UNSHIELDED TWISTED PAIR (UTP)

UNSHIELDED TWISTED PAIR (UTP)

A. SEJARAH UTP (Unshielded Twisted Pair)
Sebelum kita membahas sejarah kabel UTP, akan lebih baik jika kita mengetahui pengertian dari kabel UTP terlebih dahulu. Kabel UTP (Unshielded Twisted Pair) adalah kabel yang biasa digunakan untuk membuat jaringan atau network computer berupa kabel yang didalamnya berisi delapan buah kabel yang dipilin, dimana setiap kabel mempunyai warna yang berbeda-beda yang digunakan sebagai standart pemasangan kabel jaringan computer, yang setiap pasangnya adalah kembar dengan ujung konektor. Disebut unshielded karena kurang tahan terhadapinterferensi elektromagnetik. Dan disebut twisted pair karena di dalamnya terdapat pasangan kabel yang disusun spiral alias saling berlilitan.

Ada dua macam Twisted Pair, yaitu:
1. Unshielded Twisted Pair (UTP)
2. Shielded Twisted Pair (STP)

· Perbedaan kedua jenis Twisted Pair adalah:
a. STP terdapat lapisan pelindung atau selubung kabel internal.
b. UTP tidak mempunyai lapisan pelindung kabel.

· Kabel UTP lebih terkenal daripada STP, karena kabel UTP lebih sering digunakan
sebagai kabel jaringan.

· Kabel UTP (Unshielded Twisted Pair) ada 2 macam:
1. Untuk kabel telepon yang berisi 4 buah kabel.
2. Untuk jaringan computer yang berisi 8 buah kabel.

· UTP dispesifikasikan oleh organisasi Electronic Industries Association (EIA) dan
Tellecommunication Industries Association (TIA).

· Ada 2 standard untuk strtuktur pengkabelan :
1. EIA/TIA-568 yang dikeluakan oleh Electronic Industries Association dan Telecommunications Industry Association.
2. ISO 11801 yang dikeluarkan oleh ISO.


B. KATEGORI UTP (Unshielded Twisted Pair)

UTP dikategorikan menjadi delapan (7) kategori :
1. Kategori 1
Hanya mampu mentransmisi suara/voice saja, tidak termasuk data.
2. Kategori 2
Kecepatan transmisi data maksimal 4 Mbps.
3. Kategori 3
Kecepatan transmisi data maksimal 10 Mbps.
4. Kategori 4
Kecepatan transmisi data maksimal 16 Mbps.
5. a. Kategori 5
Kecepatan transmisi data maksimal 100 Mbps.
b. Kategori 5 enhanced
Kecepatan transmisi data maksimal 1000 Mbps.
6. Kategori 6
Kecepatan transmisi data maksimal 1000 Mbps.
7. Kategori 7
Kecepatan transmisi data maksimal 1000 Mbps.
Perbedan tiap kategori adalah pada kecepatan transmisi data. Di bawah ini terdapat keterangan Tiap-Tiap Kategori UTP :

Type CAT 1, Type UTP
dengan kategori ini biasanya digunakan untuk perangkat telepon dan digunakan juga
pada jalur ISDN (Integrated Service Digital Networks). UTP dengan jenis ini juga sering digunakan untuk menghubungkan modem dengan line telepon.

Type CAT 2, Type UTP
Kabel ini dapat mentransmisikan data hingga 4 megabit perdetik. UTP dengan kategori ini biasanya digunakan pada jaringan bertopologi token ring.

