1 / 9

Understanding Firewall Configurations: Types, Criteria, and Practical Applications

Firewalls serve as essential network appliances that filter traffic based on various criteria, primarily operating at layers 3 to 5 of the OSI model. They examine headers for destination/source IPs, ports, and TCP flags. Different types of firewalls include static, dynamic, stateful packet filtering, and proxy servers, each with unique capabilities. Static filtering relies on access control lists (ACLs), while dynamic and stateful filtering improve upon it by maintaining session tables and better handling application behaviors. Understanding these aspects is crucial for effective network management and security.

ignatius-bates
Télécharger la présentation

Understanding Firewall Configurations: Types, Criteria, and Practical Applications

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Internet Intranet Firewalls  network appliances to filter network traffic  filter on header (largely based on layers 3-5)

  2. Firewall Filtering Criteria Destination IP Source IP Destination Port Source Port Flag (TCP-only) ACK - acknowledge FIN - final PSH - push RST - reset SYN - synchronize URG - urgent

  3. Firewall Types  static packet filtering  dynamic packet filtering  stateful packet filtering  proxy server

  4.  static packet filtering packet  Network manager configures access control lists  Packets are compared to access control lists  Example: block

  5. 0 - echo reply 3 - destination unreachable 4 - source quench (from overloaded router) 5 - redirect (indicates a better path) 6 - echo request 9 - router advertisement (fore new routers) 10 - router solicitation (host request for advertisement) 11 - time exceeded (packet header may include time) 12 - parameter problem (catch all for errors) 13 - time stamp request (checking link speed) 14 - time stamp reply Problems with static filtering • Blocking FIN scanning • Difficult to filter • Difficult to filter Internet Control Message Protocol - designed for Internet testing/maintenance - does not use ports - has type field

  6.  dynamic packet filtering ACLs packet  Includes all capabilities of static filtering  Maintains an Active Sessions Table  Example: block external FIN scan

  7.  stateful packet filtering ACLs Active Sessions Table packet  Includes all capabilities of dynamic filtering  Also “understands” certain application behavior  Example: better control over UDP, NFS, RPC

  8.  proxy server packet destination  Messages to destination IP are rerouted to a proxy  The proxy communicates on behalf of the destination  The proxy may also communicate with destination

  9. Firewalls in Practice

More Related