Firewall

Ercan Sancar

&

Caner Sahin

Index

• History of Firewall

• Why Do You Need A Firewall

• Working Principle Of Firewalls

• Can a Firewall Really Protect Me?

• Multiple Firewalls

• Firewall Functions in Windows

• Choosing a Firewall that Meets

History Of Firewall

Firewall technology emerged in the late 1980s...

Why Do you Need a Firewall?

What is Firewall???

• A firewall is a piece of software or hardware...

What Firewall Do???

• Block incoming network traffic based on source or destination.

• Block outgoing network traffic based on source or destination.

• Block incoming network traffic based on content.

• Make internal resources available.

• Allow connections to internal network.

• Report on network traffic and firewall activities.

What Firewall Can’t Do???

• Inside attack!

• Social engineering.

• Viruses and Trojan horse programs.

• Poorly trained firewall administrators.

A Firewall That Fits

• Personal Firewall

• Departmental or small organiztion Firewall

• Enterprise Firewall

Some Firewall Rules

• Allow everyone to access all Web Sites• Allow outgoing e-mail from the internal mail server• Drop all outgoing network traffic unless it mathces the

first two rules• Allow incoming Web request to the public Web server• Drop all incoming network traffic expect for connections

to the public Web server• Log all connection attempts that were rejected by the

firewall• Log all access to external Web sites

Basic Function of Firewall

• Packet filtering

• Network Address Translation(NAT)

• Application Proxy

Working Principle of Firewalls

• General Strategy: Allow-All or Deny-All

• Filtering Properties

General Strategy of Firewall

• Allow-all Strategy:Allow all network packets except those that are explicitly denied.

• Deny-all Strategy:Denies all network packets except those that are explicity allowed.

Example Firewall Rules

Filetering Properties

• Packet Filtering

• Network Address Translation(NAT)

• Application Proxy

Packet Filtering

• What is Packet Filtering?

• Filtering IP data.

Example of Fragment

Network Address Translation(NAT)

• What is NAT?

• Security Aspects of NAT.

• Consequences of NAT.

Application Proxy

• What is Application Proxy

• Differnce between Application Proxy and Packet Filtering

• Advantages of Application Proxy

• Drawbacks of Application Proxy

Comparison of NAT & Proxy

• Network and Transport layer

• Not concerns with contents

• Users don’t need any settings

• Every program uses the same

• Application Layer

• Interface with the content

• Users need to setup the settings

• Differnt programs can use differnt proxies

ProxyNAT

Can a Firewall Really Protect Me?

A firewall is indeed a very effective method of protection against many of these

threats, but...

Multiple Firewall

• When Two Firewall Are Better Than One

• Designing Demilitarized Zones(DMZ)

Designing Demilitarized Zones

Advantages of DMZ with Two Firewall

• Clear Definition of The DMZ• Increased Security• Reduce Network Loads on the Two Firewalls

Disadvantages of DMZ with Two Firewall

• Increased Cost• Extra Training Required• Multiple Firewall Rule Listing Must be Maintained• Configuration Complexity When more Than Two

Firewall are Deployed

Firewall Functions in Windows

• Packet Filtering

• Network Address Translation(NAT/ICS)

• Encrypted Tunnel

Firewall Functions Which is not provide in Windows

• No application Proxies• No (or less-than-ideal)monitoring and logging• No data caching

Choosing a Firewall That Meets

• How do you decided?

• What compare?

Thank you For Listening