Wednesday, October 28, 2009

10 Physical Security Measures Every Organization Should Take

Every general computer networking class teaches the OSI and/or DoD networking models, and we all learn that everything begins at the bottom, with the physical level. Likewise, when it comes to IT security, physical security is the foundation for our overall strategy. But some organizations, distracted by the more sophisticated features of software-based security products, may overlook the importance of ensuring that the network and its components have been protected at the physical level.

In this article, we’ll take a look at 10 of the most essential security measures you should implement now, if you haven’t already done so.

#1: Lock up the server room
Even before you lock down the servers, in fact, before you even turn them on for the first time, you should ensure that there are good locks on the server room door. Of course, the best lock in the world does no good if it isn’t used, so you also need policies requiring that those doors be locked any time the room is unoccupied, and the policies should set out who has the key or keycode to get in.
The server room is the heart of your physical network, and someone with physical access to the servers, switches, routers, cables and other devices in that room can do enormous damage.

#2: Set up surveillance
Locking the door to the server room is a good first step, but someone could break in, or someone who has authorized access could misuse that authority. You need a way to know who goes in and out and when. A log book for signing in and out is the most elemental way to accomplish this, but it has a lot of drawbacks. A person with malicious intent is likely to just bypass it.
A better solution than the log book is an authentication system incorporated into the locking devices, so that a smart card, token, or biometric scan is required to unlock the doors, and a record is made of the identity of each person who enters.
A video surveillance camera, placed in a location that makes it difficult to tamper with or disable (or even to find) but gives a good view of persons entering and leaving should supplement the log book or electronic access system. Surveillance cams can monitor continuously, or they can use motion detection technology to record only when someone is moving about. They can even be set up to send e-mail or cell phone notification if motion is detected when it shouldn’t be (such as after hours).

#3: Make sure the most vulnerable devices are in that locked room
Remember, it’s not just the servers you have to worry about. A hacker can plug a laptop into a hub and use sniffer software to capture data traveling across the network. Make sure that as many of your network devices as possible are in that locked room, or if they need to be in a different area, in a locked closet elsewhere in the building.

#4: Use rack mount servers
Rack mount servers not only take up less server room real estate; they are also easier to secure. Although smaller and arguably lighter than (some) tower systems, they can easily be locked into closed racks that, once loaded with several servers, can then be bolted to the floor, making the entire package almost impossible to move, much less to steal.

#5: Don’t forget the workstations
Hackers can use any unsecured computer that’s connected to the network to access or delete information that’s important to your business. Workstations at unoccupied desks or in empty offices (such as those used by employees who are on vacation or have left the company and not yet been replaced) or at locations easily accessible to outsiders, such as the front receptionist’s desk, are particularly vulnerable.
Disconnect and/or remove computers that aren’t being used and/or lock the doors of empty offices, including those that are temporarily empty while an employee is at lunch or out sick. Equip computers that must remain in open areas, sometimes out of view of employees, with smart card or biometric readers so that it’s more difficult for unauthorized persons to log on.

#6: Keep intruders from opening the case
Both servers and workstations should be protected from thieves who can open the case and grab the hard drive. It’s much easier to make off with a hard disk in your pocket than to carry a full tower off the premises. Many computers come with case locks to prevent opening the case without a key.
You can get locking kits from a variety of sources for very low cost, such as the one at Innovative Security Products.

#7: Protect the portables
Laptops and handheld computers pose special physical security risks. A thief can easily steal the entire computer, including any data stored on its disk as well as network logon passwords that may be saved. If employees use laptops at their desks, they should take them with them when they leave or secure them to a permanent fixture with a cable lock, such as the one at PC Guardian.
Handhelds can be locked in a drawer or safe or just slipped into a pocket and carried on your person when you leave the area. Motion sensing alarms such as the one at are also available to alert you if your portable is moved.
For portables that contain sensitive information, full disk encryption, biometric readers, and software that “phones home” if the stolen laptop connects to the Internet can supplement physical precautions.

#8: Pack up the backups
Backing up important data is an essential element in disaster recovery, but don’t forget that the information on those backup tapes, disks, or discs can be stolen and used by someone outside the company. Many IT administrators keep the backups next to the server in the server room. They should be locked in a drawer or safe at the very least. Ideally, a set of backups should be kept off site, and you must take care to ensure that they are secured in that offsite location.
Don’t overlook the fact that some workers may back up their work on floppy disks, USB keys, or external hard disks. If this practice is allowed or encouraged, be sure to have policies requiring that the backups be locked up at all times.

#9: Disable the drives
If you don’t want employees copying company information to removable media, you can disable or remove floppy drives, USB ports, and other means of connecting external drives. Simply disconnecting the cables may not deter technically savvy workers. Some organizations go so far as to fill ports with glue or other substances to permanently prevent their use, although there are software mechanisms that disallow it. Disk locks, such as the one at, can be inserted into floppy drives on those computers that still have them to lock out other diskettes.

#10: Protect your printers
You might not think about printers posing a security risk, but many of today’s printers store document contents in their own on-board memories. If a hacker steals the printer and accesses that memory, he or she may be able to make copies of recently printed documents. Printers, like servers and workstations that store important information, should be located in secure locations and bolted down so nobody can walk off with them.
Also think about the physical security of documents that workers print out, especially extra copies or copies that don’t print perfectly and may be just abandoned at the printer or thrown intact into the trash can where they can be retrieved. It’s best to implement a policy of immediately shredding any unwanted printed documents, even those that don’t contain confidential information. This establishes a habit and frees the end user of the responsibility for determining whether a document should be shredded.

Remember that network security starts at the physical level. All the firewalls in the world won’t stop an intruder who is able to gain physical access to your network and computers, so lock up as well as lock down.

Tuesday, September 8, 2009

PC Components

Introduction to PC Components
Here you will learn computer hardware tutorials introduction, basic pc components, networking devices, ram, vga, monitor and printer etc. Computer hardware is the physical part of the computer including the digital circuits inside the computer as opposed to the software that carry out the computing instructions. The hardware of a computer is unlikely to change frequently unless due to the crash or for upgrading them. The devices that is capable of storing, executing system instructions and controlling other logical outputs.

Hardware comprises all of the physical part of the computer such as Monitor, CPU, motherboard, ram, CD-Rom, printer, scanner, hard disk, flash drive (AKA pen drive), processor, pci buses, floppy disk, power supply, VGA card, sound card, network interface card, peripherals, joystick, mouse, keyboard, foot pedal, computer fan, camera, headset and others.
On the other hard software is a logical part of a computer and is used to carry out the instructions, storing, executing and developing other software programs. A typical PC consists of a case or chassis in the desktop or tower case and these components.
• Computer Fan
• Digital Circuitry
• Computer Fan
• PCI Slots

PC Buses
• Hyper-transport

• CD-Rom
• DVD-Rom
• Combo box
• Joystick
• BD-Rom drive

Internal storage
• Hard disk (ATA & SATA)
• Data array controller
• Floppy disk

Other Peripheral Devices
• Mouse
• Modems
• Digital Camera
• Sound, Video Cards
• Printer

Output Devices
• Printer
• Scanner
• Monitor
• Speakers
• Headset
• Video output devices

CPU (Central Processing Unit): CPU or central processing unit relates to a specific or processor. The performance of the computer is determined by the CPU chip (processor speed) and the other computer circuitry. Currently, the Pentium chip (processor) is the most popular even though there are other chips available in the market today such as AMD, Motorola and others. The clocks speed becomes most important factor in determining the performance of a computer. The motherboard contains the hardware circuitry and connections that allow the different hardware components of the PC to interact and communicate with each other. Most computer software is being developed for the latest processors so it would be difficult to use the older systems.

Hard Disk Drives – Disk drive is the mechanism to run the disks. All disks need a drive to get the information, read it and put it back to the disks. Hard disk is used to store the data permanently. Often the terms disk and drive used to describe the same thing but it should be clear that a disk is a storage device.

Modem – A modem is used for the modulation and demodulation of the data that is transferred through the modem and the telephone lines. Modem translates the data from digital to analog from analog to digital. Because on the telephone lines data can travel in the form of the analog signals and in the computer data transmits in the form of digital signals. Modems are measured by the speed which is called baud rate. The typical baud rate is 56Kb.

Keyboard – The keyboard is used to type something or input information to the computer. There are different designs and models of the keyboards in the market. The most common layout of the keyboard is QWERTY layout. A standard keyboard has 101 keys and embedded keys.

Video cards-Video cards allow computer to display video, graphics and animation. Some video cards allow computers to display television. A video card with a digital video camera allows users to produce live video. A high speed broadband internet connection is required to watch the videos on net.

