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This is my tutorial by me Irongeek on Firewalls.(Also can be found on various forums) It teaches you about firewalls, types of firewalls, and how these can influence your ability to surf. Please keep in mind this is more for the 'Novice' user.

Key Concepts

Software Firewall

Hardware Firewall


FTP Test

Error 10065

What does this tutorial Cover?

What is a firewall?

What are the types of firewalls?

How does a firewall work?

What protection does a firewall offer?

How can a software firewall affect my internet connection?

Test if a firewall is blocking internet access?

What is a firewall?

A firewall is a system designed to prevent unauthorized access to or
from a computer or private network. A firewall can be implemented in both
hardware and software, or a combination of both. They are frequently used to
prevent unauthorized Internet users from accessing computers or private
networks connected to the Internet. All messages entering or leaving the
computer or private network pass through the firewall, which examines each message
and blocks those that do not meet the specified security criteria.

What are the types of firewalls?

Software (or Personal)

Hardware Firewall (physical device)

Software (or Personal)

A software firewall is an application that has been installed on the
computer. The firewall will inspect internet traffic and traffic generated from
the pc intended for the internet.

Popular Vendors:




Black Ice

Hardware Firewall

A hardware firewall is a separate physical device. In general, a
hardware firewall can inspect internet traffic faster and more in-depth than a
software firewall.

Popular Vendors:




How does a firewall work?

Firewalls use one or more of following three methods to inspect

internet traffic flowing in and out of the PCs internet connection:

Packet Filtering – Internet traffic is compared against a list of
rules. If the traffic matches a rule, then the traffic is allowed. If the traffic
does not match a rule, then the traffic is discarded.

Proxy Service - Information from the Internet is retrieved by the firewall and then sent to the requesting system and vice versa.

Stateful Inspection - A newer method that doesn't examine the contents of each packet but instead compares certain key parts of internet traffic to a database of trusted information.

What protection does a firewall offer?

One of the best things about a firewall from a security standpoint is
that it stops anyone on the outside from logging onto your computer.
A firewall can block the following type of traffic

Remote login


SMTP session hijacking

Operating system bugs

Denial of Service

E-mail bombs




Redirect Bombs

Source Routing

HTTP (Ability to view Web Pages!)

HTTPS (Ability to view secure Web Pages!)

How can a software firewall affect my internet connection?

A software firewall can block the following:

Access to secure websites

Internet traffic

Prevent applications from reaching the internet, Ex. Email Client
(Outlook, Outlook Express)

Test if a firewall is blocking internet access?

Access a DOS Prompt

FTP Test

Test if a firewall is blocking internet access? How?

Click on Start, Select Run, Type Command or cmd, Click OK button
At the DOS prompt, type FTP (or FTP “modem’s LAN
Address”) Then hit the ENTER key on the keyboard.

Now, If you receive a socket error 10065, it means that a software
firewall application may be blocking traffic.

But If you receive an Unknown Error Number (Windows XP), this is
normal. If you receive a socket error 10061 then a firewall is not blocking
traffic. Just type "bye" then hit the ENTER key to return
to a normal prompt. Next type Exit and press ENTER key.

Please Remember: Even though disabled, the firewall may still be 'active' in the background.

I hope you enjoyed my tutorial on Firewalls. All feedback is appreciated. Irongeek
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Hello Irongeek,

NICE TUTORIAL, I would definetly recommend it for most novice users. It covers most of the basic types of firewalls and common related problems with them all. Also gives reasoning for using one or the other. Of course there are other firewall options that are out there being used, for virtually all home/new users, this tutorial covers about 90% of questions. You could maybe include a small, brief list of some of the most common port numbers that users of this forum would have a need for, or point them to a reference for that information. That way, once they understand what their firewall is doing, they will also know what ports to open so they can do what they want.

GREAT JOB Irongeek!

Greazy Mcgeezy
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