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VIVA-Tech International Journal for Research and Innovation Volume 1, Issue 4 (2021)
ISSN(Online): 2581-7280
VIVA Institute of Technology
9th
National Conference on Role of Engineers in Nation Building – 2021 (NCRENB-2021)
F-71
www.viva-technology.org/New/IJRI
Firewall Security
Ankit kadam1
, Shreya bhamare2
1
(Department of MCA, Viva School Of MCA/ University of Mumbai, India)
2
(Department of MCA, Viva School Of MCA/ University of Mumbai, India)
Abstract : When your computer is connected to the Internet, you expose your computer to a variety of
potential threats. The Internet is designed in such a way that if you have access to the Internet, all other
computers on the Internet can connect to your computer.This leaves you vulnerable to various common attacks.
This is especially troubling as several popular programs open services on your computer that allow others to
view files on your computer! While this functionality is expected, the difficulty is that security errors are
detected that always allow hackers to attack your computer with the ability to view or destroy sensitive
information stored on your computer. To protect your computer from such attacks you need to "teach" your
computer to ignore or resist external testing attempts. The common name for such a program is Firewall. A
firewall is software that creates a secure environment whose function is to block or restrict incoming and
outgoing information over a network. These firewalls actually do not work and are not suitable for business
premises to maintain information security while supporting free exchange of ideas. Firewall are becoming more
and more sophisticated in the day, and new features are being added all the time, so that, despite criticism and
intimidating development methods, they are still a powerful defense. In this paper, we read a network firewall
that helps the corporate environment and other networks that want to exchange information over the network.
The firewall protects the flow of traffic through the internet and limits the amount of external and internal
information and provides the internal user with the illusion of anonymous FTP and www online
communications.
Keywords - Firewall technologies, network security, access control, security policy, protective mechanisms.
I. INTRODUCTION
Today's networks change and develop on a regular basis to adapt to new business situations, such as
organisations, acquisitions, outsourcing, mergers, joint ventures, and strategic partnerships, and the increasing
degree to which internal networks are connected to the Internet. The increased complexity and openness of the
network thus caused makes the question of security more complicated than hitherto, and necessitates the
development of sophisticated security technologies at the interface between networks of different security
domains, such as between Intranet and Internet or Extranet. The best way of ensuring interface security is the
use of a firewall.
A Firewall is a computer, router or other communication device that filters access to the protected network.
Cheswick and Bellovin define a firewall as a collection of components or a system that is placed between two
networks and possesses the following properties:
 All traffic from inside to outside, and vice-versa, must pass through it.
 Only authorised traffic, as defined by the local security policy, is allowed to pass through it.
 The firewall itself is immune to penetration.

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Such traditional network firewalls prevent unauthorised access and attacks by protecting the points of entry into
the network. As Figure 1 shows, a firewall may consist of a variety of components including host (called bastion
host), router filters(or screens), and services. A gateway is a machine or set of machines that provides relay
services complementing the filters. Another term illustrated in the figure is "demilitarised zone or DMZ". This is
an area or sub-network between the inside and outside networks that is partially protected. One or more gateway
machines may be located in the DMZ. Exemplifying a traditional security concept, defence-indepth, the outside
filter protects the gateway from attack, while the inside gateway guards against the consequences of a
compromised gateway. Depending on the situation of the network concerned, there may be multiple firewalls,
multiple internal networks, VPNs, Extranets and perimeter networks. There may also be a variety of connection
types, such as TCP and UDP, audio or video streaming, and downloading of applets. Different types of firewall
configuration with extensive practical guides can be found in. There are also many firewall products on the
market from different vendors. See for an updated list of products and vendors.

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II. History of Firewall
Open Door Networks shipped the first Macintosh firewall (for Mac OS 8.1) in 1998. With the DoorStop X
Firewall and the DoorStop X Security Suite, Open Door has gotten back into the business that it helped get
started.
figure 2: History of Firewall
III. Basic Approaches and Limitations
Firewall technology can be used to protect networks, by installing it strategically at a single security screen
station where the private network or the Intranet connects to the public Internet, making it easier to ensure
security, audit and monitor traffic, and trace break-in attempts. It can also be used to isolate sub-networks, in
order to provide additional layers of security (defence-in-depth) within the organisation.
There are three basic approaches or services that a firewall uses to protect a network: packet filtering,
circuit proxy, and application proxy. Some authors broadly classify these into two kinds of approach: transport
level and application level (by including circuit proxy in this category).
3.1. Packet filtering
Firewalls having this function perform only very basic operations, such as examining the packet
header, verifying the IP address, the port or both, and granting and denying access without making any changes.
Due to this simplicity of operation, they have the advantage of both speed and efficiency. The filtered packets
may be incoming, outgoing or both, depending on the type of router. An additional advantage is that they do
their job quiet independently of the user's knowledge or Internal & External Gateway Systems Inside Filter
Demilitarized Zone (DMZ) Filter Outside 3 assistance, i.e., they have good transparency. Packets can be filtered
on the basis of some or all of the following criteria: source IP address, destination IP address, TCP/UDP source
port, and TCP/UDP destination port. A firewall of this type can block connections to and from specific hosts,
networks and ports. They are cheap since they use software already resident in the router, and provide a good
level of security since they are placed strategically at the choke point.

