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Hack 47 Use a Proxy Server to Protect Your PC

Many private businesses protect their networks
with proxy servers. But you can get the same kind of protection at
homefor freewithout buying any new hardware.

Proxy servers
protect your PC by offering a kind of relay protection. When you use
a proxy server, Internet Explorer contacts the proxy instead of the
Web site. The proxy delivers the page to you if the page is in its
cache. If the page is not in its cache, it contacts the site, grabs
the page, and then delivers the page to you. In this way, you never
directly contact a web site or other Internet location; instead, the
proxy server does, so it, rather than you, will be the target of
attack or privacy invasion by the site. Proxy servers can be
configured for any kind of Internet access, not just web browsing.

Some businesses use proxy servers as
part of corporate-wide security precautions, and if you work at such
a business your work PC has been specifically set up to use those
servers. But even if you are not at a business with a proxy server
you can still use one to protect your PC. You won't
have to set up and run the proxy server yourself; instead, you can
use one of the many free ones available on the Internet.

Setting up a proxy server in this way is a two-step process.


First, find a free, public proxy
server. Then, set up your PC to use it. To find a free, public proxy
server, go to Stay Invisible
(http://www.stayinvisible.com)
and click on View Proxies. The site lists hundreds of free, public
proxies from around the world and updates the list daily, as shown in
Figure 5-11.

Figure 5-11. Stay Invisible's list of free public proxy servers around the world

Choose a proxy server from the list, and copy down its IP address and
port number. If you want to double-check that the server is
functioning, go to the Check Your Proxy section on the left side of
the web page, type its IP address and port number, and click on
Check. If the server is functioning, a page will pop up with the
server's IP address and name (often, the name is the
same as the IP address). If the server is not functioning,
you'll get a message telling you the connection
can't be made.

Once you've confirmed
a working proxy server and copied down its IP address and port
number, it's time to configure


Internet Explorer to use it. Open Internet
Explorer, choose Tools Internet Options
Connections, and click on Settings if you use a dial-up connection
and LAN Settings if you access the Internet using an always-on
connection, such as over a LAN or via a cable modem or DSL modem. The
options will be the same for both ways of access. Figure 5-12 shows the LAN
Settings dialog box for configuring a proxy server.

Figure 5-12. Configuring your proxy settings using the LAN Settings dialog box

Type in the address of the proxy server and its port number. For
local domains, you need to use a proxy server because they will be
secure. Check the "Bypass proxy server for local
addresses" box if you know your local domain is
secure.

If
you're at work and the company uses separate proxy
servers for different Internet services, such as FTP and Gopher,
click on the Advanced button. From there, you'll be
able to fill in the specific information about proxy servers for each
Internet service.

5.7.1 Hacking the Hack

If
you have a reason for wanting
to limit your PC to visiting only certain web sites and banning it
from visiting any otherssuch as for a child's
computer, which you want to have only very limited Internet
accessyou can hack the proxy server settings to accomplish
that.

Go to the LAN Settings dialog box (shown in Figure 5-12), and enable use of a proxy server. Then,
click on the Advanced button and the Proxy Settings dialog screen
appears, as shown in Figure 5-13.

Figure 5-13. Use the Proxy Setting dialog box to limit the Web sites your PC can visit

For the HTTP: entry, type in a word, such as
nowhere, or type in an Internet address that
doesn't exist. When you do this,
you're telling Internet Explorer to use a proxy
server that isn't there. This effectively blocks
access to the Internet, because instead of going to a web site,
Internet Explorer will go to a proxy server. But because the proxy
server doesn't exist, your browser
won't be able to visit any site.

Next, check the box next to "Use the same proxy
server for all protocols." This will ensure that
you're blocking Internet access for other services,
such as FTP, not just for the Web.

You've now effectively blocked access to the
Internet for the PC. Now you can enable a setting that will let the
PC visit only specific web sites. In the Exceptions section, type the
locations of the web sites you want to allow to be visited, separated
by a semicolon. This Exceptions box tells Internet Explorer to bypass
the proxy server for the listed sites, so it will go straight to
those sites, bypassing the not-there proxy.

Once you put those settings into effect, whenever your PC tries to
access the Web it will look for a proxy server that
doesn't exist, so it won't be able
to get onto the Internet. However, it will let you go to the web
sites that you've put in the Exceptions section.

5.7.2 See Also

[Hack #51]

[Hack #43]

[Hack #39]