It's sad, but true—there are some not so nice people out there, and that includes Internet abusers who want to wreak havoc on your computer and make your life miserable. While just about everyone on the planet has a good anti–virus program installed these days, this type of protection may not be enough. So, what should your first line of defense be? A firewall can stop invaders from gaining access to your computer. In essence, a firewall provides protection from port scanning and disables access to shared folders, files, and printers, which keeps the bad guys from copying files and programs to your computer that can cause serious problems when executed.
A good rule of thumb is that any computer connected directly to the Internet should also be protected by a firewall. A personal firewall can be your ticket to strong intruder protection and peace of mind.
A good rule of thumb is that any computer connected directly to the Internet should also be protected by a firewall. A personal firewall can be your ticket to strong intruder protection and peace of mind.
And now for the good news! If you are running Microsoft Windows XP Professional or Home Edition, Windows XP Media Center Edition, or Windows XP Tablet PC Edition, you've already got access to a built–in basic firewall. Microsoft Internet Connection Firewall (ICF) is included as a Windows XP networking feature and you should enable it if you need firewall protection. (If you've set up your Internet connection using the wizard and selected a direct or dial–up connection to the Internet, ICF may already be enabled.)
When running Windows XP, ICF opens and closes most ports on the firewall dynamically as you access services but there are a few exceptions. (See the [url=http://www.pccode.net]asp#ICF"Windows Messenger and ICF section below for details on manually configuring ports to enable file transfer and voice calls). Since Internet Connection Firewall provides inbound protection only, if you have concerns about programs that “phone home” or send outbound data to an unknown destination over the Internet, you may want to consider a third–party firewall.
Who Needs Firewall Protection? You need protection if you have a direct, dial–up connection to the Internet, a single computer connected to a cable modem, or a single computer connected to a DSL modem. You'll also want to enable a firewall on the Windows XP–based host computer (and only the host computer) that is used for Internet Connection Sharing (ICS). If you're a broadband user with two or more ISP assigned IPs connected through a hub, you'll need to protect each computer individually. An easy rule of thumb—if a computer connects directly to the Internet, it needs protection.
To activate ICF:
1.
Click Start , and then click My Network Places .
2.
Under Network Tasks , click View Network Connections . (Alternatively, you can right–click My Network Places and then click Properties .)
3.
Right–click the connection used for the Internet, and then click Properties .
4.
Click the Advanced tab, and select the Protect my computer and network check box to turn on ICF. (This also makes the Settings button active, allowing you to configure advanced parameters.)
Network Connections Properties dialog box – Advanced tab" src="/article/UploadPic/20063615156951.jpg" width="363"
[/url][url=http://www.chinamx.com.cn/#top]Top of page Windows Messenger and ICF Most of the time, my computers are connected wirelessly through one of my Network Address Translation (NAT) boxes that is connected to an AT&T Broadband cable modem. I'm waiting for UPnP firmware for these units that will enable Nat traversal so I can use all of the features of programs like Windows Messenger behind them. (Voice and video instant messaging were not working behind these NAT boxes when I wrote this column, but I'm hoping for firmware that will make this possible and when it arrives, I'll share information on the new UPnP NAT capabilities here in the Expert Zone.) When I wish to use the voice and video instant messaging real time communications (RTC) features, I connect a computer directly to my cable modem, and I enable the Internet Connection Firewall for these sessions.
Windows Messenger version 4.0, which ships with Windows XP, as well as the updated [url=http://www.pccode.net]aspx?FamilyID=b475d2d1-6266-4d82-bf78-14597545a6b4&displaylang=en"Windows Messenger 4.7 that is now available, also include the ability to transfer files. However, by default, ICF blocks file transfer and you will need to manually configure the appropriate ports to open. Here's how it's accomplished:
1.
Click Settings on the Advanced tab of the Properties dialog box for your Internet connection, then click Add .
2.
In the Service Settings window, type a description of the service.
3.
Type the IP address or the computer name.
4.
For Windows Messenger file transfer capabilities, the External and Internal Ports are the same and both are TCP. Use 6891 for both. If you wish to enable simultaneous transfer of up to 10 files, after clicking OK, set up additional ports in the same manner, numbering sequentially through 6900. You'll need 10 service entries total.
Additionally, you will have open Port 6901 for both TCP and UDP to receive incoming computer to computer voice calls and UDP Ports 6801, 6901, 2001–2120 for computer to phone voice calls.
As shown in the image above, I've enabled a single port only for a single file transfer only. The process to open ports to add other services is the same. Settings needed for some of the other more popular programs appear in the table below:
Program TCP ports UDP ports Incoming Voice (computer to computer)
6901
6901
Voice (comp