Network cards: Network interface cards allow PCs to connect with each other and communicate. Every network computer is required to have a NIC card. NIC cards are required both in wired and wireless networking.

Cables: There are two broad types of cables internal cables, which are embedded on the mother board circuit that performs the communication between the devices and CPU. The other types of the cables are the network cables like coaxial cable, CAT 5, Ethernet cables. These cables are used for the communication purposes between the devices or computers.

Memory – Memory is the one of the important piece of the hardware. Sometimes memory chip memory is confused with the hard disk memory. Sometimes unallocated space of the hard disk is used as virtual memory also known as page file. This type of memory is a temporary memory and is used actual memory is less and requires some additional memory to perform a specific task.

RAM (Random Access Memory) RAM is a memory that is being used by the computer to store the information temporarily. For example when some work is performed on some applications that work is temporarily stored in the RAM. More RAM in the computer more faster computer works. Today at least requirement of a modern PC is 64 RAM. RAM is in the form of a chip and different vendors have developed the RAM of different capacities.

Mouse – Every modern computer requires a mouse for faster operations. Generally a mouse has two buttons left and right to perform different functions. One type of the mouse has a round ball under the bottom. Another type of the mouse use optical system to track the movement of the mouse.

Monitors – The monitor is used to display the information on the screen. All the activities of a computer, functions and tasks are seen on the computer screen and this is called outputting information. Monitors come in many sizes and shapes, monochrome or full colors. Today most computers use LCD screens. It is light weight and consumes less power as compared to the monitors.

Printers – The printer takes the information from the PC and transfers it to the paper of different sizes, which are placed in the printer device. There are three basic types of a printer such as dot matrix, inkjet and laser.
Scanners- Scanners allow you to transfer pictures and photographs to your computer. A scanner is used to scan the images and pictures. You can then send the image to someone, modify it or take a print out of it. With optical character recognition software you can convert printed documents into the text that you can use in the word processor. Digital camera- You can take the digital photographs with the digital cameras. The images are stored on the memory chip of the digital cameras and you can transfer them to your computer with the USB drive.

Case – Case or casing covers the whole computer’s circuitry. There are two types of casings desktop and tower casing. There is room inside the casing to add or remove components. Cases come in many sizes like desktop, mini, midi and tower. There are some additional empty slots inside the cases such as IDE, USB, ASI, PCI and firewire slots.

Cards – Cards are the hardware components that are added to the computer to increase their functionalities and capabilities.
Sound cards produce the sound like music and voice. The older cars were 8, 16 and then 32 bits. Color cards allow computers to produce colors. Initially there were 2, 4 and then 16 bits. The main types of the graphic cards are EGA, VGA and SGA. The 32 cards are the standard to display almost billions of the colors on the monitor.


Here you will get the basic Introduction Home Computer Networking-Basic Setup, wireless access point, lan troubleshooting, lan connectivity, dsl modem, gateway device, vpn and wi-fi. Computer Networks exists for more than 30 years and only recently they have become more popular at home both in forms of wired and wireless networking. Now many computer literate people from all over the world wish to have a computer network at home. There are many advantages and usage of a network, which we have described in the other sections of this website.

Millions of people have adopted the home network and now they are looking for the more advanced technology in the home networking and that is “wireless home networking”.We will discuss the various basic and advance aspects of the home networking considering that no prior knowledge of the network technology. We will briefly explain the setup, troubleshooting, installation, network devices used and other aspects of the home networking. Today in the age of Information technology, it’s not difficult for someone to have more than one PCat home.

If I apply this situation to you (that you have more than one computer at your home) then most probably you would wish to have access on the data and resources like, hard disk, printer, modem of the other PC and you can even access the broadband Internet like DSL or cable modem and you can also play a multi-player network game. All this is possible by just connecting and configuring the two computers at your home. There are several ways to do the home networking but all it depends on budget, security needs and nature of your work
Your cable/DSL modem plugs straight into the computer. The computer is exposed to the public Internet (indicated by the color red). There is no connection for more than one computer. You only have one IP address from your ISP.

If you have a broadband Internet connection at your home like DSL or cable net then you can share your internet connection with more than one PC at your home by installing the network card in each PC and configuring the hub/switch or a router.

If you have two PCs at your home and you want to share your internet connection with the other computer then you can simply share the internet connection by following these steps.

1. Connect two PCs with CAT5 cable and make it a cross over cable.
2. After connecting both the PCs, assign a different IP addresses by going in the properties of the
LAN card like and or you can assign any other IP address.
(Please note that these IP addresses that you use for your home networking are the private IP
addresses and they have nothing to do with the IP address that are used on the internet
(public IP addresses).
3. After assigning the IP addresses install software on the computer one, which will be used for
sharing the Internet connection and this will be called proxy software (and your computer one
will act as a Proxy Server). The more common proxy software is Wingate, Win Proxy and

Internet connection sharing (ICS). ICS is by default installed in Windows operating systems and can be configured separately.

Internet access by using a hardware router/gateway/firewall device In this situation, you have to install a hardware router, which will be act as a gateway. Your router will be connected with the public IP address, which will be assigned to your by your ISP and hub/switch will be attached to the router. All the other PCs in your home or small network will be directly attached to that hub or switch.

How to setup the Gateway Device
Gateway device – There are different gateway devices available from different companies like,, and Cisco systems. Each device has difference setup configurations but the basic purpose of all these devices is the same.

The Gateways have a number of common features and functions such as NAT (Network Address Translation) that translate your public IP address into the private IP address on your network, DHCP server, PPP. Before buying any gateway device, make sure gateway device must have all these features.

Some advance gateways have the following features.

• wireless access point
• print server
• DMZ (make one PC available to the Internet but still protect it through the firewall
• multi-port
• Content filtering

Most advance gateways comes with integrated hubs or switches and if your gateway don’t have the functionality of a hub/switch then you will have to buy a hub/switch for your home network. Before buying a hub/switch you should consider the two main things 1. it should support dual
speed i.e 10mbps and 100mbps and 2. it should have maximum available ports. Cat5 cable – For setting up a home network, you will need a several pieces of the CAT5 Ethernet cables. These cables can be used in the different scenarios like for connecting the two PCs (if you have a two computer network) and if you have more than two computers then each computer will be directly connected with the hub/switch or gateway device. The most commonly used cable for computer networking is Cat5 cable.

Once you have all the required things like cables, hub/switch, LAN cards etc. then install a network card in each PC. You must make sure that each card is properly installed and is not showing any signs of conflict with the other network devices.

How to connect two computers wirelessly
In some recent years, wireless networking solutions have became very popular. There are several wireless technologies exists to support the wireless networking.

These technologies include Wi-Fi, Bluetooth and infrared.

Wi-Fi connections can reach at a greater distance than the other wireless solutions that are mentioned above. Many new PCs and Laptops now have the built-in capability of the Wi-Fi. Wi-Fi can be used with or without network fixture. In the two computers Wi-Fi networking minus a fixture also called ad-hoc Wi-Fi.

Bluetooth technology supports high speed wireless connectivity and communication between the two computers without the need of a network fixture. Bluetooth is commonly used when networking a computer with the consumer’s cell phone or handheld device. Bluetooth works well if both the devices are in the same room or location. While networking among the handheld devices consider the Bluetooth technology solution.

Infrared networking exists before the Wi-Fi or Bluetooth technologies on the Laptops. Infrared wireless connections only work between two computers and do not require a fixture. Infrared networking is relatively fast so consider using it if your computer supports it and you don’t have
the Wi-Fi and Bluetooth features in your computer.

How to Choose a Right Network Type

In this section you will learn about computer network how to, troubleshooting tips, configurations, IT help, basic configurations help, wireless access point, hardware components and cables. Data commmunication is an important thing to share the data and resources and if you want to share the one internet connection with the other PCs, share your server's hard drive with the client computers, share printer, fax, scanner, DVD writer then this information will help you make the right choice. Before starting the installation and configurations you should be aware of all the hardware, software, cables, drivers and all the necessary other things.
Basic Introduction
• STEP 1: Router: A router relays the data between your computers and your internet
• STEP 2: Network Adapter: A Network Adapter or NIC card is connected to each computer and
it is used to send the data to each every computer and the router.
• STEP 3: IP Address (Internet Protocol) is your computer’s unique identification on the
computer network and over the internet. In your home network and a small network of a
company all the computers share the same IP address over the internet.

• STEP 4: Print Server A print server is a specialized network adapter that is used to connect the
printer machine to a network and with the print server several computers in a network share
the same printer or print device.

