A SYN attack simply buries its target by swamping it with TCP SYN packets. Each SYN packet demands a SYN-ACK response and causes server to wait for proper ACK in reply. Of course, attacker never gives ACK, or, more commonly, it uses a bad IP address so there's no chance of an ACK returning. This quickly hogties a server as it tries to send out SYN-ACKs while waiting for ACKs.

When SYN-ACK queues fill up, server can no longer take any incoming SYNs, and that's end of that server until attack is cleared up. The Land attack makes SYN one-step nastier by using SYN packets with spoofed IP addresses from your own network.

There are many ways to reduce your chances of getting SYNed, including setting your firewall to block all incoming packets from bad external IP addresses like 10.0.0.0 to 10.255.255.255, 127.0.0.0 to 127.255.255.255, 172.16.0.0 to 172.31.255.255, and 192.168.0.0 to 192.168.255.255, as well as all internal addresses. But, as SCO discovered, if you throw enough SYN packets at a site, any site can still be SYNed off net.

Brute Force Attacks

Common brute force attacks include Smurf attack and User Datagram Protocol (UDP) flood. When you're Smurfed, Internet Control Message Protocol (ICMP) echo request packets, a particular type of ping packet, overwhelm your router. Making matters worse, each packet's destination IP address is spoofed to be your local broadcast address. You're probably already getting picture. Once your router also gets into act of broadcasting ICMP packets, it won't be long before your internal network is frozen.

A UDP flood works by someone spoofing a call from one of your system's UDP chargen programs. This test program generates semi-random characters for received packets with another of your network's UDP echo service. Once these characters start being reflected, your bandwidth quickly vaporizes.

Fortunately, for these two anyway, you can usually block them. With Smurfing, just setting your router to ignore broadcast addressing and setting your firewall to ignore ICMP requests should be all you need.

To dam up UDP floods, just block all non-service UDP services requests for your network. Programs that need UDP will still work. Unless, of course, sheer volume of attack mauls your Internet connection.

That's where DDoS attack programs such as Tribe Force Network (TFN), Trin00, Trinity, and Stacheldraht come in. These programs are used to set DDoS attack agents in unprotected systems. Once enough of them have been set up in naÃ?Æ?Ã?¯ve users' PCs, DDoS controller sets them off by remote control, burying target sites from hundreds or even thousands of machines.

Unfortunately, as more and more users add broadband connections without least idea of how to handle Internet security, these kinds of attacks will only become more common.

Deflecting DDoS Attacks

So what can you do about DDoS threats? For starters, all usual security basics can help. You know drill: make sure you have a firewall set up that aggressively keeps everything out except legal traffic, keep your anti-viral software up to date so your computers do not become a home for DDoS agents like TFN, and keep your network software up to date with current security patches. This won't stop all DDoS attacks, but it will stop some of them like Smurfing.

You may not think you need these services, since in a worse case scenario you're still going to get knocked off net. But not every attack will be a massive one with thousands of attackers. For most attacks, these services can definitely help.

And, let's face it, today we have PC's net 24-7. With DDoS attacks on rise, you'd be wise to at least familiarize yourself with DDoS prevention services. After all, it's not only your network in danger, it's your business.

Most computer experts rely on removable hard drives for memory backups. The most popular of these drives are Zip drive from Iomega and ORB drive from Castlewood. They’re relatively inexpensive and hold up to two gigs of data. Basically, you’ll save your data on a Zip disk, then transfer it from disk to portable drive. The catch is that removable drives fail about as often as regular hard drives. They may even be more susceptible to damage from dust and rough handling. A sub-option here is to use a permanent hard drive as a removable drive. At up to two hundred gigs, conventional hard drives are bigger than removable drives, and prices have dropped enough in recent years to make this idea practical. Whatever kind of hard drive you decide to use, make sure to keep it isolated from dust, magnetic charges, and static electricity.

Optical drives use a laser to store information, rather than a magnet. Even if you’re not a tech junkie, that’s probably enough information to give you a clearer idea what we’re talking about: namely, CDs and DVDs. Less common are EO (erasable optical) and WORM (write once, read many) media; they’re less common because they cost over $1000 per drive. CDs, on other hand, cost less than a buck and can hold up to 650 megabytes. DVDs hold up to five gigs and cost about fifteen dollars apiece. Most computers nowadays have either a CD or DVD writer (or both), but write times can be slow. My CD writer, for example, works best on 300 kilobyte per second setting—if then. I’ll be using remote server option. At $250 and up, tape drives are more expensive and slower than hard drives or optical media, hence less common, but also extremely reliable.

Remote servers are third party companies that store data online for a fee. This is a great option for broadband Internet users, especially people like me who don’t own a reliable data writer. SkyDesk runs Backup.com, Back-Up Solutions maintains BackUpHelp.com, and Iomega hosts iServer (Iomega.com/iStorage). XDrive.com, once a free service, now charges ten bucks a month for up to five gigs of storage. Promotions and other rates change, so it’s a good idea to shop around before selecting a remote storage service.

STEP THREE: Git ’er Done

Now it’s time to put files you want to save on storage medium you’ve chosen. There are several ways to do this. Your CD writer, for example, may come with proprietary disk writing software. That application may even include a backup option. If it does, and you’re more familiar with that software than Windows features, then that’s way to go. Otherwise, backup is still relatively easy on all MS operating systems since Windows 98. Windows 98, Windows ME, and Windows XP Professional include a built-in Backup utility. To run it, just click on Start, then Programs, then Accessories, then System Tools, then Backup. How easy was that? If you’re using XP Home edition, you may need to add utility manually. If so, insert Windows XP CD into your disk drive and wait for “Welcome to Microsoft Windows XP” screen. (You may need to double-click CD icon in My Computer.) Then click on Perform Additional Tasks and Browse This CD. In Windows Explorer, double-click ValueAdd folder, then Msft, then Ntbackup. Double-clicking on Ntbackup.msi will install utility. Once it’s installed, you can also run program by clicking Start and Run, then typing msbackup.exe (Windows 98 and Windows ME) or ntbackup.exe (Windows XP) in Open field. Click OK, and you’ll be off to races.

Incidentally, Windows XP Backup utility also includes a bonus application called Automated Recovery Wizard. This creates a bootable floppy that initiates backup if hard drive must be replaced. Other options for “disaster recovery” include BackUp MyPC from Stomp (StompInc.com, $79) and Norton Ghost 9.0 from Symantec (Norton.com, $69.95). Ghost actually allows users to duplicate contents of their computer over Internet. Both have earned stellar reviews from top PC magazines.

Don’t let another month go by without protecting files you value most. My girlfriend justifies her messy car by saying she “lives out of it.” Well, I live out of my computer. It’s not just my office; it’s home of cherished memories in form of pictures, MP3, and other data files. I’m resolved to keep it safe.