How do firewalls work??

Question

I was wondering how firewalls work. Like...what are they?

Answer 1

There are different types of firewalls; hardware and software. A personal firewall is most commonly a software program that is installed on the user’s computer. The program is used to prevent unauthorized programs or other users from accessing a private network and personal computers. The internet is basically a road full of information being passed to and from computers along wires which make up a huge network. When a firewall is in place, all information entering or leaving the computer network is examined and only the information that passes certain criteria are allowed to pass through.

There are three categories that a personal firewall uses to allow the information being passed to it access to go in our out of the network. The three categories are:
• Allow: The Personal Firewall Allows some information to flow. This is usually information that is known to be "safe", most likely because you have defined it, by application, to be "safe."
• Block: The Personal Firewall Blocks some information. This is usually information that is known to be problematic or dangerous to your computer.
• Ask: The Personal Firewall Asks whether incoming and outgoing traffic is allowed to access your computer. When you run the Firewall, it normally initially asks you whether to permit your applications to access network resources. Most firewalls will remember your response and not ask you the next time the program needs access to the internet.

By using a personal firewall on your computer, you are in control of what accesses your computer. You are able to configure the firewall and other security settings that will protect your computer. A personal firewall does not guarantee 100% protection; it is always a good idea to run an anti-virus program on your computer to scan your computer for possible viruses that have infected your computer and was not blocked by your firewall. However, with a firewall, you are at less risk of a malicious criminal attacking your computer and you becoming the next victim of a computer crime.

Answer 2

When your computer has firewall protection, everything that goes in and out of it is monitored. The firewall monitors all this information traffic to allow ‘good data’ in, but block ‘bad data’ from entering your computer.





Firewalls use one or a combination of the following three methods to control traffic flowing in and out of the network:



Packet filtering

The most basic form of firewall software uses pre-determined security rules to create filters – if an incoming packet of information (small chunk of data) is flagged by the filters, it is not allowed through. Packets that make it through the filters are sent to the requesting system and all others are discarded.



Proxy service

A firewall proxy server is an application that acts as an intermediary between systems. Information from the internet is retrieved by the firewall and then sent to the requesting system and vice versa. Firewall proxy servers operate at the application layer of the firewall, where both ends of a connection are forced to conduct the session through the proxy. They operate by creating and running a process on the firewall that mirrors a service as if it were running on the end host, and thus centralise all information transfer for an activity to the firewall for scanning.



Stateful inspection

The most modern method of firewall scanning, that doesn't rely on the memory-intensive examination of all information packets is ‘stateful inspection’. A ‘stateful’ firewall holds significant attributes of each connection in a database of trusted information, for the duration of the session. These attributes, which are collectively known as the ‘state’ of the connection, may include such details as the IP addresses and ports involved in the connection and the sequence numbers of the packets being transferred. The firewall compares information being transferred to the copy relevant to that transfer held in the database – if the comparison yields a positive match the information is allowed through, otherwise it is denied.

Answer 3

Hi, imagine that a woman is walking on a street and some guys try to attack her and all of a sudden there is a wall of fire, bricks whatever u can think of around her. Will they be able to attack her, no right? This is how a firewall works, but since u need to communicate outside as well there will always be paths to communicate outside for safe applications. Now imagine if one of the guys takes a flame extinguisher and makes a path for himself exactly how some viruses get through ur firewall. So now the woman is vulnerable that is why she needs extra protection as well and that is why ur computer still needs anti virus protection. Now lets say the woman has some body guards to protect her as well just like u have anti virus software to protect ur pc. So as soon the attacker enters u take him out. I hope u understand what I just said u can also think of it as ur body for example the skin is the firewall which blocks harmful stuff but viruses still get in right? So once they r in ur white blood cells r like an antivirus which attack it after it enters. I hope u understand that all firewalls do is monitor what goes in and what goes out. I hope I helped.
Good Luck and take care!

Answer 4

Firewalls are software acting like filters between the computer and the web;

A newbie way of explaining it;

Your PC -> Your Firewall -> The Web
The Web -> Your Firewall -> Your PC

Everything goes through the firewall, enabling you to watch what's happening, block unwanted intrusions and avoid getting what they call nowadays "hacked".

Firewalls come in software and hardware, some are free, some are not.

It's good to have one, Windows has a built in one, FYI.

Answer 5

you need one or your computer will get hacked and everything
on it is exposed to a hacker, firewalls block unsolicited traffic
coming into your computer and do packet inspection to make
sure no attack or unwanted traffic is coming in to your computer
and this will block hackers telling them no access and saying your computer doesnt exist because firewalls make your computer also stealth. here is a very good free firewall
www.personalfirewall.comodo.com

Answer 6

http://www.howstuffworks.com/firewall.htm