How to Choose a Right Network Type
• STEP 1: Connecting your computer wirelessly over the radio waves is carried out by a
specialized router called an access point. One access point is enough for networking an
averaged sized home. The trade name of this technology is Wi-Fi or 802.11b. One important
thing is that all the Wi-Fi products should be compatible with each other. Wireless
communication is important for the people who go from room to room with their wireless
laptops or they want to use their laptops in airports, hotels, cafes and other places where
wireless service is available.
• STEP 2: Next you use your home’s wiring to connect the router to each computer with a
powerline network. HomePlug is the trade name of this technology. It is seen that HomePlug
networks are more secure than the Wi-Fi. But as compared to the Wi-Fi it is a new technology
and is more expensive than Wi-Fi technology.
• STEP 3: Hook up with the Ethernet 10-Base-T or 100-Base-7. Ethernet is the best choice if
your router, broadband internet connection and all the computers all in one room. Due to the
cabling, involved in the Ethernet, it’s less flexible than the others.

Buying Equipment Instructions
• STEP 1: First of all get one router and if you want to go wireless this router will called an access
• STEP 2: Next get compatible NIC cards for each computer and plug them into the computer’s
universal serial bus (USB
• STEP 3: If you are using a wired network the purchased extra long CAT 5 Ethernet cables.
• STEP 4: Next buy a print server if you want to put a printer in your home.One important thing
to note is that all the hardware should be compatible with each other.Setup Instructions
• STEP 1: First of all read the manuals of the devices and start experimenting. Many products
have good manuals and online support. You can easily get answers of the basic and advance
questions. Many manufacturers provide online help and advice so there is no need to worry
about any kind of technical support. Good technical support can save your lot of time and
efforts. So before starting make a thorough plan to work on it.
• STEP 2: If you are planning to install a wired Ethernet, then run the cables to your home
theaters or stereo. Now many new digital home products like digital video recorders and game
systems are having the internet capability.

General Tips
In summary you should look for these things for installing a home network such as Router or access point, Ethernet cables, NIC adapter, Print Server and the technical support from the vendor or a useful website or forum on the internet. Hybrid networks have many advantages and so they are very popular. For example, you can have Ethernet going to a desktop computer and printer in your home office and additionally wireless router or access point for a roaming laptop and desktop computer in your bedroom.

Some cordless phones and the microwave ovens can interfere with a wireless communication. If you have any interference problems then move the access point and router and place them at some different positions.

It is very important that when you setup your router for the first time at your home, change its password because every hacker on the internet can know the default password of a router. Additionally, while making the wireless connectivity you must enalbe the WEP to keep the information private and secure from the hackers.Additionally, install some anti spyware, good anti virus software on your server and client machines in your computer network and regulary update Windows operating sytem through the Microsoft's website.

What is Windows Networking?

Introduction To Windows Networking

The term networking covers a broad range of the topics and technologies. A computer network is segmented into different parts to share the data and resourced between the different computers of a network. Microsoft has released the operating systems that have the networking capabilities so Microsoft Windows 98, Microsoft Windows 2000, Windows 2003, Windows XP Professional and Windows Vista all are the network operating systems.
All these operating systems have built inn capabilities of files and printer sharing, security, network administrative control, protocols support such as TCP/IP, NetBIOS, IPX/SPX and network hardware support.

Naming Computers
All computers in a Windows based network requires a unique name for their identification i.e. the name of the computer A cannot be assigned to the computer B and so on. Assign a meaningful computer name to all the computers and the name should be easy to remember.

All the names should be configured properly and ensure that the name is not longer than the 15 characters and they contain no spaces in them. Also try to avoid the special names while naming the computers such as / \ *,:,. To assign a computer name in Windows XP and Windows 2000 do the following things.

1. Right click on the My Computer.
2. Click Properties
3. Click on Computer name.
4. Assign a unique and meaningful computer name.

Naming Workgroup and Domains
A Windows based computer network can be a workgroup (Peer to Peer) or domain (client/server). You can make your computer a part of the workgroup or a domain. If you have centralized server then your computer will be part of the domain and if you have no server then all computers will be having peer to peer networking. In both cases, while joining your computer to a domain or a workgroup always assign unique, sequenced, memorable and meaningful names to the computers. Do not use duplicate names and the special characters such as / \ *,:,,. In order to join a computer to a domain or workgroup in Windows 2000 and Windows XP Professional do the following.

1. Right Click on My Computer
2. Click Properties
3. Click on Computer Name
4. In Workgroup or domain, enter the name of the workgroup or domain.

If everything is correct such as unique computer name, unique IP address, correct workgroup or domain name then you computer will be the part of the workgroup or domain in the few seconds and you will be see a welcome to domain or workgroup message and will be prompted to restart the computer name.

Files Sharing
Being on network computer files and printer sharing is a must. To enable the files and folder sharing in Windows XP Professional 2000 and Windows 2000 do the following.

1. Right Click on the folder name you want to share.
2. Click on the properties.
3. Click Sharing.
4. Click on Share this computer on the network.
5. Assign a shared computer name.

You can set the sharing rights for the users and also control the shared folder access by allowing and denying permissions to specific users or groups. If you want to share the individual files, you can put the files in the same shared folder. All the files and folders in the parent shared folder will be automatically shared.

Network Cable Errors in Windows
If your computer network cable is not working properly, you will see a repeated message or pop up “network cable is unplugged” on your desktop and the blinking status lights of the network will also stop blinking. There can be many causes of this problem and you can fix this error with these simple tips. If you have another Ethernet adapter installed but not using it, then disable it by right clicking on the monitor icons on the right side of the desktop and select the disable option. Check both ends of the cables and ensure that the RJ 45 connectors are properly inserted in the LAN card and in the Hub/Switch. Update the drive of the LAN card from the vendor’s website and if the problem still exist then replace the cable with new one. If the problem is still not resolved then replace the LAN card with a new one and try to use a new hub or switch and put cable’s one end into it. By these simple steps, you will be able to trace out and troubleshoot the problem.

Introduction to Windows Firewall
Windows firewall is a protective layer or boundary that monitors the in and out traffic from your network and internet. The firewall is a protective and defensive boundary against the intruders and unauthorized persons. You can enable the firewall in XP Professional with these simple steps.

1. Click Start > Settings > Control Panel
2. Windows Firewall > Double click.

Network Troubleshooting Tips
If you find a communication failure error in the TCP/IP network then try to find and troubleshoot the errors with the following methods.

1. Make sure you can ping the other computer by name.
2. Make sure you can pint the other computer by IP address.
3. Make sure you have assigned unique IP address and computer name to all the computers in
the network.
4. Make sure you have assigned the correct gateway, subnet mask, DNS and DHCP addresses.
5. For troubleshooting purpose try to uninstall any firewall software and see if the problem is

Windows Network Security
Security a computer network should be the top priority of the network administrators, system managers and security specialists. You can secure your computer network by doing these things such as installing the updated operating system, up-to-date antivirus program, event log monitoring, encryption, group policy management, patch management, security scanners, auditing, firewall security, web application security, web content filtering and controlling the access to only the authorized users.

Mobile Network Technology

Introduction to Mobile Technology and Communications
Here you will learn about mobile technologies, mobile phones, wireless communication introduction, overview to gsm, gprs, sms and mms reviews. A cellular or mobile phone is a long range portable electronic device for communication over long distance.
Current Mobile Phones can support many latest services such as SMS, GPRS, MMS, email, packet switching, WAP, Bluetooth and many more. Most of the mobile phones connect to the cellular networks and which further connected with the PSTN (Public switching telephone network).

Mobile Network Technology
Mobile phones and their network vary very significantly from provider to provider and country to country. However the basic communication method of all of them is through the electromagnetic microwaves with a cell base station. The cellular companies have large antennas, which are usually mounted over towers, buildings and poles. The cell phones have low-power transceivers that transmit voice and data to the nearest sites usually within the 5 to 8 miles (8 to 13 kilometers away).

When a mobile device or phone is turned on, it registers with the mobile telephone exchange or switch. It is a unique identifier and is alerted by the mobile switch when there is an incoming phone call.

The handset listens for the strong signals from the nearest base stations. When a user moves, the mobile device handoff to various nearest sites during phone calls or while waiting between calls it reselect the nearest cell phone sites.

Cell sites have relatively less power radio transmitters. They broadcast their presence and relay communications between the mobile handsets and the switch. On the other hand, the switch connects the call to the same or another mobile network or subscriber. The dialogue between the mobile phone handset and the cell phone site is a stream of the digital data, which includes the digitized audio. This technology depends on the same system as of mobile phone operator. Some mobile phone technologies have adopted the AMPS for the analog communication and D-AMPS, CDMA2000, EVDO, GSM, UMTS, and GPRS for the digital communication. Each mobile phone network has a unique radio frequency.

