The Client Server Networking

Published Date: 02 Nov 2017

The Sidebar is a prominent feature of Google Desktop. It holds many of the installed gadgets and can be seen on one side of the desktop. Below are the preinstalled gadgets.

- Email

- Photos

- Web Clips

- Google talk

Privacy Concerns

Google Desktop has a feature that able to search my desktop remotely. If this feature is turned on, the files on the indexed computer are copied onto Google servers thus increasing the chances that my information will be accessed without my permission.

Google Toolbar

Google Toolbar is an Internet toolbar that is available for Mozilla Firefox and Internet Explorer. It has a search area that allow user to perform web searches. The toolbar can allow users to login to their Gmail accounts and access their email and saved bookmarks. It also have features like AutoFill, translating mechanism (translate entire webpages) and popup blocker.

Privacy Concerns

Google Watch has raised some privacy concerns of installing the Google Toolbar, such as tracking browsing patterns, automatically updating the client without notice and privacy policy can change without mention. The toolbar does not track personally identifiable browsing activities unless more advanced features are turned on by the user, like the PageRank service.

b)

Google Chrome

Google Chrome is a web browser that is developed by Google. First released in September 2008, it is a popular web browser worldwide. The web browser Chrome is part of an open-source project called Chromium.

Chrome aims to be fast, secure, stable and simple. Chrome periodically receives and updates two lists, one list for phishing and the second one for malware. it uses this list to warn the user when they are about to access a harmful website. Chrome able to allocates a separate process to each tab and prevents malware from installing itself and also prevents the activities in one tab from affecting activities in another.

c)

Google Mail

Google Mail (Gmail) is a free web email service provided by Google. Google provides over 11000 megabytes of free storage for emails. An additional storage can be rented for a yearly fee depending on the size. The Gmail interface focuses on its search and an appropriately named ‘conversation view' of emails. It groups all the replies to an email on a single page to make it feel like an email conversation. Gmail has an in-built community driven spam filter. For example, when a user marks a message as spam, it helps the system identify similar messages for all Gmail users. Gmail also has an integrated chatting facility.

Privacy Concerns

Google automatically scans emails and adds advertisements that are content-sensitive to them. Furthermore, Google can scan the content of an email and this information can be linked to Internet searches made from the Google.com website. Such information can potentially be used by law enforcement agencies.

d)

Google Apps

Google Apps is a service provided by Google that has customizable versions of several Google products. It features many web applications including Gmail, Google Groups, Google Docs and Google Talk. Google Apps comes in three editions:

- Google Apps for Government

- Google Apps for Business features additional email storage and is available for a fee payable annually

- Google Apps for Education combines features from the standard and business editions and, like the standard edition, is free of charge.

e)

Google AdWords

AdWords is Google's main advertising product, also a primary source of revenue. AdWords have following three types of advertising:

- Pay-per-click: advertisers choose the words that will activate their advertisements and the maximum amount of money that they will pay Google per click. The ads that are triggered by this process appear as ‘Sponsored Links' at the right of the search results page.

- Cost-per-thousand

- Site-targeted advertising for text, banner, and rich-media ads.

Two prominent features of AdWords as below:

- IP address exclusion: This allows advertisers to specify a range of IP addresses where they do not want the ads to appear. Maximum 20 IP addresses can be used in this feature.

- Frequency Capping: This feature limits the number of times a particular ad appears for a unique user.

Task 2

a)

Domain Name System (DNS)

The Domain Name System (DNS) is a system that assigns names to computers, services or any other resource that connects to the Internet or private network. It translates alpha-numeric characters used by networking equipment for locating and addressing these devices. This resolving of names follows below steps:

- A host is configured with an initial cache of a known DNS server

- If the known DNS server does not contain the information the host requires, it queries the root DNS server

- The root server responds with the relevant top-level domain (TLD) server

- The TLD server is queried for the second-level domain server

- The process is repeated until the domain name is found.

Internet Protocol (IP) address

An IP address is a fascinating product of modern computer technology designed to allow one digital device to communicate with another via the Internet. IP addresses allow the location of literally billions of digital devices that are connected to the Internet to be pinpointed and differentiated from other devices.