Type CAT 3, Type UTP/STP
Kabel ini didesain untuk mendukung komunikasi data dan suara pada kecepatan hingga 16
megabit perdetik. Kabel ini menggunakan kawat-kawat tembaga 24-gauge dalam konfigurasi
4 pasang kawat yang dipilin (twisted-pair) yang dilindungi oleh insulasi. Sering digunakan
pada topologi token ring atau 10BaseT.
Type CAT 4, Type UTP,STP
Mentransfer data dengan kecepatan 20Mbit. Kabel ini menggunakan kawat tembaga 22-
gauge atau 24- gauge dalam konfigurasi empat pasang kawat yang dipilin (twisted pair) yang
dilindungi oleh insulasi. Kabel ini dapat mendukung jaringan Ethernet 10BaseT, tapi
seringnya digunakan pada jaringan IBM Token Rin
Type CAT 5, Type UTP, STP-up to100Mhz
Mentransfer data dengan kecepatan 100Mbit. Kabel ini menggunakan kawat tembaga dalam
konfigurasi empat pasang kawat yang dipilin (twisted pair) yang dilindungi oleh insulasi.
Kabel ini telah distandardisasi oleh Electronic Industries Alliance (EIA) dan
Telecommunication Industry Association (TIA).
Type CAT 5enhanced, Type UTP,STP-up to100Mhz
1 Gigabit Ethernet up to 100meters- 4copper pairs.(kedua jenis CAT5 sering digunakan pada
topologi token ring 16Mbps, Ethernet 10Mbprs atau pada FastEthernet 100Mbps) Type CAT
6 up to 155 MHz or 250 MHz 2,5 Gigabit Ethernet up to 100meters or 10Gbit/s up to 25
meters .20,2db(Gigabit Ethernet) Type CAT 7 up to 200 MHz or 700 Mhz (Gigabit Ethernet)
Giga-Ethernet / 20.8 db
Pemberian kategori 1/2/3/4/5/6 merupakan kategori spesifikasi untuk masingmasing
kabel tembaga dan juga untuk jack. Masing-masing merupakan seri revisi
atas kualitas kabel, kualitas pembungkusan kabel (isolator) dan juga untuk kualitas
“belitan” (twist) masing-masing pasang kabel. Selain itu juga untuk menentukan
besaran frekuensi yang bisa lewat pada sarana kabel tersebut, dan juga kualitas
isolator sehingga bias mengurangi efek induksi antar kabel (noise bisa ditekan
sedemikian rupa). Perlu diperhatikan juga, spesifikasi antara CAT5 dan CAT5
enchanced mempunyai standar industri yang sama, namun pada CAT5e sudah
dilengkapi dengan insulator untuk mengurangi efek induksi atau electromagnetic
interference. Kabel CAT5e bisa digunakan untuk menghubungkan network hingga
kecepatan 1Gbps.
C. KEGUNAAN UTP (Unshielded Twisted Pair)
· Sebagai contoh penggunaan kabel UTP untuk sehari-hari adalah kabel telepon. Salah satu
alasan utama mengapa jenis kabel UTP ini sangat popular dibandingankan dengan jenis kabel
lainnya adalah karena penggunaannya kabel UTP sebagai kabel telepon. Banyak gedung
menggunakan kabel ini untuk sistem telepon dan biasanya ada kabel ekstra yang dipasang
untuk memenuhi pengembangan dimasa mendatang.
· Karena kabel ini juga bisa digunakan untuk mentransmisikan data dan juga suara, maka \
menjadi pilihan untuk membangun jaringan komputer. Yang membedakan antara telepon
dengan computer dalam hal penggunakan kabel UTP ini terletak pada jack-nya atau
konektornya.
· Pada komputer digunakan RJ-45 yang dapat menampung 8 koneksi kabel sedangkan pada
telepon digunakan RJ-11, dapat menampung 4 koneksi kabel dan ukurannya lebih kecil.
Lebih jelasnya bisa dilihat koneksi dari telepon Anda yang menggunakan RJ-11.
· Penjelasan Kegunaan Tiap Kategori : 1. Kabel UTP Kategori 1 (Cat1) adalah kabel UTP
dengan kualitas transmisi terendah, yang didesain untuk mendukung komunikasi suara
