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Sacramento Computer Repair Technician
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What Does "Firewall" Mean? |
How to Keep Data on Your Laptop
Secure |
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The bottom line is that a large class of viruses and other types of malware can be prevented simply by using a good firewall. What’s a firewall? Well, in your car it’s the “wall” of metal behind the dashboard that sits between you and the engine. Its purpose is to prevent engine fires from roasting you and your passengers. A firewall for your computer is much the same – its purpose is to keep you from getting burned. A firewall is at its core very simple: it blocks or filters certain types of network traffic from reaching your computer. What do I mean by “certain types”? There’s network traffic you do want to reach your computer: like the pages of web sites you visit or the software you might download. And then there’s other traffic you might not want like malicious people or computers trying to access your computer remotely or viruses and worms trying to infect your machine. A firewall knows the difference. It lets the good stuff in and keeps the bad stuff out. Firewalls can also usually be configured; they can allow you to say “this kind of connection from the outside is OK”. A good example is remote desktop. A firewall may by default block any attempt to connect via remote desktop. But you can also configure the firewall to allow that type of connection to come through. Doing so you would be able to access your computer from another computer, be it across the room or across the internet. But even though you’ve allowed one type of traffic – remote desktop – other types of traffic like certain types of viruses are still blocked. Some firewalls will also monitor outgoing traffic for suspicious behavior. One characteristic of many viruses is that once you’re infected they attempt to establish connections to other computers in order to spread. Many software firewalls will detect and either warn you or simply prevent those attempts. And that leads to a very important distinction. There are two types of firewalls: hardware and software. A hardware firewall is just that – a separate box that sits between you and the internet that performs the filtering function. Traffic that is filtered out never even reaches your computer. Even the least expensive broadband router can perform the function of a firewall quite nicely. The downside for a hardware device is that most will not filter outgoing traffic. A software firewall is a program that runs on your computer. It operates at the very lowest level, as close to the network interface as possible, and monitors all your network traffic. While all network traffic still reaches your machine, the firewall prevents malicious traffic from getting past it and on to the operating system. The firewall prevents your system from actually noticing or doing anything with malicious traffic. The good news is that all versions of Windows after XP have a software firewall built in, and all versions after Windows XP SP2 have it turned on by default. In fact, the security center will take steps – perhaps even annoying you in the process – to ensure that the firewall is either turned on or that you’re aware of the risks in not having it turned on. The bad news is that a firewall can’t protect you from everything. A firewall is focused on protecting you from threats that arrive via malicious connection attempts over the internet. A firewall will not protect you from things you invite onto your machine yourself such as email, attachments, software downloads and removable hard drives. But even so, protecting from those network threats is important. In general, I recommend a hardware firewall such as a broadband router and leaving the Windows firewall turned off. However, regardless of your approach, be it a router, be it the Windows firewall, or be it some other software or hardware solution, some kind of firewall is always a necessary part of keeping your computer safe when connected to the internet. |
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Understandably, the biggest fear most people have about losing
their laptops, is not actually centered on the laptop itself.
The biggest fear is having sensitive information end up in the
wrong hands. Most can handle the material loss, but all that
data in the hands of malicious individuals is scary! There is a solution which is secure, fairly easy, and best of all, free. Of course, you can just encrypt all of your data with different archiving tools which allow you to assign each file a password. The problem associated with this method is that these passwords are often easy to crack and this process is a pretty big hassle. Instead, consider the free, open source program called TrueCrypt. This software provides industrial-strength encryption while being very easy to use. TrueCrypt can be used many ways, but the two most common are: • Encrypting an entire disk such as a floppy disc, USB thumb drive, or entire hard disk. • Creating an encrypted virtual disk container or “volume”. The latter approach is the easiest for copying entire containers from machine to machine. Truecrypt simply mounts the encrypted virtual disk so that it appears as an additional drive on your laptop. You enter the pass phrase once when you mount the virtual drive and from then on everything read from there is decrypted and everything written there is encrypted automatically. For example, you can have Truecrypt generate a drive called C:/windows/secritstuff. Then, if someone were to look at that file directly, they’d see nothing but random gibberish as a result of the encryption. When you use TrueCrypt to mount the virtual drive (such as selecting the drive letter “P”) then that drive – P: – would look just like any other disk on the machine. Every file placed in the drive is encrypted, so encryption becomes as easy as simply moving your sensitive files into that drive. While the encrypted drive is mounted, the contents can be accessed in their unencrypted form by any program you wish to use to access them. The trick is to set the drive so that it never mounts automatically. As your machine boots up the virtual drive would be nowhere to be found. The corresponding file c:/windows/secritstuff would be visible only as encrypted gibberish. Someone trying to access your files would only find that. The data is not accessible until you use the TrueCrypt software to select the file at c:/windows/secritstuff, choose the drive to mount it as P: and type the correct pass phrase. TrueCrypt also supports a variety of high-powered encryption algorithms. TrueCrypt documentation is obviously targeting the overly paranoid, including directions on how to use “plausible deniability” if a thief ever forced you to give them your password. Let’s all hope that’s just an extreme of little probability for most of us. Here are a few warnings: • The passphrase or word you use is going to be the weakest link. Encryption is still easily cracked if you use a bad password. If you choose a passphrase which is easy or obvious, then a dictionary attack can always be mounted on your machine to unlock the encrypted volume quickly. • Having an encrypted volume is useless if your important files are also elsewhere in unencrypted form on your machine. • Be sure to have secure backups which are updated regularly. It’s preferable to keep these unencrypted, but secure, just in case you lose the encrypted volume or happen to forget the password. Without your password, the data cannot be recovered. • Understand that files are never 100% secure. All encryption can theoretically get hacked. The reason for encryption is to make the effort and cost of hacking the files so astronomical that it is simply impractical. Data encryption is a very important aspect of an overall security strategy. Keeping your important files secure doesn’t require much more than forethought and planning. With spyware and viruses running rampant, not to mention possible theft, there is really no excuse not to take the little bit of time and save yourself a lot of grief should the unthinkable happen. |
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