Dynamic Host Configuration Protocol - Research Paper Example

? DYNAMIC HOST CONFIGURATION PROTOCOL (Internet and Network Engineering) of (affiliation) Introduction Therehas been so much scientific and technological advances in the last few decades as compared to the progress achieved by humans in the last few centuries and millennia. This great leap in knowledge started more or less during the Industrial Revolution and has been accelerated ever since, resulting in an explosion of data, information, knowledge and wisdom. One of the most transformative technological invention or innovation has been the development of Internet, originally a secret project of the United States government under its Advanced Research Projects Agency (ARPANET) for military purposes to secure its communications network in case of any nuclear attack during the Cold War period. Communications security was provided by a principle of redundancy, in which a wide-area network (WAN) gives several lines of communication so if one line is cut, another line still exists by which to transmit messages in wartime conditions. This technology has since been given away for free by the United States military for civilian use. The development and continued evolution of Internet technology has been fairly rapid, in part due to the main principles which still stand today: it should be freely accessible by anyone and it should be free from any forms of control or censorship. This free environment contributed to rapid advances because of so many good ideas pooled together to further enhance an Internet infrastructure that is now ubiquitous in most people's lives. From its early beginnings of sending only electronic messages (e-mails), it has now evolved into its advanced form by which people can interact with each other through voice and video, order or buy some product or service using secure on-line technologies, go shopping, do banking transactions, get in touch through its social networking sites, and transformed the business landscape by requiring a digital presence in order to maintain a strategic competitive advantage or edge against similar businesses. Discussion The free flow of ideas contributed to the advances in Internet technology because it is so conducive to innovation. The basic Internet infrastructure consists of eleven major nodes whose exact locations are kept secret from possible saboteurs. The Internet or cyberspace, as it is often called alternatively, is virtually limitless such that there are now over a billion Web pages being published and still counting. It is a miracle the Internet (or WWW, short for World Wide Web) has not crashed although some experts expect a major or large scale collapse from a system-wide malfunction between now and the year 2025 (Boehm, 2006, p. 20) and if ever this happens, then almost everything will grind to a sudden halt, causing widespread chaos and confusion. Various industry sectors such as communications, transportation, financial transactions, banking services, power generation and distribution, health care services and all major industrial production will be adversely affected if there is a major software malfunction on the Internet. It is just one side of the same coin, as the Internet infrastructure is also largely dependent on all its major hardware components, such as hosts, servers and routers. There are many vendors who are offering their products and services in this regard, such that it is necessary to adopt some form of standard to make all the various hardware and software components interconnect with each other seamlessly and virtually assure users and consumers a zero-downtime Internet service. The necessity for a standard system has been met with the adoption of protocols (digital message formats and rules agreed to by everyone) by which all Internet stakeholders operate on a common platform to assure constant and reliable communications. This is the topic of this brief paper, the dynamic host configuration protocol, or known by its initials, DHCP. As the evolution of the Internet is quite fast, it is necessary to impose some protocols in order to put some sense and order, before things get out of hand. As the number of Web pages is exploding, so is the number of computer-enabled devices that connect to the Internet. This is the case today, especially with the proliferation of so many Internet-enabled devices such as popular personal consumer electronics products like cellular phones, laptops, netbooks, and even video computer consoles for gaming purposes. The Internet infrastructure must allow for expansions or extensions or upgrades while still maintaining its stability without any danger of a collapse. The Internet is one giant digital network but it also consists of many much smaller kinds of networks, giving rise to several competing networking standards like the local area networks (LAN) composed of computers and other related devices such as printers, servers, storage disks, and routers. This is just one example but there are other types of small networks such as WAN (wide area network), PAN (personal area network), HAN (home area network), SAN (storage area network), and MAN (metropolitan area network). All these related hardware devices