There are different mobile communication methods, such as SMS, WAP, WLAN, WIFI, GPRS, Bluetooth, Infrared, IrDA and I-Phone etc. Mobile phones are different from the cordless telephones because they only operate within the specific range. Many types of the mobile computers have been introduced including the Laptop computer, Subnotebook, Portable data terminal (PDT), Personal digital assistance (PDA), Tablet personal computer and smart phone.

Mobile phone features
Mobile phones have features beyond sending text messages and making the short or long distance voice calls, the other features including internet browsing, mp3 playback music, email, personal organizer, built in cameras, MMS, PPT, SMS, call registries, built in games, voice mails, downloading, video call, Bluetooth, infrared and they also serve as the wireless modem for a pc. In many countries of the world such as Australia, Pakistan, India, Maldives and Israel the incoming calls are free. However, in Canada, Hong Kong and the United states a person can be charged per minute for the incoming calls. Few mobile phones carriers in the United States are beginning to receive unlimited phone calls. Mobile technology has both negative and positive impact on every day’s life.

Health impact
Since the invention of the mobile phones many concerns have been raised about the potential health from the mobile phones. Study at the Danish Institute of cancer epidemiology does not show any link between cancer and mobile phone usage. This study only covers the analog phone usage till 1995. However the study by the International Agency for research on cancer shows link between cellular phone usage and tumor frequency.

Mobile dating
Mobile dating also known as cell dating and it allows users to chat, meet and possible involves in romance by SMS, chatting and the web. These services allow their subscribers to provide information about themselves in a short profile and which is stored in the cell phone sets as a dating ID. The users can search for the other IDS or call at a number given to them by the service. Users can find others with the criteria of age, location and gender. Most of these sites are free to use but the standard fees of SMS and dating service charges can apply per minute. Mobile dating websites focus attention on users that share the same social network and proximity.Some cellular companies offer services such as homing device. This service alerts the users when someone is within the thirty feet of the user. Some cellular companies use Bluetooth technology to connect the users in the bars, clubs and social gatherings and this service is called proximity dating. These services are more popular in European countries, United States, Australia and Canada. Mobile dating websites are gaining popularity.

Mobile Learning
M-learning’ is the follow up of E-learning and which originates from D-learning (distance learning). M-learning is the delivery of education to the students who are not having fixed location or who prefer to use mobile phone technology for learning. The rapid growth in the mobile and communication sector make it possible to develop new forms of education. M-learning means delivery of education by means of the mobile phone devices, PDAs and audio players. M-learners seek the lessons in the small format.

Mobile software
Windows mobile, Palm OS and Symbian OS supports typical application binaries as found on the personal computers. Windows mobile also supports portable executable format which is associated with the .NET Framework. Both Windows Mobile and Palm OS provide free SDK and integrated development environment for the developers. BREW is another format which gives complete control of the handset and access to all its functions. Java (J2ME, Java ME) runs atop a virtual machine, which allows reasonable functionalities. Because of the extra security and compatibility, it is quite simple to write, distribute and execute the mobile Java applications.

Mobile Internet
According to the many sources, one of the major factors of the usage of mobile internet is its speed. Mobile internet has faster connection. Due to this fact, many users tend to use mobile internet. The introduction of the 3G cards has a competitive high speed. All the current service providers and trying to increase their bandwidth to get more customers. The numbers of mobile phones that are cable of surfing the net have been increasing rapidly. One of the greatest problems when browsing the net on the cell phones is the small size of the screen. Because of this many developers are developing the websites that can easily be seen on the cell phones as well
Mobile society.

Ongoing debates about the cyberspace, e-computing and E-commerce have suggested that the online world somehow will be dramatically different from the life in the analog world. It is true that E-commerce continues to grow and the specific locations of the persons and businesses do not matter that much anyone. This is also true that now we are seeing forums, blogs, discussion groups and social network to re-socialize and form new tribes on the internet. It seems that everyday we are increasingly connected via technologies such as email, cellular phones, instant messaging and all of these technologies are increasingly interconnected with each other. When we communicate on our cell phones, we are also mobile in the sense that we can move freely while in the constant communication.


Here you will get the software and hardware network gateway overview and general introduction, basic configurations, software configuration, bandwidth, firewall overview and routing methods. Gateway is a network point that acts as the entrance point to another network.

A gateway can be a hardware or software. On the Internet, a node or a stopping point can be a gateway or a host. A router also acts as a gateway. The computers that control and manage traffic and bandwidth within your company’s network or at the ISP are the gateway nodes. In the enterprise network the gateway node acts as a proxy server and a firewall. The gateway is also associated with a router and a switch.

A network gateway is an internetworking system that joins two networks together and it can be configured in software, hardware or both. Network gateway can operate at any level of OSI layers model.

The gateway has two sides: The WAN side connects to your cable DSL modem and LAN side connects to your private network via a hub or switch. The main function of it is to route the traffic from computer to the Internet and back to the computer. A computer with the two NIC cards can act as a gateway. It routes the network traffic between two logically and physically different networks.

In its configurations, you first configure the public side of the gateway and the IP address, which is assigned to you by your ISP. The public side configurations generally includes, assigning the IP address, DNS server, subnet mask, ISP gateway IP address and host name. Additionally, if your ISP uses PPPoE, you simply have to enable PPPoE in your gateway.

On the other hand to configure the private side , you have to enable DHCP. By enabling this feature each computer in your network, will automatically pick the settings from the DHCP server that are required for a computer to be a part of the network and communicate.

The last step in the configurations, is to configure each PC in such a way that it automatically gets the all the settings from the DHCP server. Make sure that TCP/IP protocol is properly installed in each computer of your network. After configuring each PC in your network perform a reboot.

After rebooting the each PC in your network, you will see a blinking underneath network icon on the right side of the task bar. If everything is done then you can access the internet, share the printer and data in your network. The firewall can also be configured with it to put a check on the unauthorized network traffic from the internet to your computer or network

The firewall can also be configured with it to put a check on the unauthorized network traffic from the internet to your computer or network.

Network Routing

What is Network Routing
You will be able to find the basic network routing overview, router configuration, router working, simulations static routes and routing table. Routing is the process of defining routes for the packets to its destination through an internetwork and this is performed by the router. Routing is consist of two separate tasks.

1. Defining paths for the packets through and internetwork.
2. Forwarding data packets based on their predefined paths. Generally, there are two types of

Routing can be performed by manually defining the routes or paths for packets to reach its destination. This is called static routing.

Stating routing works well for the small networks and when using the static routing, the routing table of the each router should be updated each time there is any change in the network configuration or topology. A router, whose routing table is not regularly updated, cannot communicate with the other routers.

While on the other end in most of the networks, routing is accomplished through the use of the dynamic routing. In the dynamic routing, routing protocols, such as RIP, OSPF etc create and maintain the routing tables of each router. Practically, dynamic routing functions very well than the static routing

A routing table is a set or rules, viewed in a tabular format and this used to define the routes of the data packets. All the network devices, which have IP, enabled functionality such as routers and switches use the routing tables. Routing table stores the information and configurations of every router in the IP enabled network. A routing table contains the information necessary to transmit the packets toward its destination.

When a packet is received, the network devices matches the information contained in the packets and the information in the routing tables and then it defines the shortest possible route for the transmission of the packets towards its destination.

Each packet contains the information of its origin and destination and the routing table contains the following information.
• Destination: The IP address of the packet’s final destination (next hop). Next hop: The IP
address to which the packet is forwarded
• Metric: It assigns the cost to each route so that most-effective paths can be picked up.
• Routes: It includes directly attached direct subnets, indirect subnets, that are not directly
connected to the device but it can be accesses through one ore more hops
• Interface: The outgoing network interface the device should use when forwarding the packet to
its final destination.

Routing tables can be maintained manually by the network administrator or by dynamically (automatically). The static network tables do not change unless the network administrator changes them. Routing tables can be maintained manually or dynamically. Tables for static network devices do not change unless a network administrator manually changes them. In the dynamic routing, the network devices such as routers and switches maintain the routing tables dynamically by using the routing protocols, such as RIP, OSPF etc. In the dynamic routing, the network devices listen and detect any network or devices failure and packet congestions.

Routing in the Internet
Routing is the method in which data finds its destination from one computer to the next. In the Internet there are 3 major aspects of routing.

1. Physical Address Finding
2. Determination of inter-network gateways
3. Numeric and symbolic Addresses

Physical address finding is the method of the Internet Routing and is used when datagram is transmitted from a computer. It is necessary to encapsulate the IP datagram. This encapsulation requires the local network or physical address.

