Table of Contents

Declaration iAcknowledgement iiAbstract iiiIntroduction vChapter 1 : System Study 6

1.1 Identification of need..............................................................................6

1.2 Feasibility study......................................................................................6

1.2.1 Technology.....................................................................................61.2.2 Cost and Benefit Analysis...............................................................6

Chapter 2 : System Analysis 7

2.1 Requirement Specification.....................................................................7

2.1.1 User requirement............................................................................72.1.2 Requirement Analysis.....................................................................7

2.1.2.1 Modeling...............................................................................82.1.2.2 Data Modeling.......................................................................92.1.2.3 Functional Modeling and Information Flow.........................11

2.1.3 Software Requirements..................................................................16

Chapter 3 : System Design 17

3.1 Data Design...........................................................................................17

3.1.1 HTTP Request................................................................................173.1.2 HTTP Response.............................................................................173.1.3 Cache.............................................................................................183.1.4 Error Message................................................................................183.1.5 Files................................................................................................18

3.1.5.1 Valid IP’s.............................................................................183.1.5.2 Blocked Sites......................................................................183.1.5.3 Cache Folder......................................................................18

3.2 Architectural Design:............................................................................18

3.2.1 Functional Modules.........................................................................193.2.1.1 Proxy User Interface...........................................................193.2.1.2 Proxy Server Listener.........................................................193.2.1.3 Connection Manager..........................................................203.2.1.4 Cache Manager..................................................................203.2.1.5 Log Manager.......................................................................203.2.1.6 Configuration......................................................................20

3.3 User Interface Design...........................................................................20

Chapter 4 : Testing 21

4.1 SOFTWARE TESTING...........................................................................21

4.1.1 Unit Testing.....................................................................................224.1.2 Integration Testing..........................................................................234.1.3 System Testing...............................................................................23

4.2 Unit Testing of Proxy Server................................................................24

4.2.1 Port Listening Test..........................................................................244.2.2 Connection......................................................................................254.2.3 Cache Test.....................................................................................254.2.4 Log Test..........................................................................................254.2.5 IP Validation Test............................................................................254.2.6 URL Blocking Test..........................................................................26

4.3 Integration Test.....................................................................................26

4.4 System Testing......................................................................................26

Conclusion 27Bibliography 28

DECLARATION

We here by declare that our project “Proxy Server” and its report submitted in

the partial fulfillment of requirement for the award of degree of Bachelor of

Engineering in Computer Science and Engineering of Jai Narayan Vyas

University, Jodhpur, is authentic work done by us and is not reproduced as it is

from any kind of source.

DEVSHREE GEHLOT

NEELU LAKHANI

B.E. Final yr. C.S.E.

Dept. OF CSE

M. B. M. Engg. College

Proxy Server i

ACKNOWLEDGEMENT

The beatitude that accompanies the successful completion of any task would not

be completed without the appreciation of colleague who made it possible. So with

veneration honor, we acknowledge all those whose guidance and

encouragement has made successful in winding up the project.

It is our privilege to acknowledge with deep sense of gratitude and devotion the

keen interest and invaluable guidance rendered to us by revered guide Mr. N.C.

Barwar, Head, Department of Computer Science & Engineering, M. B. M.

Engineering College, Jai Narain Vyas University, Jodhpur

It’s our privilege to thank Sh. Rajesh Purohit, Sh. Alok Gehlot and Sh. K.R.

Choudhary who have with their unflinching faith, been a source of inspiration for

us always to move towards success.

We are also thankful to whole Department of Computer Science &

Engineering family who provide us the environment for shaping our thoughts in a

statue of success.

Date : 1/06/2007

Place : Jodhpur

DEVSHREE GEHLOT

NEELU LAKHANI

B.E. Final yr. C.S.E.

Dept. OF CSE

M. B. M. Engg. College

Proxy Server ii

ABSTRACT

1. Introduction:

A proxy server is a computer that offers a computer network service to allow

clients to make indirect network connections to other network services. A client

connects to the proxy server, and then requests a connection, file, or other

resource available on a different server. The proxy provides the resource either

by connecting to the specified server or by serving it from a cache. In some

cases, the proxy may alter the client's request or the server's response for

various purposes, usually to view websites that are normally not allowed, such as

game sites in school or work place.

