40 Idioms with First

40 Idioms with First 40 Idioms with First 40 Idioms with First By Mark Nichol Many expressions include the word first, often referring to beginnings or initial experiences. Here is a list of idiomatic phrases featuring the word, and their meanings. 1. First aid: medical care for minor injuries such as mild abrasions, cuts, bruises, and burns 2. First among equals: the sentiment that a leader is merely the premier person among his or her colleagues 3. First base: the first step or stage in a process or procedure, from baseball terminology 4. First blood: referring to the rite of passage of a hunter making a first kill 5. (At) first blush: referring to reconsideration of one’s initial thought 6. First call: the right to priority in use of something 7. First cause: the philosophical concept of the original self-created cause of which all other causes are by-products 8. First chair: the lead musician among those playing a particular instrument in an orchestra (such as first violin) 9. First class: the best category of travel accommodations, or the best in terms of performance or quality 10. First come, first served: the principle that the customer who arrives first is given priority 11. First cousin: a son or daughter of one’s aunt or uncle 12. First crack: the earliest chance or opportunity 13. First dance: the tradition of the guests of honor being the first couple on the dance floor to start a ball or other dance event 14. First dibs: see â€Å"first call† 15. First down: the first in a series of plays in American football after one team takes possession of the ball from the other team 16. First edition: the initial publication of a book 17. First estate: the clergy as the highest of the three orders of society in the Middle Ages and for some time afterward (the others were the nobility and the common people) 18. First floor: the ground floor (in American English usage) or the second floor (in British English usage) 19. First flush (of success): an initial period of achievement (the term is also used technically to refer to the initial runoff of rainwater after a storm) 20. First glance: a superficial examination or review 21. (At) first hand: with direct experience (as an adjective, firsthand) 22. First impression: the initial evaluation of information or an experience, generally before having time to consider or ponder 23. First lady: the wife of a government’s leader 24. First leg: the first part of a journey 25. First light: the earliest part of day 26. First night: the evening of a premiere performance, or the premiere performance itself 27. (In the) first place: in the beginning, or as an initial consideration 28. (Right of) first refusal: the privilege of being able to accept or reject an offer or proposal before anyone else is given consideration 29. (Love at) first sight: the sentiment of an instant romantic connection 30. (The) first step (is always the hardest): the notion that starting a task is the most difficult part 31. (Cast the) first stone: used to refer to hypocritical behavior akin to throwing a stone at someone as punishment for a crime when the thrower may be culpable for the same crime or another one 32. First string: the group of athletes who participate from the beginning an athletic competition, as opposed to players who may substitute for first-string teammates at some point; by extension, the best among any group 33. (Don’t) know the first thing about: the model for an expression stating that someone is unacquainted with even the basics of a certain procedure or topic 34. First things first: refers to the importance of considering the relative priority of steps 35. First-timer: someone engaging or participating in some activity the person has not done before 36. First water: the highest quality, especially in gems but also said figuratively of people of high character 37. First world: the developed, industrialized nations 38. (If at) first you don’t succeed (try again): the sentiment that one should persist after initial failure 39. Ladies first: a sentiment that, according to proper etiquette, females should have priority in passing through a doorway or into another area 40. Shoot first (and ask questions later): referring to the supposed wisdom, in a confrontation, of disabling a potential adversary first and then ascertaining whether the person is in fact a foe Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Expressions category, check our popular posts, or choose a related post below:20 Words with More Than One Spelling20 Words Meaning "Being or Existing in the Past"Quiet or Quite?

How to Order Coffee in France

How to Order Coffee in France If you think ordering coffee in a French cafà © or bar is the same as back home, you might be in for an unpleasant surprise. Ask for un cafà © and youll be presented with a tiny cup of espresso, and if you then request milk, youre likely to get a dirty look or sigh of exasperation. Whats the problem? Le Cafà © Franà §ais In France, un cafà ©, which may also be called un petit cafà ©, un cafà © simple, un cafà © noir, un petit noir, un cafà © express, or un express, is an espresso: a tiny cup of strong black coffee. Thats what the French drink, so thats what the simple word cafà © refers to. Many visitors to France, however, prefer a large cup of filtered, relatively weak coffee, which in France is known as un cafà © amà ©ricain or un cafà © filtre. If you like the taste but not the strength of espresso, order un cafà © allongà © and youll get an espresso in a large cup which you can dilute with hot water. On the other hand, if youd like something even stronger than espresso, ask for un cafà © serrà ©. In the unlikely event that you find a place serving iced coffee, it will be called cafà © glacà ©. For decaffeinated coffee, add the word dà ©ca to your order: un cafà © dà ©ca, un cafà © amà ©ricain dà ©ca, etc. Du Lait, Sil Vous Plaà ®t If you want milk, you have to order it with the coffee: un cafà © au lait, un cafà © crà ¨me, un crà ¨me - espresso with hot milk (large cup)un cappuccino - espresso with foamed milk (large cup)un cafà © noisette, une noisette - espresso with a dash of milk or a spoonful of foam (small cup) Et Du Sucre? You dont need to ask for sugar - if its not already on the bar or table, it will arrive with your coffee, in little envelopes or cubes. (If its the latter, you can do like the French and faire un canard: dip a sugar cube in your coffee, wait a moment for it to turn brown, and then eat it.) Coffee Notes At breakfast, the French like to dip croissants and day-old baguettes into cafà © crà ¨me - indeed, thats why it comes in such a large cup or even a bowl. But breakfast is the only meal at which coffee is consumed (1) with milk and (2) with food. The French drink un express after lunch and dinner, which means after- not with- dessert. French coffee is not meant to be consumed on the street, so theres no takeaway. But if youre in a hurry, drink your petit cafà © standing up at the bar, rather than sitting at a table. Youll be rubbing elbows with locals, and youll save money to boot. (Some cafà ©s have three different prices: bar, indoor table, and outdoor table.) Un cafà © lià ©geois is not a drink, but rather a dessert: a coffee ice cream sundae. (Youre also likely to encounter un chocolat lià ©geois.) Other Hot Drinks un chocolat - hot chocolateun thà © - black teaun thà © vert - green teaune tisane, une infusion - herbal tea In the mood for something different? This article has an extensive list of other drinks and their French pronunciations.

Federal Trade Commission and Merger - Arbitron, Nielsen Research Paper

Federal Trade Commission and Merger - Arbitron, Nielsen - Research Paper Example This implies that for any merger to be acceptable it must comply with the business laws as provided by the government. For example, in US, Federal Trade Commission (FTC) is an agency that has been established by the government to ensure unfair business practices are avoided. Additionally, FTC is responsible for prevention of fraudulent business strategies that would jeopardize not only the shareholders investments but also the consumer’s money. Another notable function of FTC is to create a competitive business atmosphere. In this way, the negativities of monopoly as well as price discriminative policies are addressed. During the merging and acquisition processes, it is imperative for managers and directors to engage all the stakeholders that include the shareholders, creditors, auditors and other investors. This paper aims at discussing the merger between Arbitron, and Nielsen companies and the implications of FTC on the merger. Nielsen Holdings is an American based firm that deals in providing its local and global clients with information regarding the behaviors of their consumers in the market. With its headquarters based in New York and in Netherlands, the company operates in more than 100 countries in various regions world wide. In this regard, the company enjoys wide market segment that places it at a competitive position. Key people who oversee the operations of the company includes David Calhoun and Rick Kash, the CEO and the vice chair respectively. Other individuals in the management team include Brian West, Steve Hasker, Mary Liz, Mitchell Habib and Itzhak Fisher among others. One of the notable aspects that have contributed to the success of the company is the establishment of quality services that are highly demanded by companies that are focused at facing off the various challenges in the local and international markets. The three key products by Nielsen include provision of consumer information, market measurement as well as consumer resea rch. Nielsen has been involved in a number of business strategies that have not only positive impact on its capital base but also in its marketing strategies. These include strategic alliances, mergers as well as acquisitions. Some of the companies that the company has either acquired or formed a merger with include WPP Group, VNU, Buzzmetrics, Blackstone Group, IAG Research, The Cambridge Group and more recently Arbitron among others1. Arbitron is a US based firm with its headquarters in Columbia, Maryland. Having been founded in 1949 by Jim Seiler, the company original services included collection of television ratings that it adopted during the research process2. Just like Nielsen Holdings, Arbitron is engaged in a number of mergers immediately after it was established. Some of the notable companies that the company has merged with include Cooper, Clay and Coffin. In a deal that was aimed at making the company more competitive in the global market, Arbitron merged with Nielsen Ho ldings in 2012 resulting into change of names to Nielsen Audio. Key person who oversee the acquisition process was Sean Creamer, the company chief executive officer. Summary about the merger between Arbitron and Nielsen Arbitron and Nielsen Companies have for a long time been used by firms to provide with information regarding the consumption of their brands. Based on the need for two firms to improve their market

Occupy wall street movement Essay Example | Topics and Well Written Essays - 1500 words

