Contents

Introduction to Firewall

Generations of Firewall

Types of Firewall

Firewall Topology

Firewall Rules

Conclusion

References

Introduction to Firewall

What is Firewall? Firewall is a network security system

that controls the incoming and outgoing network traffic based on applied rules.

It establishes a barrier between a trusted, secure internal network and another network ( e.g., the Internet) that is assumed not to be secure and trusted.

Generations of Firewall

First Generation : Packet Filter

STATIC PACKET FILTERS

• One of the simplest and least expensive forms of firewall protection is known as static packet filtering.

• Each packet entering or leaving the network is checked and either passed or rejected depending on set of user-defined rules.

STATEFUL PACKET INSPECTION

• Within the same generation of static packet filtering firewalls are firewalls known as Stateful packet inspection.

• It examines the contents of packet rather than just filtering them, it consider their contents as well as their addresses

Generations of Firewall

First Generation :

Second Generation Firewalls

PROXY SERVICES

• The next generation of firewalls attempted to increase the level of security between trusted and untrusted networks.

• The Proxy program evaluates data sent from the client and decides which to pass on and which to drop.

Third Generation

This new generation evolved to meet the major requirements demanded by corporate networks f increased security while minimizing impact.

The requirement of this generation of firewalls will be more demanding due to growing supports for VPNS , wireless communication , and enhanced virus protection.

Types of Firewall

HARDWARE FIREWALLS

• Hardware firewalls can be effective with little or no configuration, and they can protect every machine on local networks.

• Hardware firewall uses packet filtering to examine the header of a packet to determine its source and destination.

Types of Firewall

SOFTWARE FIREWALLS

• Software firewalls are to be installed on individual home users and you can customize it; allowing some control over its function and protection features.

• It could also provide protection against the most common Trojan programs or e-mail worms.

Firewall Topology

SCREENED SUBNET

• This architecture uses a single firewall with three network card.

• It provides a solution that allows organizations to offer services securely to internet users.

Firewall Topology

DUAL FIREWALLS

• In this case, the DMZ is placed between the two firewalls.

• The use of two firewalls still allows the organization to offer services to Internet users through the use of a DMZ.

Firewall Rules

Allow : Traffic that flows automatically because it has been deemed.

Block : Traffic that is blocked because it has been deemed dangerous to your computer.

Ask : Ask the user whether or not the traffic is allowed to pass through.

How Firewalls Work

IP addresses : A typical IP address looks like: 216.27.61.137.

Domain Names : A company might lock all access to certain domain names or allow access only to specific domain names.

Ports : If server machine is running a Web server and an FTP server , the web server would be on port 80 and FTP on 21 port.

WHAT FIREWALL CAN’T DO

Can’t protect you against malicious insiders.

Can’t protect you against connections that won’t go through it.

Can’t protect you against completely new threat.

Can’t protect against viruses.

Some Good Firewalls

ZoneAlarm Firewall

Comodo Firewall

Tinywall

Conclusion

Whatever firewall you currently use or are considering the most important thing is to match the product with specific security requirements of your organization.

References

www.wikipedia.com

www.techrepublic.com

www.wibopedia.com

www.searchsecurity.techtarget.com

www.howstuffworks.com

Queries??