require a specific Internet address each, so they can be identified and linked properly to a network. This is where the dynamic host configuration protocol proves most useful. The Internet Engineering Task Force (IETF) has been formed precisely to allocate Internet addresses in such a manner as to allow an almost infinite addition of whatever Internet-enabled device to a network without bogging it down. This task force issues requests for comments (RFC) from time to time, to solicit ideas, comments, suggestions and feedback on Internet experts from all over. This was exemplified by the RFC 2131 issued March 1997 which established DHCP as the protocol to be used when it comes to the assignment of network Internet addresses (Droms, 1997, p. 2). Prior to the adoption of the DHCP, the prevailing standard was the bootstrap protocol (BOOTP), but this system had limitations, a major one being it was cumbersome as computers had to use a boot floppy disk to obtain an IP (Internet-protocol) address from a server. This had been done away with by embedding the said software in interface cards, eliminating one step and allowing for a faster direct network booting. BOOTP had in turn replaced the earlier reverse address resolution protocol (RARP), and introduced one significant innovation, which is the use of a relay agent which now allows for only one central BOOTP server to serve several hosts on many subnets (Croft & Gilmore, 1985, p. 1) with the diskless device able to discover its own IP address (“address determination”) which is a significant improvement for its automation. Much of the recent explosive growth in the Internet infrastructure has been anchored on the IPv4 standard, the first truly workable Internet protocol to be widely used for addresses. But it has been quickly nearing depletion in terms of unallocated or available addresses, due to high popularity of many consumer electronics devices such as the personal computers, smart phones, laptops, netbooks, tablets, and iPads, which all require a unique IP address each. This had posed a serious problem which the DHCP as the critical component to the modern computer network infrastructure was able to solve satisfactorily. DHCP can connect all these devices seamlessly; it also does this without slowing down the network from its auto configuration capability. DHCP proved its utility with the recent migration from the IPv4 to the IPv6 standard, as the Internet address book neared exhaustion; new devices like those mentioned above would not be able to connect to a network without such unique IP address. The Internet Society has adopted this better IP standard, with new enough addresses for future growth (Goldman, 2012, p. 1). The advantage of DHCP is it can be used for both the older IPv4 and the newer IPv6. In the former, it uses the so-called link-local addressing but achieves only limited connectivity but in the IPv6 version, it can do with stateless address autoconfiguration, which is very ideal for big local networks with many devices connected to that particular network. DHCP differs for both versions but serve the same purpose, but the differences are quite significant (Droms & Lemon, 2003, p. 436) that the two versions can be considered as entirely separate protocols. In this case, DHCP is entirely compatible with the requirements of IPv6 in terms of scalability. Network configuration pertains to a complex set of activities needed to establish and to maintain a data network. It encompasses two issues, which are the enabling protocols in terms of software requirements and the correct assignment of individual IP addresses to routers, switchers and other related devices from a hardware perspective. In this regard, DHCP confers the several advantages as will be enumerated and discussed in the succeeding paragraphs. This had made the DHCP such an indispensable part of the entire Internet network infrastructure even today. In RFC 2131, Droms had mentioned three possible ways or mechanisms by which the DHCP can support the IP address allocation process (Droms, 1997, p. 2). The first is automatic allocation wherein the DHCP itself assigns a permanent IP address to a particular client while its second mechanism is the dynamic allocation where the DHCP assigns an IP address for a limited time period only (called as “lease”) which is theoretically renewable until such time that a client relinquishes that address and frees it for use by another client, while the third and last mechanism is the manual allocation, a process requiring intervention by the network administrator. However, it is only dynamic allocation that allows for automatic re-use of an address no longer needed. Autoconfiguration of network devices – this is the most critical function of the DHCP, as it simplifies the procedures in establishing a data network and saves considerable time from a usual delay when errors are inadvertently committed during the configuration process. This is the capability of the DHCP which saves administrative work because it allows for individual devices or computers to be connected to the network to automatically obtain their network configurations from the server, instead of being manually configured, which makes it prone to errors. It