What does a firewall actually, physically do? Please be as specific and technical as you can.?

Question

I know how the computer itself works, I'm A+ certified, but I never got into the internet and network technology. I mean I know how to use it, I just don't completely understand how it works. Starting with the modem/NIC all the way to the actual internet access.

Answer 1

Physically, the firewall does nothing. It is software and monitors the IP headers of every packet. It blocks those it has been told to block and alerts you went something suspicious is trying to come through.

The firewall in XP monitors only inbound traffic. This means that, if you get adware, spyware or one of the nastier viruses, these programs can send information out without restriction.

A 'stateful' firewall, such as Zone Alarm, monitors traffic in and out. This allows you to prevent certain programs from accessing the network / Internet. This is a real plus if you DO get infected by something your antivirus / antispyware missed as it will ask you for permission to let the program transmit data.

You should not be confused by the many security appliances out there (usually combined with a router). Their firewalls are still software, but installed on a chip in the appliance rather than on a computer or server. Appliances differ from stand-alone firewalls in that they often have other security software for things like intrusion detection, authentication, and Layer 7 (Application) monitoring. And, of course, the router itself provides Network Address translation, masking the IP addresses of the computers on the inside of the network.

Hope that helps.

Answer 2

In computer science, a firewall is a piece of hardware and/or software which functions in a networked environment to prevent some communications forbidden by the security policy, analogous to the function of firewalls in building construction. A firewall is also called a Border Protection Device (BPD), especially in NATO contexts, or packet filter in BSD contexts. A firewall has the basic task of controlling traffic between different zones of trust. Typical zones of trust include the Internet (a zone with no trust) and an internal network (a zone with high trust). The ultimate goal is to provide controlled connectivity between zones of differing trust levels through the enforcement of a security policy and connectivity model based on the least privilege principle.

Proper configuration of firewalls demands skill from the administrator. It requires considerable understanding of network protocols and of computer security. Small mistakes can render a firewall worthless as a security tool.

Answer 3

You are A+ certified and have no idea how a firewall works? I can't change jobs because I'm not A+ certified, but have 10 years of computer experience, a 2 year degree in computer information systems, know about firewalls, and networking etc.

This sucks, It's all about that piece of paper isn't it?

I'd like to help you, but I'm disgusted now.

Try looking it up in Wikipedia, they are the best source for technical questions like yours.
Enjoy

Answer 4

Every internet connection happens through computer ports. which are predetermined. Such as port 80 for http,port 21 for FTP in the same way different ports are assigned for different tasks such as SMTP, Telnet, etc. What firewall does that it closes communication through all ports. And keeps only those ports which are used by the user, ie. outgoing requests. Such as port 80 for connecting to internet and browsing etc. When some program wants to use some other port, it notifies the user if it is allowed to do so.
In the same way, it blocks all uninvited incoming requests on ports. In this way you are aware of all incoming and outgoing activities on your computer.

Without a firewall you will be unaware of such communications, and unable to block if you want to.

Here is a list of commonly used TCP/IP ports, which will give you an idea how vast this range of ports is.
http://www.chebucto.ns.ca/~rakerman/port-table.html

Answer 5

There's 65535 (or something) Ports on a computer.... WHen there's no firewall, all these ports are open to the internet.... A firewall makes sure that only the necessary ports are open (such as port 80).

Answer 6

It monitors which programs you start up, some will ask you if it's ok some just work it out like it know microsoft internet explorer is ok so allows it to operate so it knows what shoud happen then when it recieves something out of the ordanary it will tell you that should not happen and useally ask you if you will accept it or not and give you a clue as to what just happend

Answer 7

A firewall is router software. Routers pass on signals sent to them. A firewall is an "exception" to this fowarding. Some signals reach the router and are not forwarded on, so if you put one between you and the internet, it will filter out certain ports, etc.... and they will never reach your internal network.

Answer 8

prevents hacking , viruses,etc