What are the demerits of firewalls?

Answer 1

• No firewall provides protection against viruses, continuously new viruses and new methods are released everyday which affect the system.
• Firewall can't give protection against all attacks which don't pass through firewall.
• Firewall reflects overall security level of network, an architecture which depends on one security mechanism or one method has a point of failure which may open the system to intruders.
• If firewall is incorrectly configured it can't tell you the problem, only professional want to minimize the risk using their experience.
• It is highly difficult for firewall if someone hacked into your network to notify you, for which you need separate monitoring tools.
• If a hacker masquerades like trusted user or employee it is highly impossible for firewall to protect from such type of hackers, because today we have numbers of ways to find user names and passwords.
• Firewall can't protect system from malicious codes also.
• Firewalls don't encrypt e-mail messages or confidential documents which are sent inside the organization or outside of the organization.
• Firewalls can't give 100% security to the system or organization.
• Firewall can't find other vulnerabilities which might allow hacker to access internal network.
• Firewall cannot decide which is legitimate decision and which is not, it works entirely based on the set of rules and criteria and policy mentioned by the management part during the planning of security policy.