1. Information Technology Unit 1 Outcome 2: Networks
Communications software & Channels
Network Security

2. Communications Software
Some communications devices are pre-programmed to accomplish communications tasks; while others require a separate communications software program to ensure proper data transmission.
Communications software include a number of programs that help you to establish a connection to another computer or network.
Separate communications programs often serve different purposes.

3. Communications Software
Windows includes a number of programs that help to establish a connection with another computer over the Internet (Internet Connection Wizard/Network & Sharing Center).
Some communications applications support FTP, which is an Internet standard that allows you to up/download files to/from a web server (aka FTP server).

4. Communications Channel
A communications channel is the communications path between two devices.
Bandwidth is the “width” of the channel; higher the bandwidth, the more data & information the channel can transmit.
Communications channels consist of one or more transmission media, of which can be physical or wireless.

5. Communications Channel
Baseband media can only transmit one signal at a time, whereas broadband media can transmit multiple signals simultaneously.
Baseband media transmit data at much slower rates than those that use broadband.
Most homes and businesses now opt for broadband services, such as ADSL & cable TV, due to the higher speeds offered.

6. Communications Channel
Physical transmission media
Twisted Pair cabling (CAT5/6)
Coaxial Cable
Fibre-optic cable
These are generally used within buildings or where some sense of permanency is in place.
LANs will always use one or more types of cabling throughout the LAN.

7. Physical Transmission Media Transfer Rates

8. Physical Transmission Media
Twisted Pair cabling
Most commonly used
Contains one or more twisted pair wires bundled together, each of which consist of two separate insulated copper wires that are twisted together.
Twisted pair cable systems are graded according to categories that describe the components & the installation technique. The current standard lies with CAT5 & CAT6.
What is the difference between the two?

9. Physical Transmission Media

10. Physical Transmission Media
Coaxial Cabling
Consist of a single copper wire surrounded by at least 3 layers of insulation.

11. Physical Transmission Media
Coaxial Cabling
Cable TV wiring often uses coaxial cable as it can be laid over longer distances than twisted-pair cables can.
Most networks are now moving away from utilising coaxial cabling, as fibre-optic offers higher data transfer rates.

12. Physical Transmission Media
Fibre-optic cabling
The core of a fibre-optic cable consists of dozens of thin strands of glass or plastic that use light to transmit signal.
Each strand of glass/plastic is called an optical fibre and is as thin as a human hair.

13. Physical Transmission Media

14. Physical Transmission Media
Fibre-optic cabling
Advantages
Capability of carrying significantly more signals than wire cables
Faster rate of data transmission
Less susceptibility to interference from other devices
Much thinner and lighter in weight
Disadvantages
Costs significantly more than twisted pair & coaxial cabling
Can be difficult to install & modify
Is less durable than twisted pair & coaxial cabling.

15. Activity Think About IT 2-16
The proposed Australian NBN will connect homes, businesses & schools by a fibre-optic cable system of speeds up to 100Mbps. It will become the largest fibre-to-home network built anywhere in the world.
What do you see as the challenges that make this such an ambitious project for the Australian Govt to undertake?
It is anticipated that up to 10% of homes may be too remote to be able to connect to the NBN.
What alternative connection media could be used to provide access for remote homes?

16. Communications Channel
Wireless transmission media
Wireless transmission media are used when it is inconvenient, impractical or impossible to install cabling.
Wireless transmission media currently in use include:
Broadcast & cellular radio
Microwaves
Communications satellites
Infrared

17. Wireless Transmission Media Transfer Rates

18. Wireless Transmission Media
Broadcast radio
Broadcast radio is a wireless transmission medium that distributes radio signals through the air over both short and long distances.
Bluetooth is one such example of broadcast radio technology.

19. Wireless Transmission Media
Cellular radio
Cellular radio is a form of broadcast radio that is widely used for mobile communications, specifically wireless modems & mobile phones.
Some mobile phones have the ability to be tethered, whereby a notebook computer is able to access the Internet via the mobile phone’s Internet connection.
Currently, the standard is 3G (144Kbps – 2.4Mbps, dependent on location) however there are tentative plans for Telstra to begin upgrading their network to 4G (100Mbps-300Mbps) later this year.