Internet Protocol version 4

Internet Protocol version 4 (IPv4) is the fourth revision of the Internet Protocol (IP). IPv4 is a connection-less protocol, It does not guarantee the packets will be delivered, in a proper sequence or prevent duplication.

IPv4 uses a 32-bit addressing scheme, which limits the addressing space to 232 (approximately 4.3 billion) unique addresses. Some of addresses are reserved for special purposes, such as private networks or for multi-cast addressing. This reservation reduces the number of available IPs or public IPs that can use over the Internet. Due to the demand for IP addresses has been increasing rapidly with the growth. So that the IPv4 address has been becomes not enough for use.

A variety of technologies have been developed to delay the depletion of the addresses, such as below:

- Network Address Translation (NAT)

- Use of private networks

- Use of Dynamic Host Configuration Protocol (DHCP) server

DNS name server

A DNS server runs special-purpose networking software, have a IP address, and contains a database of network names and addresses for other hosts.

Resolver

Also called DNS resolvers. Resolvers are the names given to computers that used to respond to a user request to resolve a domain name. These computers translate a domain name into an IP address.

DNS Infrastructure

The DNS infrastructure consists of DNS servers that run the DNS Server service and DNS clients that run the DNS Client service.

Fully qualified domain name (FQDN)

A fully qualified domain name (FQDN) is the complete domain name for a specific computer or host. The FQDN has two parts: the hostname and the domain name. For example, www.google.com is the FQDN on the web for IU. In this case, www is the name of the host in the google.com domain.

Network ID

A Network ID is a term used to describe the basic part of a network. For example, 192.168.1.0 is a Network ID. 

Given the Network ID of 192.168.1.0 and the Subnet Mask of 255.255.255.0, the network is 254 usable addresses, since 192.168.1.0 is the first number so that is not a valid addressable IP address and 192.168.0.255 is the network's broadcast address.

Subnet mask

A Subnet Mask is a number. It is determined using binary from 0.0.0.0 to 255.255.255.255. Subnet Mask defines a range of IP addresses that can be used in a network. Subnet masks are used to designate subnetworks or subnets. Systems able to communicate directly with each other if they are within the same subnet, but systems on different subnets that must communicate through a router. Thus, subnetworks can be used to partition multiple networks and limit the traffic between them.

b)

c)

Briefly discuss the common vulnerabilities of DNS- There are common vulnerabilities in Domain Name Servers (DNS) that are documented in the CERT Advisories. They are-

A remote intruder can gain root-level access to name server.

A remote intruder is able to disrupt normal operation of name server.

The DNS protocol in BIND 8 and 9 before 9.5.0-P1, 9.4.2-P1, and 9.3.5-P1 allow remote attackers to spoof DNS traffic via cache poisoning techniques.

A cryptographic weakness in the generation of DNS query IDs could expose the DNS server to a cache poisoning attack. This bug only affects outgoing queries, generated by BIND 9 to answer questions as a resolver, or when it is looking up data for internal uses, such as when sending NOTIFYs to slave name servers.

c) What measures can be taken to secure DNS-

To protect DNS servers from spoofing of DNS records it should be used the only secure dynamic updates option for dynamic update.

Use internal firewall to block all unused ports to prevent exploitation of remote vulnerabilities (for example RPC vulnerabilities, although generally RPC services should not run on DNS server).

If an organization has an intranet, it should be providing separate views of DNS for internal users and external customers.

d) i)

I have to establish a network within 1000-1500 PCs. So I have choused Class B IP address. Because Class B IPs supports 65000 hosts over 16000 networks. The IP list given bellow-

ii)

For domain registration fist I go to the site name www.4domains.com. Then input my propose domain name. The name is "dnetworld" and the domain is not booked. It is now free in.Net root domain. So I can use the domain www.dnetworld.net .The charge per domain is $9.95 /year.

Go to 4domains.com and select a domain name

Press check button and then display the root domains names.

The domain added in shopping chart

iii)

Design of Subnets

iv)

Here describing the rang of TWO subnet IP address-

Describing subnet IP address 128.168.0.0- This is first subnet IP of this network or first Network ID. It is a class B IP address. Here Host IP starts from 128.168.0.1 to 128.168.0.62. Here 62 PCs can establish a sub network. This network has a broad cast address and its IP is 128.168.0.63.

