What is firewalls.
Hardware vs softwares firewalls.
How does Software firewall work
What a firewall can’t protect against
Packet level filter
What is a Firewall?
• A firewall is hardware, software, or a
combination of both that is used to
prevent unauthorized programs or
Internet users from accessing a private
network and/or a single computer
Hardware vs. Software Firewalls
• Hardware Firewalls
– Protect an entire network
– Implemented on the router level
– Usually more expensive, harder to configure
• Software Firewalls
– Protect a single computer
– Usually less expensive, easier to configure
How does a software firewall work?
• Inspects each individual “packet” of data as it
arrives at either side of the firewall
• Determines whether it should be allowed to pass
through or if it should be blocked
What a Firewall Cannot Protect
• Trojan horse
• Social engineering
• Physical outrages
A category of firewall that provides a high
degree of convenience, but a relatively low level of
security. A packet-level filter blocks or forwards a packet
solely on its merits, without taking into account past
history; the filter may also look at the source and
destination address information contained in the packet.
A category of firewall that provides a
high degree of security but at the cost of lower
speed and greater complexity.
Typical application-level filters can
provide proxy services for applications and
protocols such as Telnet, FTP and HTTP
• proxy server is a computer that offers a computer
network service to allow clients to make indirect
network connections to other network services.
• A proxy server can also serve as a firewall.
A firewall is a necessity if you are going to connect your
LAN to the Internet. Firewalls can examine the traffic coming into
and going out of your LAN and make decisions on what kinds of
traffic to permit or deny .
• Ingham, Kenneth; Forrest, Stephanie
(2002). "A History and Survey of Network