Occupy wall street movement - Essay Example The sentiment becomes contagious and spreads to all countries of the world. 1. What are the Moral and economic implications involved in the movement?   Moral implications of the movement reflect in recklessness on the part of few powerful corporations as in the case of Enron or powerful industry like financial services as in the case of subprime crisis which has not only affected various stakeholders and the nation, but destroyed the fabric of the system. The government’s policies in dealing with the crises have been in favour of the corporations at the cost of the common man. Pittman (2008) states that â€Å"Without the government money, Goldman, Merrill Lynch & Co.,  Morgan Stanley, Deutsche Bank AG and other firms could have become some of the biggest creditors in a bankruptcy filing by AIG, the world's largest insurer, because of its billions in losses on  subprime bonds  and corporate debt.† Disintegration of the system over a period of time is the root cau se of various economic and social issues which led to the uprising of this movement. The decay in the system erodes the values of democracy and demoralizes our capitalist society. The renaissance in thinking which forms the basis for the movement indicates the spiritual strength of the society and the nation which calls for a change. Economic development in a country is possible and sustainable only in a healthy society with equality in opportunities. Moral and economic implications are inseparable. Tax cuts to the rich corporate companies in the name of encouraging industrial development, and subsidies in the name of social welfare to protect insurance companies and financial deregulation measures in the garb of liberalization, hitherto gone unnoticed by the public or misinterpreted in press to the benefit of big corporate entities have been brought under public debate. This has given rise to the questions related to issues such as morality of the corporations and relevance of the capitalism. Greed of the companies, for example pharmaceutical companies and the patent laws which protect them in their exploitation of the general public has become the common subject for public discussion. The dilemma of common men in prioritizing their resources even between rent and food under inflationary conditions led them to unite under â€Å"We are the 99%† that reflects the economic inequality and lack of distribution of wealth. It is now believed that increase in wealth of 1% can be equated to the losses of the rest. Since Wall Street symbolizes the economic power of 1%, it lends focus to the agitations. Poverty has become the single most economic issue to be tackled by the nation, and obviously, this responsibility cannot be left to the 1%, going by the experience. The technological innovations in the field of software development and telecommunication though increased the complexities in the manipulation of the system by the corporations on the one hand the same developments and rise of social networks have opened new opportunities and avenues for cohesiveness in the society and its self-realization. 2. How can we theoretically analyze the implications? According to utilitarian theory, good actions form the basis for overall happiness. The underlying cause of actions in the case of subprime crisis or other major financial scams is greediness on the part of the corporate companie

Technology for Network Security

Technology for Network Security 2.0 CHAPTER TWO 2.1 INTRODUCTION The ever increasing need for information technology as a result of globalisation has brought about the need for an application of a better network security system. It is without a doubt that the rate at which computer networks are expanding in this modern time to accommodate higher bandwidth, unique storage demand, and increase number of users can not be over emphasised. As this demand grows on daily bases, so also, are the threats associated with it. Some of which are, virus attacks, worm attacks, denial of services or distributed denial of service attack etc. Having this in mind then call for swift security measures to address these threats in order to protect data reliability, integrity, availability and other needed network resources across the network. Generally, network security can simply be described as a way of protecting the integrity of a network by making sure authorised access or threats of any form are restricted from accessing valuable information. As network architecture begins to expand, tackling the issue of security is becomes more and more complex to handle, therefore keeping network administrators on their toes to guard against any possible attacks that occurs on daily basis. Some of the malicious attacks are viruses and worm attacks, denial of service attacks, IP spoofing, cracking password, Domain Name Server (DNS) poisoning etc. As an effort to combat these threats, many security elements have been designed to tackle these attacks on the network. Some of which includes, firewall, Virtual Private Network (VPN), Encryption and Decryption, Cryptography, Internet Protocol Security (IPSec), Data Encryption Standard (3DES), Demilitarised Zone, (DMZ), Secure Shell Layer (SSL) etc. This chapter starts by briefly discussi ng Internet Protocol (IP), Transmission Control Protocol (TCP), User datagram Protocol (UDP), Internet Control Message Protocol (ICMP), then discussed the Open system interconnection (OSI) model and the protocols that operate at each layer of the model, network security elements, followed by the background of firewall, types and features of firewalls and lastly, network security tools. 2.2 A BRIEF DESCRIPTION OF TCP, IP, UDP AND ICMP 2.2.1 DEFINITION Going by the tremendous achievement of the World Wide Web (internet), a global communication standard with the aim of building interconnection of networks over heterogeneous network is known as the TCP/IP protocol suite was designed (Dunkels 2003; Global Knowledge 2007; Parziale et al 2006). The TCP/IP protocol suite is the core rule used for applications transfer such as File transfers, E-Mail traffics, web pages transfer between hosts across the heterogeneous networks (Dunkels 2003; Parziale et al 2006). Therefore, it becomes necessary for a network administrator to have a good understanding of TCP/IP when configuring firewalls, as most of the policies are set to protect the internal network from possible attacks that uses the TCP/IP protocols for communication (Noonan and Dobrawsky 2006). Many incidents of network attacks are as a result of improper configuration and poor implementation TCP/IP protocols, services and applications. TCP/IP make use of protocols such as TCP, UDP, IP, ICMP etc to define rules of how communication over the network takes place (Noonan and Dobrawsky 2006). Before these protocols are discussed, this thesis briefly looks into the theoretical Open Systems Interconnection (OSI) model (Simoneau 2006). 2.2.2 THE OSI MODEL The OSI model is a standardised layered model defined by International Organization for Standardization (ISO) for network communication which simplifies network communication to seven separate layers, with each individual layer having it own unique functions that support immediate layer above it and at same time offering services to its immediate layer below it (Parziale et al 2006; Simoneau 2006). The seven layers are Application, Presentation, Session Transport, Network, Data, Link and Physical layer. The first three lower layers (Network, Data, Link and Physical layer) are basically hardware implementations while the last four upper layers (Application, Presentation, Session and Transport) are software implementations. Application Layer This is the end user operating interface that support file transfer, web browsing, electronic mail etc. This layer allows user interaction with the system. Presentation Layer This layer is responsible for formatting the data to be sent across the network which enables the application to understand the message been sent and in addition it is responsible for message encryption and decryption for security purposes. Session Layer This layer is responsible for dialog and session control functions between systems. Transport layer This layer provides end-to-end communication which could be reliable or unreliable between end devices across the network. The two mostly used protocols in this layer are TCP and UDP. Network Layer This layer is also known as logical layer and is responsible for logical addressing for packet delivery services. The protocol used in this layer is the IP. Data Link Layer This layer is responsible for framing of units of information, error checking and physical addressing. Physical Layer This layer defines transmission medium requirements, connectors and responsible for the transmission of bits on the physical hardware (Parziale et al 2006; Simoneau 2006). 2.2.3 INTERNET PROTOCOL (IP) IP is a connectionless protocol designed to deliver data hosts across the network. IP data delivery is unreliable therefore depend on upper layer protocol such as TCP or lower layer protocols like IEEE 802.2 and IEEE802.3 for reliable data delivery between hosts on the network.(Noonan and Dobrawsky 2006) 2.2.4 TRANSMISSION CONTROL PROTOCOL (TCP) TCP is a standard protocol which is connection-oriented transport mechanism that operates at the transport layer of OSI model. It is described by the Request for Comment (RFC) 793. TCP solves the unreliability problem of the network layer protocol (IP) by making sure packets are reliably and accurately transmitted, errors are recovered and efficiently monitors flow control between hosts across the network. (Abie 2000; Noonan and Dobrawsky 2006; Simoneau 2006). The primary objective of TCP is to create session between hosts on the network and this process is carried out by what is called TCP three-way handshake. When using TCP for data transmission between hosts, the sending host will first of all send a synchronise (SYN) segment to the receiving host which is first step in the handshake. The receiving host on receiving the SYN segment reply with an acknowledgement (ACK) and with its own SYN segment and this form the second part of the handshake. The final step of the handshake is the n completed by the sending host responding with its own ACK segment to acknowledge the acceptance of the SYN/ACK. Once this process is completed, the hosts then established a virtual circuit between themselves through which the data will be transferred (Noonan and Dobrawsky 2006). As good as the three ways handshake of the TCP is, it also has its short comings. The most common one being the SYN flood attack. This form of attack occurs when the destination host such as the Server is flooded with a SYN session request without receiving any ACK reply from the source host (malicious host) that initiated a SYN session. The result of this action causes DOS attack as destination host buffer will get to a point it can no longer take any request from legitimate hosts but have no other choice than to drop such session request (Noonan and Dobrawsky 2006). 2.2.5 USER DATAGRAM PROTOCOL (UDP) UDP unlike the TCP is a standard connectionless transport mechanism that operates at the transport layer of OSI model. It is described by the Request for Comment (RFC) 768 (Noonan and Dobrawsky 2006; Simoneau 2006). When using UDP to transfer packets between hosts, session initiation, retransmission of lost or damaged packets and acknowledgement are omitted therefore, 100 percent packet delivery is not guaranteed (Sundararajan et al 2006; Postel 1980). UDP is designed with low over head as it does not involve initiation of session between hosts before data transmission starts. This protocol is best suite for small data transmission (Noonan and Dobrawsky 2006). 