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your multiplayer gaming (or videoconferencing or whatever application
requiring port forwarding) now works ” where it didn™t before.
310 Part V: The Part of Tens

However, the opposite is not always so easy to determine: that is, when you
have open ports that should be closed. This often happens when you open
ports for an application that you™re no longer using (but forgot to close the
ports again).

Plus, you might not have set things correctly in the first place.

We recommend the program ShieldsUP!! (www.grc.com). This program will
systematically test your router, effectively trying to break into your system
by using all commonly known techniques. The program will then issue you a
report that tells you how secure your router is ” and if it™s not, what to do to
fix it. We highly recommend this.

Q. What is firmware, and why might I need to upgrade it?
Any consumer electronics device is governed by software that™s seated in
onboard chip memory storage. When you turn on the device, it checks this
memory for what to do and loads the software in that area. This turns the
device on.

This firmware, as it™s referred to, can be updated through a process that™s
specific to each manufacturer. Often you™ll see options in your software con-
figuration program for checking for firmware upgrades.

Some folks advocate never, ever touching your firmware if you don™t need to.
Indeed, reprogramming your firmware can upset a lot of the logical innards of
your device that you struggled so hard to get right in the first place. In fact,
you might see this advice on a vendor site (like this is from the D-Link site):
“Do not upgrade firmware unless you are having specific problems (“If it ain™t
broke, don™t fix it”). Upgrading firmware will reset the settings to default
which means you will lose all your settings. You cannot use the backup set-
tings feature and apply it to the newer firmware. Do NOT upgrade firmware
with a wireless connection. You will damage the router.” Although not all
vendor firmware upgrades will reset your settings to default, many do. Be

Okay, we don™t necessarily disagree with any of that except to say, “Never say
never.” The standards in the wireless arena are changing, particularly in the
802.11a and 802.11g areas. One of the key ways that you can keep current
with these standards is by upgrading your firmware. You will find over time
that your wireless network will fall out of sync with these standards, and
you™ll have to upgrade at some point. When you do so, follow all the manufac-
turer™s warnings.

In Chapter 10, we discuss a forthcoming security enhancement for 802.11
LANs called Wi-Fi Protected Access (WPA). Many existing APs and network
adapters will be able to use WPA but only after they™ve had their firmware
Chapter 17: Ten FAQs about Wireless Home Networks

Q. Isn™t NAT the same as a firewall?
If you finding networking confusing, you™re not alone. (If it were so easy, we™d
have no market for our books!) One area of a lot of confusion is Network
Address Translation (NAT). And no, NAT is not the same as a firewall. It™s
important to understand the difference, too, to make sure that you set up
your network correctly. Firewalls provide a greater level of security than a
NAT router, and as a result, are generally more expensive than simple routers.

Often you™ll hear the term firewall used to describe a router™s ability to pro-
tect LAN IP addresses from Internet snoopers. But a true firewall actually
goes deeper than this, using SPI. This allows the firewalls to look at each IP
address and domain requesting access to the network; the administrator can
specify certain IP addresses or domain names that are allowed to be let in
while blocking any other attempt to access the LAN. (Sometimes you™ll hear
this called filtering.)

Firewalls can also add another layer of protection through a Virtual Private
Network (VPN). This enables remote access to the private network through
the use of secure logins and authentication. Finally, firewalls can help protect
your family from unsavory content by enabling you to block content from
certain sites.

So firewalls go well beyond NAT, and we highly recommend that you have a
firewall in your home network. Check out Chapter 10 for more information on

Q. How can I find out my IP address?
Well, first off, you have two IP addresses: your public IP address and your pri-
vate IP address. There are instances where you need to know one or the
other (or both) of these.

Your private IP address is your IP address on your LAN so that your router
knows where to send traffic in and among LAN devices. If you have a LAN
printer, that device will have its own IP address, as will any network device
on your LAN.

The address that these devices have, however, is rarely the public IP address
(the address is the “Internet phone number” of your network) mostly
because public IP addresses are becoming scarce. Your Internet gateway has
a public IP address for your home. If you want to access a specific device
that™s on your home network but from a public location, you typically have to
enable port forwarding and address that port on your public IP address,
something like, where 80 is the port.

You can usually find out your wide area network (WAN; public IP address) and
LAN (private IP address) from within your router configuration software. You
might see a Status screen; this is a common place where it shows your present
IP addresses and other key information about your present Internet connection.
312 Part V: The Part of Tens

If you have Windows 2000 or XP, you can find your computer™s private IP
address by choosing Start➪Run. When the Run dialog box pops up, type cmd
and then click OK. In the window that opens, type ipconfig at the command
prompt and then press Enter. You™ll see your IP address and a few other net-
work parameters.

This IP address is your internal or private IP address, not the public address
that people on the Internet use to connect to your network. So if you try to
give this to someone (perhaps so that they can connect to your computer to
do some videoconferencing or to connect to a game server that you™re host-
ing), it won™t work. You need the public IP address that you™ll find in the con-
figuration program for your access point/router.

Q. If everything stops working, what can I do?
The long time that it can take to get help from tech support these days actually
does lead a lot of people to read the manual, check out the Web site, and work
hard to debug their present situation. But what happens if you™ve tried every-
thing, and it™s still a dead connection ” and tech support agrees with you?

In these instances, the last resort is to do a reset of the system back to the
factory defaults and literally start over. If you do this, be sure to upgrade
your firmware while you™re at it because it will reset your variables, anyway.
And who knows, the more recent firmware update might resolve some issues
that could be causing the problems.

