How does a firewall work!?!

[lsakhvoruk]

I just would like to know how does a firewall work and what is it used for. Thanks to all and any that reply. Leo.

[mairving]

In a builing, a firewall would be put up to prevent the spread of fire from building to building. It is a similar thing for a computer firewall. Basically it is a way to prevent your network from burning up. You can have either a hardware based or software based fireballs or you can use both. Two basic purposes:

1. To limit what people externally not on your network can access on your system. You can be very broad or very narrow. In other words, if you had a webserver, everyone would have access to your site. But you wouldn't want everyone to have access to your server config files.
   
2. The second purpose is to limit what users internally can do on your network. It helps to keep some of the nasties out.
   

Here are a couple of firewall sites that will explain in detail what firewalls are:
http://grc.com/su-firewalls.htm
http://www.interhack.net/pubs/fwfaq/

[Floppyman]

If you're interested in aquiring a firewall check out Zonealarm at http://www.zonealarm.com I've been using it for quite sometime even though I'm on a dial up, and it has worked great and best of all--FREE.

Norton and BlackICE make some as well, but you're gonna have to pay for those.

[bob]

A firewall is a network level software that can be run on your pc, a router, or a special firewall router.

It blocks access from the internet (or a hostile connected network). It usually is configured to allow most access from your network to the internet while blocking access from the internet.