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  1. 1. FIREWALLS Antonio Arthur
  2. 2. Question <ul><li>What is a firewall? </li></ul><ul><li>Describe with examples the different types of firewalls. </li></ul><ul><li>Describe the drawbacks of each type of firewall and known successful attacks </li></ul>
  3. 3. What is a firewall? <ul><li>A firewall is defined as a security system that prevents outside users from accessing private network resources. They can be set up between segments of a network, but are usually used to improve security between the internet and a network. </li></ul><ul><li>In order to understand the concept, it is useful to think of a castle with a mote dug around it. All traffic into and out of the castle, is thus forced to pass over the single drawbridge. The drawbridge is like the firewall (See diagram 1). </li></ul>
  4. 4. Diagram 1
  5. 5. Different types of firewalls <ul><li>There are 2 main types of firewalls: </li></ul><ul><ul><li>1. Packet-level Firewalls </li></ul></ul><ul><ul><li>2. Application-level Firewalls </li></ul></ul>
  6. 6. Packet-Level Firewall <ul><li>Packets are allowed or denied access based on source and destination IP addresses. </li></ul><ul><li>Router which has been configured with IP address filtering rules is used to screen out data from unidentified sources. </li></ul><ul><li>Weakness : susceptible to IP spoofing. </li></ul>see example below
  7. 7. VisNetic Firewall 2.2, Software
  8. 8. Application-Level Firewall <ul><li>Uses additional software, called a proxy, to filter incoming or outgoing data. Most secure firewall. </li></ul><ul><li>Data is screened on the basis of content as opposed to IP addresses. </li></ul><ul><li>Drawbacks: causes noticeable speed decrease, may be susceptible to attacks from inside the network. (e.g. sasser worm, see slide 11) </li></ul>see example below
  9. 9. SonicWall Pro 2040, Hardware Price: $2,000 Data Transfer Rate: 200 Mbps Port Qty: 5
  10. 10. Common Network Layout
  11. 11. Successful Attacks <ul><li>Sasser worm </li></ul><ul><ul><li>Although there may be an actual firewall between the internal network, and the Internet, the virus can be spread once a computer (this may be for example, a laptop brought onto the network) on the internal network becomes infected. It then propagates itself, without user help. Results in the shutdown message shown below. </li></ul></ul>
  12. 13. Successful Attacks <ul><li>IP Spoofing </li></ul><ul><li>IP spoofing is a fairly simple concept. It simply involves changing the source address in the IP header file. </li></ul><ul><li>see diagram below </li></ul>
  13. 15. Why firewalls are so important <ul><li>There is a tendency among local businesses to overlook the importance of security. These business generally adopt the attitude that it ‘couldn’t happen to them’. On Wednesday, September 22 nd , 2004, the nation newspaper company, and the Starcom Network Company were both proven wrong in this belief as both their websites were hacked.(nationnews.com, vob929.com) </li></ul><ul><li>The screenshot below shows the contents of the nation website on the day in question. </li></ul>

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