Discuss Firewalls in brief?

Introduction: We have seen evolution of information systems

  1. now everyone want to be on the Internet
  2. and to interconnect networks
  3. has persistent security concerns
    • can’t easily secure every system in org
  4. typically use a Firewall
  5. to provide perimeter defence
  6. as part of comprehensive security strategy

Firewalls: It’s a choke point of control and monitoring

  1. interconnects networks with differing trust
  2. imposes restrictions on network services
    • only authorized traffic is allowed
  3. auditing and controlling access
    • can implement alarms for abnormal behavior
  4. provide NAT & usage monitoring
  5. implement VPNs using IPSec
  6. must be immune to penetration

Fig.:- General Firewall Position

Firewall Limitations:

  1. Cannot protect from attacks bypassing it
    • eg sneaker net, utility modems, trusted organisations, trusted services (eg SSL/SSH)
  2. cannot protect against internal threats
    • eg disgruntled or colluding employees
  3. cannot protect against access via WLAN
    • if improperly secured against external use
  4. cannot protect against malware imported via laptop, PDA, storage infected outside

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