Networks/ Network Security

Network and Network Security

1. Switches - Is a device in a network that allows info to be shared and sent within a network. It is a Layer 2 (data) device in a network algorithm and uses MAC addresses. It is either on or off. If on, it allows all broadcast data packets (of info) to pass along in the same network broadcast domain. (S. Jones, 9/17)

2. Routers - similar to switches (above), but differs; Is also a device in a network that allows info to be shared and sent within a network. It is a Layer 3 (network) device in a network algorithm and uses IP addresses. It is only able to pass along broadcast data packets (of info) if it has the specific address of the other devise, regardless of the broadcast domain. (S. Jones, 9/17)

3. Fiber Optic Cable - Fiber optic cables consist of a bundle glass threads, each of which is capable or transmitting messages onto light waves. Fiber Optic cables have a greater bandwidth than metal cables and can carry more data. They are also less susceptible to interference, are much thinner and lighter, and data can be transmitted digitally rather than analogically. The only disadvantage is that Fiber Optics are fragile and expensive to install. (PW)

4. Star Topology - Contains a single, centralized host computer with which all the devices in the network communicate, thus forming a star. (DMW); + the start topology is a network configuration that kind of resembles a "wagon wheel" - wherein the center is called the "hub" and the spokes are the nodes. In this network, whenever a node sends a signal to the hub, the hub sends the info to all of the other nodes in the network. In the old days, (MLO)there was no filtering or routing involved. In this network configuration all the nodes receive the same info from the hub.(S. Jones, 9/17) Nowadways, the hub is an intelligent router that reads the address and sends the message to the correct address whether it's destination is whithin the network or an outside destination on th web. The adaptation of the star topology allows for a more efficient method of sending messages. (MLO)

5. Bus topology - another network configuration like the star topology. In the bus topology it is configured similar to a fishbone. Wherein there is a back bone, and then each Node is connected off of the backbone one right after the other. It is also analogied to a set of Christmas lights. Info is sent from one node and travels along the backbone until it reaches its destination node. In order to stop the info from bouncing back when it gets to the end of the back bone, there is a terminator attached at each end of this configuration. (S. Jones, 9/17)

6. Dial-up - Accessing the internet through a phone line. You literally dial into the Internet service provider which then connects you to the internet. Very slow. (9/16/07 JD)

7. Modem - Stands for MOdulator-DEModulator. It is a device that converts the digital signals form input/output devices into appropriate frequencies at a transmission terminal and converts them back into digital signals at a receiving terminal. (MLO) A modem is used to send digital data over a phone line. The standard modem that communicates at 56 Kbps is very slow when compared to DSL and Cable network speeds. A faster modem known as an ASDL modem can communicate as speeds 1 Mbps between your home and the phone company (upstream) and 8 Mbps between the phone company and the home (downstream) under ideal conditions. The same line can transmit both a phone conversation and the digital data. (ww)

8. DSL - DSL stands for "digital subscriber line," and is used to connect a computer to the internet. It uses the existing copper phone lines and connects to a special switch over the phone lines by wiring inside the computer/switch. This provides a continuous connection to the internet through your phone line connection at home, and is much faster than dial up connection. It is a digital connection, and you can use the phone line to talk while also using it for internet connection at the same time. Provided by Melissa - 9/13/07.

9. FiOS -An Irish (Gaelic) work for knowledge. (mme)
FiOS is a broadband service designed to provide Internet access with maximum connection speeds of up to 50 Mbps depending on where you live. FiOS runs on a fiber-optic network. (ww)

10. Bandwidth- The frequency rnage of a telecommunications channel. (MLO) In refering to computers it is the data rate measured in bit/s, (bits per second MLO) for example channel capacity (Digital bandwidth capacity) or throughput (digital bandwidth comsumption). There is no single universal precise definition for bandwidth, and it can best be defined to be a measure of how wide a function is in the frequency domain.(sford 9/13/07)

11. IP Address- short for Internet Protocol Address, an address of a computer or other network device on a network. These addresses are similiar to a house number address. The address helps data reach the correct destination. An example of an IP address is There are five classes of addresses: Class A, Class B, Class C, Class D, and Class E. The A, B, and C classes are the most commonly used. Each class allows for a range of IP addresses. (9/13/07, W. Watson)

12. firewall - A general term that refers to both hardware and software used to restrict access to data and information on a network. Organizations use firewalls to deny network access to outsiders and to restrict employees' access to sensitive data such as payroll or personnel records. (DMW)