analog saja. Kabel Cat1 digunakan sebelum tahun 1983 untuk menghubungkan telefon
analog Plain Old Telephone Service (POTS). Karakteristik kelistrikan dari kabel Cat1
membuatnya kurang sesuai untuk digunakan sebagai kabel untuk mentransmisikan data
digital di dalam jaringan komputer, dan karena itulah tidak pernah digunakan untuk tujuan
tersebut.
2. Kabel UTP Kategori 2 (Cat2) adalah kabel UTP dengan kualitas transmisi yang lebih baik
dibandingkan dengan kabel UTP kategori 1 (Cat1), yang didesain untuk mendukung
komunikasi data dan suara digital. Kabel ini dapat mentransmisikan data hingga 4 megabit
per detik. Seringnya, kabel ini digunakan untuk menghubungkan node-node dalam jaringan
dengan teknologi Token Ring dari IBM. Karakteristik kelistrikan dari kabel Cat2 kurang
cocok jika digunakan sebagai kabel jaringan masa kini. Gunakanlah kabel yang memiliki
kinerja tinggi seperti kategori 3, kategori 4, atau kategori 5.
3. Kabel UTP Kategori3 (Cat3) adalah kabel UTP dengan kualitas transmisi yang lebih baik
dibandingkan dengan kabel UTP kategori 2 (Cat2), yang didesain untuk mendukung
komunikasi data dan suara pada kecepatan hingga 10 megabit per detik. Kabel UTP Cat3
menggunakan kawat-kawat tembaga 24-gauge dalam konfigurasi 4 pasang kawat yang dipilin
(twistedpair) yang dilindungi oleh insulasi. Cat3 merupakan kabel yang memiliki
kemampuan terendah (jika dilihat dari perkembangan teknologi Ethernet), karena memang
hanya mendukung jaringan 10BaseT saja. Seringnya, kabel jenis ini digunakan oleh jaringan
IBM Token Ring yang berkecepatan 4 megabit per detik, sebagai pengganti Cat2.
4. Kabel UTP Kategori 4 (Cat4) adalah kabel UTP dengan kualitas transmisi yang lebih baik
dibandingkan dengan kabel UTP kategori 3 (Cat3), yang didesain untuk mendukung
komunikasi data dan suara hingga kecepatan 16 megabit per detik. Kabel ini menggunakan \
kawat tembaga 22-gauge atau 24- gauge dalam konfigurasi empat pasang kawat yang dipilin
(twisted pair) yang dilindungi oleh insulasi. Kabel ini dapat mendukung jaringan Ethernet
10BaseT, tapi seringnya digunakan pada jaringan IBM Token Ring 16 megabit per detik.
5. Kabel UTP Kategori 5 (Cat5) adalah kabel dengan kualitas transmisi yang jauh lebih baik
dibandingkan dengan kabel UTP kategori 4 (Cat4), yang didesain untuk mendukung
komunikasi data serta suara pada kecepatan hingga 100 megabit per detik. Kabel ini
menggunakan kawat tembaga dalam konfigurasi empat pasang kawat yang dipilin (twisted
pair) yang dilindungi oleh insulasi. Kabel ini telah distandardisasi oleh Electronic Industries
Alliance (EIA) dan Telecommunication Industry Association (TIA). Kabel Cat5 dapat
mendukung jaringan Ethernet (10BaseT), Fast Ethernet (100BaseT), hingga Gigabit Etheret
(1000BaseT). Kabel ini adalah kabel paling populer, mengingat kabel serat optik yang lebih
baik harganya hamper dua kali lipat lebih mahal dibandingkan dengan kabel Cat5. Karena
memiliki karakteristik kelistrikan yang lebih baik, kabel Cat5 adalah kabel yang disarankan untuk semua instalasi jaringan. Kategori Enhanced 5 Kabel ini merupakan versi perbaikan dari kabel UTP Cat5, yang menawarkan kemampuan yang lebih baik dibandingkan dengan
Cat5 biasa. Kabel ini mampu mendukung frekuensi hingga 250 MHz, yang
direkomendasikan untuk penggunaan dalam jaringan Gigabit Ethernet, meskipun
menggunaan kabel UTP kategori 6 lebih disarankan untuk mencapai kinerja tertinggi.

