Transcript firewalls - Anvari.Net

FIREWALLS
What Is A Firewall?
• A computer firewall protects networked computers
from intentional hostile intrusion that could
compromise confidentiality or results in data
corruption or denial of service.
• It may be a hardware device or a software program
running on a secure host computer.
• A network firewall sits at the junction point or
gateway between two networks, usually a private
network and a public network such as the Internet.
• The earliest computer firewall were routers.
How Firewalls Work
• A firewall is simply a program or hardware
device that filters the information coming
through the Internet connection into your
private network or computer system.
• If an incoming packet of information is
flagged by filters, it is not allowed through.
Software Firewall
• Such as ZoneAlarm, can be installed on the
computer in your home that has an Internet
connection. This computer is considered a
gateway because it provides the only point
of access between your network and the
Internet.
Hardware Firewall
• With a hardware firewall, the firewall unit
itself is normally the gateway. A good
example is the Linksys Cable/DSL router. It
has a built-in Ethernet card and hub.
Computers in your home network connect
to the router, which in turn is connected to
either a cable or DSL modem. You can then
set any filters or additional information.
Hardware Firewall….
• …are incredibly secure and not very
expensive.
• Home versions that include a router,
firewall and Ethernet hub for broadband
connections can be found for well under
$100.
What It Protects You From
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Remote Login
Application Backdoors
SMTP Session Hijacking
Operating System Bugs
Denial of Service
E-mail Bombs
• Macros
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Viruses
Spam
Redirect Bombs
Source Routing
Access Denial Methodologies
used by Computer Firewalls:
• A firewall may allow all traffic through
unless it meets certain criteria.
– Type of traffic
– Source or Destination addresses and ports
• or It may deny all traffic unless it meets
certain criteria
FIREWALLS
Everything You Wanted To Know
About Firewalls