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Windows Vista Security: Praxisorientierte Sicherheit für Profis by Marcus Nasarek

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Understanding Home and Small-Business Networks
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For secure connectivity to the Internet, you’ll need a firewall. While Windows Vista
includes Windows Firewall, this software firewall protects only your computer. It
doesn’t protect the other computers or devices on your network. Both of the broad-
band Ethernet routers mentioned previously include a hardware firewall, which will
fully protect your network.
On a home or small-business network, you shouldn’t stop using Win-
dows Firewall just because your network has a firewall. In most cases,
your computer still needs the protection Windows Firewall offers.
You can expand your home or small-business network beyond the ports on your
Ethernet router by connecting network hubs or switches to the router instead of indi-
vidual computers or devices. Hubs and switches work in a similar manner, allowing
computers or devices to connect to a network. While each allows a central point of
connectivity, hubs and switches work in different ways.
Hubs send all packets transmitted on the network to each host, making connectivity
very simple. The downside of hubs falls directly on their inability to send packets to
only a single host, which forces shared connectivity to each host connected to the
hub. This drastically decreases the amount of available bandwidth to transmit data.
If you have a 100 Mbps hub with 10 hosts connected, each host has approximately
10 Mbps of network bandwidth available to transmit data. The transmission of data
happens only in a half-duplex manner, greatly reducing network throughput. The
upside of a hub lies in its capability to transmit data to all ports at the same time.
When you have network difficulties and you want to mirror the data on the network
for monitoring purposes, hubs offer this functionality by default.
Switches differ from hubs with their inherent capability to transmit data from a sin-
gle host to another single host, without sending the packets to all the hosts on the
switch. This functionality allows for greater data throughput. If you have a 100 Mbps
switch, each host on the switch may transfer data at 100 Mbps. A switch stores a
routing table to keep track of the hosts connected. The routing table holds the
machine (MAC) address of the network adapter for each computer or device, and the
switch uses this table to determine to which host to send the data.
Installing Network Adapters in Your Computers
Installing network adapters in your computers requires you to open the case of the
computer and install a card. If you do not feel comfortable completing this task, con-
tact a computer repair or service company to install the network card. If installing
cards falls into the “old hat” routine, then power down, unplug the computer, open
the case, find the first available slot in your machine, insert the card with the gold leads
down into the slot, and press firmly to insert the card. Once you have completed this
task, screw in the top of the card to connect it to your chassis. This alleviates “wiggle”
in the card, which could create shorts or cause intermittent connectivity problems.

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