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Auditing Network Security System

Audit system is one of the stages in order to ensure that "security goal" is maintained properly. After all policies related to computer network security made by an organization, then the next stage is to test whether all the policies and rules that have made it had correctly applied or not.
There are 3 types of audits are usually done on network security systems within an organization, namely:
1. "Audit privilege" that would audit how the permissions settings applied at the company's appropriate or not and how the implementation in the field.
2. "Usage audit" bagaiaman audit of resource use within the organization. Is it in accordance with the policy of the organization or not.
3. "Escalation audit" to audit how the security system in an organization facing a critical situation. For example how fast the system recoveri process in the event of an attack by "hackers", how the standard operating procedures applied by the organization if a problem occurs on a network system infrastructure, how to cope in the event of natural disasters. So from all of the audit process can identify weaknesses anything contained in the computer network systems organization. To further search can be an appropriate solution to deal with these problems.

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Wireless Security

Background

Wireless network (wireless LAN) currently used by more and more companies in support of the company's business processes. Increased implementation of wireless LAN networking technology can not be separated from many advantages offered by technology in this. Excess among flexibility offered, because to implement wireless LAN technology is not constrained topology problems / conditions. This technology can be applied in which Just to reach a good signal depends on the quality of the device wireless LAN is used. Along with the many users of technology wireless-based network, then the more the parties trying to do a "crime" of this network.

This can be seen from the number of software / tool that was created to take the offensive for both wireless networks was the kind of active attacks and passive types of attacks. Such software is usually distributed through the internet for free and There are also some who paid. Requiring a security method the right to address security issues for wirelessLAN network.

Wireless networks are vulnerable to attack, it is because network with this technology can not be confined by a building like that in cable-based network protected by a wall in a building cable-based network which is attached. Radio frequency signals used by the wireless network in the data transmission process in these networks can be easily accepted / in caught by user other than the user's computer wireless network is only with using a wireless network card compatible / fit with the network wireless is installed on the computer user's computer. Security holes in wireless networks can be divided into 2 (two) types of attack, namely: passive attacks and active attacks.

Passive Attack
Passive attack is a real type of attack does not endanger of a network system. This type of attack does not cause loss of resources in a network or causes damage to the a network of systems that were attacked using this type of attack. Source power contained in the system including a data network, bandwidth network, printer, memory in a computer processing unit (processor) and more. The point of this attack is only to observe the all the resources contained in a computer network system. like network traffic monitor a computer network system. Information resulting from these observations is very useful for those who do not reserves the right to conduct further attacks against the system. so that this type of attack is very difficult to detect by the manager of a computer network systems. Wireless network communications are usually used common radio frequency that is not listed that can be accessed by anyone with a compatible network card. so to This type of network is very easy to tap by using the technique of "sniffing" or "wardriving". We have a lot of "sniffer" using software such as NetStumbler in combination with each other antennas work together with the card wireless network (wireless) to detect the network "access points" (AP) which in range and the signal can be accessed wirelessly network card it. Then the data traffic is happening in the wireless network in captured by the "sniffer" for later in the analysis by using tools such as Microsoft Network Monitor to microsoft windows operating system or using TCPDump to Linux Linux operating system.

Programs such as NetStumbler but can be used to detect network access point located within range can also be used to displays the information on the Service set identifiers (SSID) and manufacturer information access point is. So if the Access Point remain in the configuration is still using the default SSID settings are included by the manufacturer when the access point is purchased, then the wireless network use the access point device is very susceptible to problems security.

If the SSID contains information about organizations that provide services wireless network or the network may not use security methods such as encryption by Wireless Equivalent Privacy (WEP) is capable of doing encryption of all data traffic that occur within the wireless network, if it happens the right network security it would be easy to pass by the parties who are not interested (unauthorized users). Once a "sniffer" managed to get the SSID information an access point, the "sniffer" that can take pictures of traffic in wireless network and open information about all the things in the network these, such as user name and password. When a sniffer successfully perform have observed and use the information obtained to entered into the network and accessing or using the resources within system without permission, then at this stage passive attacks (passive attack) turned into a kind of active attacks (active attack).