2. Features:

HTTP Request Sharing and Caching: A proxy server receives a request

for an Internet service (such as a Web page request) from a user. If it

passes filtering requirements, the proxy server, assuming it is also a

cache server, looks in its local cache of previously downloaded Web

pages. If it finds the page, it returns it to the user without needing to

forward the request to the Internet. If the page is not in the cache, the

proxy server, acting as a client on behalf of the user, uses one of its own

IP addresses to request the page from the server out on the Internet.

When the page is returned, the proxy server relates it to the original

request and forwards it on to the user.

Blocking:

There are two types of blocking:

1. URL Blocking

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2. Client IP Blocking

Better response time : An advantage of a proxy server is that its cache

can serve all users. If one or more Internet sites are frequently requested,

these are likely to be in the proxy's cache, which will improve user

response time. In fact, there are special servers called cache servers. A

proxy can also do logging.

Proxy Server iv

Proxy

ServerClientWeb Server

INTRODUCTION

About this project

Currently there are billions of web pages on the Internet but only a fraction of

them are frequently accessed. If these frequently used web pages are stored

much nearer to the client and retrieved directly from there instead of accessing

from original server. The network traffic can be brought down to a very

considerable extent. This will also improve the client observed latency. Here we

are implementing the Proxy Server for a LAN, which also acts as a firewall

between LAN and Internet.

Proxy Server v

System Study

CHAPTER 1 : SYSTEM STUDY

1.1 Identification of need

In a LAN, it is needed that there should be some security provided by the

administrator and that some unauthorized sites should not be shown to that client

in LAN. It was needed to decrease the web page access time so that those web

pages that have been accessed earlier should not be asked from the web

directly.

1.2 Feasibility study

Following points are to be considered in feasibility study:

1.2.1 Technology

Mechanism for Client Server communication

Browser

Connection to server

Cache management

1.2.2 Cost and Benefit Analysis

Building proxy server for LAN does not require any financial investment. Cost is

only in form of time and effort of the developer.

Proxy servers are application gateways originally created as part of firewall

systems to improve security. Internal systems connect to the outside world

through the proxy server, and external systems respond to the proxy server. The

external systems do not see a network of internal systems. They see only one

system - the proxy server. Proxy server reduces the response time for any

request from the client.

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System Analysis

CHAPTER 2 : SYSTEM ANALYSIS

2.1 Requirement Specification

To develop a system according to the need of the end user and compatible to the

most frequently used and easily available software and hardware, a detailed

requirement specification is needed to be performed. The various requirement

specifications are as follows:

2.1.1 User requirement

A major requirement is to develop an application which reduces network

and server load and provides increased client performance for most

frequently used web pages by caching.

The application should act as a firewall between the LAN and the

Internet. The firewall has to make sure that it denies the requests for any

blocked site.

It should block those clients in LAN which are restricted for Internet

access.

It should have a user friendly interface so that even a layman can use it

and understand it with ease.

The software should be easily upgradeable in which new modules and

features can easily be added.

It needs to be specified that in case of a proxy server the user will be proxy

server administrator.

2.1.2 Requirement Analysis

The firewall of proxy has to block the HTTP request emanating from an invalid IP

address. It also has to not to service the request for any link which is blocked by

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System Analysis

the proxy administrator. The proxy has to have cache to store the web pages

locally to reduce latency and network load. A user friendly Graphical User

Interface also needed to be supplied for proxy administrator.

2.1.2.1 Modeling

Now what will follow is a series of modeling tasks that lead to a complete

specification of requirement and a comprehensive design representation. We will

follow the structured analysis model in which we create and partition data,

functional and behavioral models. Below is the figure for structured analysis.

