CAT5 (Category 5) is an ethernet network cable standard that describes the physical charateristics of the wiring used to carry data along digital networks. CAT5 cable is made up of 4 twisted pairs of unshielded wires encased in a polyethelyne sheath. A completed cable will have a RJ-45 plug at each end.

The outer sheath of CAT5 cable is generally blue, but can be any color, “CAT5″ will be printed on the outer sheathing to indicate its certification. Each separate wire inside is also sheathed in plastic with a standard color scheme.

A Router is a networking device that directs the flow of data along networks. Routers are connected to at least two separate networks, commonly two LANs (Local Area Network) or WANs (Wide Area Network) or, as in your home network, your LAN and the Internet. Routers are also known as gateways, located where two or more networks connect, and are the critical device that keeps data flowing between the networks.

Simply put, you are playing with fire if you aren’t using a firewall to protect your PC and home network from unauthorized access from outside your network.

The term “firewall” originally referred to a physical barricade against the potential spread of fire. In home computing terms, a firewall is a component of a computer or network that acts as a barrier between your home network or PC and the Internet. The firewall blocks unauthorized access while allowing authorized access to your systems. Firewalls can be hardware devices or based in software, both serving the same function.

Firewalls work by inspecting all traffic, both inbound and outbound, and deciding whether the traffic is denied or allowed passage based on a set of pre-established rules or policies. These rules and policies can work in one or more of several methods:

The Doc is writing a series of articles on Home networking.

You can see it here