2.2.6 INTERNET CONTROL MESSAGE PROTOCOL (ICMP). ICMP is primarily designed to identify and report routing error, delivery failures and delays on the network. This protocol can only be used to report errors and can not be used to make any correction on the identified errors but depend on routing protocols or reliable protocols like the TCP to handle the error detected (Noonan and Dobrawsky 2006; Dunkels 2003). ICMP makes use of the echo mechanism called Ping command. This command is used to check if the host is replying to network traffic or not (Noonan and Dobrawsky 2006; Dunkels 2003). 2.3 OTHER NETWORK SECURITY ELEMENTS. 2.3.1 VIRTUAL PRIVATE NETWORK (VPN) VPN is one of the network security elements that make use of the public network infrastructure to securely maintain confidentiality of information transfer between hosts over the public network (Bou 2007). VPN provides this security features by making use of encryption and Tunneling technique to protect such information and it can be configured to support at least three models which are Remote- access connection. Site-to-site ( branch offices to the headquarters) Local area network internetworking (Extranet connection of companies with their business partners) (Bou 2007). 2.3.2 VPN TECHNOLOGY VPN make use of many standard protocols to implement the data authentication (identification of trusted parties) and encryption (scrambling of data) when making use of the public network to transfer data. These protocols include: Point-to-Point Tunneling Protocol PPTP [RFC2637] Secure Shell Layer Protocol (SSL) [RFC 2246] Internet Protocol Security (IPSec) [RFC 2401] Layer 2 Tunneling Protocol (L2TP) [RFC2661] 2.3.2.1 POINT-TO-POINT TUNNELING PROTOCOL [PPTP] The design of PPTP provides a secure means of transferring data over the public infrastructure with authentication and encryption support between hosts on the network. This protocol operates at the data link layer of the OSI model and it basically relies on user identification (ID) and password authentication for its security. PPTP did not eliminate Point-to-Point Protocol, but rather describes better way of Tunneling PPP traffic by using Generic Routing Encapsulation (GRE) (Bou 2007; Microsoft 1999; Schneier and Mudge 1998). 2.3.2.2 LAYER 2 TUNNELING PROTOCOL [L2TP] The L2TP is a connection-oriented protocol standard defined by the RFC 2661which merged the best features of PPTP and Layer 2 forwarding (L2F) protocol to create the new standard (L2TP) (Bou 2007; Townsley et al 1999). Just like the PPTP, the L2TP operates at the layer 2 of the OSI model. Tunneling in L2TP is achieved through series of data encapsulation of the different levels layer protocols. Examples are UDP, IPSec, IP, and Data-Link layer protocol but the data encryption for the tunnel is provided by the IPSec (Bou 2007; Townsley et al 1999). 2.3.2.3 INTERNET PROTOCOL SECURITY (IPSEC) [RFC 2401] IPSec is a standard protocol defined by the RFC 2401 which is designed to protect the payload of an IP packet and the paths between hosts, security gateways (routers and firewalls), or between security gateway and host over the unprotected network (Bou 2007; Kent and Atkinson 1998). IPSec operate at network layer of the OSI model. Some of the security services it provides are, authentication, connectionless integrity, encryption, access control, data origin, rejection of replayed packets, etc (Kent and Atkinson 1998). 2.3.3.4 SECURE SOCKET LAYER (SSL) [RFC 2246] SSL is a standard protocol defined by the RFC 2246 which is designed to provide secure communication tunnel between hosts by encrypting hosts communication over the network, to ensure packets confidentiality, integrity and proper hosts authentication, in order to eliminate eavesdropping attacks on the network (Homin et al 2007; Oppliger et al 2008). SSL makes use of security elements such as digital certificate, cryptography and certificates to enforce security measures over the network. SSL is a transport layer security protocol that runs on top of the TCP/IP which manage transport and routing of packets across the network. Also SSL is deployed at the application layer OSI model to ensure hosts authentication (Homin et al 2007; Oppliger et al 2008; Dierks and Allen 1999). 2.4 FIREWALL BACKGROUND The concept of network firewall is to prevent unauthorised packets from gaining entry into a network by filtering all packets that are coming into such network. The word firewall was not originally a computer security vocabulary, but was initially used to illustrate a wall which could be brick or mortar built to restrain fire from spreading from one part of a building to the other or to reduce the spread of the fire in the building giving some time for remedial actions to be taken (Komar et al 2003). 2.4.1BRIEF HISTORY OF FIREWALL Firewall as used in computing is dated as far back as the late 1980s, but the first set of firewalls came into light sometime in 1985, which was produced by a Ciscos Internet work Operating System (IOS) division called packet filter firewall (Cisco System 2004). In 1988, Jeff Mogul from DEC (Digital Equipment Corporation) published the first paper on firewall. Between 1989 and 1990, two workers of the ATT Bell laboratories Howard Trickey and Dave Persotto initiated the second generation firewall technology with their study in circuit relays called Circuit level firewall. Also, the two scientists implemented the first working model of the third generation firewall design called Application layer firewalls. Sadly enough, there was no published documents explaining their work and no product was released to support their work. Around the same year (1990-1991), different papers on the third generation firewalls were published by researchers. But among them, Marcus Ranums work received the most attention in 1991 and took the form of bastion hosts running proxy services. Ranums work quickly evolved into the first commercial product—Digital Equipment Corporations SEAL product (Cisco System 2004). About the same year, work started on the fourth generation firewall called Dynamic packet filtering and was not operational until 1994 when Check Point Software rolled out a complete working model of the fourth generation firewall architecture. In 1996, plans began on the fifth generation firewall design called the Kernel Proxy architecture and became reality in 1997 when Cisco released the Cisco Centri Firewall which was the first Proxy firewall produced for commercial use (Cisco System 2004). Since then many vendor have designed and implemented various forms of firewall both in hardware and software and till date, research works is on going in improving firewalls architecture to meet up with ever increasing challenges of network security. 2.5 DEFINITION According to the British computer society (2008), Firewalls are defence mechanisms that can be implemented in either hardware or software, and serve to prevent unauthorized access to computers and networks. Similarly, Subrata, et al (2006) defined firewall as a combination of hardware and software used to implement a security policy governing the flow of network traffic between two or more networks. The concept of firewall in computer systems security is similar to firewall built within a building but differ in their functions. While the latter is purposely designed for only one task which is fire prevention in a building, computer system firewall is designed to prevent more than one threat (Komar et al 2003).This includes the following Denial Of Service Attacks (DoS) Virus attacks Worm attack. Hacking attacks etc 2.5.1 DENIAL OF SERVICE ATTACKS (DOS) â€Å"Countering DoS attacks on web servers has become a very challenging problem† (Srivatsa et al 2006). This is an attack that is aimed at denying legitimate packets to access network resources. The attacker achieved this by running a program that floods the network, making network resources such as main memory, network bandwidth, hard disk space, unavailable for legitimate packets. SYN attack is a good example of DOS attacks, but can be prevented by implementing good firewall polices for the secured network. A detailed firewall policy (iptables) is presented in chapter three of this thesis. 2.5.2 VIRUS AND WORM ATTACKS Viruses and worms attacks are big security problem which can become pandemic in a twinkle of an eye resulting to possible huge loss of information or system damage (Ford et al 2005; Cisco System 2004). These two forms of attacks can be programs designed to open up systems to allow information theft or programs that regenerate themselves once they gets into the system until they crashes the system and some could be programmed to generate programs that floods the network leading to DOS attacks. Therefore, security tools that can proactively detect possible attacks are required to secure the network. One of such tools is a firewall with good security policy configuration (Cisco System 2004). Generally speaking, any kind of firewall implementation will basically perform the following task. Manage and control network traffic. Authenticate access Act as an intermediary Make internal recourses available Record and report event 2.5.3 MANAGE AND CONTROL NETWORK TRAFFIC. The first process undertaken by firewalls is to secure a computer networks by checking all the traffic coming into and leaving the networks. This is achieved by stopping and analysing packet Source IP address, Source port, Destination IP address, Destination port, IP protocol Packet header information etc. in order decide on what action to take on such packets either to accept or reject the packet. This action is called packet filtering and it depends on the firewall configuration. Likewise the firewall can also make use of the connections between TCP/IP hosts to establish communication between them for identification and to state the way they will communicate with each other to decide which connection should be permitted or discarded. This is achieved by maintaining the state table used to check the state of all the packets passing through the firewall. This is called stateful inspection (Noonan and Dobrawsky 2006). 2.5.4 AUTHENTICATE ACCESS When firewalls inspects and analyses packets Source IP address, Source port, Destination IP address, Destination port, IP protocol Packet header information etc, and probably filters it based on the specified security procedure defined, it does not guarantee that the communication between the source host and destination host will be authorised in that, hackers can manage to spoof IP address and port action which defeats the inspection and analysis based on IP and port screening. To tackle this pit fall over the network, an authentication rule is implemented in firewall using a number of means such as, the use of username and password (xauth), certificate and public keys and pre-shared keys (PSKs).In using the xauth authentication method, the firewall will request for the source host that is trying to initiate a connection with the host on the protected network for its username and password before it will allow connection between the protected network and the source host to be establi shed. Once the connection is been confirmed and authorised by the security procedure defined, the source host need not to authenticate itself to make connection again (Noonan and Dobrawsky 2006). The second method is using certificates and public keys. The advantage of this method over xauth is that verification can take place without source host intervention having to supply its username and password for authentication. Implementation of Certificates and public keys requires proper hosts (protected network and the source host) configuration with certificates and firewall and making sure that protected network and the source host use a public key infrastructure that is properly configured. This security method is best for big network design (Noonan and Dobrawsky 2006). Another good way of dealing with authentication issues with firewalls is by using pre-shared keys (PSKs). The implementation of PSKs is easy compare to the certificates and public keys although, authentication still occur without the source host intervention its make use of an additional feature which is providing the host with a predetermined key that is used for the verification procedure (Noonan and Dobrawsky 2006). 