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Data Object Process SpecificationDescription [PSPEC]

Control Specification

Data Object Process SpecificationDescription [PSPEC]

Control Specification

Entity Data flowRelation Diagram

State Transition Diagram

State Transition Diagram

Entity Data flowRelation Diagram

State Transition Diagram

State Transition Diagram

Data Dictionary

Data Dictionary

System Analysis

2.1.2.2 Data Modeling

Data modeling method make use of the entity relationship diagram. The entity

relationship diagram is used to depict between data objects. The ERD defines all

data that are entered, stored, transformed and produced with in an application.

First of all by having a glance again at the requirement specification we pick up a

list of “things” or ”objects” (here it does not mean object of OOP) that the

application is going to address. Following are the things that evolve into

input/output objects:

User

Firewall

User Interface

Proxy Administrator

Cache Manager

Internet (abstract entity which generates HTTP response)

Associative ER Diagram (Data Desc.)

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Cache Cache

Firewall Firewall Cache Manager Cache Manager User Interface User Interface

Proxy Server Proxy Server

System Analysis

Expanded ER Diagram

Firewall

Firewall has to block the HTTP request from the invalid IP’s, for the blocked

URLs reformat for the allowed Content Type. Therefore, it must maintain the list

of all the three. It also has to generate the error message for invalid request.

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Internet Internet

User User Cache ManagerCache Manager

Firewall Firewall

Cache Cache

User InterfaceUser Interface

Proxy Administrator Proxy Administrator

Handles

1 stores

2 checks

3 retrieves

Sends request

Updates

Sends modified

Request

Expanded ER Diagram

System Analysis

Cache

The Cache stores the web documents (HTTP Response) that could be

accessed for the future use.

2.1.2.3 Functional Modeling and Information Flow

As information moves through software, it is modified by a series of

transformations. Data Flow Diagrams is a graphical representation that depicts

information flow and transformations that are applied as data moves from input to

output.

Here while depicting DFD we have assumed that the user views proxy and

Internet as the system.

Context Flow Diagram

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USERUSER

ADMINISTRATORADMINISTRATOR

USERUSER

ADMINISTRATORADMINISTRATOR

Proxy Proxy

HTTP Request HTTP Response

URL’s IP’s Log

System Analysis

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USER USER

PROXY

MANAGERPROXY

MANAGER

WEB

SERVERWEB

SERVERFIREWALLFIREWALL

USER

INTERFACEUSER

INTERFACE

CACHE

MANAGERCACHE

MANAGER

PROXY ADMINISTRATOR PROXY ADMINISTRATOR

Data flow diagram - Level 1

IP’s URL’s

HTTP RequestHTTP

Response

HTTP

Request/Response

URL’s

IP’sCACHE

Log

Valid

IP

Parsed

URLs

Modified

Requests

System Analysis

Process Specification [PSPEC]:

Firewall:

It has to act as a filter to block the HTTP request from the user. It has to compare

the IP address in request header with those made available to it, if address

matches then it checks whether the requested links is blocked or not. If it is

blocked then it returns error message to the user. Else it modifies the request

header according to the Content Type enabled/disabled in firewall. Then it sends

the request to the Cache Manager.

User Interface:

It is handled by the Proxy Administrator. He supplies the list of valid IP addresses

from which the proxy can provide services through the UI. The UI then updates

the corresponding file. Same holds for blocked sites.

Cache Manager:

It is responsible for storing, deleting and searching of web pages in the cache. It

is process which has to handle HTTP request and response after it is forwarded

by the firewall. When it gets HTTP request from the firewall: it first checks

whether the links associated with that request is present in cache or not. If not, it

will send the request to the Internet to get appropriate response: it will update the

cache and send response to the user simultaneously. The policy for adding or

deleting cache will be specified by the cache only.

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System Analysis

Proxy Server 14

Web ServerWeb Server

Check URL

Check URL

CacheCache

Cache Manager

Cache Manager

Get from Web

Get from Web

Validate IP

Validate IP

Search Cache

Search Cache

HTTP Response

Error code Resolve

Error code Resolve

HTTP Request

InternetInternet ForwardedRequest

Cache Updating Data

Cached Response

URL

ErrorCode

Configuration Files

Valid IP’s

Blocked URL’s

HTTP Request

HTTP Request

LAN PCLAN PC

Cached Response

PROXYINTERFACE

PROXYINTERFACE

HTTP Response

ErrorCode

ErrorMessage

Data Flow Diagram – Level 2

HTTP Response

System Analysis

Process Specification [PSPEC]:

Validate IP:

It reads the IP address from the HTTP request header and matches with the list

of IP’s presented by the Proxy Administrator. If the match is found then it will

forward the request header to the nest process. If match is not found, it will return

an error code.

