Hardware Reference
In-Depth Information
Firewalls
Firewalls
prevent unauthorized activity on particular ports. A
port
is a TCP channel used
to transport network traffi c. There are many TCP ports, with some reserved for common
services such as FTP, HTTP, email, and so on. Most fi rewalls fi lter traffi c based on rules,
which are based on ports and trusted zones. These can be open pathways for a hacker to
abuse. Most OSs have a software-based fi rewall that is enabled by default. Hardware-based
fi rewall devices are also available, but they're usually used on servers and not on individual
user PCs.
When you're connected to a network that you may be sharing with others whom you
don't know, you should make sure a fi rewall is running. A fi rewall is also important
whenever you're connected to the Internet, which is essentially just a big public network.
Some fi rewalls block all incoming traffi c on any port, unless your system has initiated
a network connection with an outside service (such as a website you've visited). You can
confi gure a fi rewall to let certain applications in and to keep others out. See Exercise 6.6,
“Confi gure the Windows Firewall,” in Chapter 6 for practice confi guring a fi rewall.
Internet Privacy and Security
After you've established an Internet connection, a whole new set of security and privacy
concerns come into play. There are threats from many directions, including from pop-ups,
cookies, phishing, and so on, as well as more human threats such as con artists who try to
get you to reveal information you shouldn't.
Identity Fraud and Social Engineering
Online, it's easy to impersonate someone. You don't even have to look or sound similar. All
you need is enough personal information about them to trick a website or service provider
into thinking you're that person. That's how millions of consumers are ripped off each
year. Identity fraud is a very real and present danger online.
The most important thing you can do to prevent someone from stealing your online identity
is to use strong passwords, as described earlier in this chapter, and change them frequently.
Gaining access to someone's username and password for a site is one of the most common
ways that criminals operate. If you keep your passwords written down somewhere, guard that
piece of paper (or electronic fi le) as closely as you would guard a valuable possession.
Ironically, many people freely give away the information that thieves need to impersonate
them, out of naivety. Tricking someone into sharing personal information or letting their
guard down so a criminal can exploit them is called
social engineering
. This isn't new—
people have been ripping off others through deception since the beginning of history. Here
are some examples:
Someone (in person) trying to gain your trust, in order to get you to reveal personal
information
