what do you mean firewall, how to insaatll?

Answer 1

In computing, 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.

Types of firewalls
There are three basic types of firewalls depending on:

Whether the communication is being done between a single node and the network, or between two or more networks.
Whether the communication is intercepted at the network layer, or at the application layer.
Whether the communication state is being tracked at the firewall or not.
With regard to the scope of filtered communications there exist:

Personal firewalls, a software application which normally filters traffic entering or leaving a single computer.
Network firewalls, normally running on a dedicated network device or computer positioned on the boundary of two or more networks or DMZs (demilitarized zones). Such a firewall filters all traffic entering or leaving the connected networks.
The latter definition corresponds to the conventional, traditional meaning of "firewall" in networking.

In reference to the layers where the traffic can be intercepted, three main categories of firewalls exist:

Network layer firewalls. An example would be iptables.
Application layer firewalls. An example would be TCP Wrappers.
Application firewalls. An example would be restricting ftp services through /etc/ftpaccess file
These network-layer and application-layer types of firewall may overlap, even though the personal firewall does not serve a network; indeed, single systems have implemented both together.

There's also the notion of application firewalls which are sometimes used during wide area network (WAN) networking on the world-wide web and govern the system software. An extended description would place them lower than application layer firewalls, indeed at the Operating System layer, and could alternately be called operating system firewalls. Some firewalls have higher privileges than others like mysql and pj.

Lastly, depending on whether the firewalls track packet states, two additional categories of firewalls exist:

Stateful firewalls
Stateless firewalls
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Network layer firewalls
Main article: network layer firewall
Network layer firewalls operate at a (relatively) low level of the TCP/IP protocol stack as IP-packet filters, not allowing packets to pass through the firewall unless they match the rules. The firewall administrator may define the rules; or default built-in rules may apply (as in some inflexible firewall systems).

A more permissive setup could allow any packet to pass the filter as long as it does not match one or more "negative-rules", or "deny rules". Today network firewalls are built into most computer operating systems and network appliances.

Modern firewalls can filter traffic based on many packet attributes like source IP address, source port, destination IP address or port, destination service like WWW or FTP. They can filter based on protocols, TTL values, netblock of originator, domain name of the source, and many other attributes.

Answer 2

A firewall is software that runs on your computer that constantly monitors your Internet activity. If you have a good one it will stop all intrusions from coming into your machine. It also watches for programs on your machine that is trying to connect to the Internet and warns you. This is important because there are a lot of Trojan horse programs, easily installed on your computer, that will allow someone to connect to you and watch what you are doing, as well as anything else they want, like deleting files.

In today's world it is a must have just like a virus checker.

Answer 3

hi, friend firewall is software or hardware that checks information coming from the Internet or a network, and then either blocks it or allows it to pass through to your computer, depending on your firewall settings. Even if you think there's nothing on your computer that would interest anyone, a worm could completely disable your computer, or someone could use your computer to help spread worms or viruses to other computers without your knowledge.

Answer 4

firewall is a program that protects your computer against intruders, hackers, etc.. there are many sites that you can go to to download one, for example, go to www.majorgeeks.com and press on "firewall" on the left side, and choose a firewall, there are a lot of programs, the good ones are.. norton, alarmzone, sygate, and others, you can read about them once you click on one. but you need a firewall, without, hackers will get in your computer and mess it up. so try to get one ASAP.
there are also anti-viruses if you don't have one. just click on "anti-viruses" and choose one.

Answer 5

Firewall is ssomething that is in the system..Good idea to keep it on as it works well with anti virus ...go to control panel and put in in on mode....Above answer is good if u wanted to search it on net ......dont copy and paste