sample program of firewall and how can i install it?

Answer 1

I am not sure what you mean by sample program?

Anyway, best firewall softwares are zonealarm(free version, kerio or outpost. I personally like zonealarm because it is very easy to install and use.

Try zonealarm. They have tutorial also which will guide you to configure it. http://www.zonelabs.com/store/content/company/products/znalm/freeDownload.jsp?

Answer 2

Firewalls allow or disallow ports network access to and from your machine. Since all applications that utilize networking communicate on a certain port, you can more or less control which programs have access to your computer. They can also do some much more complicated processing on packets coming into and going out of your machine. Ideally, you would want to block everything coming in to your computer from the outside unless you were providing a service on certain ports. Some examples of which would be port 80 for a web server, port 139 for Windows file sharing, etc. Some popular firewalls for Windows include Windows Firewall, ZoneAlarm, BitDefender, AVG Firewall, and Norton Personal Firewall. For Linux and Mac, iptables is popular. Windows Firewall (as much as I hate to say it) is actually a pretty good firewall, and would likely suit your needs. To get to it, go to Start -> Control Panel -> Windows Security Center. Then click on Windows Firewall. In the window that comes up, you can turn the firewall on or off. If you click the exceptions tab, you can allow programs to access the network. The best thing about Windows Firewall? Its already installed.

check here for more info: http://www.microsoft.com/windowsxp/using/networking/security/winfirewall.mspx