To protect wireless networks against computer programs that mengeteksi existence capable wireless network signal, then a manager wireless networks (administrator) to do the reconfiguration of all the basic configuration of the wireless network device if the configuration is still using a standard onfiguration / defaults provided by the vendor maker wireless network devices such as the device was first purchased. Among them is to implement a security system that is closed with how to configure an Access Point that can not respond connection requests (request) to the status of his SSID that is usually requested by programs such as NetStumbler. In this way an access point in a fixed wireless network can not be detected (invisible) by the parties not entitled to access the wireless network.

Currently most devices access point for wireless network very easy to its configuration in order to facilitate its users and using the network. But with all these facilities was has weaknesses, too. By prioritizing ease of configuration, then some makers access point vendors do not provide a touch of aspects security in the basic configuration provided on the access point they production. This is due to the configuration of security in a network access point device is quite complicated and must consider many aspects. So if the included network security into the basic configuration of access point devices must process is not easy longer and requires special skills of the user.
Here are some basic things that can be done to protect the network wireless passive attacks and active attacks:

1. Secure the wireless router or interface page Administrator Access Point.
Almost all routers and access points have the password for the administrator required at the time of login into the wireless device and to make configuration settings in the access point device. Most access point device using the default password is very simple and not safe. For example the password with the keyword "password" as well or use keyword company names, and some even do not has a password at all. In such cases, the first step performed by an administrator during the first setting wireless router to the device or access point is to change The default password on the device with another password more secure. Because this password is rarely used because to do configuration the access point device is usually very rarely done, then use a password that is easy to remember but difficult to guess or can also be a way to write these passwords are not easily forgotten but stored in a safe place if it is to passsword written so as not to forget. If finally the password is forgotten then satusatunya way is to reset the access device point is that all the onfiguration is returned to the default configuration as previously when the wireless device was first purchased from the vendor.

So the administrator must do the reconfiguration of the device to aspects of wireless security.
Here are a few tricks to create a relatively secure password:
• passwords do not use personal information such as name, date of born.
• passwords must be easy to remember but difficult to predict.
• use a different password to access the system different.
• change the password regularly to prevent attacks on password using the program "password cracking".
• if the password should be written and stored in a computer file because it is difficult to remember so keep a safe place and files is the encryption.

2. Do not Make Broadcast of SSID access point.
Most access points and routers automatically broadcast process for the network name, or SSID (Service Set Identifier). This setting is of course facilitate the wireless network settings on the client and create a device access point can be seen by all wireless network systems are included in coverage access point device is. So by activating SSID on the access point that allows all parties to detect presence of a network access point is either by the party entitled or by parties who are not entitled to access the network. This is of course can lead to security holes in wireless networks are. To securing the feature should disable SSID broadcast on the network so that wireless is to become invisible (invisible) by the other users who do not eligible and not enrolled in these wireless networks. For ordinary users this This can not be detected, but for a "sniffer" of course this does not influential because by using computer programs specific like NetStumbler the "sniffer" can still detect the presence of the device access point for the wireless network.

3. Security Features Enable WPA encryption instead of WEP.
Keamaanan features WEP encryption (Wired Equipment Privacy) which during the many applied to the access point device has been known to have many weakness that is relatively easy for someone to open the code encryption and access the wireless network using only appropriate device. A better way to protect wireless networks current is to use WPA (Wi-Fi Protected Access). WPA provides more security features and ease of its use, unlike the WEP limit the use of characters password only on the numbers 0-9 and letters from AF. Support for WPA have been included in the operating system Windows XP (with latest service packs)

and virtually on the latest wireless networking devices today and in operating system. The latest version of the current WPA WPA2 which is to be found on the latest wireless network devices today and provides a mechanism better encryption. But to use this feature may be WPA2 must download the latest patch on Windows XP operating system. Because feature This relatively new and not all Windows XP operating system supports use.

4. Use WEP than not using at all.
If you find that there are several wireless devices on the market today only supports WEP encryption key (usually found on the device non-PC based such as media players, PDAs, and DVR), then use this feature WEP encryption, although relatively safe than not at all and use keys that are difficult to predict.

