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Firewallpresentation 100826052003-phpapp02(1)

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Firewallpresentation 100826052003-phpapp02(1)

  2. 2. Introduction  FireWall is device that provides secure connectivity between networks..  A firewall may be a 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. 2
  3. 3. Hardware vs. Software Firewalls 3  Hardware Firewalls  Protect an entire network  Implemented on the router level  Usually more expensive, harder to configure  Software Firewalls  Protect a single computer  Usually less expensive, easier to configure
  4. 4. How does a software firewall work? 4  Inspects each individual “packet” of data as it arrives at either side of the firewall  Determines whether it should be allowed to pass through or if it should be blocked
  5. 5. Types of Firewalls  Common types of Firewalls: 1. Packet-filtering routers 2. Application-level gateways1 3. Circuit-level gateways1 5
  6. 6. 6 ◦ Packet-filtering Router • Applies a set of rules to each incoming IP packet and then forwards or discards the packet ◦ Filter packets going in both directions ◦ The packet filter is typically set up as a list of rules based on matches to fields in the IP or TCP header ◦ Two default policies (discard or forward)
  7. 7. 7 Packet Filtering Firewall Trusted Network Firewall rule set Packet is Blocked or Discarded Untrusted Network
  8. 8. 8 Packet Filtering Firewall A packet filtering firewall is often called a network layer firewall because the filtering is primarily done at the network layer (layer three) or the transport layer (layer four) of the OSI reference model.
  9. 9. 9  Application-level Gateway  Gateway sits between user on inside and server on outside. Instead of talking directly, user and server talk through proxy.  Allows more fine grained and sophisticated control than packet filtering. For example, ftp server may not allow files greater than a set size.  A mail server is an example of an application gateway ◦ Can’t deposit mail in recipient’s mail server without passing through sender’s mail server host-to-gateway ftp session gateway-to-remote host ftp session application gateway
  10. 10. 10 Application Gateways/Proxies
  11. 11. 11 Circuit-level Gateway 1. Stand-alone system 2. Specialized function performed by an Application-level Gateway 3. Sets up two TCP connections 4. The security function consists of determining which connections will be allowed 5. Typically use is a situation in which the system administrator trusts the internal users
  12. 12. 12 Circuit-level Gateway
  13. 13. Firewall Rules 13  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 – asks the user whether or not the traffic is allowed to pass through
  14. 14. Making The Firewall Fit  IP address  Domain names  Protocols 14
  15. 15. What It Protects You From  Remote login  Simple Mail Transfer Protocol session hijacking  Operating system bugs  Spam 15
  16. 16. 16 Conclusion
  17. 17. 17 What a personal firewall can do ? • Stop hackers from accessing your computer. • Protects your personal information. • Blocks “pop up” ads and certain cookies. • Determines which programs can access the Internet. • Block invalid packets.
  18. 18. 18 • What a personal firewall cannot do ? • Cannot prevent e-mail viruses – Only an antivirus product with updated definitions can prevent e-mail viruses. • After setting it initially, you cannot forget about it – The firewall will require periodic updates to the rulesets and the software itself.
  19. 19. 19 Thank you