| Gaming in general is fun, but there's something about | | | | traffic for benign applications that youwant to have |
| multiplayer gaming that'seven more enjoyable. Perhaps | | | | access to the Internet, such as your Web browser, |
| it's the satisfaction of realizing that the caryou just | | | | your e-mailapplication, and online games? |
| passed in the last lap is being driven by a real person, | | | | The answer is sort of. Picture a computer firewall in |
| like you, andnot some computer program. | | | | terms of its namesake. |
| But the Internet connection that makes gaming so | | | | A firewall in construction terms is a specially insulated |
| much fun also serves as adoorway through which | | | | wall between officesuites or apartments, which |
| nefarious hackers can send malicious code, causing | | | | prevents fires in one suite from spreading to thenext |
| havocwith your computer. Broadband users are | | | | suite. But sometimes builders want water or electrical |
| especially fertile targets for badseeds. That's why a | | | | conduits to passthrough the firewall. That's easy |
| firewall is so important. A good firewall, such as | | | | enoughthey just poke a hole through thewall, run |
| Internet | | | | their conduit through, and insulate around it. Computer |
| Connection Firewall (ICF) that comes with Windows | | | | firewallslet you do just that. They let you open specific |
| XP, protects your computerfrom attacks. | | | | ports while keeping otherports sealed off. |
| A firewall works by blocking communication ports that | | | | Gaming through ICF |
| are used to transferdata to and from your PC. | | | | So when do you need to open ports? Believe it or not, |
| However, games (and all applications that work | | | | when you want to playclient-server games like Return |
| overthe Internet) use those ports to communicate. This | | | | to Castle Wolfenstein or Call of Duty on adistant |
| raises some questions thatwe frequently encounter on | | | | server, you don't have to open any ports. That's |
| message boards and in the Usenet: how does | | | | because firewallsblock data coming in, but not going |
| afirewall affect the performance of online gaming? | | | | out. When your PC sends handshake dataout to the |
| What do you have to do toenjoy online gaming with a | | | | server, a connection is established, and once that |
| firewall in place? I'll answer these questions inthis article. | | | | connection isfired up, it allows your game to |
| How Ports Work | | | | communicate through the firewall. |
| To get the most out of online gaming through a secure | | | | However, when you wish to host a multiplayer session |
| connection, you have tohave some idea of how | | | | or play a peer-to-peergame like Age of Empires, you |
| games communicate over the Internet and how a | | | | do have to do a little footwork. In the caseof starting a |
| firewallworks. Don't worry; this discussion won't get | | | | server, your PC does not initiate a connection. When |
| inaccessibly technical. I'llstick to layman's terms. To start | | | | you startup a game and choose to host a server, it |
| with, let's look at how programs talk toeach other over | | | | just sits there and waits for othercomputers to |
| the Internet. All Internet-aware programs communicate | | | | connect to it. When ICF is in place, those other |
| witheach other through ports. What, exactly, is a port? | | | | computers can'tconnect. In fact, they can't even see |
| Think of your Internet connection as a water conduit. | | | | that your PC is hosting a server. |
| But instead of thinkingof it as one big pipe, picture it as | | | | You'll have to open one or more ports to allow other |
| a conglomeration of thousands of smallpipes: 65,535 of | | | | players to connect toyour server. Such is also the |
| them, to be exact. That is the number of Internet | | | | case with peer-to-peer games, in which |
| portsthrough which communications can take place. | | | | eachparticipant has to connect to everyone else's |
| Different services use different portsthe | | | | computer. Thankfully, mostgames use a client-server |
| assignment of which service useswhich port is more | | | | implementation. |
| or less arbitrary. For example, World Wide Web | | | | To open ports in your ICF firewall: |
| communi-cations use port 80. Why port 80? Because | | | | 1) Click Start, click My Network Places, and under |
| a few years ago, a bunch of | | | | Network Tasks, click Viewnetwork connections. |
| Internet-related people got together and decided that | | | | 2) Right-click the connection that you use for the |
| that's how it would be. | | | | Internet, and then click |
| Similarly, SMTP e-mail traffic uses port 25. Those | | | | Properties. |
| same people decided thatthat's how that would go, | | | | 3) On the Advanced tab, click Settings, and then click |
| and so on. These and other services use protocolsto | | | | Add. |
| transmit and receive their data through these ports. | | | | In the Description of service box type a name for the |
| Two protocols thatthey use are Transmission Control | | | | port you're opening. Forexample, "Halo Server." |
| Protocol (TCP) and User Datagram Protocol | | | | 4) In the Name or IP address of the computer hosting |
| (UDP). | | | | this service on yournetwork box, type 127.0.0.1. |
| The 65,535 ports are divided into three groups: Well | | | | 5) In both the External Port and Internal Port boxes, |
| Known Ports (ports 0through 1023), Registered Ports | | | | type the port number youwant to open. |
| (ports 1024 through 49151), and Dynamic or | | | | 6) Click either TCP or UDP, and then click OK. If you're |
| Private Ports (all the rest). A list of port numbers and | | | | unsure, repeat theprocess for both protocols. |
| what servicescommonly use them is kept up by the | | | | If you choose to make things easier, you can opt to |
| Internet Assigned Numbers Authority. | | | | turn off ICF when hostinga game and turn in it back on |
| Like other services, the Internet components of games | | | | when you're done. However, this leaves yourcomputer |
| use ports and protocolsto communicate over the | | | | vulnerable while your PC is acting as the game server. |
| Internet. When you play Halo online with a bunch | | | | Which ports do you open? Different games use |
| ofother people, it has to transmit your keyboard and | | | | different ports and some use TCP,some use UDP, and |
| mouse-click data to theserver so it can tell when you | | | | some use both. You can often find out which ports |
| move around or fire your weapon. In turn ithas to | | | | are usedby a given game by consulting the game's |
| transmit world data back to your computer so you | | | | documentation, its Readme file, or byvisiting its Web |
| can see where otherpeople move so you can aim at | | | | site and checking the FAQ pages. Some games make |
| them and chase them around. Halo and | | | | portinformation readily accessible, and for others, it's |
| othermultiplayer games like the Quake family, Half-Life | | | | hard to come by. Youmight try visiting a game's |
| and mods such as Team | | | | Usenet group or the message boards at its officialsite |
| Fortress Classic and the popular Counter-Strike, Medal | | | | or fan sites and posing the question: which ports do I |
| of Honor: Allied | | | | open to host aserver? In some cases, you'll not only |
| Assault, Battlefield 1942 send their data down ports | | | | have to open ports for the game's ownneeds, but also |
| and listen for data fromthe same or other ports. Game | | | | to meet the needs of its matchmaker service, so that |
| matchmaker services like GameSpy Arcade alsouse | | | | yourserver can be listed in other players' server |
| ports to communicate. | | | | browsers. |
| Firewalls block ports. They are, by their very nature, | | | | Be sure to close the affected ports when you're not |
| communications-blocking applications. By closing off | | | | hosting a gaming serverto keep your connection |
| ports, they prevent malicious entitiesfrom gaining | | | | secure. That sounds like a lot of footwork, but it'sworth |
| access to your computer through your Internet | | | | it to keep your computer safe. |
| connection. Butdoesn't that mean they also block | | | | |