If a computer wishes to transmit IP datagram it needs to encapsulate the physical address of the destination network device in the frame. This address can be achieved by using the table that will map the IP address with the physical address. Such table can be configured into a file that can be read into the memory at the boot up time. Computer normally uses the Address

Resolution Protocol (ARP), which operates dynamically to maintain the translation table.
The second method is necessary because the Internet consists of a large number of local networks, which are interconnected with each other by gateways. Such gateways are known as routers, which has physical as well as logical connectivity with many networks.
The determination of the best suitable gateway and port for a particular IP address is called routing.

The third method generally involves the translation of the human friendly form (names) to the number address (IP Address). IP address can’t be remembered due to its numeric form but the simplest names (domain names) are easy to remember e.g,, are easiest to remember as compared to the IP addresses,, DNS translates the domain names into the IP address and IP address into the domain name. This domain to IP translation is a must for communicating on the Internet because communication on the Internet is performed by the IP addresses.

Communication between routers
The Internet is a network of networks. The Internet consists of large number of autonomous systems, each of which further consists of routing domains. Such autonomous systems are usually run by the larger companies or universities. Within the Autonomous system, a router communicates with the other router using the best intra domain routing protocols, which are known as interior gateway protocols. Autonomous system are connected via gateways, these exchange information using inter domain routing protocol, which are also called exterior gateway protocols.

The RIP or (Routing Information Protocol) is the commonest interior gateway protocol and the recent protocol such as open shortest path first (OSPF). The purpose of these protocols is to enable routers to exchange locally so that all the routers in the autonomous system must a have coherent and up to date information.

When a host receives the new routing information, it is likely to update not only to it but also sends this new updated information to all the connected hosts so that they can updated themselves. Hence these changes propagate across the entire network.

Wireless Networking

An Overview of the Wireless Networking
Here you will find wireless networking tutorials, what is wifi, general security overview, wlans, wpans, wmans, wep and wireless access control overview. Whether you want to make a phone call from your mobile, received a message on your pager, checked your email from a PDA we have come across a wireless data or voice network.

If a user or a company wants to make a data portable then Wireless networking is the answer. A wireless networking system can avoid the downtime, which may be caused in the wired network. A wireless network is also save your time and efforts in installing the lot of cables.

Also, if you need to relocate a client machine in your office, you only need to move the computer with wireless network card.

Wireless networking is very useful in the public places, libraries, hotels, schools, airports, railway stations where one might find wireless access to the internet. A drawback in the wireless internet is that quality of service (QOS) is not guaranteed if there is any interference then the connection may be dropped.

Wireless Network Types
Wireless Local Area Networks (WLANS)
WLANS allow users in local area, such as in a university or a library to form a network and gain wireless access to the internet. A temporary network can be formed by a small number of users without the need of access point; given that they do not need to access the resources.

Wireless Personal Area Networks (WPANS)
There are two current technologies for wireless personal network Bluetooth and Infra Red. These technologies will allow the connectivity of personal devices within an area of 30 feet. Infra Red requires a direct line and the range is less as compared to Bluetooth technology.

Wireless Metropolitan Area Networks (WMANS)
WMANS allow the connectivity of multiple networks in a metropolitan area such as building in a city. The network connectivity is the alternative of copper or fiber cabling.

Wireless Wide Area Networks (WWANS)
WWANS or Wireless Area Networks can be maintained over large areas such as in different cities or between different countries, via multiple satellite systems or antenna sites. The types of system are called 2G systems.
The following table shows the range those different types of wireless network covers.
Network Meter
Personal Area Network 0-10
Local Area Network 0-100
Wide Are Network 0-10000
Security in Wireless Networking
The following different types of security methods are available in the wireless networking.

Wired Equivalent Privacy (WEP)
Wired Equivalent Privacy is intended to stop the interference of radio frequency that is signaled by unauthorized users and this security measure is most suitable for the small networks. There is not key management protocol and each key is entered manually into the clients that’s why this is very time consuming administrative task. The WEP security method is based on the RC4 encryption algorithm. In the WEP all the client computers and Access points are configured with the same encryption and decryption keys.

Service Set Identifier (SSID)
Service Set Identifier (SSID) acts a simple password by allowing WLAN network to be split up into different networks and each having a unique identifier. These identifiers are configured in the multiple access points. To access any of any networks, a computer is configured in such a way that each is having a corresponding SSID identifier for that network. If the SSID match between the two computers or networks then access is granted to each other.

Media Access Control filtering (MAC Access Control)
A list of the MAC addresses of the client computers can be inputted into an Access point and only those computers are granted to give the access to the network. When a computer makes a request, its MAC address is compared to the list of the MAC addresses to the Access point and based on this access permission granted to deny.This is a good security method but it is mainly involved in the small wireless networks because there is more manual work is involved of entering the MAC address into the Access point.

Bluetooth is a simple type of the wireless networking that operates in the digital devices, like mobiles phones, personal computers, PDA, Laptops, digital camera, MP3 players and other Bluetooth enabled devices to form a small network. In the Bluetooth technology eight devices can be connected to each other at the same time. Bluetooth can also be found in the headsets, hands-free kits, wireless keyboards and mouse. Bluetooth technology was invented by Ericsson in 1994 and after four years in 1998 some major mobile phone companies such as Nokia, Ericsson, Intel and Toshiba formed a group to promote this technology.
Bluetooth technology falls in the category of personal area networking because it operates in the range of 30 to 300 feet. Bluetooth uses the radio waves technology, which is not very expensive and has low power consumption. Many different companies are intended to add the Bluetooth chip in their digital devices. Bluetooth technology is getting very popularity because of its low cost and portability.

The Future of Wireless Networking
WLANS wireless networking type is very popular in home networking and more than 20 percent homes with broadband internet are using WLANS and this number is increasing. In a general estimate worldwide hotspots have now reached more than 30,000 and will grow about 210,000 in the next few years. Most large hotels already offer Wi-Fi and the business travelers are willing to pay wireless access. 802.11 is the next Wi-Fi speed standard is set to offer bandwidth around 108Mbps and is still under development. With the speed of 70 Mbps and a range up to 30 miles, the 80216 standard, known as WiMAX is sure to get boost.

Some Tips & Tricks
• When purchasing a wireless NIC card try to get one that is having external antenna. When you
are out and using Wi-Fi enabled laptop, disable Microsoft file and sharing, which enables other
computers in a network to access data and resources on your computer. In this way, your
computer or laptop will be saved from hackers.
• If you are concerned about the interference from the other wireless access point set the AP and
wireless computers to use a non-overlapping channel.
• Change the configuration interface password of the access point before you enable it.
• Only buy an access point that is having upgradeable capabilities. By this way you can take the
advantage of security enhancements.
• Keep the access point up to date.

OSI 7 Layers Reference Model

Here you will learn OSI Model Layer Introduction, overview of the 7 OSI reference model, applicaion, session, transport, network and physical layers. If you want to remember the sequence of the OSI layers model name then the following two sentences can help you a lot for this purpose.“All People Seems To Need Data Processing”. Open Systems Interconnection (OSI) model is developed by ISO (International organization for standardization) in 1984. OSI reference model is a logical framework for standards for the network communication.

OSI reference model is now considered as a primary standard for internetworking and inter computing. Today many network communication protocols are based on the standards of OSI model. In the OSI model the network/data communication is defined into seven layers.
These 7 layers further divide the tasks of moving the data across the network into subtask and hence complete one communication cycle between two computers or two network devices. Each layer is assigned a task and the task is completed independently. The OSI layers have the clear and independent characteristics and tasks.

The 7 layers of the OSI models can be divided into upper and lower layers. I have defined the characteristics, tasks and features of each layer separately.

Layer 7: Application Layer
The application layer defines the interfaces for communication and data transfer. This layer also provides and support services such as job transfer, handles network access, e-mail, supports user applications and error recovery.

Protocols: FTP, DNS, SNMP, SMTP, FINGER, TELNET, TFTP, BOOTP and SMB protocol are operated on the application layer.
Network Devices: Gateway network device is operated on the application layer.

Layer 6:Presentation Layer
The presentation layer presents the data into a uniform format and masks the difference of data format between two dissimilar systems. It also translates the data from application to the network format. Presentation layer is also responsible for the protocol conversion, encryption, decryption and data compression. Presentation layer is a best layer for cryptography.
Network Devices: Gateway Redirector is operates on the presentation layer.

Layer 5: Session Layer
Session layer establish and manages the session between the two users at different ends in a network. Session layer also manages who can transfer the data in a certain amount of time and for how long. The examples of session layers and the interactive logins and file transfer sessions. Session layer reconnect the session if it disconnects. It also reports and logs and upper layer errors.
Protocols: The protocols that work on the session layer are NetBIOS, Mail Slots, Names Pipes, RPC Network Devices: Gateway

Layer 4: Transport Layer
Transport layer manages end to end message delivery in a network and also provides the error checking and hence guarantees that no duplication or errors are occurring in the data transfers across the network. Transport layer also provides the acknowledgement of the successful data transmission and retransmits the data if no error free data was transferred. It also provides and error handling and connectionless oriented data deliver in the network.
Protocols: These protocols work on the transport layer TCP, SPX, NETBIOS, ATP and NWLINK. Network Devices: The Brouter, Gateway and Cable tester work on the transport layer.