2.5.5 ACT AS AN INTERMEDIARY When firewalls are configured to serve as an intermediary between a protected host and external host, they simply function as application proxy. The firewalls in this setup are configured to impersonate the protected host such that all packets destined for the protected host from the external host are delivered to the firewall which appears to the external host as the protected host. Once the firewalls receive the packets, they inspect the packet to determine if the packet is valid (e.g. genuine HTTT packet) or not before forwarding to the protected host. This firewall design totally blocks direct communication between the hosts. 2.5.6 RECORD AND REPORT EVENTS While it is good practise to put strong security policies in place to secure network, it is equally important to record firewalls events. Using firewalls to record and report events is a technique that can help to investigate what kind of attack took place in situations where firewalls are unable to stop malicious packets that violate the access control policy of the protected network. Recording this event gives the network administrator a clear understanding of the attack and at the same time, to make use of the recorded events to troubleshoot the problem that as taken place. To record these events, network administrators makes use of different methods but syslog or proprietary logging format are mostly used for firewalls. However, some malicious events need to be reported quickly so that immediate action can be taken before serious damage is done to the protected network. Therefore firewalls also need an alarming mechanism in addition to the syslog or proprietary logging format whe n ever access control policy of the protected network is violated. Some types of alarm supported by firewalls include Console notification, Simple Network Management Protocol (SNMP), Paging notification, E-mail notification etc (Noonan and Dobrawsky 2006). Console notification is a warning massage that is presented to the firewall console. The problem with this method of alarm is that, the console needs to be monitored by the network administrator at all times so that necessary action can be taken when an alarm is generated. Simple Network Management Protocol (SNMP) notification is implemented to create traps which are transferred to the network management system (NMS) monitoring the firewall. Paging notification is setup on the firewall to deliver a page to the network administrator whenever the firewall encounters any event. The message could be an alphanumeric or numeric depending on how the firewall is setup. E-mail notification is similar to paging notification, but in this case, the firewall send an email instead to proper address. 2.6 TYPES OF FIREWALLS Going by firewall definition, firewalls are expected to perform some key functions like, Application Proxy, Network Translation Address, and Packet filtering. 2.6.1 APPLICATION PROXY This is also known as Application Gateway, and it acts as a connection agent between protected network and the external network. Basically, the application proxy is a host on the protected network that is setup as proxy server. Just as the name implies, application proxy function at the application layer of the Open System Interconnection (OSI) model and makes sure that all application requests from the secured network is communicated to the external network through the proxy server and no packets passes through from to external network to the secured network until the proxy checks and confirms inbound packets. This firewall support different types of protocols such as a Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP) and Simple Mail Transport Protocol (SMTP) (Noonan and Dobrawsky 2006; NetContinuum 2006). 2.6.2 NETWORK ADDRESS (NAT) NAT alter the IP addresses of hosts packets by hiding the genuine IP addresses of secured network hosts and dynamically replacing them with a different IP addresses (Cisco System 2008; Walberg 2007). When request packets are sent from the secured host through the gateway to an external host, the source host address is modified to a different IP address by NAT.  When the reply packets arrives at the gateway, the NAT then replaces the modified address with genuine host address before forwarding it to the host (Walberg 2007).The role played by NAT in a secured network system makes it uneasy for unauthorized access to know: The number of hosts available in the protected network The topology of the network The operating systems the host is running The type of host machine (Cisco System 2008). 2.6.3 PACKET FILTERING. â€Å"Firewalls and IPSec gateways have become major components in the current high speed Internet infrastructure to filter out undesired traffic and protect the integrity and confidentiality of critical traffic† (Hamed and Al-Shaer 2006). Packet filtering is based on the lay down security rule defined for any network or system. Filtering traffic over the network is big task that involves comprehensive understanding of the network on which it will be setup. This defined policy must always be updated in order to handle the possible network attacks (Hamed and Al-Shaer 2006). 2.6.4 INSTRUCTION DETECTION SYSTEMS. Network penetration attacks are now on the increase as valuable information is being stolen or damaged by the attacker. Many security products have been developed to combat these attacks. Two of such products are Intrusion Prevention systems (IPS) and Intrusion Detection Systems (IDS). IDS are software designed to purposely monitor and analysed all the activities (network traffic) on the network for any suspicious threats that may violate the defined network security policies (Scarfone and Mell 2007; Vignam et al 2003). There are varieties of methods IDS uses to detect threats on the network, two of them are, anomaly based IDS, and signature based IDS. 2.6.4.1 ANOMALY BASED IDS Anomaly based IDS is setup to monitor and compare network events against what is defined to be normal network activities which is represented by a profile, in order to detect any deviation from the defined normal events. Some of the events are, comparing the type of bandwidth used, the type of protocols etc and once the IDS identifies any deviation in any of this events, it notifies the network administrator who then take necessary action to stop the intended attack (Scarfone and Mell 2007). 2.6.4.2 SIGNATURE BASED IDS Signature based IDS are designed to monitor and compare packets on the network against the signature database of known malicious attacks or threats. This type of IDS is efficient at identifying already known threats but ineffective at identifying new threats which are not currently defined in the signature database, therefore giving way to network attacks (Scarfone and Mell 2007). 2.6.5 INTRUSION PREVENTION SYSTEMS (IPS). IPS are proactive security products which can be software or hardware used to identify malicious packets and also to prevent such packets from gaining entry in the networks (Ierace et al 2005, Botwicz et al 2006). IPS is another form of firewall which is basically designed to detect irregularity in regular network traffic and likewise to stop possible network attacks such as Denial of service attacks. They are capable of dropping malicious packets and disconnecting any connection suspected to be illegal before such traffic get to the protected host. Just like a typical firewall, IPS makes use of define rules in the system setup to determine the action to take on any traffic and this could be to allow or block the traffic. IPS makes use of stateful packet analysis to protect the network. Similarly, IPS is capable of performing signature matching, application protocol validation etc as a means of detecting attacks on the network (Ierace et al 2005). As good as IPS are, they also have t heir downsides as well. One of it is the problem of false positive and false negative. False positive is a situation where legitimate traffic is been identified to be malicious and thereby resulting to the IPS blocking such traffic on the network. False negative on the other hand is when malicious traffic is be identified by the IPS as legitimate traffic thereby allowing such traffic to pass through the IPS to the protected network (Ierace N et al 2005). 2.7 SOFTWARE AND HARDWARE FIREWALLS 2.7.1 SOFTWARE FIREWALLS Software-based firewalls are computers installed software for filtering packets (Permpootanalarp and Rujimethabhas 2001). These are programs setup either on personal computers or on network servers (Web servers and Email severs) operating system. Once the software is installed and proper security polices are defined, the systems (personal computers or servers) assume the role of a firewall. Software firewalls are second line of defence after hardware firewalls in situations where both are used for network security. Also software firewalls can be installed on different operating system such as, Windows Operating Systems, Mac operating system, Novel Netware, Linux Kernel, and UNIX Kernel etc. The function of these firewalls is, filtering distorted network traffic. There are several software firewall some of which include, Online Armor firewall, McAfee Personal Firewall, Zone Alarm, Norton Personal Firewall, Black Ice Defender, Sygate Personal Firewall, Panda Firewall, The DoorStop X Fi rewall etc (Lugo Parker 2005). When designing a software firewall two keys things are considered. These are, per-packet filtering and a per-process filtering. The pre-packet filter is design to search for distorted packets, port scan detection and checking if the packets are accepted into the protocol stack. In the same vein, pre-process filter is the designed to check if a process is allowed to begin a connection to the secured network or not (Lugo and Parker 2005). It should be noted that there are different implantations of all Firewalls. While some are built into the operating system others are add-ons. Examples of built-in firewalls are windows based firewall and Linux based. 