20. Wireless Transmission Media
Read the issue “Wireless advertising: cellular radio” on page 81
Answer the questions posed through Think About IT 2-17

21. Wireless Transmission Media
Microwaves
Microwaves are high-powered radio waves that provide high-speed signal transmissions.
Microwave transmissions involve sending signals from one microwave station to another. They are often a more viable option to cabling where an organisation has premises on different sides of the road, as the cost of digging under roads can be expensive and repairs difficult.
Use line-of-sight transmission, which means that microwaves must transmit in a straight line with no obstructions.

22. Wireless Transmission Media

23. Wireless Transmission Media
Communications Satellites
Communications satellites are space stations that receive microwave signals from an Earth-based station, strengthen the signal & then broadcast them back over a wide area to any number of Earth-based stations.
These stations are often microwave stations, however also include GPS receivers & hand-held computers.

24. Wireless Transmission Media
Communications Satellites
Connection & transmission to a satellite is called an uplink, while connection & transmission from a satellite is called a downlink. Generally downlink speeds are much faster than uplink speeds.
Users are not usually phased by this as they generally download more than they upload.

25. Wireless Transmission Media
Infrared (IrDA)
Standard that uses infrared light waves to transmit signals.
Requires line of sight between the sending & receiving devices. Any obstruction will block the signal from reaching its destination.
Current transfer rates range between 115Kbps & 4Mbps.

26. Wireless Transmission Media

27. Wireless Transmission Media Activity
Read the issue “Wireless advertising: cellular radio” on page 81.
Will Australian users willingly accept wireless adverts to be sent to them over mobile phones & other devices?
What incentive might convince someone to accept the messages? Free air time? Free information?
Would you accept the advertising in return for a free service?
Would the answer to the previous question change if they were targeted to your particular profile? Would this make a difference to you willingness to accept the adverts?

28. Network Security
Many security techniques, such as usernames & passwords, firewalls & biometrics, are used by network administrators to protect a network.
On a vast public network, like the Internet, the risk to you or your company’s data & information is very high.

29. Network Security Security Threats
The integrity & security of data and information stored within & communicated between information systems can be threatened by a number or actions, devices & events.
These threats can be accidental, deliberate or as a result of an unforeseen event.

30. Network Security & Activity
Accidental Threats
These are usually very hard to protect against.
Have you ever accidently deleted a file that you still needed?
Have you ever lost a USB stick?
Have you ever sent an attachment via to the wrong person or group?
For the above situations, what could have been done to prevent these?
Is there any way of limiting the consequences?

31. Network Security Deliberate Threats
Unauthorised access to computers & networks
A hacker finding a way into a network by bypassing security measures, finding a flaw in the security structure or by using an authorised client using a password that is predictable or is in someway compromised.
Regardless of the method used, an unauthorised user can seek to steal secure information for their own advantage, cause mischief in some way, or seek to damage files critical to the computer or network’s operation.

32. Network Security Deliberate Threats
Networks should also be protected from deliberate attacks from malware.
Malware (MALicious softWARE) refers to the group of programs that are designed to infiltrate & cause harm to a computer or network without the user’s knowledge or consent. These include viruses, worms, adware, spyware, keyloggers & logic bombs.

33. Activity Define each of the types of malware Virus: Worm: Trojan:
Adware
Spyware:
Keylogger:
Logic bomb:
Virus: attaches itself to a program or file in order to cause some form of damage to a computer
Worm: copies itself in memory or over a network using up system resources and possibly shutting the system down
Trojan: type of virus that pretends that its something that the user wants, in order to gain access to the system
Adware: advertising material that appears automatically after you install a piece of software
Spyware: software that selfinstalls on a computer that covertly reports a users actions on a computer or their Internet use
Keylogger: a program that logs each keystroke in order to gain access to sensitive information
Logic bomb: program that lies dormant until a particular event or program occurs in order to run a piece of code that may cause malicious damage to a computer.

