The World of Grandpa Don
What is a Firewall?
Feb, 2003
In a building, a firewall is a wall made of fire retardant material intended to keep a fire from spreading from one part of a building to the adjacent rooms. In general, a firewall is a barrier.
In a computer which is connected to the internet by means of a high speed broadband internet service provider, the internet connection is always there. This is not the case for a "dial-up" modem connection. Being always connected, is a great convenience as you can imagine. However, being on at all times makes it more vulnerable to access from outside.
Normally, two way communications are instigated from the local computer. One example is the request you may make to download a file. The software on your PC requests the file and directs it to a location for storage. It, in effect, opens the door for the transfer of data.
There are other computers out there which can try to access the data on you computer. A firewall limits access only to traffic that originates on your PC unless you specifically allow access from a designated outside source. This would be in the case of an internet network and it's server.
Another way for unauthorized access to occur is by means of a "Trojan Horse". This is a small program that has entered your computer attached to a file. It then initiates calls to open your files to an intruder. The firewall software always checks outgoing requests and will not permit connections unless specifically authorized by you. An example is that after the firewall installation, my financial software, which is set up to download market information on a regular basis, was blocked from doing so until I gave permission. Once the firewall recorded the permission for this program to access the internet, it was allowed to continue to do it.
If a Trojan Horse were to try to access the internet from my PC, it would be blocked and I would be notified. I would not authorize an internet connection that I did not recognize.
Sometimes you can get too much of a good thing. I have a program that automatically looks up the correct time and adjusts the clock on my computer. It is not working and I can not find the way to get it past my firewall. No big deal but I'll find the secrete someday.
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What is a Firewall? |
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The
World of Grandpa Don www.plefka.net |
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by The JavaScript Source | |