2.7.2 WINDOWS OPERATING SYSTEM BASED FIREWALL. In operating system design, security features is one important aspect that is greatly considered. This is a challenge the software giant (Microsoft) as always made sure they implement is their products. In the software industry, Mi Technology for Network Security Technology for Network Security 2.0 CHAPTER TWO 2.1 INTRODUCTION The ever increasing need for information technology as a result of globalisation has brought about the need for an application of a better network security system. It is without a doubt that the rate at which computer networks are expanding in this modern time to accommodate higher bandwidth, unique storage demand, and increase number of users can not be over emphasised. As this demand grows on daily bases, so also, are the threats associated with it. Some of which are, virus attacks, worm attacks, denial of services or distributed denial of service attack etc. Having this in mind then call for swift security measures to address these threats in order to protect data reliability, integrity, availability and other needed network resources across the network. Generally, network security can simply be described as a way of protecting the integrity of a network by making sure authorised access or threats of any form are restricted from accessing valuable information. As network architecture begins to expand, tackling the issue of security is becomes more and more complex to handle, therefore keeping network administrators on their toes to guard against any possible attacks that occurs on daily basis. Some of the malicious attacks are viruses and worm attacks, denial of service attacks, IP spoofing, cracking password, Domain Name Server (DNS) poisoning etc. As an effort to combat these threats, many security elements have been designed to tackle these attacks on the network. Some of which includes, firewall, Virtual Private Network (VPN), Encryption and Decryption, Cryptography, Internet Protocol Security (IPSec), Data Encryption Standard (3DES), Demilitarised Zone, (DMZ), Secure Shell Layer (SSL) etc. This chapter starts by briefly discussi ng Internet Protocol (IP), Transmission Control Protocol (TCP), User datagram Protocol (UDP), Internet Control Message Protocol (ICMP), then discussed the Open system interconnection (OSI) model and the protocols that operate at each layer of the model, network security elements, followed by the background of firewall, types and features of firewalls and lastly, network security tools. 2.2 A BRIEF DESCRIPTION OF TCP, IP, UDP AND ICMP 2.2.1 DEFINITION Going by the tremendous achievement of the World Wide Web (internet), a global communication standard with the aim of building interconnection of networks over heterogeneous network is known as the TCP/IP protocol suite was designed (Dunkels 2003; Global Knowledge 2007; Parziale et al 2006). The TCP/IP protocol suite is the core rule used for applications transfer such as File transfers, E-Mail traffics, web pages transfer between hosts across the heterogeneous networks (Dunkels 2003; Parziale et al 2006). Therefore, it becomes necessary for a network administrator to have a good understanding of TCP/IP when configuring firewalls, as most of the policies are set to protect the internal network from possible attacks that uses the TCP/IP protocols for communication (Noonan and Dobrawsky 2006). Many incidents of network attacks are as a result of improper configuration and poor implementation TCP/IP protocols, services and applications. TCP/IP make use of protocols such as TCP, UDP, IP, ICMP etc to define rules of how communication over the network takes place (Noonan and Dobrawsky 2006). Before these protocols are discussed, this thesis briefly looks into the theoretical Open Systems Interconnection (OSI) model (Simoneau 2006). 2.2.2 THE OSI MODEL The OSI model is a standardised layered model defined by International Organization for Standardization (ISO) for network communication which simplifies network communication to seven separate layers, with each individual layer having it own unique functions that support immediate layer above it and at same time offering services to its immediate layer below it (Parziale et al 2006; Simoneau 2006). The seven layers are Application, Presentation, Session Transport, Network, Data, Link and Physical layer. The first three lower layers (Network, Data, Link and Physical layer) are basically hardware implementations while the last four upper layers (Application, Presentation, Session and Transport) are software implementations. Application Layer This is the end user operating interface that support file transfer, web browsing, electronic mail etc. This layer allows user interaction with the system. Presentation Layer This layer is responsible for formatting the data to be sent across the network which enables the application to understand the message been sent and in addition it is responsible for message encryption and decryption for security purposes. Session Layer This layer is responsible for dialog and session control functions between systems. Transport layer This layer provides end-to-end communication which could be reliable or unreliable between end devices across the network. The two mostly used protocols in this layer are TCP and UDP. Network Layer This layer is also known as logical layer and is responsible for logical addressing for packet delivery services. The protocol used in this layer is the IP. Data Link Layer This layer is responsible for framing of units of information, error checking and physical addressing. Physical Layer This layer defines transmission medium requirements, connectors and responsible for the transmission of bits on the physical hardware (Parziale et al 2006; Simoneau 2006). 2.2.3 INTERNET PROTOCOL (IP) IP is a connectionless protocol designed to deliver data hosts across the network. IP data delivery is unreliable therefore depend on upper layer protocol such as TCP or lower layer protocols like IEEE 802.2 and IEEE802.3 for reliable data delivery between hosts on the network.(Noonan and Dobrawsky 2006) 2.2.4 TRANSMISSION CONTROL PROTOCOL (TCP) TCP is a standard protocol which is connection-oriented transport mechanism that operates at the transport layer of OSI model. It is described by the Request for Comment (RFC) 793. TCP solves the unreliability problem of the network layer protocol (IP) by making sure packets are reliably and accurately transmitted, errors are recovered and efficiently monitors flow control between hosts across the network. (Abie 2000; Noonan and Dobrawsky 2006; Simoneau 2006). The primary objective of TCP is to create session between hosts on the network and this process is carried out by what is called TCP three-way handshake. When using TCP for data transmission between hosts, the sending host will first of all send a synchronise (SYN) segment to the receiving host which is first step in the handshake. The receiving host on receiving the SYN segment reply with an acknowledgement (ACK) and with its own SYN segment and this form the second part of the handshake. The final step of the handshake is the n completed by the sending host responding with its own ACK segment to acknowledge the acceptance of the SYN/ACK. Once this process is completed, the hosts then established a virtual circuit between themselves through which the data will be transferred (Noonan and Dobrawsky 2006). As good as the three ways handshake of the TCP is, it also has its short comings. The most common one being the SYN flood attack. This form of attack occurs when the destination host such as the Server is flooded with a SYN session request without receiving any ACK reply from the source host (malicious host) that initiated a SYN session. The result of this action causes DOS attack as destination host buffer will get to a point it can no longer take any request from legitimate hosts but have no other choice than to drop such session request (Noonan and Dobrawsky 2006). 2.2.5 USER DATAGRAM PROTOCOL (UDP) UDP unlike the TCP is a standard connectionless transport mechanism that operates at the transport layer of OSI model. It is described by the Request for Comment (RFC) 768 (Noonan and Dobrawsky 2006; Simoneau 2006). When using UDP to transfer packets between hosts, session initiation, retransmission of lost or damaged packets and acknowledgement are omitted therefore, 100 percent packet delivery is not guaranteed (Sundararajan et al 2006; Postel 1980). UDP is designed with low over head as it does not involve initiation of session between hosts before data transmission starts. This protocol is best suite for small data transmission (Noonan and Dobrawsky 2006). 2.2.6 INTERNET CONTROL MESSAGE PROTOCOL (ICMP). ICMP is primarily designed to identify and report routing error, delivery failures and delays on the network. This protocol can only be used to report errors and can not be used to make any correction on the identified errors but depend on routing protocols or reliable protocols like the TCP to handle the error detected (Noonan and Dobrawsky 2006; Dunkels 2003). ICMP makes use of the echo mechanism called Ping command. This command is used to check if the host is replying to network traffic or not (Noonan and Dobrawsky 2006; Dunkels 2003). 2.3 OTHER NETWORK SECURITY ELEMENTS. 2.3.1 VIRTUAL PRIVATE NETWORK (VPN) VPN is one of the network security elements that make use of the public network infrastructure to securely maintain confidentiality of information transfer between hosts over the public network (Bou 2007). VPN provides this security features by making use of encryption and Tunneling technique to protect such information and it can be configured to support at least three models which are Remote- access connection. Site-to-site ( branch offices to the headquarters) Local area network internetworking (Extranet connection of companies with their business partners) (Bou 2007). 2.3.2 VPN TECHNOLOGY VPN make use of many standard protocols to implement the data authentication (identification of trusted parties) and encryption (scrambling of data) when making use of the public network to transfer data. These protocols include: Point-to-Point Tunneling Protocol PPTP [RFC2637] Secure Shell Layer Protocol (SSL) [RFC 2246] Internet Protocol Security (IPSec) [RFC 2401] Layer 2 Tunneling Protocol (L2TP) [RFC2661] 2.3.2.1 POINT-TO-POINT TUNNELING PROTOCOL [PPTP] The design of PPTP provides a secure means of transferring data over the public infrastructure with authentication and encryption support between hosts on the network. This protocol operates at the data link layer of the OSI model and it basically relies on user identification (ID) and password authentication for its security. PPTP did not eliminate Point-to-Point Protocol, but rather describes better way of Tunneling PPP traffic by using Generic Routing Encapsulation (GRE) (Bou 2007; Microsoft 1999; Schneier and Mudge 1998). 2.3.2.2 LAYER 2 TUNNELING PROTOCOL [L2TP] The L2TP is a connection-oriented protocol standard defined by the RFC 2661which merged the best features of PPTP and Layer 2 forwarding (L2F) protocol to create the new standard (L2TP) (Bou 2007; Townsley et al 1999). Just like the PPTP, the L2TP operates at the layer 2 of the OSI model. Tunneling in L2TP is achieved through series of data encapsulation of the different levels layer protocols. Examples are UDP, IPSec, IP, and Data-Link layer protocol but the data encryption for the tunnel is provided by the IPSec (Bou 2007; Townsley et al 1999). 2.3.2.3 INTERNET PROTOCOL SECURITY (IPSEC) [RFC 2401] IPSec is a standard protocol defined by the RFC 2401 which is designed to protect the payload of an IP packet and the paths between hosts, security gateways (routers and firewalls), or between security gateway and host over the unprotected network (Bou 2007; Kent and Atkinson 1998). IPSec operate at network layer of the OSI model. Some of the security services it provides are, authentication, connectionless integrity, encryption, access control, data origin, rejection of replayed packets, etc (Kent and Atkinson 1998). 