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3.2. Circuit Proxy
The second approach is the use of what is called a circuit proxy. The main difference between the
circuit proxy and the packet filtering firewall is that the former is the addressee to which all communicators
must address their packets. Assuming access has been granted, the circuit proxy replaces the original address (its
own) with the address of the intended destination. It has the disadvantage of laying claim to the
processing resources required to make changes to the header, and the advantage of concealing the IP address of
the target system.
3.3. Application Proxy
The third approach involves the use of what is known as an application proxy. An application proxy is
more complicated in operation than a packet filtering firewall or a circuit proxy. The application proxy
understands the application protocol and data, and intercepts any information intended for that application. On
the basis of the amount of information available to make decisions, the application proxy can authenticate users
and judge whether any of the data could pose a threat. The price to be paid for this more comprehensive function
is that users or clients often have to be reconfigured to them, sometimes a complicated process, with a
consequent loss of transparency. Application proxies are referred to as proxy services, and the host machines
running them as application gateways.
3.4. Packet Inspection Approach
This approach, in contrast to the technologies so far described, involves inspecting the contents of
packets as wells as their headers. An inspection firewall carries out its inspection by using an inspection module,
which understands, and can therefore inspect, data destined for all layers (from network layer to application
layer). It carries out its inspection by integrating all information gathered from all layers into a
single inspection point, and then examining it. A state-full inspection firewall is one which also registers the
state of any connection it is handling, and acts on this information. An example of a state-full inspection firewall
is the state-full packet filtering mode in Checkpoint's “Firewall-1” or Network Associates' Gauntlet. Inspection
firewalls can provide address translation and hiding, virus scanning, Web
site filtering, screening for key words (typically in e-mail), and context-sensitive security for complex
applications.
3.5. Firewall Limitations
As pointed out in, "Information security professionals often find themselves working against
misconception and popular opinions formed from incomplete data. Some of these opinions spring more from
hope than fact, such as the idea that internal network security can be solved simply by deploying a firewall".
While it is true that firewalls play an important and central role in the maintenance of network
security and any organisation that ignores them, does so at its peril, they are neither the panacea of every
security aspect of a network, nor the sole sufficient bulwark against intrusion. Knowing what firewalls can't do
is as important as knowing what they can. The following are limitations one should be aware of.
A firewall is by its nature perimeter defence, and not geared to combating the enemy within, and consequently
no useful counter measure against a user who abuses authorised access to the domain.
A firewall is no real defence against malicious code problems like viruses and Trojan horses, although some are
capable of scanning the code for telltale signs.
Configuring packet-filtering rules tends to be complicated process in the course of which errors can easily occur,
leading to holes in the defence. In addition, testing the configured rules tends to be a lengthy and difficult
process due to the shortcomings of current testing tools. Normal packet-filtering routers cannot enforce some
security policies simply because the necessary information is not available to them.

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IV. Additional Important Features
Firewalls are becoming more complex and sophisticated by the day, and thus more efficient at identifying
intrusions and logging them, and automatically notifying the right people. They provide multiple layers of
protection and some cache data to improve performance, and support Virtual Private Network (VPNs), Web-
based administration, authentication, etc. There is also a tendency to add non-security related functions to the
firewall such as built-in Web servers, FTP servers, and e-mail systems, and even proxy servers for streaming
audio and video. We agree with those who feel that some additions to firewalls make sense and are useful when
they enhance security, while others don't make sense and may even be
dangerous, especially over time, when they represent a decrease in security and an increase in vulnerability. For
example, to add services that increase the administration load adds another potential avenue of attack.
4.1.Content Caching
While caching is not traditionally a function of firewalls, it is becoming an increasingly frequent and
important feature. An increase in performance is achieved by caching the contents of an accessed location with
the result that subsequent requests for access will lead to already cached contents being used, without it being
necessary to access the location again (except when it is necessary to refresh).
4.2.Logging and Alerts
It is important for a firewall to log events, determine their legitimacy or otherwise, and notify the
network administrator. It should be noted that it is essential to protect the integrity of the log, since unauthorised
access to, and editing of, the log will, of course, neutralise its raison d’être. Whether the function of protecting
the log is fulfilled by the firewall itself or not, is a matter of implementation.
4.3.Management
Management ranges from command line to sophisticated GUI-based and secured remote access.
Security management and administration, particularly as it applies to different firewalls using different
technologies and provided by different vendors, is a critical problem. As more and more security services are
introduced and applied to different firewall components, properly configuring and maintaining the services
consistently becomes increasingly difficult. An error by an administrator in maintaining a consistent
configuration of security services can easily lead to security vulnerability. A firewall should thus provide a
security management interface that enables it to be locally or remotely managed in a coherent and
comprehensible fashion.
4.4.Virtual Private Networks (VPNs)
A VPN is an encrypted tunnel over the Internet or another untrusted network providing confidentiality
and integrity of transmissions, and logically all hosts in a VPN are in one Intranet . Some firewalls include VPN
capabilities (reasonable extension) to secure networks, so that they can safely communicate in private over the
public network. They achieve this by strong authentication and encryption of all traffic between them.
4.5.Adaptive Firewalls
The new trend is towards adaptive firewalls that tie filters, circuit gateways and proxies together in
series. This gives the firewall administrator greater control over the level of security used for different services
or at different points in the use of those services. He may, for example, configure the firewall to give priority to
speed of transfer at the expense of security when this is appropriate. The firewall will then
on such occasions reduce security to a lower level, thus allowing for greater speed of transfer, and return it to its
original level on completion of the transfer. Phoenix states that Adaptive Firewall Technology provides fluid,
self-adapting control of network access, a key to establishing an effective network security policy by examining
every packet (and adapting rules "on-the-fly" based on information in the packet) passing through the network
interface.
4.6.Quality of Service (QoS)
Some firewalls include QoS features that allow administrators to control what proportion of a given
network connection is to be dedicated to a given service. There are those who feel that QoS should be handled
by Internet routers, while others insist that this is a matter of access control, and thus should be included in the

