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Network Security
Below is a brief description about Network Security.
Firewall
A properly configured firewall can provide you with a vital line of defense against
malevolent Internet invaders. Firewalls filter both inbound and outbound network
traffic. They can control access to host applications, and keep track of all attempts
to access the network—authorized and unauthorized. Depending on how they're designed
and configured, they can do a number of other useful things to keep the crooks out
and your proprietary information in. They may even filter out spam and spyware.
However, there are quite a few things that firewalls can't do:
- They can't stop an employee from writing down her password on a yellow post-it
and sticking it on her monitor.
- They can't stop another employee from inadvertently giving away vital access codes to a telephone confidence man.
- They certainly can't keep your IT people from mis-applying security clearances.
Still, it goes without saying that no network should be without a firewall.
How Do Firewalls Work?
All internet data travels in packets. A traditional network-level firewall (the
kind that's probably built-into your router) examines packet headers, and refuses
to allow packets to pass through the firewall unless their headers match the rules—as
defined by the firewall administrator or designer.
Alternatively, a firewall can be configured to allow any packet to pass through
as long as it does not match one or more "negative-rules."
Network-level firewalls are not very good at detecting and defusing worms, viruses,
and the latest application-specific attacks. Defending the network against this
broader set of threats requires deeper inspection of the packet payload itself.
The latest application-level firewalls use complex rules to look at the content
of a packet, the type of traffic it represents, its source or destination address,
the ports involved, the application being called, and many other factors to discover
and block packets that contain malicious payloads.
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