2.3.3.4 SECURE SOCKET LAYER (SSL) [RFC 2246] SSL is a standard protocol defined by the RFC 2246 which is designed to provide secure communication tunnel between hosts by encrypting hosts communication over the network, to ensure packets confidentiality, integrity and proper hosts authentication, in order to eliminate eavesdropping attacks on the network (Homin et al 2007; Oppliger et al 2008). SSL makes use of security elements such as digital certificate, cryptography and certificates to enforce security measures over the network. SSL is a transport layer security protocol that runs on top of the TCP/IP which manage transport and routing of packets across the network. Also SSL is deployed at the application layer OSI model to ensure hosts authentication (Homin et al 2007; Oppliger et al 2008; Dierks and Allen 1999). 2.4 FIREWALL BACKGROUND The concept of network firewall is to prevent unauthorised packets from gaining entry into a network by filtering all packets that are coming into such network. The word firewall was not originally a computer security vocabulary, but was initially used to illustrate a wall which could be brick or mortar built to restrain fire from spreading from one part of a building to the other or to reduce the spread of the fire in the building giving some time for remedial actions to be taken (Komar et al 2003). 2.4.1BRIEF HISTORY OF FIREWALL Firewall as used in computing is dated as far back as the late 1980s, but the first set of firewalls came into light sometime in 1985, which was produced by a Ciscos Internet work Operating System (IOS) division called packet filter firewall (Cisco System 2004). In 1988, Jeff Mogul from DEC (Digital Equipment Corporation) published the first paper on firewall. Between 1989 and 1990, two workers of the ATT Bell laboratories Howard Trickey and Dave Persotto initiated the second generation firewall technology with their study in circuit relays called Circuit level firewall. Also, the two scientists implemented the first working model of the third generation firewall design called Application layer firewalls. Sadly enough, there was no published documents explaining their work and no product was released to support their work. Around the same year (1990-1991), different papers on the third generation firewalls were published by researchers. But among them, Marcus Ranums work received the most attention in 1991 and took the form of bastion hosts running proxy services. Ranums work quickly evolved into the first commercial product—Digital Equipment Corporations SEAL product (Cisco System 2004). About the same year, work started on the fourth generation firewall called Dynamic packet filtering and was not operational until 1994 when Check Point Software rolled out a complete working model of the fourth generation firewall architecture. In 1996, plans began on the fifth generation firewall design called the Kernel Proxy architecture and became reality in 1997 when Cisco released the Cisco Centri Firewall which was the first Proxy firewall produced for commercial use (Cisco System 2004). Since then many vendor have designed and implemented various forms of firewall both in hardware and software and till date, research works is on going in improving firewalls architecture to meet up with ever increasing challenges of network security. 2.5 DEFINITION According to the British computer society (2008), Firewalls are defence mechanisms that can be implemented in either hardware or software, and serve to prevent unauthorized access to computers and networks. Similarly, Subrata, et al (2006) defined firewall as a combination of hardware and software used to implement a security policy governing the flow of network traffic between two or more networks. The concept of firewall in computer systems security is similar to firewall built within a building but differ in their functions. While the latter is purposely designed for only one task which is fire prevention in a building, computer system firewall is designed to prevent more than one threat (Komar et al 2003).This includes the following Denial Of Service Attacks (DoS) Virus attacks Worm attack. Hacking attacks etc 2.5.1 DENIAL OF SERVICE ATTACKS (DOS) â€Å"Countering DoS attacks on web servers has become a very challenging problem† (Srivatsa et al 2006). This is an attack that is aimed at denying legitimate packets to access network resources. The attacker achieved this by running a program that floods the network, making network resources such as main memory, network bandwidth, hard disk space, unavailable for legitimate packets. SYN attack is a good example of DOS attacks, but can be prevented by implementing good firewall polices for the secured network. A detailed firewall policy (iptables) is presented in chapter three of this thesis. 2.5.2 VIRUS AND WORM ATTACKS Viruses and worms attacks are big security problem which can become pandemic in a twinkle of an eye resulting to possible huge loss of information or system damage (Ford et al 2005; Cisco System 2004). These two forms of attacks can be programs designed to open up systems to allow information theft or programs that regenerate themselves once they gets into the system until they crashes the system and some could be programmed to generate programs that floods the network leading to DOS attacks. Therefore, security tools that can proactively detect possible attacks are required to secure the network. One of such tools is a firewall with good security policy configuration (Cisco System 2004). Generally speaking, any kind of firewall implementation will basically perform the following task. Manage and control network traffic. Authenticate access Act as an intermediary Make internal recourses available Record and report event 2.5.3 MANAGE AND CONTROL NETWORK TRAFFIC. The first process undertaken by firewalls is to secure a computer networks by checking all the traffic coming into and leaving the networks. This is achieved by stopping and analysing packet Source IP address, Source port, Destination IP address, Destination port, IP protocol Packet header information etc. in order decide on what action to take on such packets either to accept or reject the packet. This action is called packet filtering and it depends on the firewall configuration. Likewise the firewall can also make use of the connections between TCP/IP hosts to establish communication between them for identification and to state the way they will communicate with each other to decide which connection should be permitted or discarded. This is achieved by maintaining the state table used to check the state of all the packets passing through the firewall. This is called stateful inspection (Noonan and Dobrawsky 2006). 2.5.4 AUTHENTICATE ACCESS When firewalls inspects and analyses packets Source IP address, Source port, Destination IP address, Destination port, IP protocol Packet header information etc, and probably filters it based on the specified security procedure defined, it does not guarantee that the communication between the source host and destination host will be authorised in that, hackers can manage to spoof IP address and port action which defeats the inspection and analysis based on IP and port screening. To tackle this pit fall over the network, an authentication rule is implemented in firewall using a number of means such as, the use of username and password (xauth), certificate and public keys and pre-shared keys (PSKs).In using the xauth authentication method, the firewall will request for the source host that is trying to initiate a connection with the host on the protected network for its username and password before it will allow connection between the protected network and the source host to be establi shed. Once the connection is been confirmed and authorised by the security procedure defined, the source host need not to authenticate itself to make connection again (Noonan and Dobrawsky 2006). The second method is using certificates and public keys. The advantage of this method over xauth is that verification can take place without source host intervention having to supply its username and password for authentication. Implementation of Certificates and public keys requires proper hosts (protected network and the source host) configuration with certificates and firewall and making sure that protected network and the source host use a public key infrastructure that is properly configured. This security method is best for big network design (Noonan and Dobrawsky 2006). Another good way of dealing with authentication issues with firewalls is by using pre-shared keys (PSKs). The implementation of PSKs is easy compare to the certificates and public keys although, authentication still occur without the source host intervention its make use of an additional feature which is providing the host with a predetermined key that is used for the verification procedure (Noonan and Dobrawsky 2006). 2.5.5 ACT AS AN INTERMEDIARY When firewalls are configured to serve as an intermediary between a protected host and external host, they simply function as application proxy. The firewalls in this setup are configured to impersonate the protected host such that all packets destined for the protected host from the external host are delivered to the firewall which appears to the external host as the protected host. Once the firewalls receive the packets, they inspect the packet to determine if the packet is valid (e.g. genuine HTTT packet) or not before forwarding to the protected host. This firewall design totally blocks direct communication between the hosts. 2.5.6 RECORD AND REPORT EVENTS While it is good practise to put strong security policies in place to secure network, it is equally important to record firewalls events. Using firewalls to record and report events is a technique that can help to investigate what kind of attack took place in situations where firewalls are unable to stop malicious packets that violate the access control policy of the protected network. Recording this event gives the network administrator a clear understanding of the attack and at the same time, to make use of the recorded events to troubleshoot the problem that as taken place. To record these events, network administrators makes use of different methods but syslog or proprietary logging format are mostly used for firewalls. However, some malicious events need to be reported quickly so that immediate action can be taken before serious damage is done to the protected network. Therefore firewalls also need an alarming mechanism in addition to the syslog or proprietary logging format whe n ever access control policy of the protected network is violated. Some types of alarm supported by firewalls include Console notification, Simple Network Management Protocol (SNMP), Paging notification, E-mail notification etc (Noonan and Dobrawsky 2006). Console notification is a warning massage that is presented to the firewall console. The problem with this method of alarm is that, the console needs to be monitored by the network administrator at all times so that necessary action can be taken when an alarm is generated. Simple Network Management Protocol (SNMP) notification is implemented to create traps which are transferred to the network management system (NMS) monitoring the firewall. Paging notification is setup on the firewall to deliver a page to the network administrator whenever the firewall encounters any event. The message could be an alphanumeric or numeric depending on how the firewall is setup. E-mail notification is similar to paging notification, but in this case, the firewall send an email instead to proper address. 