means a lot to network administrators, considering all the possible devices that can now be connected; it saves a lot not only of time but also in manpower resources (Barrett & King, 2005, p. 471). The convenience and simplicity offered by this autoconfiguration capability translates to other benefits, especially in a home setting, where people can now connect their other devices. It can now include not just computers or other Internet-enabled devices but consumer electronics devices that make life a whole lot easier, like refrigerators, air-conditioners, washing machines, alarm clocks, wristwatches, television sets and even motor vehicles (Goldman, 2012, p. 1). The point is all those mentioned devices can easily be networked together by anybody. CISCO predicts that with the continued popularity of consumer electronics and with all the new inventions and innovations coming out to the mass market, by year 2016 there will soon be at least three networked devices per person on earth (ibid.) Moreover, software developers are targeting other more common everyday items for possible networking through both wired and wireless modes, such as clothes, eyeglasses (to easily locate them if misplaced) or the pill bottles (with chips embedded in them to contain various information such as dosage and frequency of the medications to be taken), each item requiring a specific IP address provided by IPv6. Centralized database of network addresses – this database contains all the addresses that are available for allocation and the addresses which had been allocated already. The DHCP allows for tracking and monitoring all these addresses through a computer software, rather than by a network administrator, who can sometimes be overworked and prone to commit errors. This system makes it relatively easy to re-allocate those expiring IP addresses if no longer needed for possible re-use by other network devices and is especially useful if there are limited addresses. It is the dynamic allocation mechanism that allows for this process of tracking expiring leases. This allows the server to re-use an IP address that is no longer renewed and re-assign it. This centralized tracking system prevents an allocated IP address from being mistakenly assigned again, resulting in duplication. Further, the automatic system in dynamic allocation can keep track of all expiring leases, with a default lease time of six hours and a maximum lease of twelve hours; otherwise, if it is not renewed, it becomes available for re-allocation in order to be efficient in the use of finite network IP addresses (Shekhar, 2008, p. 643). The DHCP never assigns the same IP address to any two computers, machines or devices within the same network. It detects this automatically and prevents this simple but irritating error when configuring. With RFC 2131, the previously minimum lease time limit has been removed. This make allocated IP addresses due for renewal based on their maximum lease times (Droms, 1997, p. 3). It further saves time because constantly renewing expiring addresses has been eliminated; unless an IP address has been surrendered, then it is considered valid until indicated otherwise. DHCP is very helpful in managing all the IP addresses especially in a big network, minimizes errors and virtually eliminates duplication or assignment of invalid IP addresses (Ranjan, 2006, p. 507). Ease in joining new computers to a network – with the prices of computers continuing to drop, it is now cheaper to provide almost anyone with a computer either in the workplace or at home in a local area network. The point of market saturation in personal computers has been in a static state for a while already, but this slack in demand has been taken up with the proliferation of new consumer electronics gadgets which may also require connection to a network, eventually sometime in the near future. Connectivity is the key word in everything computerized these days. Interconnectivity in almost all devices today makes life much easier, such as turning on the lights or opening the garage door or shutting down the heater. DHCP makes everything possible. In small or stable networks, the use of DHCP may not be markedly felt in terms of ease, but this functionality and utility becomes much more appreciated when operating big networks (Walshaw, 2000, p. 448) where the number and frequency of computers being connected can be increased significantly due to changing work requirements. There are also instances where many computers, machines, or devices leave or get transferred to another network and new ones take their place within the said network; DCHP eases this task considerably with automation. DHCP becomes even more useful as more networks gradually migrate to the new IPv6. In most cases, new devices are connected to a network as time goes and DHCP allows this in a systematic and orderly manner without necessarily overwhelming the network. Besides the two benefits of automatic configuration and maintenance of a centralized database of addresses, the other advantages of using DHCP include its scalability, whether managing 10 or 1000 clients, the DHCP makes it easier and the other incentive to use it is flexibility in configuration as computers and devices