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Subject:
From:
David Gillett <[log in to unmask]>
Reply To:
PCBUILD - Personal Computer Hardware discussion List <[log in to unmask]>
Date:
Mon, 5 Dec 2005 18:35:25 -0800
Content-Type:
text/plain
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  In a wired LAN, you have four basic components:

1.  Client devices:  PCs, and maybe some other networked things like
printer, PDA, network-attached storage drives.

2.  Distribution infrastructure:  Could just be a hunk of cable, but it is
often a switch or hub.  This is what each of the devices connects to.

3.  Gateway:  This can be a PC running ICS (Internet Connection Sharing),
but more and more often it's a router, which may provide additional services
to the client devices.

4.  Internet connection:  This might just be a cable from your phone or
cable company, but might require a "modem" device.

  No "modem" is needed if the cable from the provider is sufficiently
compatible with Ethernet.  Small home routers often incorporate a switch
(this is how they offer 4 or 8 LAN ports) and sometimes also a "modem" for
cable access.

  The role of most consumer wireless is to replace the cables which connect
clients to the distribution infrastructure.  So the built-in wireless
capability in your wife's new laptop is an alternative to a wired NIC
(Network Interface Card).
  You can obtain equivalent devices for your desktop which go into a PCI
slot or a USB connection ... but note that you may have difficulty finding
Windows 95 *drivers* for these devices.  (USB support wasn't added until
after Win98 was released....)

  A wireless device which functions like a switch, but connects to client
devices via radio waves rather than cables, is called an "Access Point".
Think of this as being like the base station of a cordless phone.  It will
have a wired port by which you can connect it to an existing hub or switch.
  Access points are rather over priced, and I don't know why.

  Instead, more and more small routers are including an access point as well
as a switch -- and for some reason these devices are much more reasonably
priced.  I found a NetGear WGR614 on sale for $29, and I don't think I've
seen an access point that was less than $80.
  [You probably don't move the desktop around much, so you might want to
consider just getting a PCI Ethernet NIC and connecting it to one of the
wired LAN ports of the router.]

  There are two frequency bands used for wireless networks:  2.4 GHz and 5
GHz.  The 802.11a standard uses 5 GHz.  The original 802.11, and the derived
802.11b and 802.11g standards all use the 2.4 GHz band.  As do some cordless
phones (although most have now moved to a 900 MHz band) and microwave
ovens....
  Each band is subdivided into channels -- in North America, there are 11
channels designated, numbered 1 through 11.  Typically, an access point or
router is configured for a specific channel, and the clients check all
channels to find their network service.  Many devices come already set to
channel 11 by default; when I checked last night, there were nine other
routers active within range of my apartment, and five of them were all
competing for use of channel 11.
  Each channel can only carry so much traffic, and so devices are allowed to
spread out to adjacent channels to get more bandwidth.  At full bandwidth
for any of these standards, five channels are used, two on each side of the
main configured channel.  So in an area where three radio services in the
band overlap in coverage, interference can be avoided by configuring one on
channel 1, one on channel 6, and one on channel 11.  More APs or other
channel assignments mean that some cannot provide maximum throughput because
of interference from others.

  Each service is identified by a string called an SSID.  If two APs use the
same SSID, they are asserting that clients can switch from one to the other
and remain connected to the same network.  So you'll want to change the
manufacturer's default SSID to something more unique.
  By default, each AP broadcasts its SSID something like 10 times a second
so clients know it's there.  You can turn this off, so that the AP only
responds if a client broadcasts a request for its SSID.  But once an AP and
client are talking, every packet carries the SSID, so this won't stay secret
for long.

  An AP can be configured to only communicate with a specific list of client
NICs, identified by their "MAC" addresses.  But again, this information is
broadcast over the air and so this restriction provides little protection
from hackers.

  The best defense against people overhearing or abusing your wireless
service is encryption, which comes in three basic flavours.  WEP is
supported by virtually all wireless gear, but can be broken by a determined
intruder.  It's more like a "no trespassing" sign than an actual fence.  But
I haven't ever heard of anyone cracking it by accident; unless an intruder
has singled you out for some reason, they're likely to opt for a neighbor's
unsecured system instead.
  WPA/WPA2 provide more powerful protection, but I don't think you can use
them without adding a RADIUS server to your network -- not something most
home users are prepared to do.
  The best protection is to use a VPN over the wireless link, but that's
going to require a VPN server on your network -- same problem.
  WEP comes in two strengths, 64-bit and 128 bit.  (Since 24 bits are
predetermined, you might see these referred to as 40-bit and 104-bit
respectively, which more truly represents the strength of the encryption.
In contrast, the SSL encryption used by secure web sites is often up to 2048
bits in strength.)

  If you use WEP, you'll want to change the "authetication type" from "Open"
to "Shared Key", and you'll need to configure a matching WEP key on each
client device.  If you disable AP broadcast of the SSID, you'll need to tell
each client what SSID to request.

Summary:
  You probably want a wireless "G" router for best capability/price
performance.  "B" offers less (but compatible) performance; "Super G" and
"Pre-N" charge a premium for capabilities which probably require a matching,
non-standard client device.  Enable WEP and consider not broadcasting the
SSID.
  If you have a spare PCI slot in your desktop, you can probably install a
PCI wireless NIC, if you can find one with drivers for Win 95.  The router
will probably also have wired LAN ports, so you could just add a PCI or ISA
Ethernet NIC.  [Routers generally support cable and DSL access, but not
dialup.]

David Gillett

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