC) to manage the keys for all groups active in the LAN. The SKC is responsible for access control of all members of all groups that are active in its LAN, generating the group keys for all local groups, and updating the keys on group-member joins and leaves when a group is active. The keys managed by an SKC are entirely local to its LAN, and do not affect the key management in any other LAN in the network. The SKC uses the LKH algorithm to manage keys in its LAN, creating a logical key tree that we term the SN Tree. Each group active in a LAN has its own SN Tree. The leaves of the SN Tree for a group correspond to the longterm shared secrets between the SKC and the local users in the LAN who are active as sources and/or receivers in the group. The root of the SN Tree corresponds to the session key that is used for encrypting the group traffic within the LAN at any particular instant. On member joins and leaves, the session key, and all the keys on the path from the root to the leaf node corresponding to the member joining/leaving, are updated, while all other keys in the SN Tree remain unchanged. The overlay has its own key management, 58 IEEE Wireless Communications †¢ December 2005 Overlay RP tree root key Level-1 Satellite Overlay network NOC Gateway Gateway Gateway SN tree SKC RP (root) RP (leaf) SKC RP tree RP (leaf) Gateway Level-0 SKC Subnet n Subnet 1 Subnet 2 (a) Subnet 3 Subnetwork Subnetwork (b) Subnetwork n Figure 9. A hierarchical approach to key management in hybrid networks: a) hierarchy in the hybrid network; b) tiered tree key management. also based on the LKH algorithm. At the overlay level, the key management for a particular group is controlled by the satellite gateway/RP (known as the root RP for that group) of the LAN that has group sources active for the longest continuous period in the group. The logical key tree for any group thus formed at the overlay is termed the RP Tree. The root RP is responsible for generating keys for the RPs of the LANs who subscribe to the particular group, that is, have sources and/or receivers active in the LAN. Each group has its own RP Tree. The design ensures that the NOC cannot receive/transmit data to any active group, unless it explicitly subscribes to the group as a member node. However, LANs joining any particular group initially register with the NOC, which maintains a group membership table for all active groups, so that at all times the NOC is aware of the LANs which are participating in all active groups. The NOC is also responsible for selecting the root RP of the RP Tree for each group, which it does based on the earliest-to-join policy. The root RP also might be different for different groups, since the LAN with the longest continuously active sources might be different for different groups. Our algorithm has the provision to allow the root RP for any group to change — this happens if the currently active root RP leaves the group, when all sources/receivers within its local LAN cease to participate in the group. Our algorithm therefore builds a hierarchy of logical key trees that closely follow the hierarchy in the network topology, as shown in Fig. 9b. We term this framework Tiered Tree-based Key Management. In this hierarchy of key trees, the gateway RPs are responsible for performing key translation on all the multicast group traffic as it transmits the data from local sources to receivers in remote LANs, or when it receives group traffic from remote sources for local receivers. This translation is necessary since the data traffic is encrypted with the RP Tree session key in the overlay, and with the SN Tree session ey within the local LAN, with the two session keys being independent of one another. The detailed design of Tiered Tree-based Key Management, analysis of its security, and experimental results can be found in [25]. The primary objective in our design is to minimize the amount of key-management control traffic n Figure 10. Tiered tree framework: total key management traffic vs. RP tree traffic for three groups (Y-axis shows the traffic in bytes per second; X-axis is the simulation duration in minutes). hat flows over the satellite links, due to the long delay involved as well as susceptibility to channel errors. We have attempted to ensure that the security of the data traffic does not add any overhead in terms of delay other than that absolutely unavoidable, and that the security protocol does not contribute to deadlocks in group-data dissemination where some group members in certain LANs cannot read the data due to having wrong keys. From the simulation results, Fig. 10 shows the reduction in key-control traffic over the satellite links using our tiered-tree approach. The graph