James wrote:All right, Antony. Work with me here.
I'm wondering exactly "how" a firewall works. Does it physically prevent anything from outside entering one's computer OR does it simply render the computer invisible?
Well, if you think "firewall" as a filter, it would be easier to understand.
Firstly any packets (information) sending to firewall will be checked if that is legitimate (correct packet format...)
Next it would check if such packet is allowed or not (by user's rules or pre-set rules)
James wrote:If it sort of gives my computer a Star Trek-like cloak of invisibility, would it be possible for someone (although highly improbable) to penetrate to my computer? Currently my little network (two computers) sits behind a Linksys router as indicated before and both computers have software firewalls. So... is it a physical impossibility of penetrating to my computer or not?
Well, I don't watch Star Trek, but it is possible to hide the existence of your computer from someone else, but this does not help much in my opinion.
In order to other people to attack your network, they need to connect to your computer in two aspects... physical link (including wireless), ports.
Say you connect to SillyDog701 website (or in fact any website), there must be at least two ports open. On for you to transmit requests to SillyDog701 (e.g. which link you clicked), another one for SillyDog701 to transmit back your request.
Those ports are opened between the browser you use and SillyDog701 server. In other words, if you use Firefox to connect to SillyDog701, SillyDog701 server can only send information to your Firefox, not anywhere in your computer (unless your Firefox has been comprised).
James wrote:If it "is" possible, what is the best advice in terms of being "away" from the computer for several hours? Do you actually turn if "off" or just log off and let it be? And besides... just logging off really does nothing, right... since you're still connected (cable connection here) even though no web pages may be up on your monitor.
My advice is ... install a firewall and let the computer sleep, and don't download files from untrusted sources (*). OR even better, log off and let it sleep. ZoneLabs'
ZoneAlarm is a good one, I've been using it in my Windows PCs.
Once the computer is in sleep mode, the operating system is not running, so any connections from outside won't have any effects.
(*) This includes music etc. Some applications you downloaded may create ports and hackers may attack your computer from that.
To download music, I recommend download music from legal source,
iTunes Music Store, and please use any iTunes link from SillyDog701, so I get paid.

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