Layer 3: Network Layer
The network layer determines that how data transmits between the network devices. It also translates the logical address into the physical address e.g computer name into MAC address. It is also responsible for defining the route, managing the network problems and addressing. Router works on the network layer and if a sending device does not break the data into the similar packets as the receiving device then network layer split the data into the smaller units and at the receiving end the network layer reassemble the data.
Network layer routes the packets according to the unique network addresses. Router works as the post office and network layer stamps the letters (data) for the specific destinations. Protocols: These protocols work on the network layer IP, ICMP, ARP, RIP, OSI, IPX and OSPF. Network Devices: Network devices including Router, Brouter, Frame Relay device and ATM switch devices work on the network layer.

Layer 2:Data Link Layer
Defines procedures for operating the communication links
Frames packets
Detects and corrects packets transmit errors
Protocols: Logical Link Control
• error correction and flow control
• manages link control and defines SAPs802.1 OSI Model
802.2 Logical Link Control Media Access Control
• communicates with the adapter card
• controls the type of media being used:
802.3 CSMA/CD (Ethernet)
802.4 Token Bus (ARCnet)
802.5 Token Ring
802.12 Demand Priority Network Devices: Bridge
NICAdvanced Cable Tester

Layer 1: Physical Layer
Physical layer defines and cables, network cards and physical aspects. It defines raw bit stream on the physical media. It also provides the interface between network and network communication devices. It is also responsible for how many volts for 0 and how many for 1. Physical layer also checks the number of bits transmitted per second and two ways or one way transmission. Physical layer also dealing with the optical, mechanical and electrical features.
Protocols: Protocols that work on the physical layer are ISDN, IEEE 802 and IEEE 802.2 Network Devices: Hubs, Repeaters, Oscilloscope and Amplifier works on the network devices.

Introduction to ISDN Line

Find here ISDN Network, introduction to ISDN line, bri, t1 lines, d1 lines, primary rate interface, connection time and setup instructions. The regular phone line, which is used at home and offices is an analogue phone line. Your voice is picked up by telephone mouthpiece and then sent down the phone line as an analogue wave. Regular modem converts the digital signals of the computer into the analogue waves, which then travels on the regular phone lines. At the other end, modem receives that analogue signals and then convert back into the digital signals that are understandable by a computer

ISDN network is a digital communication system that is capable of producing the maximum transmission speed of 1.4Mbps. 128Kbps speed is however more common in the digital technology. It's a international standard for sending data, voice, video over regular digital telephone lines. ISDN uses UTP (unshielded twisted pair cable) for transmission.

Types of ISDN Network
There are two basic types
• Basic Rate Interface (BRI) – It consists of two 64 B-channels and one D-channel for
transmitting control information.
• Primary Rate Interface (PRI) -- It consists of 23 B-channels and one D-channel (for U.S.) or 30
B-channels and one D-channel (for Europe).

The actual version of ISDN employs base band transmission. Another version, called B-ISDN, uses broadband transmission, which is able to support transmission rate of 1.5 Mbps. B-ISDN mainly requires fiber optic cables.

To access the B channel, it is necessary to subscribe the ISDN phone line. Customers are also required to have some special ISDN devices, which are known as terminal adapters, which are used to communication with the telephone company switch or other ISDN devices.

How ISDN Works
In an analog network, a regular telephone line that is provided by the telephone company supports a single transmission channel, which normally can carry only one service, voice, data or video at a single time. With ISDN, this same pair telephone line is logically divided into the multiple channels. A typical line has two channels.

The first type of channel is called B channel. This channel can carry about 64Kbps of data. Typical ISDN line has 2 B channels. One channel is used for voice and other channel is used for data communication. This data/voice transmission process occurs on the regular one pair copper wire.

The second type of channel is used for link and call setup. This channel is known as D channel or Delta Channel.

The third channel has only 16Kbps of bandwidth.


There is an upper limit of the speed in the commonly used dial up modems, which is 56kbps. But due to the quality and other factor, the maximum attainable speed is 45kbps. ISDN allows multiple digital channels to operate simultaneously through the same regular one pair copper wire. If the telephone company supports the digital connections then a change can occur. The digital signals instead of the analogue signals, transmitted across the telephone line. In the digital scheme, there is much more data transfer rate than the analog lines.

Multiple Devices
A separate telephone line is required for using the fax, telephone, computer, router and live video conferencing systems. A separate line is required for each device. ISDN network lines can handle the multiple devices on the single line. Up to eight devices such as, computer, faxes, cash registers, credit card readers or other devices can directly be connected to a single ISDN line, all these devices can work simultaneously.

Connection Time
V.34 modems typical take 30-60 seconds to establish a connection and on the other end an ISDN call usually takes less than 2 seconds to establish a connection. DisadvantagesThere are some disadvantages of the ISDN lines, which I have discussed below.1. ISDN is more expensive than the Plain old telephone system. 2. The telephone company and the ISDN user both are required to have the specialized digital devices.

There is a noticeable difference between the two services.
• ISDN provides two voice channels or one 128Kbps data channel while ADSL is basically a data
• The power for ADSL is sent by carrier over copper wire; as with the local phone service. The
line works even when local power fails. This is an advantage over the ISDN lines, which
requires the local power supply.

What is Ethernet ?

In this section you will learn about the lan terminology, basic ethernet networking overview, a general introduction to LAN, introduction to IEEE, lan topologies, wan standards. You can also find these categories in this site such as network tutorials, computer networking guide, what is networking, tech study guides, topologies, what is data recovery, wireless communication, computer interview questions and network certification. The IEEE standards have been developed by the International Standards Organization (ISO). The Institute of Electrical and Electronic Engineers (IEEE) in 1985 produced a series of standards for the Local Area Networks, which are called IEEE 802 standards.

These standards have been accepted widely throughout the IT world. One of the IEEE 802 standards, the IEEE 802.3 is known as “Ethernet”. Ethernet is the most widely used LAN technology. Ethernet was developed by Xerox corporations in 1972 and it was the first LAN.
According to the ISO standards allows manufactures to produce the devices and equipments, which are guaranteed to operate anywhere.

The Ethernet in its simplest form uses a passive bus that operates at 10 Mbps. The bus is formed from the co-axial cable, which connects all the PCs in the LAN.

A single LAN may have 1024 attached computers, although in the real practice most LANS have fewer computers than this number. One or more segments of the co-axial cable are attached to end to end to create the Ethernet Cable Segment. Each segment is terminated by 50 ohm resistors.

In today’s IT world the reliable and timely access to the information has become vital. Today coworkers thousands of miles apart from each other can share data, voice, video etc with the fractions of seconds. Similarly a larger number of the coworkers can review the research data simultaneously. The Internet allows businesses to share information and resources with their customers.

Ethernet is a communication protocol that is embedded in software and hardware devices that intended. Ethernet has become the standard computer networking protocol with the help of the Xerox, Intel and Digital

A basic LAN consists of the following components.
• Two or more computers.
• Network Interface card or LAN Card in each PC.
• Ethernet cable (Cat5, UTP/SPT) cable to connect the two computers.
• A hub, switch or router to route or direct the network traffic.
• Software for the communication/computer networking.

A network interface card (NIC) is attached and installed in each PC and is assigned a unique address. An Ethernet cable is used to connect two computers; Ethernet cable has RJ45connectors at both ends. There can be two scenarios 1. Two computers can directly connect with each other or 2. Each computer is directly connected with the hub/switch and hence communication occurs in the network. The hub or switch acts as relay.

Computer Network can be wireless. Despite of using Ethernet cable for the communication, Wireless Network Interface cards use radio waves to communicate with the wireless switch or hub. A small antenna is used in the wireless NICs, switches and hubs. Although the wireless networks are more easy to use as compared to the cabled networks, but more configurations and extra care is required to setup and run a wireless network.

The alternate technologies to Ethernet are “Token Ring”, which is used in the Ring Topologiesnetworks. Token Ring is designed by the IBM and ATM. In ATM networking, devices are connected with each other over a very large distance (thus forms the WAN), and behaves like LANs.

