Elementary Computing CSC 100 1
Networking History of Voice and Data Networks Dialup Modem and ADSL Ethernet and Local Area Network Network Speed Wired and Wireless Routers Eavesdropping and Network Security Mobile Telephone and Data Networks 2
Outcomes Networking is an essential service for computers and mobile devices. Most homes and offices are equipped with a Local Area Network. LANs are connected through gateways or routers to form a Wide Area Network. Mobile phone data networks are independent of our traditional Internet. 3
Study Guide What is a dialup or ADSL modem? What is a router or a hub? What is a LAN? What is a WAN? What is Ethernet? What is a wired or wireless router? How are IP addresses assigned by a router? 4
Study Guide How network speed is measured? What is SSID? What is packet sniffing? What is a rogue router? What is a firewall? How is mobile data network connected to the Internet? What is roaming & 4G mobile data network? 5
History of Telephones & Networks 6
Telephone Networks Telephone networks are older than the Internet by at least 60 years. Public Switched Telephone Network (PSTN) is a global network of regional telephone networks. They are designed primarily for voice communication. 7
The Internet The Internet was created in the 70 s as an experimental data network connecting up to 15 sites across the US, known as the ARPANET. Initially, connections were made over existing telephone networks. 8
How do we send data (1 s and 0 s) over a voice only network? 9
Dial- up Modems 10
A dialup modem is an equipment that converts 1s and 0s to audible sound, and vice versa. 11
Dialup Data/Fax Modem 12
Sound of a Dial- up Modem 13
A fax machine sends/receives a scanned document (in 1s and 0s) over the telephone using an internal dialup modem. 14
A Poor Man Email Machine 15
Sending Fax in Windows 16
Sending Fax in OS X 17
As the demand for faster speed increases, dialup modems are replaced by ADSL modems. 18
Asymmetric Digital Subscriber Line 19
Local Area Network (LAN) 20
LAN and Ethernet In 1974, XEROX research lab developed a personal office system called Alto. This system includes a GUI, a mouse, a laser printer and a Local Area Network (LAN) called Ethernet. This LAN connects several local computers to share printers and files. 21
Ethernet Port and Cable Ethernet Cable (8 pins) Ethernet Port 22
Ethernet Port and Cable Ethernet Cable (8 pins) Ethernet Port Telephone Modem Port Telephone Cable (4 pins) 23
A LAN is designed to work within an office or a building, typically under 100 meters. 24
How do you connect offices across blocks, streets, or towns? 25
Router 26
A Telephone Switch Board M. Cheng, Computer Science 27
What is a Router? It is an electronic switch board for computer communication. It allows data to be sent from one computer to another, and back. It has a Wide Area Network (WAN) connection to outside computers or networks. 28
What is a Router for? Several local computers can share a printer or files (e.g., documents, music, videos). A router has multiple LAN ports, one for each locally connected computer. It connects to the Internet via a WAN port; all local computers shared this WAN connection. 29
The Router Ports LAN ports (for local Computers and Printers) 30
The Router Ports WAN port (for ADSL modem and access to the Internet) LAN ports (for local Computers and Printers) 31
A Home Local Area Network WAN connection A Router or Gateway 32
A Home Local Area Network An ADSL modem connected to local Telephone or Cable network 33
Today, wireless LAN (or WiFi) is commonly used in offices and homes. 34
A WiFi Router LAN Ports 35
A WiFi Router WAN Port LAN Ports 36
Typical WiFi Router Setup 37
Router and IP Addresses Every connected computer or device is assigned a locally unique IP address. The WAN connection is assigned an external IP address by your Internet Service Provider (ISP). All connected devices will share this same external IP address when accessing the Internet. 38
Router s IP Address Assignment 192.168.1.1 WiFi Router 96.54.211.26 (When a router is connected to the Internet, it will have an IP address for its WAN port.) 39
Router s IP Address Assignment 192.168.1.1 WiFi Router 96.54.211.26 192.168.1.103 (When a computer is connected M. to Cheng, the router, Computer Science it will be assigned an IP address.) 40
Router s IP Address Assignment (When a laptop is connected to the WiFi router, it will be assigned an IP address.) 192.168.1.102 192.168.1.1 WiFi Router 96.54.211.26 192.168.1.103 41