Resetting your device is considered a pretty drastic action and taken only
after you™ve tried everything else. Make sure that you at least get a tech sup-
port person on the phone to confirm that you have tried everything else and
that a reset makes sense.
Chapter 18
Ten Ways to Troubleshoot
Wireless LAN Performance
In This Chapter
Moving your access point(s)
Flipping channels
Boosting your signals
Checking your cordless phones

A lthough troubleshooting any piece of network equipment can be frus-
trating, when you deal with wireless equipment, it™s a little more so
because there™s so much that you just can™t check. After all, radio waves
are invisible. That™s the rub with improving the throughput (performance)
of your wireless home network, but we™re here to help. And don™t get hung up
on the term throughput ” it™s just the actual rate of the data flowing when you
take into account retransmissions attributable to errors.

The trick to successful troubleshooting anything is to be logical and system-
atic. First, think about the most likely issues and work from there (no matter
how improbable). The second thing to do is to be systematic. Networks are
complicated things, which mandates sequential troubleshooting thinking on
your part. Patience is a virtue when it comes to network debugging.

But perhaps hardest of all is making sense of performance issues, which
is the subject of this chapter. First of all, you can™t get a lot of great perfor-
mance reporting from consumer-level access points (the much more expen-
sive ones sold to businesses are better at that). And even so, debugging
performance based on performance data in arrears is tough. Fixing perfor-
mance issues is a trial-and-error, real-time process. At least most wireless
client devices have some sort of signal strength meter, which is one of the
best sources of information that you can get to help you understand what™s
happening. (This is a key point, and these signal strength meters are used by
the pros, says Tim Shaughnessy at NETGEAR: “I would highlight it as a tool.”
We agree.)
314 Part V: The Part of Tens

It™s a good idea to work with a friend or family member. Your friend can be in
a poor reception “hole” with a notebook computer with the wireless utility
showing the signal strength. You can try moving or configuring the AP to see
what works. Just be patient ” it can take a few seconds for the signal meter
to react to changes.

Because not all performance issues can be tracked down . . . or at least not
easily . . . in this chapter, we introduce you to the most common ways to
improve the performance or your wireless home network. These are tried-
and-true tips, having been there ourselves. We™re pretty good at debugging
this stuff by now. We just can™t seem to figure out when it™s not plugged in!
(Well, Pat can™t . . . read the next section to see what we mean.)

Check the Obvious
Sometimes, what™s causing you trouble is something simple ” and which you
can fix simply.

For instance, one of us (and we won™t say who . . . Pat) was surprised that his
access point (AP) just stopped working one day. The culprit was his beagle,
Opie, who had pulled the plug out of the wall. As obvious as this sounds, it
took the unnamed person (Pat) an hour to figure it out. Now if someone told
you, “Hey, the AP just stopped working,” you™d probably say, “Is it plugged
in?” The moral: Think of the obvious and check that first.

Following are a couple more simple problems to think of first. . . .

Problem: The power goes out and then comes back on. Different equipment
takes different periods of time to reset and go through to restart, causing loss
of connectivity and logical configurations in your network.

Solution: Sometimes you need to just turn everything off and then turn
them back on in order ” from the wide area network (WAN) connection
(your broadband modem, for instance) back to your machine ” allowing
each device to start up with everything upstream properly in place and
turned on.

Problem: Your AP is working fine, with great throughput and a strong signal
footprint, until one day when it all just drops off substantially. No hardware
problem. No new interferers installed at home. No new obstructions. No
changes of software. Nothing. End cause: The next door neighbor got an
access point and was using his on the same channel.
Chapter 18: Ten Ways to Troubleshoot Wireless LAN Performance

Solution: This is hard to debug in the first place. How the heck do you
find out who is charging invisible interference ” by going door to door?
“Uh, pardon me, I™m going door to door to try to debug interferers on my
access point. Are you suddenly emitting any extraneous radio waves? No,
I™m not wearing an aluminum foil hat, why?” Often with debugging perfor-
mance issues, you need to try a lot of the one-step solutions, such as chang-
ing channels, to see whether that has an effect. If you can find the solution,
you will have a lot of insight as to what the problem was. (If changing chan-
nels solved the problem, someone nearby was probably using the same chan-
nel, and you can then start tracking down whom!)

The wireless utility for the adapter might have a tab listing the APs in range
called a Site Survey or Station List. It might show your neighbor™s AP and the
channel that it™s on.

And before you chase a performance issue, make sure that there is one. The
advertised rates for throughput for the various wireless standards are pretty
misleading. What starts out at 54 Mbps for 802.11a is really more like a maxi-
mum of 36 Mbps in practice (less as distance grows). For 802.11b, it™s more
like 6 Mbps at best, rather than the 11 Mbps that you hear bandied about.
You will occasionally see the high levels (like when you™re within a few yards
of the access point), but that™s rare. The moral: If you think that you should
be getting 54 Mbps but you™re only getting 38 Mbps, consider yourself lucky.

Move the Access Point
Fact: A wireless signal degrades with distance. You might find that the place
where you originally placed your AP doesn™t really fit with your subsequent
real-world use of your wireless local area network (LAN). A move might be in

After your access point is up and working, you™ll probably forget about it ”
people often do. Access points can often be moved around and even shuffled
aside by subsequent gear. Because the access connection is still up (that is to
say, working), sometimes people don™t notice that the access point™s perfor-
mance degrades when you hide it more or move it around.

Make sure that your AP is where you want it to be. Check that other gear isn™t
blocking your AP, that your AP isn™t flush against a wall (which can cause
interference), that the vertical orientation of the AP isn™t too close to the
ground (more interference), and that your AP isn™t in line of sight of radio
wave interference (like from microwaves and cordless phones).
316 Part V: The Part of Tens

Even a few inches can make a difference. The best location is in the center of
your desired coverage area (remember to think in three dimensions!) and on
top of a desk or bookcase.

For more about setting up access points, check out Chapter 6.


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