Check URL:

On receiving the request header from the validate IP function it will check that the

web document represented by the URI is blocked by the Proxy Administrator or

not. It does so by comparing the URL with the list of URL’s presented by the

Proxy Administrator. If match is not found it will forward the header to the next

process. If found then it will return an error code.

Search Cache:

It reads the URI from the header and searches the cache to find whether the web

document is present in cache or not. If found it will return the cached web

document to the IP address specified in the header.

Get From Web:

It sends the request header to the proxy server or the web server to which it is

connected. It returns the fresh web document to the user or the error code.

Cache Manager:

The cache policy implementer works as the interface to manipulate or update the

cache. Only this function can write or delete anything from the cache. Any

algorithm for page replacement can be implemented in this interface only.

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System Analysis

System Recommended

In this step we draw up an understandable plan of what type of Hardware and

system is required to run the application in a compatible manner. So the system

requirements for the proposed system are as follows:

Network Interface Card.

Modem.

Dial Up Connection/Leased Line

2.1.3 Software Requirements

In this step we draw up an understandable plan of the requirement of the various

software needed to run the application in a compatible manner. So the software

requirements for the proposed system are as follows:

Windows 98/NT/2000/XP.

Internet Explorer

Tomcat Apache server4.0(for testing purpose).

JDK 1.4

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System Design

CHAPTER 3 : SYSTEM DESIGN

Our goal is to produce a model or representation of the proxy application, which

will be built later. By passing through the phases of diversification and

convergence we focus on four aspects:

Data Design

Architectural Design

Interface Design

Component Design

3.1 Data Design

The data Design transforms the information domain model created during

analysis to the data structures that will be required to implement the software.

The data Objects and relationships defined in the entity relationship diagram and

detailed data content depicted in the data dictionary provide the basis for the

data design activity.

Following are the data structures that will be used to implement the application:

3.1.1 HTTP Request

This will be the input to the proxy system. It has to accept the HTTP Response

and validate and manipulate it in the firewall.

3.1.2 HTTP Response

This is required to be the output to the LAN PCs. It also has to store the HTTP

Response in the Cache for the future user.

Proxy Server 17

System Design

3.1.3 Cache

The basic requirement of cache is to store the Web Documents, which could be

referenced by the LAN PCs in future. The Cache needs to be stored in main

memory for fast and efficient access.

3.1.4 Error Message

Appropriate error messages are to be shown to the user for any error

encountered. The user can only view web page, hence messages should be

HTML tagged.

3.1.5 Files

3.1.5.1 Valid IP’s

The file contains the list of IP address on the LAN, which can access the services

of the Proxy Server.

3.1.5.2 Blocked Sites

It contains the list of blocked URL’s.

3.1.5.3 Cache Folder

The Cache Folder will store cache present in the main memory in the form of

files. Each HTTP Response will be stored as a separate file corresponding to its

URI. This will be used only on start-ups or shutting down the proxy server.

3.2 Architectural Design:

The software architecture of a program o computing system is the structure

or structures of the system, which comprise software components, the externally

visible properties of those components and the relationship among them.

Proxy Server 18

System Design

The architecture is not the operational software. Rather, it is representation

that enables a software engineer to:

Analyze the effectiveness o the design in meeting its stated requirements.

Consider architectural alternatives at a stage when making design changes is still

relatively easy, and

Reducing the risks associated with the construction of the software.

3.2.1 Functional Modules

The various functional modules needed to perform its basic functions of a proxy

server are:

3.2.1.1 Proxy User Interface

This Module is responsible to control and manage the User Interface. It will

provide the user with an easy to use GUI, a window with menu.