5. Use filtering to control access to wireless networks with using MAC filtering.
Unlike the use of IP address, MAC address of a unique nature to distinguish between one network device to another one. So that the switch uses MAC filtering feature it can be limited access to the wireless network by only those MAC addresses his MAC address of each user in the wireless network must be known first 12 characters are the MAC address of each network devices that will connect to the access point device.

Of course this means a little uncomfortable and inflexible because of a administrator must register all MAC addresses for each user / client which will be connected into the network. If the number of client users wireless network is of course a lot of trouble a administratori network. We have had many programs including the category of "hacking tools" which can be used to make counterfeiting / "spoofing" the address MAC. Necessitating careful enough attention from an administrator wireless network to determine which MAC addresses are valid and which addresses MAC false. So with falsified / MAC address spoofing in accordance with MAC address listed in the wireless network is the is not entitled to enter and access these wireless networks.

6. Reducing the beam power wireless devices (access points).
This feature is not available in all wireless routers and access points, but there are some wireless devices that provide features for lower power wireless devices in the transmit signal so that the narrower the range of the signal. Although not always possible to make the process of setting appropriate to the size of the signal but this still managed to reduce the potential for gaps security on wireless network system and minimize the chance of outside parties systems that are not entitled to access the wireless network device.

7. Turn off the features / remote administration service.
Almost all wireless routers provide the device features to be managed remotely through the Internet. Ideally, the use of this feature when deciding on a specific IP address or to limit the reach the use of IP addresses that may access the router device. instead for the two activities mentioned above, this feature should be disabled. because the This feature will enable everyone in range signal wireless router device has the potential to discover and access these wireless router devices. So that always turn off this feature as a policies in the management of the router device in a wireless network. So that an administrator can not perform network management wirelessnya remotely via the Internet. This feature is usually disabled by default by the vendor making the router device when it was first purchased for security reasons. But it never hurts to check on a regular basis against this feature in a wireless network device if it is true been disabled or still active.

Conclusion
Wireless network is a computer network is very open and vulnerable the security hole. This is due to constituent components This network is physically very difficult to secure. In contrast to the network cable-based physical security for the secured easily and at control, wireless-based networks is very difficult to control. Transmitting frequency signals used by wireless device allows all parties can detect and access this network while using the compatible wireless receiver and the signal can reach. Today many all types of computer programs that can be used to perform attacks on wireless networks, both types of passive attacks that nature does not destroy and steal just to the type of information to active attacks that can damaging the system and use all the resources contained in the these wireless networks. Because the characteristics of wireless devices that are difficult to physically secured so security can only be done by using policies or use a computer program that usually provided by vendors such wireless device makers with only perform simple settings and easy.

Bibliography

• CompTIA Security+, Part 1 – security concepts., www.comptia.net


• Network Security Essentials., Stalling W., Prentice Hall., 2004


• http://www.more.net –Network Auditing-, 2007

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Attack Tools for System Security and Computer Network Security Audit

Along with the rapid development of network technology and the many computer connected in the world today, the increase in the crime world mayapun continue to happen. This is because more and more computer users interconnected via the internet. With the trend of increasing crime in the world virtual moment, then takes a security mechanism to the system of attacks from the hackers system (hackers) or from virus attack and other software that are considered dangerous to the workings of a system computer networks in both local and internet.
To find out how the hackers computer systems can do action against a target computer, it is necessary to know what tools used by hackers so that by knowing the workings of the tools it then can be made an appropriate security mechanism.

Nmap

Nmap is a utility to explore and audits of the system computer security. Nmap is free and available as open source code (open source code) that can be used under license from the GNU General Public License (GPL)

Nmap is a major project to make computer networks more secure and provide facilities / equipment for more sophisticated network security auditor computer and network administrators in the data exploration in managed computer network. Nmap is designed quite capable of doing quickly scan the process of large-scale computer networks and to a host for security, audit process, and exploration of computer networks.