change their respective IP addresses from time to time (Bender, 2010, p. 127). The technical details of DHCP operations can be categorized into four broad classes; the four operational phases are IP discovery, IP lease offer, IP request, and IP acknowledgment that are shortened to the initials DORA (discovery, offer, request, and acknowledgment). Despite the attractiveness of using DCHP for network configuration purposes, there are some serious issues which network administrators must be made aware of: namely, security and confidentiality. The vulnerabilities can be exploited by potential hackers due to lack of an authentication process. The hacking can take several forms of exploiting the network's flaws and weaknesses: Unauthorized access – some clients can present false identification or credentials; after gaining access, these clients will then exhaust the server's storage of addresses, preventing other legitimate clients from availing of the limited number of valid IP addresses (termed as scopes). It is some form of a denial-of-service (DOS) type of attack, consuming available addresses. Unauthorized servers – in this type of attack, fake servers mimic the real servers which can fool the clients into providing information and then re-direct or hijack the network traffic. It enables the hacker to gain unauthorized access to sensitive information in the classic man-in-the-middle (MITM) attack and eavesdrop on connections between the client and servers contacted. Unauthorized use of network resources – this allows the attacker to consume network resources besides valid IP addresses, such as constantly asking for new addresses that effectively prevents other legitimate clients from availing of network connectivity and hence render network connections useless to other client-users. Although there are measures to somehow mitigate the problems mentioned, these only provide limited protection against determined hackers. One way is to attach tags to DHCP messages as authentication to know if messages received are valid. Confidentiality – because the DHCP software keeps records or logs of addresses that were assigned, these logs contain the contact details of each client or provide links to personally identifiable information (PII) which spammers can utilize in their fishing expeditions (“phising”) which compromise network security and confidentiality. Network administrators can employ so-called intrusion detection systems (IDS) using what is termed as anomaly-based system (ABS) where an attempt to hack is treated or considered as an anomaly or deviation from the normal. It can be a layered-defense system, installed at both the host level and at the network level (Garera, 2009, p. 15) that is employed at the application level, system software, user layers, and finally, at the network level. Detection can be either a packet-based ABS or a connection-oriented ABS. A good IDS must prevent attacks with a detection rate approaching one hundred percent and at the same time provide a false alarm rate that approaches to near zero (Marchette, 2001, p. 78). Conclusion Dynamic host configuration protocol has served its purpose of being the mainstay in the normal functioning of the computer networks so essential to modern life today. It has proven its usefulness by being compatible with the new IPv6 that is now gradually being implemented with the assurance that networking will not run out of needed valid IP addresses, providing more than enough addresses that figuratively and literally extends to infinity and beyond. DHCP provided a smooth transition slightly more than a year ago, on June 08, 2011 when the Internet switched and tested the IPv6 without any major glitches (Goldman, 2012, p. 1) and hopefully continue to do so and support the Internet's frenzied expansion well into the future until such time a better protocol can be invented. It has been a proven workhorse for the entire networked world so far. Reference List Barrett, D. & King, T. (2005). Computer networking illuminated. Burlington, MA: Jones & Bartlett Publishers. Bender, M. (2010). MCTS guide to Microsoft Windows Server 2008 network infrastructure. Florence, KY: Cengage Learning. Boehm, B. (2006, May). “A view of 20th and 21st century software engineering.” Proceedings of the 28th International Conference of Software Engineering, 12-29. Croft, B. & Gilmore, J. (1985, September). “RFC 951: Bootstrap protocol.” Network Working Group. Retrieved from http://www.ietf.org/rfc/rfc951.txt Droms, R. (1997, March). “RFC 2131: Dynamic host configuration protocol.” Internet Engineering Task Force. Retrieved from http://www.ietf.org/rfc/rfc2131.txt Droms, R. & Lemon, T. (2003). The DHCP handbook. Indianapolis, IN: SAMS Publishing. Garera, S. (2009). New techniques to defend against computer security attacks. Baltimore, MD: The Johns Hopkins University Press. Goldman, D. (2012, June 6). “IPv6: The Internet now has 340 trillion trillion trillion addresses.” CNN Money Tech. Retrieved from http://money.cnn.com/2012/06/06/technology/ipv6/index.htm?iid=GM Marchette, D. J. (2001). Computer intrusion detection and network monitoring: A statistical viewpoint. New York, NY: Springer Books. 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