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firewall. Quoting: "Moreover, some vendors, notably Check Point, have built their QoS engine using the same
technology that is in their firewall. The philosophy here seems to be, access control is access control."
4.7.Policy and Firewalls
There are two levels of network policy that directly influence the design, installation and use of a
firewall system: higher-level policy and lower-level policy. The former is the network service access policy,
which lays down which services are to be accessible to whom, and how they are to be used. The latter is the
firewall design policy, which describes how the firewall will implement the network service access
policy, and precisely how it will take access decisions in accordance with it. Firewalls typically implement one
of two design policies. The firewall may permit any service not expressly denied, or it may deny any service not
expressly permitted.
Service access policy may, for example, decree that there shall be no access to a site from the Internet, but allow
access from the site to the Internet. Alternatively, it may decree that access from the Internet shall be restricted
to certain selected services in the site. The latter is the more widespread of the two. Today’s business
environments are, however, dynamic. Organisations are continually changing to adapt to new circumstances
brought about by reorganisations, mergers,acquisitions etc. Therefore there are regularly new policies to be
enforced, and, to remain effective, today’s firewalls must be able to adapt to them.
V. CONCLUSION
As we have discussed so far that firewall is very important part of computer defense against viruses,
spyware, Trojans and other malwares and also between direct malicious attacks from outside and outside of
network. A good firewall is the one that provide full protection of network without effecting the speed of our
computer and our network access. In order to provide security, one should keep following things in mind :
 We should never install any software from suspicious sources. Always download from the respected
sites available on internet.
 Use a firewall to monitor all data or information that we want to exchange over the internet.
 On every computer a firewall software must be installed else it will only take one PC to become
infected and very fast it will effect the all computers available on that network.
Acknowledgements
I am thankful to my college for giving me this opportunity to make this research a success. I
give my special thanks and sincere gratitude towards Prof. Shreya Bhamare for encouraging me to
complete this research paper, guiding me and helping me through all the obstacles in the research.
Without her assistance, my research paper would have been impossible and also I present my
obligation towards all our past years teachers who have bestowed deep understanding and knowledge
in us, over the past years. We are obliged to our parents and family members who always supported
me greatly and encouraged me in each and every step.
REFERENCES
Journal Papers:
[1] F. M. Avolio, Firewalls: Are We Asking Too Much?, http://www.crossnodes.com/icsa/perimeter.html.
[2] S. M. Bellovin, Distributed Firewalls, “;login:” November 1999, Special Issue on Security, ISSN 1044-6397, Also at:
http://www.usenix.org/.
[3] Check Point Firewall-1, version 3.0 White Paper, June 1997. http://www.checkpoint.com/products/whitepapers/wp30.pdf .
[4] ICSA,ICSAFirewall Policy Guide V2.00, Security White Paper series,
http://www.icsa.net/services/consortia/firewalls/fwpg.shtml
Books:
[5] D. B. Chapman and E. D. Zwicky, Building Internet Firewalls, O'Reilly & Associates, Inc., November 1995.
[6] H. Abie, CORBA Firewall Security: Increasing the Security of CORBA Applications, January 2000.

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[7] W. R. Cheswick and S. M. Bellovin, Firewalls and Internet Security,Repelling the Wily Hacker, Addison-Wesley Publishing
Company, 1994
[8] OMG, The CORBA Security Service Specification (Revision 1.2), ftp://ftp.omg.org/pub/docs/ptc/98-01-02.pdf, January 1998

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