Router s IP Address Assignment (When a tablet is connected to the WiFi router, it will get an IP address.) 192.168.1.100 192.168.1.102 WiFi Router 192.168.1.1 96.54.211.26 192.168.1.103 42
Router s IP Address Assignment (When a smartphone is connected to the WiFi router, it will also get an IP address.) 192.168.1.101 192.168.1.100 192.168.1.102 WiFi Router 192.168.1.1 96.54.211.26 192.168.1.103 43
OS X Network Setup My machine s IP Address My router s IP address 44
Windows Network Setup My machine s IP Address My router s IP address 45
WiFi Router A typical wireless (also known as 802.11) router has a range from 20 to 50 meters. A router will provide a dynamic IP address for each connected computer. Every WiFi router typically has a Service Set Identification (SSID) (e.g., UVic, UVicOpen). 46
Wide Area Network (WAN) 47
A WAN is designed to work across buildings and cities. 48
The Router Ports WAN port (for ADSL modem and access to the Internet) LAN ports (for local Computers and Printers) 49
A Home Local Area Network The Internet is a WAN An ADSL modem connected to local Telephone network A Router 50
LAN vs WAN LAN is typically used within an office, a home, or a building. WAN is typically used across buildings, cities, towns, states, provinces, and countries. A WAN connects many LANs (or other WANs) together to form a larger WAN. 51
Wide Area Network 52
Router and Network Security 53
What is a Firewall? It is a service which monitors all incoming and outgoing network traffic. It can block/allow certain network services, e.g., FTP, Skype, HTTP, etc. It prevents undesirable external network access by filtering certain IP packets. 54
OS X Firewall Setup 55
Windows 7 Firewall Setup 56
Packet Sniffing & Eavesdropping Any computer within the range of a wireless router can sniff all IP packets transmitted over the air. By collecting many IP packets, an intruder can determine what is being transmitted, e.g., names and passwords. 57
Security & Encryption Many WiFi routers provide a default security option (e.g., WEP, WPA, WPA2). A computer must provide a login password in order to obtain an IP address. All packets transmitted between a connected computer and the router are then encrypted. 58
OS X WiFi Security Setting 59
Windows WiFi Security Setting 60
Rouge Router & Fake SSID Any computer with a WiFi connection can be set up as a rouge router. An unsuspected user can be tricked to connect to a router with a fake SSID. As a result, all packets transmitted will be collected for analysis. 61
Mobile Telephone & Data Networks 62
First Mobile (Cellular) Telephone $4000 The Brick 63
Cellular Networks Public Switched Telephone Network 64
Mobile Phone Generations 1G mobile phones can only support voice over CDMA networks. 2G mobile phones support voice and SMS (Short Message Services up 160 chars) over GSM networks. 3G mobile phones support voice and high speed data access over GSM and CDMA networks. 65
A link between Mobile Network and the Internet 66
Mobile Data Networks Mobile Data Networks are proprietary networks supported by different mobile phone operators. Their services are not free! They charge every minute of phone calls or every byte of data transmitted. Mobile phones use phone numbers for identification; while the Internet uses IP addresses. 67
Roaming It is the ability for a mobile device to move within a mobile telephone network without losing its connection or identity. There is no such thing as mobile IP addresses!!! (Your IP address changes whenever you move.) Mobile phone numbers on the other hand can be reused across multiple mobile phone operators. 68
Roaming Mobile Devices A mobile phone is registered with a home mobile phone network operator. An agreement of billing must exist between the visited and the home phone networks. Different phone operators may charge different fees for roaming mobile phones. 69
Mobile Internet Access A modern mobile phone has both mobile data network and WiFi data network capabilities. Mobile data network is not free, while most WiFi networks are free. Mobile data network has a better coverage and provides a true roaming experience. 70
3G Modem and WiFi Router 71
4G Mobile Data Networks The 4 th generation mobile data network standards include LTE and WiMax. LTE (Long Term Evolution) is capable of up to 100 Mbps per mobile device. WiMax (similar to WiFi) is capable of up to 50 Mbps with a range of 10 Km. 72
The End. 73