5. Firewall a must for home
computer
By Mark Alberstat and
Chris Watt
THERE ARE ONLY a few universal truths. One is that if you are on the
Internet, someone at some time will try to hack into your computer.
Another is that you have software loaded that will want to get out onto
the Net without your knowledge. To prevent, or at least diminish the
chance of either of these from happening, you need a firewall.
A firewall is a piece of hardware, software, or both, designed to prevent
unauthorized access to or from your computer. If you are on a network at
your office but can't reach the Net from your own computer, a firewall is
blocking you. If you know your network is connected to another part of the
company but you can't access it, again, a firewall is at work.
Personal hardware firewalls, ranging from $80 and up, help to protect you
from other people trying to break in to your machine. These firewalls
filter incoming network traffic and reject packets that do not appear to
be replies to your own outgoing traffic. Thus, a personal firewall will
happily admit the data for that Web page you just requested, but probes
from worms or hackers looking for vulnerable network software will be
stopped cold.
More sophisticated personal firewalls, often called broadband routers,
typically feature ports allowing you to connect multiple computers and
onboard servers to manage your internal network. Normally, broadband
routers also feature network address translation (nat) capabilities,
making any number of computers behind your firewall appear as just one
system on the Net. Besides providing some measure of security, broadband
routers allow you to easily share your Net connection among multiple
computers in your home or office, making them an increasingly popular
item.
On a large network, hardware firewalls can also control traffic by
filtering on keywords or domains. If you have similar concerns at home,
programs like NetNanny are available for monitoring your children's
surfing habits.
Although hardware firewalls work well when configured correctly, they are
a bit beyond the knowledge and ability of the average computer user. As
with most software and hardware, they come with default settings that will
be adequate for most users.
Software firewalls, such as Zone Alarm, Norton Internet Security and
BlackIce Defender, can be effective in preventing software on your system
from accessing the Net (whether you want them to or not). Unfortunately,
they are not as effective against people who are bound and determined to
get into your PC.
The most popular of the lot is ZoneAlarm. This highly configurable
software package can be downloaded at several shareware sites or at zonelabs.com.
Most software firewalls will ask you if a certain program is allowed to
access the Net when it first tries to do so. You can then allow or deny it
access and the software keeps track of this for future attempts. One of
the biggest problems with software firewalls is that many users will not
recognize the name of the executable in this pop-up window. Not many users
would recognize the file wuauclt.exe as being the Windows automatic update
client and could easily tell the firewall not to allow it to access the
Net, thus missing valuable updates and security patches. Another file that
may pop up is ndisuio.sys, which is an internal Windows driver that should
be allowed to access the Net.
Another problem with these firewalls is that during the first few days
after installation, the user is constantly being asked to approve or deny
various programs. Frustration often wins out and the "allow" button will
be hit more often than is wanted or needed, diminishing the firewall's
effectiveness.
Anyone with a spare PC and a willingness to learn can set up a Linux-based
firewall for free that will outperform any firewall you can buy off the
shelf. The simplest Linux firewall distribution is "floppyfw, " which can
be downloaded from www.zelow.no/floppyfw/. This
tiny piece of software runs comfortably off a single 3.25-inch disk and
can be configured from any DOS, Windows or Linux machine (you can actually
do it from MacOS as well, but this takes work).
No matter what software or hardware solution you implement for a firewall,
hackers will continue to try to get into your computer and certain
programs will want to get out. Keeping your solution up to date with the
latest releases and patches, however, will go a long way from actually
inviting inappropriate access to or from your computer.
The Mousepad runs every two weeks. It's a service of Chebucto Community
Net, a community-owned Internet provider. If you have a question about
computing, e-mail mousepad@chebucto.ns.ca. If we use your question in
a column, we'll send you a free mousepad.
Originally published 23 March 2003