13. WEP- Wireless Equivalent Privacy, is a type of encryption, defined in the IEEE (Institute of Electrical and Electronic Engineers) standard 802.11, that helps protect a wireless network. WPA (Wi-Fi Protected Access) is an improved data encryption that is likely to replace WEP. (9/13/07, W. Watson)

14. Packets - a way for the network to break down data into smaller portions. Each packet contains information on where the data is to go and where it came from so that when it reaches its destination is is made whole again. (re) A group of data and control information in a specified format that is transmitted as an entity. (MLO)

15. SSID - is a secret key which the network administratior sets, and it is part of the packet header for every packet sent over the wireless network. All wireless devices, on the network, must use the same SSID in order to communicate with each other. (ww)

16. SSL- Public/ Private Key encryption - Secure Socket Layer, used to obtain/send secure information on the internet. Netscape developed this protocol. (re)

17. Packet sniffer - This is a computer software or computer hardware that can intercept and log traffic passing overa digital network or part of a network. When your data streams back and rforth over the network, the packet sniffer captures each packet and eventually decodes and analyzes its content according to the appropriate RFC (Request for Comments) or othe specifications. (mme)

18. Secure Password - A sequence of characters that one must input to gain access to a file, application, or computer system. Also referred to as passkey. (mme)

19. Email spoofing - fraudulent email activity. The sender address, subject line etc. can be altered to trick the receiver of the email into thinking the email is coming from a safe source or known source. Email spoofing is used with spam and phishing. This is something that is common on sites like "my space." (JD)

20. VLAN- Virtual LAN - stands for virtual local area network - basically, the purpose of a VLAN is to isolate part of a network so that not all members of the network have access to the information. It is not isolated based upon a "physical" location, but rather it is isolated through a broadcast domain. Wherein a broadcast domain is a collection of nodes or part of a network that can receive a broadcast packet from any node within the network. VLANS are used for several reasons including: 1) security- so that sensitive material is kept from the rest of the network as in a banking network, 2) special projects- so that if only certain members of the network are working on a project they can access it through the network, but others cannot, 3) business departments or special job titles - so that perhaps only the managers in a network would have access to certain information. My personal example is that I belong to the entire UPMC network. But, since I work at the Shadyside hospital facility, I can get broadcast messages to the "shadyside users" that Magee or Children's Hospital would not have access to. (S. Jones 9/17)

21 NAT- Network address translation- an internet standard that enables local area network (LAN) to use one or more IP addresses for internal traffic and second for external traffic. NAT is commonly used by homeowners to allow multiple computers to connect to a broadband connection. NAT is also used to hide internet network addresses by using a single NAT address. There are two variants of NAT used: NAPT-Network Address Port Translation and PAT- Port Address Translation. (9/19/07, W. Watson)

22. Domain Name Server (DNS)- DNS is the application that resolves IP addresses to computer names and vice versa. (re) An internet service that translates domain names into IP addresses. Because domain names are alphabetic, they're easier to remember. The internet however, is really based on IP addresses. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address. For example, the domain name might translate to (Junitermedia Corporation 2007). (DH)

23. TCP/IP- TCP /IP stands for “Transmission Control Protocol/Internet Protocol.” It is the most common language (protocol) of the internet, and can also be used in private networks, originally developped by the Department of Defense to connect a system of computer networks that became the Internet. There are two layers. The higher one, (TCP) assembles information into small packets that are sent via internet transmission to another TCP layer that decodes the packets back into the original format.(transport functions) The lower layer, (IP), is the address part of the message, which ensures that it is delivered to the correct computer or network. (addressing and routing mechanism) (MJT - 10/1/2007).

24. HTML-Hypertext Markup Language- is a worldwide web (MLO) mark up language that allows a user to create his or her own web page. The user creates tags; tags are anything between the less-than and greater-than signs. Using a tag, identifies where a command begins and ends. For example: <B>Communications Technology</B> This tells the browser to display the text within the HTML tags to be in bold print. (9/28/07, W. Watson) The very first website was buit by Tim Berners-Lee on August 6, 1991. (Try it, MLO)

25. HTTP-is HyperText Transfer Protocol. This is the Web's communication standard, that supports the exchange of information on the World Wide Web referenced in the http:// which appears at the beginning of every web page address ). All web services run over HTTP. (mme) HTP defines the process by which a Web client, called a browser, originates a request for information and sends it to a Web server, a program designed to respond to HTTP requests and provide the desired information.(MLO) When there is an s behind the HTTP it means the site is secure. LS m

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