firewalls

Firewalls(Chapter 11)

Lecture Objectives

• Security Design Concepts

– Layered Security, Controlling Access, Role Specific

Security, User Awareness, Monitoring …

• Introduction to Firewalls

– Why we need to secure our networks?

– What is a Firewall?

– Who needs a Firewall?

– Is there anything worth protecting?

Types of Firewalls

Firewalls Configuration

Trusted systems & Access controls

Secuity Design concept

• Layered Security

– Implementation of security consistently throughout a network at as many points as possible is considered good design

– Internet ~ Router ~ Firewall~ LAN Switch ~ Users/Servers

• Controlling Access

– Determine what is allowed in your network and what is not

– One highly recommended practice is to make

access decisions with the mindset of “block everything and only allow what is needed to conduct business”

– Also known as “Policy of Least Privilege (POLP)”

Secuity Design concept

• Role Specific Security

– Access and privilege should be assigned based on the user’s role in the organization

• User Awareness

– User awareness through training is essential

– Users should be truly aware of security and supportive of security policies

• Monitoring

– Monitoring is a most important aspect of security

– Strongly recommended practice is to include the provisions for IDS when designing a network’s security solution.

Definition: Firewall• A Network Firewall is a system or group of systems used to control access between two networks -- a trusted network and an untrusted network – using pre-configured rules or filters.

A firewall is a security device that sits on the edge of your Internet connection and functions as an Internet Border Security Officer

– “To keep bad guys out and let the good guys get to the resources they need to do their jobs”

Firewall II-Its sole purpose is to provide security for your network

-It constantly looks at all the traffic entering and

exiting your connection

-In response to an established rule it can block

or reject some traffic

-It is a law and provides protection in a lawless

global web.

Firewall IIIA firewall is a combination of hardware and software components that provide a single point-of-control between a "trusted" network, such as an organizational network, and an "untrusted" network such as the Internet.

A firewall is hardware, software, or a combination of both that is used to prevent unauthorized programs or Internet users from accessing a private network and/or a single computer.

Who Needs a Firewall?Who Needs a Firewall?

– If you plan on connecting to the Internet, you need a firewall.

– It doesn’t matter if you connect from home or your company is connecting

– The increased use of broadband Internet services to the home and their always-on Internet connections make home security even more important.

Why Do I Need a Firewall?

– Common Security Threats on Internet

• Viruses, Worms, Denial-of-Service (DOS) attacks, hacking, and new vulnerabilities. – SoBig, Blaster, LovSan, SQL Slammer, Code Red,

NIMDA, MyDoom etc.

Why Do I Need a Firewall?Examples:

• Nobody wants the attackers to compromise the security of their networks.

• We know that we must protect our network from these attack, and firewall is one of the most efficient method of protecting our network.Effective means of protection a local system or network of systems from network-based security threats while affording access to the outside world via WAN`s or the Internet The firewall is inserted between the premises network and the Internet

Aims:

Establish a controlled link

Protect the premises network from Internet-based attacks

Provide a single choke point

firewalls

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