I would like to know that in what way firewall provides security ?

Question

How far it works to different intruders and attackers? and what are all the disadvantages in the firewalls security access?

Answer 1

However firewall provide the network perimeter protection, but they are not the ideal solution to network security problems. Assuming that you are looking for the drawback of firewall I am listing down few -

• They are a central point for attack, and if an intruder breaks through the firewall, they may have unlimited access to the corporate network.
• They may restrict legitimate users from accessing valuable services. For example, corporate users may not be let out onto the Web, or when working away from home, a corporate user may not have full access to the organization's network.
• They do not protect against back door attacks, and may encourage users to enter and leave via the back door, like modems and importing/exporting floppy discs. This usually happens when service restrictions are severe enough.
• Firewall systems on their own cannot protect the network against smuggling, like in the importation or exportation of banned material through the firewall, like game programs coming in as attachments to e-mail messages.
• Firewalls do not provide data integrity, because it is not possible, especially in large networks, to have the firewall examine each and every incoming and outgoing data packet for anything.
• Firewalls cannot ensure data confidentiality because, even though newer firewalls include encryption tools, it is not easy to use these tools. It can only work if the receiver of the packet also has the same firewall.
• The biggest disadvantage of a firewall is that it gives no protection against the inside attacker. Since most corporate computer crime is perpetrated by internal users, a firewall offers little protection against this threat.

Credit: http://my.safaribooksonline.com/book/networking/security/9781599043791/perimeter-defense-the-firewall/c11lev1sec8