34. Network Security Power surge
A power surge occurs when the incoming electrical power increases more than 5% above the normal system voltage (240v)
A momentary surge, called a power spike, can be caused by a lightning bolt striking power lines.
Both of these events can result in immediate & permanent damage to a computer or network if adequate power protection is not in place.

35. Network Security Usernames & Passwords
A username is a unique combination of characters such as letters of the alphabet or numbers, that identifies one specific user.
What is the system that MacKillop use to create your usernames?
First 3 characters of your surname, first initial, student ID number.

36. Network Security Usernames & Passwords
A password is a secret combination of characters associated with the username that allows access to certain computer resources.
Longer passwords provide greater security than shorter ones, and passwords with obvious references to yourself, such as initials, date of birth, etc, should not be used.
Many software applications now incorporate guidelines that passwords must follow before accepting them, such as having a minimum length, must have a capital, number and/or symbol, etc.

37. Network Security
[Add table 2-36]

38. Network Security Firewalls
A firewall can be a piece of hardware and/or software that restricts access to data & information on a network.
The purpose of a firewall is to securely separate the Internet & other external networks from the LAN. The firewall does this by examining the contents of incoming packets to determine whether they should be allowed to pass through to the LAN.
A common implementation of a firewall is to route all communications through a proxy server.

39. Network Security
Firewalls
Add figure 2-37

40. Network Security Firewalls
A server on the LAN can use any of the 1024 ports available to allow servers to be accessed by the external users over the Internet.
Common ports assigned to network services include:
21: FTP
23: Telnet
25: SMTP ( )
70: gopher
80: web servers (www)
A firewall has the ability to block any or all of these ports so as to restrict access to outsiders. By blocking the incoming ports, external users cannot use the port to hack into the LAN.

41. Network Security Biometrics
Biometrics is an emerging method of computer/network authentication that involves the user’s biological or physiological data.
Biometrics that are commonly used for authentication purposes include fingerprints & retinas as these are unique to each individual person.
Scanners are inbuilt or attached to the device and a users fingerprint/retina is used as a ‘password’ so as to gain access to the system.

42. Network Security Wireless security
Wireless communications technologies has enabled billions of homes & businesses connect to a LAN with relative ease.
Although there are many conveniences associated with wireless technologies, there are additional security risks.
To avoid unauthorised network access, WiFi networks should not be left unsecured (should not use a public SSID & be password protected), as well as have the WiFi Protected Access (WPA or the improved WPA2) encryption standard enabled to protect the data travelling via the network.

43. Wireless Security Activity: “Wardriving”
Think About IT 2-20

44. Home networks The advantages of using a network at home are:
All the devices can be connected to the Internet at the same time. Dependant on the settings, each computer can also access files & programs on the other computers.
All computers can share peripherals
Each networked computer is able to play multiplayer games with players on the other computers on the network.
There are 4 types of home network:
Ethernet
Phone line
Ethernet over power
WiFi

45. Home networks Ethernet
An Ethernet network requires you to connect a cable to each computer/device.
Usually involves running cabling through walls, ceilings and floors.
For the average home user, the hardware & software of an Ethernet network can be difficult to configure.

46. Home networks Phone line network
Phone line networks are popular in the US but have not been popular here in Australia.
Easy to install & inexpensive to setup that uses the existing telephone lines in the home.
The network does not interfere with the voice and data transmissions over the telephone line – so you can talk on the telephone line and use the same line to connect to the Internet.

47. Home networks Power line network
The existing low-voltage power lines in homes & organisations can be used to transmit data.
Uses the standard Ethernet/USB ports in the sending & receiving devices, specialised networking equipment as the communications device, and the existing electricity wiring on the premises as the transmission media.

48. Home networks WiFi network
As mentioned last lesson, WiFi uses radio waves to send signals across distances between m dependant on the environment.
Each device requires wireless networking capabilities whether that be in-built or ad-hoc in order to communicate with a wireless router. However, at least one computer usually connects to the router using cable. (Wireless routers typically have at least one Ethernet port)
WiFi networks have the advantage over wired networks in that users can move around the house & maintain a live connection. Bandwidth is dependant on how the premises are built as well as distance from the router.
Most ISP’s now offer packages that include all the required hardware & software to set up and enable WiFi connections at home.