Ethernet is a well established and widely used network standard for small to medium sized Ethernet networks as well as for other networks. Ethernet has been used over the 3 decades and forms a very excellent networking/communication environment. Ethernet TermsEthernet follows a simple set of rules. To understand these rules its important to understand the
following terminology.
• Node – The devices that are attached to the segments are nodes.
• Frame – The nodes (computers or network devices) communicates in the form of short
messages that are known as frames. The frames are chunks of information with variable size.
• Segment – A single shared medium is known as a Ethernet segment.
• Medium – The Ethernet devices are attached to a common medium. The frames of the data
travel along with that medium. This medium can be coaxial cable. Today most commonly used
communication mediums are UTP/STP cable, fiber optic cables.

Frames are analogous in human language. We have some rules for constructed the sentences.

Ethernet protocol specifies a set of rules for constructing the frames. The frames length varies.
Each frame must contain source and destination address for the identification of the recipient and the send of the message. The nodes can be uniquely and easily identified. Each Ethernet devices must have a single unique address.

Compute networking standards has brought a revolution in the network computing and it made the communication very easy and standarized. Now every computer and networking devices has to to follow the same standard to communicate with each other.

Router Commands Overview

In this section you will learn about the router commands, configurations, privileged mode commands, routing protocols, cisco labs and network configurations.
There are hundreds of basic and advance level commands of a router. It is not easy to remember all the commands. But some commands are frequently used and can be remembered with some practice. I have provided a list of the most commonly used commands based on their features and usage.

You will find here some basic terminology of a router.

Routing: Routing is a process of moving the data (packets) through an inter network. Routing performs the two basic tasks. Define the paths for a packet and then forward the packets on the basis of defined paths. Routing can also be defined as the communication between two or more logically and physical networks and this communication (packet transfer) is brought by a router.

First of all you should remember the keyboard shortcuts of a router.

Keyboard Shortcuts

CTRL-N - show next command
CTRL-P - show previous command
SHIFT-CTRL-6 – Break

Configuring the Router
You will be able to learn the basic commands for configuring a router.

sh running-config - details the running configuration file (RAM)

sh startup-config - displays the configuration stored in NVRAM

setup - Will start the the automatic setup; the same as when you first boot the router

config t - use to execute configuration commands from the terminal

config mem - executes configuration commands stored in NVRAM; copies startup-config to running-config

config net - used to retrieve configuration info from a TFTP server

copy running-config startup-config - copies saved config in running config (RAM) to NVRAM or "write memory" for IOS under ver.11

copy startup-config running-config - copies from non-volatile (NVRAM) to current running config (RAM)

boot system flash - tells router which IOS file in flash to boot from

boot system tftp - tells router which IOS file on the tftp server to boot from

boot system rom - tell router to boot from ROM at next boot

copy flash tftp - Copies flash to tftp server

copy tftp flash - Restores flash from tftp server

copy run tftp - Copies the current running-config to tftp server

copy tftp run - Restores the running-config from tftp server

General Commands
Here is a list of the general commands.

These are the basic level commands and most commonly used

no shutdown - (enables the interface)reload - restarts the router

sh ver - Cisco IOS version, uptime of router, how the router started, where system was loaded from, the interfaces the POST found, and the configuration register

sh clock - shows date and time on routersh history - shows the history of your commands

sh debug - shows all debugging that is currently enabled

no debug all - turns off all debugging

sh users - shows users connected to router

sh protocols - shows which protocols are configured

banner motd # Your customized message here # - Set/change banner

hostname - use to configure the hostname of the router

clear counters - clear interface counters

Privileged Mode commands of a router
Learn how to work in the privileged mode of a router.

enable - get to privileged modedisable - get to user mode

enable password - sets privileged mode password

enable secret - sets encrypted privileged mode password

Setting Passwords on router

Here you will be able to learn how to set the password on a router.

enable secret - set encrypted password for privileged accessenable password - set password for privileged access (used when there is no enable secret and when using older software)

Setting the password for console access:
(config)#line console 0



Set password for virtual terminal (telnet) access (password must be set to access router through telnet):

(config)#line vty 0 4



Set password for auxiliary (modem) access:

(config)#line aux 0



Router Processes & Statistics
By these command you can see the statistics and different processes of the router.

sh processes - shows active processes running on router

sh process cpu - shows cpu statistics

sh mem - shows memory statistics

sh flash - describes the flash memory and displays the size of files and the amount of free flash memory

sh buffers - displays statistics for router buffer pools; shows the size of the Small, Middle, Big, Very Big, Large and Huge Buffers

sh stacks - shows reason for last reboot, monitors the stack use of processes and interrupts routines

IP Commands
Here is a list of the IP Commands

Configure IP on an interface:

int serial 0

ip address

int eth 0

ip address 2008.1.1.4

Other IP Commands:
sh ip route - view ip routing table

ip route [administrative_distance] - configure a static IP route

ip route - sets default gatewayip classless - use with static routing to allow packets destined for unrecognized subnets to use the best possible route

sh arp - view arp cache; shows MAC address of connected routers

ip address secondary - configure a 2nd ip address on an interfacesh ip protocol

CDP Commands (Cisco Discovery Protocol uses layer 2 multicast over a SNAP-capable link to send data):

sh cdp neighbor - shows directly connected neighbors

sh cdp int - shows which interfaces are running CDP

sh cdp int eth 0/0 - show CDP info for specific interface

sh cdp entry - shows CDP neighbor detailc

dp timer 120 - change how often CDP info is sent (default cdp timer is 60)

cp holdtime 240 - how long to wait before removing a CDP neighbor (default CDP holdtime is 180)

sh cdp run - shows if CDP turned on

no cdp run - turns off CDP for entire router (global config)

no cdp enable - turns off CDP on specific interface

IPX Commands
Enable IPX on router:

ipx routing

Configure IPX + IPX-RIP on an int:

int ser 0ipx network 4A

Other Commands:
sh ipx route - shows IPX routing table

sh ipx int e0 - shows ipx address on int

sh ipx servers - shows SAP table

sh ipx traffic - view traffic statistics

debug ipx routing activity - debugs IPS RIP packets

debug ipx sap - debugs SAP packets

Routing Protocols
RIP, IGPR and OSPF are the routing protocols and here is a list of the commands for the working on the routing protocols.

Configure RIP:

router rip



Other RIP Commands:

debug ip rip - view RIP debugging info

Configure IGRP:

router IGRP 200



Other IGRP Commands:

debug ip igrp events - view IGRP debugging info

debug ip igrp transactions - view IGRP debugging info

Access Lists
Here is a list of the Access list command of a router.

sh ip int ser 0 - use to view which IP access lists are applies to which int

sh ipx int ser 0 - use to view which IPX access lists are applies to which int

sh appletalk int ser 0 - use to view which AppleTalk access lists are applies to which intView access lists:

sh access-lists

sh ip access-lists

sh ipx access-lists

sh appletalk access-lists

Apply standard IP access list to int eth 0:

access-list 1 deny

access-list 1 permit any

int eth 0

ip access-group 1 in

Apply Extended IP access list to int eth 0:

access-list 100 deny tcp host host eq 23

access-list 100 deny tcp any eq 80

int eth 0ip access-group 100 out

Apply Standard IPX access list to int eth 0:

access-list 800 deny 7a 8000

access-list 800 permit -1

int eth 0ipx access-group 800 out

Apply Standard IPX access list to int eth 0:

access-list 900 deny sap any 3378 -1

access-list 900 permit sap any all -1

int eth 0

ipx access-group 900 out

WAN Configurations Commands
Networking over WAN is the main functionality of a router. The most common use of a router is for the WAN connectivity. Here is a list of the commands for the different methods of the WAN connectivity.

PPP Configuration
Point to point protocol is a method for the WAN connectivity and you will find here some commands of PPP.

encapsulation pppppp authentication

ppp chap hostname

ppp pap sent-username

sh int ser 0 - use to view encapsulation on the interface

Frame-Relay Configuration
One of the methods for the WAN connectivity is the Frame Relay. Find here some basic commands for the WAN connectivity through Frame Relay.
Encapsulation frame-relay ietf - use IETF when setting up a frame-relay network between a Ciscorouter and a non-Cisco router
Frame-relay lmi-type ansi - LMI types are Cisco, ANSI, Q933A; Cisco is the default; LMI type is auto-sensed in IOS v11.2 and up
Frame-relay map ip 100 broadcast - if inverse ARP won't work, map Other IP to Your DLCI # (local)

Keep alive 10 - use to set keep alive

sh int ser 0 - use to show DLCI, LMI, and encapsulation info

sh frame-relay pvc - shows the configured DLCI's; shows PVC traffic stats

sh frame-relay map - shows route mapssh frame-relay lmi - shows LMI info

Miscellaneous Commands
In the last but not least here is a list of the some miscellaneous and useful commands

sh controller t1 - shows status of T1 lines

sh controller serial 1 - use to determine if DCE or DTE device

(config-if)#clock rate 6400 - set clock on DCE (bits per second)

(config-if)#bandwidth 64 - set bandwidth (kilobits)

Introduction to Network Security

You will find here network security overview, networking solutions, anti virus, anti spamming tips, trojan horses, malware, adware. Security is an essential element in maintaining any network. The main focus of the IT managers and computer network administrators is to secure the computer networks.