compares the total key-management IEEE Wireless Communications †¢ December 2005 59 Our solution is a generic solution aimed specifically at multicast key management and does not deal with an end-to-end security solution for secure communication or give any implementation specifics. information sent in the network for three simultaneous groups (i. e. , sent over the RP trees, sent over the satellite links, and all SN trees limited to local LANs), to the total key information sent on the RP trees (satellite links) only. As the graph shows, the resource savings on the satellite links is substantial when the tiered-tree scheme is used. Even though the group dynamics are high, the amount of message exchanges are very few in the RP tree, that is, over the satellite links. If a flat key-management hierarchy had been used instead, the total key-management traffic would have been sent over the satellite links, thus leading to increased delay and increasing the possibility that the correct keys do not reach all the members at the same time. Our solution is therefore very scalable. It also acknowledges the fact that the group members might be located in different security domains and, therefore, a single network-wide security management might not be possible. This is a more realistic scenario, since terrestrial LANs might be individual company domains, while the satellite overlay infrastructure is usually owned by a separate entity that provides network connectivity to the LANs, and is not responsible for generating the network traffic. This framework addresses the problem that all users might not be visible to a single, centralized security authority, and the dynamics of user joins or leaves in one LAN should not create an overhead to users in other LANs. Also, in widearea satellite networks we consider that the satellite channel conditions at a given point in time might be different in different sections of the network. There might be loss in information due to bad channel conditions in some network segments; however, this should not disrupt communication in network segments where the channel conditions are better. Solutions which treat all users in a single tree will not be able to perform as robustly under such conditions. Our solution is also similar to the ML-IPSec concept in that the satellite terminals are only partially trusted; they are allowed to do partial decryption/encryption of the IP packets for efficient routing. However, it is a generic solution aimed specifically at multicast key management and does not deal with an end-to-end security solution for secure communication or give any implementation specifics. approaches for typical topologies and validating the proposed designs by simulation. Lastly, we have described our hierarchical approach of key management for providing data security in hybrid networks. We are continuing our research in this area and examining designs to integrate our keymanagement protocol with the unicast case. A considerable amount of work needs to be done with regard to secure protocols for hybrid networks, specifically for the case where users are mobile. Here we have touched upon only a small subset of the problems. None of the proposed solutions, including our own, address the question of user authentication or message integrity for group communication. However, we believe the security problems discussed here will receive further treatment from the research community, and this work will be a useful contribution to the field. ACKNOWLEDGMENT The authors would like to thank the anonymous reviewers for their valuable comments and suggestions. The research reported here is supported by the National Aeronautics and Space Administration (NASA) Marshall Space Flight Center under award no. NCC8-235. The views expressed in this article are solely the responsibility of the authors and do not reflect the views or position of NASA or any of its components. REFERENCES [1] J. Border et al. , â€Å"Performance Enhancing Proxies Intended to Mitigate Link-Related Degradations,† IETF RFC 3135, June 2001. [2] V. Arora et al. , â€Å"Effective Extensions of Internet in Hybrid Satellite-Terrestrial Networks,† University of Maryland, College Park, Tech. Rep. CSHCN TR 96-2, 1996. [3] V. Bharadwaj, â€Å"Improving TCP Performance over HighBandwidth Geostationary Satellite Links,† University of Maryland, College Park, Tech. Rep. ISR TR MS-99-12, 1999. [4] N. Ehsan, M. Liu, and R. Ragland, â€Å"Evaluation of Performance Enhancing Proxies in Internet over Satellite,† Wiley Int’l. J. Commun. Sys. , vol. 16, Aug. 2003, pp. 513–34. [5] NIST, â€Å"Digital Signature Standard (DSS),† May 19, 1994. [6] H. Krawczyk, M. Bellare, and R. Canetti, â€Å"HMAC: KeyedHashing for Message Authentication,† IETF RFC 2104, Feb. 1997. [7] R. Atkinson and S. Kent, â€Å"Security Architecture for the Internet Protocol,† IETF RFC 2401, Nov. 1998. [8] IETF Transport Layer Security Working Group, â€Å"The SSL Protocol Version 3. 