Introduction To Network

INTRODUCTION TO NETWORK

A network is a collection of computers and devices connected to each other. The network allows computers to communicate with each other and share resources and information.Or A network is a group of computers, printers, and other devices that are connected together with cables. Information travels over the cables, allowing network users to exchange documents & data with each other, print to the same printers, and generally share any hardware or software that is connected to the network. Each computer, printer, or other peripheral device that is connected to the network is called a node.
For making one Network minimum size of Computers should be 2, while maximumThere could be Millions of Computer. In one netwo6rk there could be different ComputerAnd different NOS (Network Operating System).
The Advance Research Projects Agency (ARPA) designed "Advanced Research Projects Agency Network" (ARPANET) for the United States Department of Defense. It was the first computer network in the world in late 1960's and early 1970's.

Networking Tips

Computer networks are used to share the data and resources and for the communications. To get the optimized performance, data protection, maintenance, improved reliability and the security, every system administrator and network administrator should know the basic maintenance, troubleshooting and security techniques. Downtime is very dangerous for the critical network business applications and servers. In this article, you will learn some of the best networking tips and by using them you can get the optimized performance from your network.

1. Security

A compute network is susceptible to the internet and external security related threats, which includes viruses, spyware, adware, Trojan horses, rootkits, web worms, intruders and hackers. To keep your network secure

Firewall: Install and configure a software/hardware firewall on your gateway and all other computers in your network. Firewall is used monitor the inbound and outbound traffic and block the unauthorized access and hackers’ attacks.
Antivirus: Install antivirus software such as Norton Antivirus, Trend Micro Office Scan, Panda Antivirus or McAfee and regularly scan your computer with an antivirus program.
Anti spyware: Install and configure an up-to-dated anti spyware software in your network.
Updated Operating System: Update your Windows based operating systems with the latest service packs, hot fixes and security patches.
Browser Security: Raise the level of security of your web browsers.

2. Connectivity

Computer networking sometimes considered to be complex and seems to hard to troubleshoot. The connectivity problems occur in the computer network due to the devices conflicts, outdated LAN card’s driver, faulty hardware, faulty cable or connectors and misconfigurations. To troubleshoot the connectivity related issues, you need to perform the following tasks.

• Check the LEDs of your LAN card.
• Update the driver of your LAN card.
• Scan your computer for the viruses and spyware.
• Check the UTP/STP cable, the both end of the cable should be properly inserted i.e. one end in the LAN card and one end in the hub/switch or router.
• Check the configurations of the LAN card.
• PING the destination computer and check the status.
• If your problem is still not resolved, replace the LAN card and reconfigure it.

3. Maintenance

Computer network availability and security is very critical for the businesses. Maintenance include the domain setup, dealing with the internal and external security threats, assigning IP addresses to the computes, enabling/disabling network services like DHCP, FTP SMTP, SNMP, taking data backup, adding/removing users, troubleshooting the software/hardware, configuring the firewall and implementing the security in the overall IT infrastructure. To perform the maintenance related tasks in your compute network, you need the perfect tools.

4. Troubleshooting

You can troubleshoot the computer network related problems by using the right tools and techniques. Be default, Windows based operating systems offer the TCP/IP stack, which contains the troubleshooting and diagnostic utilities such as PING, IPCONFIG, Hostname, ARP, Telnet, NSLOOKUP, Tracert and many others. Pinging a network computer is the first troubleshooting step as it checks the connectivity with the destination computer. Additionally, you can use the other troubleshooting tools such as Ethereal, IP Sniffer, LanGuard, Packeteer and many others. These tools help to diagnose the cause of the problem and troubleshoot them.

5. Performance

To get the optimized performance from your computer network, you need to perform the following actions on every computer of your network.

• Use System Tools
• Delete Unnecessary Files
• Update Device Drivers
• Update BIOS
• Uninstall Unused Programs
• Update Operating System

6. Wireless Networking Security Tips

The following tips are very helpful in securing your wireless computer network.

• Change the Default SSID
  Change the Default Administrator’s password
• Disable SSID broadcast.
• Enable Mac Address Filtering
• Assign Static IP address to the Network devices and computers.
• Turn on and configure the firewall on every computer in your network.
• Enable IPSec, SSL, Encryption, WPA and WPE according to your security requirements.

Securing Wireless Network

Wireless network has become very popular in the home and office networks. Wireless network security is required to protect your wireless network from the unauthorized access, viruses, hackers and other internal and external threats. An unsecured wireless network is an open invitation to the hackers, intruders and the viruses. Many worldwide businesses and the home users are rapidly adopting the wireless networking for the key advantages that it has like the mobility, ease of work, easy management, scalability and the lost cost.

If you plan to implement the WLAN or wi-fi then its important for you to understand the security challenges that are associated with it to protect it from the security threats. The most common security threats include the following.