Users are happy to get the data on time and without any problem. The use of the authentication and biometrics can improve the security to some extend. Computer Security in the data communication cannot be compromised. Hackers’ can exploit the sensitive and financial and corporate data. There can be many threats to a computer network and it’s the responsibility of a computer network administrator to keep the computer network secure from these threats.

IT Administrator should know about all the possible security attacks and also know their solutions. IT Administrator should look for the viruses from the Internet, Malware, Adware, Trojan horses, E-mail attachments, Floppy disk, CD or any infected computer that is attached to the network. Spyware and network intrusions are specifically designed to get the secret information from their target companies, which can do harm for the company. Everyday security threats are refined as hackers designed new security threats.

The main cause of a security threat in the small companies is the misuse of the internet without proper anti virus, anti spyware installed on the every PC of the company’s network. For example if a company’s employees browse an inappropriate website, sends or receives the infected data, leaks company’s secret information, then there are greater chances for a possible virus/malware attack.

In my opinion, the end user’s education on the security threats, preventions and precautionary measures are must. They should be trained about the possible and easy virus attacks from the internet if they browse the inappropriate sites.
Another important thing is the insider’s attack e.g if the company’s employee leave the company for any reason, then its very important that all the computer and other company’s sensitive assets access should be revoked by him immediately. I have personally seen a situation, when a company’s network administrator was dismissed and he access the company’s server by VPN and send harmful viruses to the server and the entire computer network, and it was impossible for the IT manager to control all the security attacks in one time.

It’s the responsibility to keep a closer eye on the new employee’s activities, their access to the sensitive data, and computers servers. IT managers should bring it in the knowledge of the employees that any change in their computer will be logged. So that nobody can even try to do anything that is not permitted.
There are six basic security steps for the Windows platforms. If a network administrator can follow these steps then he/she can save the computerss from all the possible security threats and virus or malware attacks.

First the IT managers should divide the computer network into the segments. They should filter the access to the internet with the help of a firewall by blocking TCP port 1433 and TCP port 1434. Internet access from the outside should be allowed to the SQL systems. All the unwanted ports should be blocked and only the required ports should be open for access.

Second, moderate the affect of the spoofed ports. The port 80 is the most commonly used port.

Third, as network administrator you should install the current patches to you’re your server computer and client’s up to date. Patches can prevent the systems from the known vulnerabilities. Latest patches can be downloaded from the Windows website. You can also configure to automatically update. Also third party patches products are also available that can be tested and installed. Additionally, by strengthening the user authentication process can be very helpful for security purposes.. You can use password security and other technological methods for the authenticate purpose.

Fourth, you can limit the number of the network administrators it can also be helpful for security a computer network. Admin rights should not be given to the local PC, until and unless it is the requirements for the applications that are installed on the local PCs.

Fifth, protect computers against the known attacks. Don’t disable any Windows known service such as clipbook, Telnet etc. Set the powerful permission the shared network resources.

Last, you can configure the security policies. Implement the security policies on your network.

Security measures and methods have expenses with their purchases. Deployment, maintenance and the implementations of these methods can increase the security cost. Some other things which a IT administrator or a IT manager should keep in mind are the education of the employees about the computer networking, security, use of the encryption and digital right management software, block the unwanted emails and audit security on the regular basis.
Network security methods should be used and implemented in order to prevent your computer network from the unauthorized access.

In this article you have discovered the Computer Network Security Overview More topics to come are Cisco Labs, Routing, IP addressing & Free IT resources.

Introduction to the Network Communication Devices

In this tutorial you will learn get the basic introduction to network devices such as nic adapters, routers, hubs, switches, modems, communication cables, lan/wan routers, gateway and other devices. A network is consists of a larger number of the communication devices. The simplest device that is used in the communication is the NIC adapter which is attached with the every computer in a network. If you want to build a LAN, you will need to have computers, hubs, switches, network adapters, UTP/STP cables, routers, internal/external modems, connectors, cable testers and clipping tool.

If the hub fails to work, the communication between the computers stops till the hub again starts working. Hub broadcasts the data to its every port, and then finding the destined computer, the data sent toward it. The switch is an advance form of the hub similar in functions but the advanced switches has a switching table in them. A advanced switch stores the MAC address of every attached computer and the data is only sent to the destined computer, unlike the hubs where data is sent to all ports. A router is a key device in the internet communication and wan communication system. A router has software called routing table and the source and destination addresses are stored in the routing table.

A router connects two logically and physically different networks. Router finds the IP address of the next hop (next router) and the data is sent toward it and so on. The well known routers developing companies are Cisco systems, Nortel, DLink and others. Every ISP, banks, corporate offices and multinational companies use routers for LAN and WAN communications and communication in their private networks. A gateway can be device or software in a network.
A gateway device connects the LAN with the internet. A gateway is directly exposed to the internet so it should be securely configured and in and out traffic should be monitored. If you are using DSL connection, you must need a DSL modem in your network. The telephone line is connected with the DSL modem and UTP/STP cable attaches your computer with the DSL modem. Modems are the devices that are used to modulate and demodulate the data. They convert analogue signals to digital and digital signals to analogue so that signals can travel on the telephone lines.

There are certain types of the cables that are used to connect two or more computers in a network. Fiber optic cable acts as a backbone between the ISPs and corporate offices. Data travels at the speed of light on the fiber optic cables. The cost and the installation cost of the fiber optic cable is very high but it is becoming very popular in the home networking and LANs also. In the local area networking, 10baseT/CAT5 cable is most commonly in use.

A server is a computer in network that provides services to the client computers such as logon requests processing, files access and storage, internet access, printing access and many other types of services. Servers are mostly equipped with extra hardware such as plenty of external memory (RAM), more data store capacity (hard disks), high processing speed and other features.

How to Configure a Network

In this section you will learn how to configure a network, peer to peer, client server, workstation, server, basic data communication.

Peer to Peer network model
Before configuring a computer network, you have to decide that, which networking model you require. There are two main types of network models. Peer to peer and client-server network model. In the peer to peer network model you simply use the same Workgroup for all the computers and a unique name for each computer.
Additionally, you will have to give a unique IP address of the same class A, B, or C for all the computers in your network and its related subnet mask e.g if you decide to use class A IP address for your three computers in your Peer to Peer network then your IP address/Subnet mask settings can be as follows.

Computer Name IP Address Subnet Mask Workgroup
PC1 Officenetwork
PC2 Officenetwork
PC3 Officenetwork

Client/Server Network Model
In the client/server network model a computer plays a centralized role and is known as a server all other computers in the network are known as clients. All client computers access the server simultaneously for files, database, docs, spreadsheets, web pages and resources like hard diver, printer, fax modem, CD/DVD ROM and others. In other words, all the client computes depends on the server and if server fails to respond or crash then networking/communication between the server and the client computes stops.

If you want to configure a client-server network model then first prepare the server. Install Windows 2000 or Windows 2003 Server from the CD on the server computer and make a domain. You can create a domain by this command on the Run “DCPROMO”. You can give this command once you install the server successfully. After you give the DCPROMO command you will be asked for a unique domain name. All the client computers will use the same unique domain name for becoming the part of this domain. This command will install the active directory on the server, DNS and other required things. A step by step wizard will run and will guide you for the rest of the steps. Make sure that a network cable is plugged in the LAN card of the server when you run the DCPROMO.exe command.

When the Active directory is properly installed on the server, restart the server. You can create network users on the server computer and also name/label the network resources like computers/printers etc.

Once you install the server successfully now come to the client computers. Install Windows 2000 professional on your all client computers. Once you install the Windows 2000 professional on the clients the next step is to make this computer (client computer) a part of the network.

Configuration Steps
1. Choose a unique name for each client computer
2. Choose unique IP address for each computer and relevant.
3. Use the same domain name for all client PCs.

Network/System administrators are required to do these administrative tasks on the server and client computers. Any shared resources on the network either on the server or the clients can be access through the My Network Places in the Windows 2000 platform. There is another way to connect to the shared resources by giving this command in the run \\ComputerName\SharedDriveLetter

Network configurations steps can be implemented by right clicking the My Computer>Properties>

For giving the IP address you will have to right click on the My Network places>properties>Local Area Connection>Properties>Internet Protocols (TCP/IP)>Properties and then give the IP address and subnet mask of the same range and class for all the computers in the network