0,† Nov. 1996, available at http://wp. netscape. com/eng/ssl3/draft302. txt [9] R. Atkinson and S. Kent, â€Å"IP Encapsulating Security Payload (ESP),† IETF RFC 2406, Nov. 998. [10] Y. Zhang, â€Å"A Multilayer IP Security Protocol for TCP Performance Enhancement in Wireless Networks,† IEEE JSAC, vol. 22, no. 4, 2004, pp. 767–76. [11] M. Karir and J. Baras, â€Å"LES: Layered Encryption Security,† Proc. ICN’04, Guadeloupe (French Caribbean), Mar. 2004. [12] E. Olechna, P. Feighery, and S. Hryckiewicz, â€Å"Virtual Private Network Issues Using Satellite Based Networks,† MILCOM 2001, vol. 2, 2001, pp. 785–89. [13] P. Chitre, M. Karir, and M. Hadjitheodosiou, â€Å"TCP in the IPSec Environment,† AIAA ICSSC 2004, Monterey, CA, May 2004. 14] SSL Accelerator, Spacenet Inc. , available at http://www. spacenet. com/technology/advantages/ssl. ht ml [15] M. P. Howarth et al. , â€Å"Dynamics of Key Management in Secure Satellite Multicast,† IEEE JSAC, vol. 22, no. 2, 2004, pp. 308–19. [16] C. Wong, M. Gouda, and S. S. Lam, â€Å"Secure Group Communications Using Key Graphs,† IEEE/ACM Trans. Net. , vol. 8, 2000, pp. 16–30. CONCLUSION Security is a critical component in hybrid IPbased satellite networks. In this article we have focused on some of the challenges that lie ahead. We have discussed the unique characteristics of hybrid satellite networks that make the problem of ensuring secure communication different from that of purely terrestrial networks. We have presented a survey of the various security solutions that have been proposed, and discussed their advantages and disadvantages. We have proposed several approaches to solve the performance problems of TCP and HTTP in satellite networks arising from secure communication. However, a lot of further work needs to be done to validate our approaches, and we are in the process of developing specific detailed security 0 IEEE Wireless Communications †¢ December 2005 [17] D. Wallner, E. Harder, and R. Agee, â€Å"Key Management for Multicast: Issues and Architectures,† IETF RFC 2627, June 1999, available at http://www. apps. ietf. org/rfc/ rfc2627. html [18] G. Noubir and L. von Allmen, â€Å"Security Issues in Internet Protocols over Satellite Links,† Proc. IEEE VTC ‘99, Amsterdam, The Netherlands, 1999. [19] L. Duquerroy et al. , â€Å"SatIPSec: An Optimized Solution for Securing Multicast and Unicast Satellite Transmissions,† 22nd AIAA Int’l. Commun. Sat. Sys. Conf. and Exhibit, Monterey, CA, May 2004. [20] Y. Song, V. Leung, and K. Beznosov, â€Å"Supporting Endto-End Security across Proxies with Multiple-Channel SSL,† Proc. 19th IFIP Info. Sec. Conf. , Toulouse, France, Aug. 2004, pp. 323–37. [21] A. Roy-Chowdhury and J. Baras, â€Å"Key Management for Secure Multicast in Hybrid Satellite Networks,† 19th IFIP Info. Sec. Conf. , Toulouse, France, Aug. 2004. [22] A. Roy-Chowdhury and J. Baras, â€Å"Framework for IP Multicast in Satellite ATM Networks,† AIAA ICSSC 2004, Monterey, CA, May 2004. [23] G. Armitage, â€Å"Support for Multicast over UNI 3. 0/3. 1 Based ATM Networks,† Internet RFC 2022, Nov. 1996. [24] S. Deering et al. , â€Å"The PIM Architecture for Wide-Area Multicast Routing,† IEEE/ACM Trans. Net. , vol. 4, no. 2, 1996, pp. 153–62. [25] A. Roy-Chowdhury, â€Å"IP Routing and Key Management for Secure Multicast in Satellite ATM Networks,† Master’s thesis, University of Maryland, College Park, 2003, available at http://techreports. isr. umd. edu/reports/2004/ MS2004-1. pdf Paper Award, 2004 WiSe Conference. He holds three patents. His research interests include wireless networks and MANET, wireless network security and information assurance, integration of logic programming and nonlinear programming for trade-off analysis, multicriteria optimization, noncooperative and cooperative dynamic games, robust control of nonlinear systems and hybrid automata, mathematical and statistical physics algorithms for control and communication systems, distributed asynchronous control and communication systems, object-oriented modeling of complex engineering systems, satellite and hybrid communication networks, network management, fast Internet services over hybrid wireless networks, stochastic systems, planning and optimization, intelligent control and learning, biologically inspired algorithms for signal processing, and sensor networks. MICHAEL HADJITHEODOSIOU [M] received an M. A. (honours) in electrical and information sciences from the University of Cambridge, United Kingdom, in 1989, an M. S. in electrical and