Describing Subnet IP address 128.168.64- This is second Subnet IP of this Network of second Network ID. It is a class B IP address. Its host IP starts from 128.168.0.65 to 128.168.126. Here 62 PCs can establish a Sub network. This network has broad cast address and its IP is 128.168.0.127.

Task 3

e)

The POST Method

POST is one of the many request methods supported by the HTTP protocol on the Internet. The POST method is used when a client needs to send data to the server, like when uploading a file or completing and submitting a form. It is part of the request body. The server receiving the data will usually send it to a CGI program along with other variables that are required for processing.

Advantages

- There is no limit to the number of characters that can be sent to the server using the method; the administrator sets this limit manually. Therefore large amounts of data can be sent through

- Data that is passed using this method are hidden in the browser, making it suitable for sending sensitive data like passwords.

Disadvantages

- The users cannot bookmark or have direct access to such pages; they will need to re-enter the information through the form to access the page

- Because these pages cannot be accessed without entering data into a form, search engines cannot index them.

The GET Method

This method is used to retrieve web pages from the server. It is part of the client request line and tells the server to pass the document to the client browser or run a CGI program.

Advantages

- Unlike pages generated using the POST method, users can bookmark pages that are generated using GET. This means that data does not need to be re-entered into a form

- Search engines can index these pages

Disadvantages

- The number of characters passed is limited, which means that it is not suitable for sending large amounts of data to the server

- The data sent is visible in the browser, making it unsuitable for sending sensitive data such as passwords.

Task 4

a)

Peer-to-Peer Networking

Peer-to-Peer (P2P) is a networking architecture that does not have a central computer or server for management. PSP divides the workload between peers. Peers (also call nodes) are both consumers and suppliers of resources such as disk storage and processing power.

In a P2P network, all nodes have equal rights, importance and priority, There are no nodes that perform a special function. All of them act as clients and servers simultaneously. The clients provide the resources to the network, which may include bandwidth, storage space and even processing power. When a new node is added onto the network, the total capacity will increases due to there are more clients providing resources at the same time.

There are many applications of P2P networking on the Internet, such as DNS, cloud computing, VoIP services. The most popular use of P2P networks is file sharing. Many file-sharing networks exist like BT was the ones that increased bandwidth utilization over the Internet.

Client-server Networking

The Client-server networking model is one that is prominently used. Clients send requests for resources to a server(s) and the server replies with that resource. Clients send requests to the servers by using only one way so that the servers no need to initiate the communication. ‘Client' and ‘server' can refer to a computer system or an application. Servers usually run on dedicated machines and are long-running applications. Clients are usually laptops, desktops and hand-held devices. Client-server systems are based on resources and resource identifiers.

For Internet, World Wide Web is one of the applications which using Client-server Networking. The main resource is the webpage, using URL to identify it. The client (web browser) requests for the webpage using URL and the server (web server) sends information on how to display the page back to the browser.

b)

c)

Comparison between client/server and peer to peer Network:

Advantages of a peer-to-peer network:

Less initial expense - No need for a dedicated server.

Setup - An operating system (such as Windows XP) already in place may only need to be reconfigured for peer-to-peer operations.

Disadvantages of a peer-to-peer network:

Decentralized - No central repository for files and applications.

Security - Does not provide the security available on a client/server network.

Advantages of a client/server network:

Centralized - Resources and data security are controlled through the server.

Scalability - Any or all elements can be replaced individually as needs increase.

Flexibility - New technology can be easily integrated into system.

Interoperability - All components (client/network/server) work together.

Accessibility - Server can be accessed remotely and across multiple platforms.

Disadvantages of a client/server network:

Expense - Requires initial investment in dedicated server.

Maintenance - Large networks will require a staff to ensure efficient operation.

Dependence - When server goes down, operations will cease across the network.

Words Count

Introduction 47 words

Task 1 84 words

Task 2 259 words

Task 3 7 words

Task 4 447 words

Total 1883 words