2.6 TYPES OF FIREWALLS Going by firewall definition, firewalls are expected to perform some key functions like, Application Proxy, Network Translation Address, and Packet filtering. 2.6.1 APPLICATION PROXY This is also known as Application Gateway, and it acts as a connection agent between protected network and the external network. Basically, the application proxy is a host on the protected network that is setup as proxy server. Just as the name implies, application proxy function at the application layer of the Open System Interconnection (OSI) model and makes sure that all application requests from the secured network is communicated to the external network through the proxy server and no packets passes through from to external network to the secured network until the proxy checks and confirms inbound packets. This firewall support different types of protocols such as a Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP) and Simple Mail Transport Protocol (SMTP) (Noonan and Dobrawsky 2006; NetContinuum 2006). 2.6.2 NETWORK ADDRESS (NAT) NAT alter the IP addresses of hosts packets by hiding the genuine IP addresses of secured network hosts and dynamically replacing them with a different IP addresses (Cisco System 2008; Walberg 2007). When request packets are sent from the secured host through the gateway to an external host, the source host address is modified to a different IP address by NAT.  When the reply packets arrives at the gateway, the NAT then replaces the modified address with genuine host address before forwarding it to the host (Walberg 2007).The role played by NAT in a secured network system makes it uneasy for unauthorized access to know: The number of hosts available in the protected network The topology of the network The operating systems the host is running The type of host machine (Cisco System 2008). 2.6.3 PACKET FILTERING. â€Å"Firewalls and IPSec gateways have become major components in the current high speed Internet infrastructure to filter out undesired traffic and protect the integrity and confidentiality of critical traffic† (Hamed and Al-Shaer 2006). Packet filtering is based on the lay down security rule defined for any network or system. Filtering traffic over the network is big task that involves comprehensive understanding of the network on which it will be setup. This defined policy must always be updated in order to handle the possible network attacks (Hamed and Al-Shaer 2006). 2.6.4 INSTRUCTION DETECTION SYSTEMS. Network penetration attacks are now on the increase as valuable information is being stolen or damaged by the attacker. Many security products have been developed to combat these attacks. Two of such products are Intrusion Prevention systems (IPS) and Intrusion Detection Systems (IDS). IDS are software designed to purposely monitor and analysed all the activities (network traffic) on the network for any suspicious threats that may violate the defined network security policies (Scarfone and Mell 2007; Vignam et al 2003). There are varieties of methods IDS uses to detect threats on the network, two of them are, anomaly based IDS, and signature based IDS. 2.6.4.1 ANOMALY BASED IDS Anomaly based IDS is setup to monitor and compare network events against what is defined to be normal network activities which is represented by a profile, in order to detect any deviation from the defined normal events. Some of the events are, comparing the type of bandwidth used, the type of protocols etc and once the IDS identifies any deviation in any of this events, it notifies the network administrator who then take necessary action to stop the intended attack (Scarfone and Mell 2007). 2.6.4.2 SIGNATURE BASED IDS Signature based IDS are designed to monitor and compare packets on the network against the signature database of known malicious attacks or threats. This type of IDS is efficient at identifying already known threats but ineffective at identifying new threats which are not currently defined in the signature database, therefore giving way to network attacks (Scarfone and Mell 2007). 2.6.5 INTRUSION PREVENTION SYSTEMS (IPS). IPS are proactive security products which can be software or hardware used to identify malicious packets and also to prevent such packets from gaining entry in the networks (Ierace et al 2005, Botwicz et al 2006). IPS is another form of firewall which is basically designed to detect irregularity in regular network traffic and likewise to stop possible network attacks such as Denial of service attacks. They are capable of dropping malicious packets and disconnecting any connection suspected to be illegal before such traffic get to the protected host. Just like a typical firewall, IPS makes use of define rules in the system setup to determine the action to take on any traffic and this could be to allow or block the traffic. IPS makes use of stateful packet analysis to protect the network. Similarly, IPS is capable of performing signature matching, application protocol validation etc as a means of detecting attacks on the network (Ierace et al 2005). As good as IPS are, they also have t heir downsides as well. One of it is the problem of false positive and false negative. False positive is a situation where legitimate traffic is been identified to be malicious and thereby resulting to the IPS blocking such traffic on the network. False negative on the other hand is when malicious traffic is be identified by the IPS as legitimate traffic thereby allowing such traffic to pass through the IPS to the protected network (Ierace N et al 2005). 2.7 SOFTWARE AND HARDWARE FIREWALLS 2.7.1 SOFTWARE FIREWALLS Software-based firewalls are computers installed software for filtering packets (Permpootanalarp and Rujimethabhas 2001). These are programs setup either on personal computers or on network servers (Web servers and Email severs) operating system. Once the software is installed and proper security polices are defined, the systems (personal computers or servers) assume the role of a firewall. Software firewalls are second line of defence after hardware firewalls in situations where both are used for network security. Also software firewalls can be installed on different operating system such as, Windows Operating Systems, Mac operating system, Novel Netware, Linux Kernel, and UNIX Kernel etc. The function of these firewalls is, filtering distorted network traffic. There are several software firewall some of which include, Online Armor firewall, McAfee Personal Firewall, Zone Alarm, Norton Personal Firewall, Black Ice Defender, Sygate Personal Firewall, Panda Firewall, The DoorStop X Fi rewall etc (Lugo Parker 2005). When designing a software firewall two keys things are considered. These are, per-packet filtering and a per-process filtering. The pre-packet filter is design to search for distorted packets, port scan detection and checking if the packets are accepted into the protocol stack. In the same vein, pre-process filter is the designed to check if a process is allowed to begin a connection to the secured network or not (Lugo and Parker 2005). It should be noted that there are different implantations of all Firewalls. While some are built into the operating system others are add-ons. Examples of built-in firewalls are windows based firewall and Linux based. 2.7.2 WINDOWS OPERATING SYSTEM BASED FIREWALL. In operating system design, security features is one important aspect that is greatly considered. This is a challenge the software giant (Microsoft) as always made sure they implement is their products. In the software industry, Mi

Liberal Arts Essay

An education conducted in a spirit of free inquiry undertaken without concern for topical relevance or vocational utility. This kind of learning is not only one of the enrichments of existence; it is one of the achievements of civilization. It heightens students’ awareness of the human and natural worlds they inhabit. It makes them more reflective about their beliefs and choices, more self-conscious and criticising, speaking, critical and logical thinking. Law schools report that by the yardsticks of law review and grades, their top students come from math, classics, and literature, with political science, economics, â€Å"pre-law â€Å"and† legal studies† ranking lower. In today’s fast evolving world, leaders across the spectrum of vocations and professions need a broad imaginative and critical capacity, not a prematurely narrow point of view. In terms of the actual world, a solid liberal arts and sciences education will generally prove the most practical preparation for many demanding, high-level careers, or for the several careers that an increasing number of adults will eventually pursue. No particular concentration or area of study is inherently a better ticket to security, leadership, or personal satisfaction than another. Students should be encouraged to follow their passions and interests, not what they guess (or what others tell them) will lead to a supposedly more marketable set of skills. Of course, higher education has a utilitarian function. In that regard, as Robert Bellah states, it possesses â€Å"its own legitimacy.† Yet, it is crucial to combine and integrate that function with other aims and ends, with what Bellah calls â€Å"education for the development of character, citizenship, and culture.† A healthy system of higher education offers many rewards: scientific discoveries, eventual and even unforeseen applications, thoughtful political leadership, intelligent public discourse, cultural vitality, and an educated workforce. Higher learning serves several goals in coordination, goals that are mutually reinforcing. The aims are at once personal and social, private and public, economic, ethical, and intellectual. Harvard College exists to serve all these goals and offers a broad array of concentrations and courses for the purpose of educating the whole individual. Why? Because that kind of education, and not one aimed at certain occupational targets, is, in the long run, the best preparation for advanced achievement. The very broad, capacious form of education that we call the liberal arts is rooted in a specific curriculum in classical and medieval times. But it would be wrong to assume that because it has such ancient roots, this kind of education is outdated, stale, fusty, or irrelevant. In fact, quite the contrary. A liberal-arts education, which Louis Menand defined in The Marketplace of Ideas as â€Å"a background mentality, a way of thinking, a kind of intellectual DNA that informs work in every specialized area of inquiry,† lends itself particularly well to contemporary high-tech methods of imparting knowledge. We all wrestle with the challenges of educating students who are used to multitasking, doing their homework while listening to music and texting on their iPhones. For such students, the Web-based facilities of exciting liberal-arts courses are particularly salient. What would Aristotle or Erasmus or Robert Maynard Hutchins not have given for a technique that allows one to tour the world’s greatest museums, looking closely at the details of countless masterpieces; explore the ruins of ancient castles and pyramids and forums; join archaeological digs at your desk, turning objects around to see all sides of them; visualize problems in geometry or astronomy or mathematics in several dimensions and work out their solutions. An excellent example of the power of multimedia coupled with the liberal arts is â€Å"Imaginary Journeys,† a general-education course sometimes taught at Harvard University by Stephen Greenblatt. The course is described as being â€Å"about global mobility, encounter, and exchange at the time that Harvard College was founded in 1636. Using the interactive resources of computer technology, we follow imaginary voyages of three ships that leave England in 1633. Sites include London’s Globe Theatre, Benin, Barbados, Brazil, Mexico.