computer engineering from the University of California, Irvine in 1992, and a Ph. D. n engineering (specializing in satellite communications) from the Centre for Satellite Engineering Research (CSER) at the University of Surrey, United Kingdom, in 1995. Among his awards are a scholarship award for studies at the University of Cambridge from the Cambridge Commonwealth Trust (1984–1986); a Fulbright Scholarship for post-graduate work in the United States (1989–1991); a Research Fellowship from the U. K. Engineering and Physical Sciences Research Council (EPSRC) (1992); and the Canadian National Science and Engineering Research Council (NSERC) post-doctoral fellowship award (1995). He worked as a research fellow in the Communication Systems group of CSER (1991–1995) and spent a year as a visiting fellow at the Canadian Government Communications Research Center (CRC) (1995–1996). In November 1996 he joined the Center for Satellite and Hybrid Communication Networks (CSHCN) at the Institute for Systems Research, University of Maryland, College Park, where he is currently an assistant research scientist. He is an expert on space communications and satellite networks. His research interests include performance optimization of wireless and hybrid networks, security and protocol support issues for satellite systems, and design optimization of next-generation broadband satellite networks and applications. He is currently working on supporting the communication needs of NASA enterprises and the communication architecture enabling space exploration. He is currently serving as secretary of the IEEE Satellite and Space Communications Technical Committee. SPYRO PAPADEMETRIOU received his B. S. in computer science from George Mason University, Fairfax, Virginia. Since then he has been actively involved in Internet research and development within both industry and academia. He was the principal Internet researcher at Synectics Corp. , where he developed network and database software. He worked as a researcher at the University of Maryland’s Institute for Systems Research, where he designed and developed their first networking laboratory, which is part of the CSHCN. At Inktomi Corp. he spearheaded client acceleration research and was a member the content-distribution network design team. These resulted in several patent filings, of which he holds one. The latter also resulted in American Online’s Web client accelerator product. Currently he is with Orbital Data Corp. working on network and application optimization. His research interests include network optimization, application optimization, satellite and terrestrial wireless networking, delay-tolerant networks, sensor networks, distributed systems, and network software architecture. We have touched upon only a small subset of the problems. None of the proposed solutions, including our own, address the question of user authentication or message integrity for group communication. BIOGRAPHIES AYAN ROY-CHOWDHURY ([email  protected] umd. edu) received his B. E. in electronics and telecommunications engineering in 1998 from Jadavapur University, India, and his M. S. in electrical engineering in 2003 from the University of Maryland, College Park, where he is currently a Ph. D. student. Between 1998 and 2000 he worked as a senior software engineer at Wipro Technologies, India. His research focuses on the design of protocols and frameworks for secure communication in hybrid networks. He is working on secure protocols for unicast and multicast routing in networks that have wired and wireless terrestrial components interconnected by satellite links. He is also looking into key management techniques for secure data transmission for these network architectures, and efficient user-authentication mechanisms for the same. As part of these topics, he is also investigating performance problems for network communication in satellite networks when security is involved. J OHN S. B ARAS [F] received a B. S. in electrical engineering from National Technical University of Athens, Greece, in 1970, and M. S. and Ph. D. degrees in applied mathematics from Harvard University in 1971 and 1973, respectively. He was founding director of the Institute for Systems Research (one of the first six NSF Engineering Research Centers) from 1985 to 1991. Since August 1973 he has been with the Electrical and Computer Engineering Department and Applied Mathematics Faculty at the University of Maryland, College Park. In 1990 he was appointed to the Lockheed Martin Chair in Systems Engineering. Since 1991 he has been director of the Center for Hybrid and Satellite Communication Networks (a NASA Research Partnership Center). Among his awards are the 1980 Outstanding Paper A