Many of you, I’m sure, have heard of firewalls. For those of you that haven’t, I am not talking about an actual flaming wall. Firewalls are protection devices that filters information from the Internet.
You see, the internet is just a ton of computers linked together. Computers can be linked to the Internet through phone-line modems, DSLs, or cable modems. These connect to an Internet Service Provider, or ISP. There are network interface cards in computers, and these connect to a local area network, or LAN. You can then connect the LAN to an ISP with a fast phone line like a T1. ISPs then connect to other ISPs, and everything is linked. And that’s where firewalls come in.
If there’s a business that has a ton of computers, all with an NIC (network interface card) connected to a LAN, and then connected to an ISP, anyone could access the company’s computers, because they would be directly connected to the Internet. Firewalls use one out of three different methods to block unwanted information. Packet filtering involves looking at little pieces of information at a time, then filtering. Proxy service is that the firewall retrieves information from the Internet. Stateful Inspection involves looking at key parts of a small packet of info, then comparing it to trusted information. So, now you know what firewalls are and what they do!
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