• Can not protect against the inside attacks
  • Firewalls may represent a significant bottleneck in communication between the protected network and the outside world.
  • Very little or no effort is taken to look in detail at the data contents of the packet.
  • Firewalls do not protect against viruses: New viruses are continuously released and there are many ways of encoding binary files…
  • They do not protect against threats that exploit flaws within the network or applications themselves.
  • They do not protect against malicious but authorized internal users.
  • A firewall can not protect against:
    • malicious insiders
    • connections that circumvent it
    • completely new threats
    • some viruses
    • the administrator that does not correctly set it up

firewalls