The menu options should provide commands to perform the following functions:

Start Proxy

Stop Proxy

Exit

Blocking URL

Blocking Client

Manage Log

Manage Cache

Modify Configuration

3.2.1.2 Proxy Server Listener

The main function of the proxy starts here. This module will serve as a Port

listening to clients i.e. page requests from a web browser. It will create a new

connection for each request from the clients.

One more important feature of this module would to block clients which are

there in the blocked list given by the user.

Proxy Server 19

System Design

3.2.1.3 Connection Manager

This module will contain the main functions of the Proxy Server. It will read the

request header from the client. It will parse the URL and determine whether the

URL is blocked or not. Else it will generate a connection to the web server.

Then it will read the reply header from the web server. If there is no copy of the

page in then cache then it will download the page from Web Server else will

check its last modified date from the reply header and accordingly will read from

the cache or serve from the Web. Then it will also check the header for caching

allowed or not and accordingly will cache the page.

3.2.1.4 Cache Manager

The Cache Manager is responsible for storing, deleting, clearing and

searching of web pages in the cache.

3.2.1.5 Log Manager

The Log Manager is responsible viewing, clearing and updating the Log.

3.2.1.6 Configuration

This module will enable the user to make his configuration settings. It will work

with the other modules to perform the desired configurations such as caching

(on/off), log (on/off), etc.

3.3 User Interface Design

The Golden rule that guides the design of effective user interface is:

Place the user in control

Reduce the user’s memory load.

Make the interface consistent.

The user interface is the window to software system. It should be convenient and

easily understandable even by the naïve users. We have provided an easy to

use user interface in the form of menu’s in which functions are categorized

according to relevance.

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Testing

CHAPTER 4 : TESTING

4.1 SOFTWARE TESTING

Software testing is a critical element of software quality assurance and

represents the estimate review of specification, design and coding. Testing is a

process of executing program with the intention of finding errors in software. Our

objective was to design test cases that uncover errors in minimum time and less

effort. As a secondary benefit, testing demonstrates that software functions

appear to be working according to requirements. The cases should be designed

in a way that:

All independent logical paths within a module are exercised, all logical decisions

are exercised, all loops are executed and all data structures are exercised for

their validity i.e. White Box Testing.

All functions are fully operational and that input is properly accepted and correct

output is produced. This is Black Box Testing.

These two test case design techniques are used invariably in a software testing

strategy which solves test planning, test case design, test execution, and

resultant data collection and evaluation. A strategy for software testing involves

four steps:

Unit Test

Integration Test

System Test

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Testing

4.1.1 Unit Testing

Unit testing focuses various verification efforts on the smaller unit of software

design module. Here the module interface is tested to ensure that information

properly flows into and out of the program unit under test. It ensures that integrity

is maintained during all the activities of a session. Boundary conditions are tested

to ensure that the module operates properly at the boundaries established to limit

or restrict processing. All independent paths through the control structure are

Proxy Server 22

Unit testing

Module testing

Acceptance testing

Sub-system testing

System testing

Unit Testing Integration Testing System Testing

Testing

exercised to ensure that all statements in a module have been executed at least

once. And finally, all error-handling paths are tested.

Testing is done with the test cases, which are supplied, from the client and also

by the prepared by the offshore, for rigorous unit testing.

4.1.2 Integration Testing

Integration testing involves testing of modules in executable combination.

Integration testing in this application is carried out as testing the system in its

entirety. The aspects that are considered are:

Testing of interfaces between the modules.

Testing of interface between the integrated modules and its

environment.

Integration testing tests both the physical and the logical interfacing. Physical

interfacing is checks the structure and form of the interfaces. It is verified that the

same data and parameters are passed, with the same order. Logical interfacing

checks the semantic content of the interfaces. In this level the range of the data

are looked that there arc in the desirable form in which the modules need.

4.1.3 System Testing

System testing is carried on to ensure that the system is consistent with its

environment. After all these tests the system is installed to the client and it is

checked with all test data to verify that is works fine with the client environment.

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Testing

This software is dually tested at each level. Sufficient time is devoted on the

testing. Testing is done; keeping in mind that how big price has to pay in case of

software failure.