† With this kind of course in mind, it seems that the liberal arts could almost have been designed for sophisticated online learning, so far from being stale or fusty are these ways of knowing. This kind of education has become more and more appealing to students and teachers at universities around the world. Donald Markwell, the warden of Oxford’s Rhodes House, recently gave a series of lectures in Canada entitled â€Å"The Need for Breadth.† He referred to a â€Å"surge of interest† in liberal education in â€Å"many other countries.† He cites a major address in London by Yale’s Richard Levin in which Levin noted that â€Å"Asian leaders are increasingly attracted to the American model of undergraduate curriculum,† specifically because of the two years of breadth and depth in different disciplines provided before a student chooses an area of concentration or embarks on professional training. Levin described liberal-arts honors programs at Peking University, South Korea’s Yonsei University, and the National University of Singapore; he also referred to liberal-arts curricula at Fudan University, Nanjing University, and the University of Hong Kong. Yet, as we know, the trends in the United States are in the opposite direction, and this is not just a recent problem. Menand cites evidence that in the United States, â€Å"the proportion of undergraduate degrees awarded annually in the liberal arts and sciences has been declining for a hundred years, apart from a brief rise between 1955 and 1970, which was a period of rapidly increasing enrollments and national economic growth.† Thus, paradoxically, as a liberal-arts education becomes more appealing to leaders and families in Asia and elsewhere in the world, it is losing ground in our own country. At least three factors are at work in this decline: a) the creation of increasingly specialized disciplines, and the rewards for faculty members for advancing knowledge in those areas; b) the economic premium that is thought to reside in a highly technical form of preparation for careers; and c) a growing focus on graduate education from the early 20th century to the present day. T hese developments have clearly not been beneficial for American undergraduate education. â€Å"Liberal education in crisis† is a tiresomely familiar theme, and countless commissions, reports, and study groups have attempted to address it. I am under no illusions that I have the magic key to resolve a problem that has stumped so many brilliant educators. But these are not just theoretical quandaries, they are the issues we confront almost every day: How do we defend liberal education against the skeptics—parents, potential students, the media, the marketplace, even some trustees and students? The first, most practical defense is that the liberal arts (and sciences) are the best possible preparation for success in the learned professions—law, medicine, teaching—as well as in the less traditionally learned but increasingly arcane professions of business, finance, and high-tech innovation. So my first defense of liberal learning is what you are taught and the way you learn it: the materials a doctor or financial analyst or physicist or humanist ne eds to know, but taught in a liberally construed fashion, so that you look at the subject from many different dimensions and incorporate the material into your own thinking in ways that will be much more likely to stay with you, and help you later on. This way of learning has several distinct advantages: It’s insurance against obsolescence; in any rapidly changing field (and every field is changing rapidly these days), if you only focus on learning specific materials that are pertinent in 2012, rather than learning about them in a broader context, you will soon find that your training will have become valueless. Most important, with a liberal education you will have learned how to learn, so that you will be able to do research to answer questions in your field that will come up years from now, questions that nobody could even have envisioned in 2012, much less taught you how to answer. The second, slightly less utilitarian defence of a liberal-arts education is that it hones the mind, teaching focus, critical thinking, and the ability to express oneself clearly both in writing and speaking—skills that are of great value no matter what profession you may choose. It’s not just that you are taught specific materi als in a liberally designed context, but more generally, the way your mind is shaped, the habits of thought that you develop. These skills were well described by a former dean of the Harvard Law School, Erwin Griswold, cited in a recent speech by the current dean, Martha Minow. Griswold was discussing an ideal vision of the law school, but his arguments fit a liberal education wherever it is provided: â€Å"You go to a great school not so much for knowledge as for arts or habits; for the art of expression, for the art of entering quickly into another person’s thoughts, for the art of assuming at a moment’s notice a new intellectual position, for the habit of submitting to censure and refutation, for the art of indicating assent or dissent in graduated terms, for the habit of regarding minute points of accuracy, for the art of working out what is possible in a given time; for taste, for discrimination, for mental courage, and mental soberness.† My third argument is that a liberal-arts education is the best education for citizenship in a democracy like ours. In her book, Not for Profit, M artha Nussbaum points out that from the early years of our republic educators and leaders have â€Å"connected the liberal arts to the preparation of informed, independent, and sympathetic †¦ citizens.† Nussbaum argues that democracies need â€Å"complete citizens who can think for themselves, criticize tradition, and understand the significance of another person’s sufferings and achievements.† Among the skills a liberal-arts education fosters, she notes, are the ability â€Å"to think about the good of the nation as a whole, not just that of one’s local group,† and â€Å"to see one’s own nation, in turn, as part of a complicated world order.† At a time when democracy is struggling to be born in countries around the world, and countries that have long enjoyed democracy are struggling to sustain it against pressures of multiple varieties, this may be the best of all the arguments for a liberal-arts education. My fourth argument I borrow from Michel de Montaigne, who thought of his own mind as a kind of tower library to which he could retreat even when he was far from home, filled with quotations from wise people and experimental thoughts and jokes and anecdotes, where he could keep company with himself. In his essay â€Å"Of Solitude,† he suggested that we all have such back rooms in our minds. The most valuable and attractive people we know are those who have rich and fascinating intellectual furniture in those spaces rather than a void between their ears. Virginia Woolf used a different spatial image to make a similar point in her book Three Guineas, when she talked about the importance of cultivating taste and the knowledge of the arts and literature and music. She argues that people who are so caught up in their professions or business that they never have time to listen to music or look at pictures lose the sense of sight, the sense of sound, the sense of proportion. And she concludes: â€Å"What then remains of a human being who has lost sight, and sound, and a sense of proportion? Only a cripple in a cave.† So my fourth argument for a liberal-arts education is that it allows you to furnish the back room of your mind, preparing you for both society and solitude. My final argument is that the liberal arts admit you to a community of scholars, both professional a nd amateur, spanning the ages. Here I would quote one of my predecessors at Wellesley, Alice Freeman (later Alice Freeman Palmer). When she presided over Wellesley in the last part of the 19th century, it was quite unusual for girls to go to college (as indeed it still is today in some parts of the world). In a speech she gave to answer the repeated question she got from girls and their families, â€Å"Why Go to College?† she said: â€Å"We go to college to know, assured that knowledge is sweet and powerful, that a good education emancipates the mind and makes us citizens of the world.† The sweet and powerful knowledge imparted by a liberal-arts education is specifically designed to fulfill this promise. But how can college presidents today best go about making the case for the liberal arts? First and most obvious, they should use the bully pulpit of the college presidency deliberately and effectively—at convocations, commencements, groundbreakings for new buildings, in speeches to the local Rotary Club or the state 4-H club convention, and addresses to alumni clubs. This is a truly precious opportunity that few other leaders have, to address the community in situations where there is likely to be respectful attention to their message, at least for a while! They should use the opportunity with zest! The second way is by using their fund-raising skills and obligations to raise money for exciting programs like Greenblatt’s â€Å"Imaginary Journeys.† They can make this case effectively to foundations and generous alumni who remember their own liberal-arts education fondly, and thus enhance the resources available for this purpose. Presidents can demonstrate their support of the liberal arts in how they honor faculty members. With the teaching awards and other distinctions their colleges offer, they should single out for praise and support those who have been most effective in advancing the liberal-arts mission. And then they can ensure that these awards and recognitions are appropriately highlighted in college publications and in messages to parents and prospective students. And perhaps the most effective way presidents can use their leadership to offer support is to speak from a liberal-arts perspective in their own discourse, both formal and informal, by citing examples of fine literature, drawing on instances from history, referring to the arts, and describing learning in the sciences in liberal terms. Rhetoric was one of the original artes liberales, and it can still be one of the most transformative. Taking my own advice about larding language with liberal learning, I will conclude with a poem by Imam Al-Shafi’i, which I discovered in a brochure on a recent visit to the Georgetown University School of Foreign Service, in Doha, Qatar: According to the measure of hardship are heights achieved, And he who seeks loftiness must keep vigil by night; As for he who wants heights without toil, He wastes his life seeking the impossible— So seek nobility now, then sleep once more (finally), He who seeks pearls must dive into the sea. As this poem reminds us, a liberal-arts education is not always easy; it involves paying close attention, taking risks, exploring uncharted territory, diving into the sea. But despite these challenges, the deep rewards of a liberal education are surely worth our best efforts on its behalf.

Heres What I Know About Cae Essay Writing Samples

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