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Securing
a wireless network
11 January
2007
Its
estimated 80,000 homes have wireless networks. Our guess is anything
up to 50% are not secured properly. How do you go about securing one?
One of the most
common problems we see are unsecured wireless networks. Unlike a wired
network, anyone can connect to a wireless network unless it has been
secured properly. While it probably doesn't matter if your neighbours
connect accidentally to check their email, there can be some serious
problems.
The most obvious
result is the risk of massive
excess Internet fees or having your service slowed when it exceeds
the monthly data allowance. But there are other risks. Some of which
can be very embarrassing.
One household
we were called to was being disconnected every month because someone
was using their network to send spam. Recently one of our techs once
walked out of setting up a new home wireless network to find a couple
snooping with a laptop.
Another risk
is an unsecured network can be used for illegal activity. Given most
viruses, spam and phishing scams start from compromised computers
and networks, it's your responsibility not to be one of them.
The risks don't
end there either. To track down the bad guys, authorities start with
the network address. This means if your Internet connection is being
used to send phishing scams, pornography or file sharing, it's your
door the police will be knocking on.
So it's important
to secure your wireless network. The manufacturers are aware of these
issues and have a number of features built into most wireless equipment.
Properly used, these settings will keep all but the most dedicated
hacker off your system.
Before securing
your network, you must read the manual that came with your wireless
router or access point. If you get your settings wrong, you will be
locked out, so you need to know how to reset it. Its also best
to use a computer wired directly to the access point when configuring
security.
Naming your wireless network
Every
wireless network has it"s own name, known as a Service Set
IDentifier. If you don't change it from how it comes from the
shop (ie "Netgear", "Default" or "Motorola") it's easy for the casual
hacker to guess your passwords. It's a good idea not to use your address
or name as the SSID, you don't want to give away too many secrets to
the neighbourhood.
Enable Wi-Fi Protected
Access
WPA
encrypts the wireless signal making it difficult for a hacker to connect
without knowing the passkey. A passkey should be something long and
relatively difficult to guess. A combination of letters, both capital
and lower case, and numbers are a good idea, your dog's name followed
by your phone number followed by your suburb is the sort of thing to
put in here but remember to write it down.
Older equipment
might only come with Wired Equivalent Privacy. WEP is an older and
less secure standard than WPA. The passkeys for WEP are usually a
mind numbing long string of letters and numbers which is a good incentive
for buying newer WPA gear.
MAC Address filtering
Every computer network
deivce has a unique number, known as the Media Access
Control address. You can set your wireless router to only accept
connections from known addresses. Even if the neighbours can see your
network, they cant connect without a permitted number.
Hide your SSID
You can hide your
network name by turning off your SSID broadcast, which means your system
doesn't tell the neighbours it's name. This is not recommended by purists
as it's against the WiFi standards. It also makes some devices stop
working, so we tend not to do this.
Disable DHCP
Every computer connected
to the Internet has it's own address, called a TCP/IP number. You can
either get one from your server or you can have a "fixed" one that you
enter yourself.
On a home network
the Internet router gives IP addresses out. This is called Dynamic Host
Configuration Protocol. By turning it off on your wireless network,
a hacker has to guess the addresses before they can connect. This should
only be done by those who understand TCP/IP
addressing and subnets.
Virtual Private Networking
A Virtual
Private Network encrypts the talk between computers. While
not strictly part of a wireless network, it adds another level of difficulty
for someone trying to figure out how your network is set up. VPNs are
notoriously difficult to setup, so this is not something we recommend
for the home user.
Reduce your power
Many wireless
routers and access points allow you to adjust the power used. The less
signal that escapes your premises, the less likely an outsider can find
your network. One everything is working, reduce the power to the minimum
you need to connect.
Secure your network
To further
hide your system from the bad guys, its a good idea to only share
the minimum you need to share. Dont share entire drives and dont
use the default network names generated by Windows.
Protect your system
Trojan horses
and viruses can creep onto your system and compromise your security.
Follow our Protection Kit guidelines.
The best secured network will be defeated by a well placed Trojan horse
or spyware.
The aim of this
is to keep your neighbours and their curious 15 year old son off your
network. If the kid next door is a serious hacker they can defeat
all these precautions with the right skills, tools and plenty of time.
Should you get infected with a trojan or virus, then all of this is
pointless anyway (which is true of a wired network as well).
As this article
shows, setting up a secure wireless network is not for the faint hearted.
No matter how much the product is improved, wired networks are more
secure, faster and more reliable. We recommend only considering wireless
networks if wiring a building is not feasible.
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