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Testing

4.2 Unit Testing of Proxy Server

Different Classes (Modules or Units) were designed for following functionalities:

Port Listening

Connection

Caching

Log

Blocking

Firstly, tests were conducted over separate classes and then these classes were

integrated to develop the total software. Testing was performed over various

independent classes i.e. classes which do not require involvement of server

classes. Once the modules (independent classes) were tested, testing start over

dependent classes by associating them with server classes. Various tests

performed and their results are:

4.2.1 Port Listening Test

In this test we tried to check whether the Proxy was actually listening or not and

also at the correct port. We tested it against different random values given to the

web browser.

Table 4.1

Port No. to Browser Port No. at Proxy Server Listening

1234 1020 No

1234 1234 Yes

1234 1112 No

1012 1012 Yes

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Testing

4.2.2 Connection

This test was conducted to check whether individual requests from clients formed

a connection to the Proxy Server or not. The very fact that there was some

output to the browser for each request accordingly, proved that there was a

connection established.

4.2.3 Cache Test

This test was conducted by checking the cache folder formed while execution.

Cache replacement and addition of files in cache storage worked properly though

the first response took quite a long time. We noted that those requests with a

copy existing in cache were read from the cache and those not in cache were

requested to the web server and subsequently saved in the cache folder.

4.2.4 Log Test

This test was conducted by checking the log folder formed while execution. We

noted that for each request from one IP a file named that IP.log was created or

updated if existing and the URL accessed was added to the file with date and

time.

4.2.5 IP Validation Test

For those clients who were blocked their IP was stored in a file. The proxy server

blocked the requests from blocked clients and generated no response to them.

Table 4.2

Blocked IP’s Client IP Blocked?

123.6.3.7

220.100.101.98

12.76.45.9

128.3.45.12

221.67.43.100

127.0.0.1 No

123.6.3.7 Yes

120.6.88.32 No

128.3.45.12 Yes

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Testing

4.2.6 URL Blocking Test

Again method similar to above was used. A list of URL’s was stored in file. Any

request for these sites was rejected instantly by the proxy server.

Table 4.3

Blocked URL’s Client Request Blocked?

www.gmail.com

www.hello.com

www.byte.com

www.zapak.com

www.yahoo.com

http://www.gmail.com\show?3ngb8g Yes

www.google.com No

www.mail.yahoo.com No

228.10.45.1 No

www.byte.com Yes

4.3 Integration Test

Since independent classes have been tested, classes which depend on each

other are tested by clustering together these dependent classes. It worked well

under IIS(Internet Information Server) but showed inconsistency with Apache

Server.

4.4 System Testing

At the validation or system level, the details of class connection disappear. The

validation of software focuses on user visible actions and user recognizable

outputs from the system. It was found that the application meshed with the

system without showing inconsistency.

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CONCLUSION

This software was tested on different testing environment and was found to be

satisfactorily running. The following limitations exist and modification is

suggested:

The most striking limitation of the software is that it cant’s interact with

other proxy in cascade.

For most of buttons in GUI keyboard support along with mouse has been

provided but other like selecting an item and then removal of that item

from the list does not have keyboard interaction. The present version can

be extended to include keyboard interaction.

The present version has no algorithm as such for cache replacement. It

can be extended to include other replacement policies like LRU (Least

recently used) based on timestamp i.e. time in which response is received

back from Web Server and hybrid policy which takes into the account all

the three factors hits, timestamp , and size.

The proxy currently runs on a single machine. It can be extended to

include facility for control from remote machine

These are several limitations that can be pointed out, and possible extension of

the present version is outlined.

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BIBLIOGRAPHY

Bibliography

1. Java 2 The Complete Reference 5th Edition , Herbert Schildt, Tata Mc

Graw Hill.

2. Sun Java Volume 1 & 2.

3. Professional Java Server Programming, Wrox Press Ltd.

4. Roger S. Pressman, Software Engineering: A Practitioner’s Approach

References

1. www.java.sun.com

2. www.jakarta.apache.org

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