• Viruses
• Hackers
• Spyware
• Intruders
• Unauthorized Users
• Denial of Service
• Network Injection
• Trojans

Solutions

The possible steps that can be taken to protect the network are the following.

• All wireless network devices including routers, access point the PCMCIA LAN cards need to be secured.
• The wireless network needs to be monitored for detecting and preventing it from the security threats and for monitoring the users’ activities.
• All the users should be educated about the security threats.

Security Solutions

A wireless computer network can be protected from the internal and external security threats by implementing the following techniques.

• Change the default password of the router.
• Disable SSID broadcast.
• Map the IP addresses with the MAC addresses
• Enable WEP, WPA and WPA2 security mechanisms.
• Enable 128-bit WEP encryption.
• Use strong passwords.
• Disable Remote Administration.
• Do not auto connect to the open Wi-Fi networks.
• Assign static IP address to the devices.
• Enable firewall and the antivirus software on each computer.
• Place the router and access point in the center of the network.
• Turn off the network when you are not using it.
• Limit access rights.
• Upgrade to wi-fi protected networks.

Network Troubleshooting

Network Troubleshooting is a form of problem solving most often applied to repair of failed products or processes. It is a logical, systematic search for the source of a problem so that it can be solved, and so the product or process can be made operational again. Troubleshooting is needed to develop and maintain complex systems where the symptoms of a problem can have many possible causes. Troubleshooting is used in many fields such as engineering, system administration, electronics, automotive repair, and diagnostic medicine. Troubleshooting requires identification of the malfunction(s) or symptoms within a system. Then, experience is commonly used to generate possible causes of the symptoms. Determining which cause is most likely is often a process of elimination - eliminating potential causes of a problem. Finally, troubleshooting requires confirmation that the solution restores the product or process to its working state.

Network Security

How To Secure A Computer

The confidentiality, availability and the integrity of the data is the most important aspect of the computer security. Computer security refers to securing your computer from the unauthorized access and from internal and external threats like virus, spyware, Trojan horses, phishing attacks, hackers and intruders. There are a large number of techniques that can be used to protect your computer from all these threats. In this article you will learn that how to secure your computer from the most common security threats.

Network security consists of the provisions made in an underlying computer network infrastructure, policies adopted by the network administrator to protect the network and the network-accessible resources from unauthorized access, and consistent and continuous monitoring and measurement of its effectiveness (or lack) combined together.

Network security concepts

Network security starts from authenticating any user, commonly (one factor authentication) with a username and a password (something you know). With two factor authentication something you have is also used (e.g. a security token or 'dongle', an ATM card, or your mobile phone), or with three factor authentication something you are is also used (e.g. a fingerprint or retinal scan). Once authenticated, a stateful firewall enforces access policies such as what services are allowed to be accessed by the network users.^[1] Though effective to prevent unauthorized access, this component fails to check potentially harmful content such as computer worms being transmitted over the network. An intrusion prevention system (IPS)^[2] helps detect and inhibit the action of such malware. An anomaly-based intrusion detection system also monitors network traffic for suspicious content, unexpected traffic and other anomalies to protect the network e.g. from denial of service attacks or an employee accessing files at strange times. Communication between two hosts using the network could be encrypted to maintain privacy. Individual events occurring on the network could be tracked for audit purposes and for a later high level analysis.

Honeypots, essentially decoy network-accessible resources, could be deployed in a network as surveillance and early-warning tools. Techniques used by the attackers that attempt to compromise these decoy resources are studied during and after an attack to keep an eye on new exploitation techniques. Such analysis could be used to further tighten security of the actual network being protected by the honeypot.^[3]

A useful summary of standard concepts and methods in network security is given by ^[4] in the form of an extensible ontology of network security attacks.

Repeaters

Introduction to Repeaters

A repeater is a communication device that retransmits the weak signals with greater power. It receives the signals over the wireless, optical transmission and network cable mediums such as copper wire, UTP/STP and fiber optic cables and regenerates the analog or digital signals. It can relay the data signals between the different subnetworks.

Repeater operates at the physical layer of the OSI layers model and it is not such as intelligent device like the switches and routers that perform the smart routing based on the MAC and IP addresses of the source and destination computers. Repeaters are also used in the broadcasting, where they are known as the relay transmitters and boosters. Repeaters restrengthen the data signals in the telecommunications. Normally a repeater consists of the following things.

• Amplifier
• Transmitter
• Isolator
• Antennas
• Radio Receiver

In a fiber optic network, a repeater consists of the following.

• Amplifier
• Photocell
• IRED
• IR
• LED

Fiber optic repeaters are less expensive and operate at low power.
Repeaters were also used to connect the segments of the cables. Repeaters are of mainly two types i.e. with internal antenna and with external antenna. If you are using repeater in your network make sure that is it compatible with other devices in your network.