Networking 101 part 4

Some general network terms:

MAC Address: Media Access Control Address. This is the physical address of the card. It's a relatively unique identifer that is linked to a spefic card. So on some networks you can have any IP you will only have generally one MAC address. The place you're most likely to use or encounter this is in a wireless network. One way to secure a wireless network is to use MAC address filtering. Saying that only certain MAC addresses can access the network. This won't stop more then a casual snoop however because a MAC address can be spoofed with ease.

DHCP: Dynamic Host Configuration Protocol. This protocol allows for a network to assign IP addresses on a first come first serve basis. Very useful in small networks where security is less of an issue then ease of use.

Bandwith: Bandwith is one measurement of how much data a network can carry. It's usually measured in bits per second. A 100 Mbps network can move 100 Mbps at a time. This isn't the same as saying it can move 100 MB (bytes is capitalised, bits are not) at a time. The general ratio is eight bits to the byte.

Network Bridge: In a nut shell it lets you join two parts of a network. Bridging a connection joins two networks together.

DMZ: DeMiliterized Zone. A machine that is on a network but beyond the firewall. Useful for some servers but I would almost always recomend proper port forwarding rather then placing an exposed machine of any kind onto the net.

ADSL: Asymmetric Digital Subscriber Line. A DSL line in which there is an uneven distrubtion of up and down bandwith. This is the most comman form of DSL which allows for fast downloads and slower uploads. There are other DSL varients but the only other one you're likely to see is SDSL which is the symmetric version of DSL.

DoS: Denial of service (not the OS). There are a couple of differant forms of it but basicly it's an attempt to cause more data to be sent to a server then it can handle. Alot of the viruses and worms attempt to set up Zombie nets of infected PC's to do this. It's not always malicious in nature, if a large site links to a smaller site it's possible for this to happen. There is a geek news site called "Slashdot" www.slashdot.org which is noted for the "slashdot effect" in which it's readers take down a site in an attempt to read an article that slashdot has linked to.

Hubs and Switches: This confuses some people. There is a differance between them however. Hubs are "dumb" devices. They recive a packet and broadcast them to everyone. Switches are "Smart" devices that can filter packets based on MAC address. Routers filter packets based on IP address. This allows for differant levels of control.

VPN: Virtual Private Network. VPN's use the internet but set up an encrypted network that is compressed. It adds a layer on top of the network to allow for a company to have it's intranet secure but available to it's employees from home.

Inter/intra nets: Internet is the big one, intra nets are internal networks for an orgranization.

WAN/LAN Wide area network. Local Area Network. WANs connect two or more physical locations, LANs connect PC's within a location.