How it works using Nmap packages Internet Protocol (IP) for determine the host / computer anywhere in the network active status is, what services are run by the host, any operating system used by the host, and type "packet filter" or whatever firewall used by the hosts in the network scanned by Nmap
at that time.

Picture. 1 Views Nmap using Command Line

Figure 1 above is an example of Nmap display, which runs through command line. This example shows Nmap scan results showing TCP ports used by the target computer.

Nmap has 3 (three) main functions, namely: detection of the operating system, scan the port, ping scans. By default, Nmap doing a ping scan process to ping to each host to ensure the host is active or not. Some methods can be used, including sweeps of the Internet Control Messaging Protocol (ICMP) and TCP ping.

By default, Nmap will use ICMP to detect whether the host Off target or not. Network monitoring system used to keep records (logs) each event and the gateway device, such as firewalls, traffic stop ICMP. This can be neutralize by switching off the ping sweeps or by using other methods used by the firewall.

The process involves TCP Ping TCP Acknowledge (ACK) or packet synchronization (SYN) to a specific port on the target host. By default Nmap uses port 80, which is also used by the protocol Hypertext Transfer Protocol (HTTP), although it can also use other ports. Depending on the complexity gateway, network traffic that there can not be detected and finally in stop.

Picture. 2 Port Scanning Nmap done to one of the Host target

Port scanning to determine what TCP port can be used to communicate. This is very useful to explore the status of a network system computer for these ports represent the communication channels potential and mapping of these ports and facilitate exchange of information between host one with another host.

There are many techniques used to find out all the activities of data in a network. All the existing techniques involve searching information differ from each other between the operating system and then writes the results difference. Prove using FIN technique is one technique which is used by Nmap. It works by sending FIN packet or a packet without an ACK or a SYN signal to an open port in target computer and wait for a response from the target computer. Replies from target computer is a very useful information for parties perform scanning using nmap it. Information obtained include: a list of computer / host which is active in the network, a list of ports and its status on the target computer, the operating system used on the target computer, what services are running on the target computer. All such information is basic information and the potential can be used by the user to perform the next action to the target computer or computer network systems while being scanned. Such action may be to such good purpose for the sake of good network management by network administration, or for the benefit of an audit of the implementation security in computer networks, in addition to the things that benefit above, the information generated by nmap can also be used for the purposes is negative. Users who are not interested (hacker) can be used potential information as a basis for an active attack which is more dangerous to the network or computer system such targets. The process to obtain confidential information of a computer network system through a tool like Nmap by a hacker can be categorized types of passive attacks (passive attack).

Picture 3. Nmap done Scanning of operating system to Host one of the targets

By using the fingerprint technique TCP / IP is right and good, can be known What operating system being used by a target computer. In picture above, Nmap scans found that the target computer is scanned using Microsoft Windows 2000, Windows XP, or Windows ME.

Conclusion

Nmap is one tool that is usually used to help a network administrator job in conducting oversight of the conditions that manages network security. Nmap includes a free software and can be downloaded freely and used by the GNU General Public License (GPL). Nmap network security side, including tools that can be used to attack a computer network system.

This tool is often used by a cyber hacker (hackers) to conduct information searches on a target computer prior to the attack on the target computer. The information generated by nmap status information includes a list of active computers in the network, the status of ports located on the target computer, type of operating system used, type of services available in the target computer, as well as security methods that are applied to the computer target if any. Activities to get information about the current state of the target computer can be categorized into types of passive attacks (passive attack). Where this type of attack does not harm a computer system is attacked, but the result of this activity was a hacker (hacker) can do to stage attacks on the attack to a target computer by using the information generated from the process of passive attacks that use tools like nmap. In addition to helping a network administration and even misused by hackers to perform a passive attack to a target computer, Nmap is also useful for security audit activities of a computer network by a Network Security Auditor. By looking at the information generated by nmap a security auditor can see whether the target computer in the audit are relatively safe or not can be determined so that appropriate security methods to the target computer. Read more...Routing Protocols and Concepts, CCNA Exploration Companion Guide

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