Networking Jamie Tees

Transcription

1 Ethernet is the main networking technology, UTP (Unshielded Twisted Pair) cabling is the main networking cable types, this cabling uses RJ-45 connectors either end. While UTP is the main type we have STP (Shielded twisted pair) and Plenum Cabling also. STP (Shielded Twisted Pair) is more expensive and is used within environments that have a lot of electrical interference as it is protected against this Plenum cabling is used within the plenum (the ceiling above an office normally) it s used in case of a fire as it doesn t put out toxic gases when set alight like normal UTP and STP cable does. Other types of connections Fiber optic: o Uses light instead of electricity, this is faster and immune to electrical interference such as lightning short circuits, static etc. o Uses 62.5/125 multimode fiber optic cable. Requires two cables for single mode unless multimode. Single mode normally uses Laser s as it s mean t for long range (2 km +) Multi mode would normally use LED s. o Uses Square SC connectors or round ST connectors. o Multimode can go up to 10,000 Mbps. With a max distance of ~ 600m o Single mode can go get to 100 Tbps. With over a 100 Mile distance. (record) Coax / BNC: o Ethernet originally ran on Coaxial cable o Had a shield of braided cable o Centre core actually carried signal o Rated with an RG name, hundreds of RG ratings we need to know RG 59 and RG Both have a 75 ohm impedance Difference is the thickness, RG-59 is thinner and carries less data. RG rating always marked on cable o Uses either a BNC connector or a F-type screw in connector. o BNC is uncommon, F-Type is on a lot of devices such as cable modems and televisions, satellite dishes. o No limit to how fast coax cable can transmit data but most internet implementations top out at around 50 Mbps 1

2 Name Speeds of Main Internet Connections Connection Type Cable RG 6/ RG 59 DSL Dial-Up Standard Telephone Line Standard Telephone Line Min Speed (Upload) Max Speed (Upload) Min Speed (Download) Max Speed (Download) Advantages 1 Mbit/s 10 Mbit/s 6 Mbit/s 100 Mbit/s Uses same coax that connects to cable TV boxes. 64 Kbit/s 1 Mbit/s 3 Mbit/s 100 Mbit/s Uses standard phone line, faster than dial up 28.8 Kbit/s 56 Kbit/s Really?! Fiber 15 Mbit/s 100 Tbit/s (dependant on mode) Satelite Coax 28.8 Kbit/s 512 Kbit/s High speed 1 Mbit/s 1 Gbit/s Only good for hard to reach locations ISDN 128 Kbit/s 1.9 Mbit/s 2G 56 Kbit/s 115 Kbit/s 3G 22 Mbit/s 168 Mbit/s 4G 50 Mbit/s 100 Mbit/s WiMAX 56 Mbit/s 128 Mbit/s Huge wireless range Network Devices Hubs: o Hubs were originally the main interconnection device for older networks o Any signal is repeated on every port and sent out. o This caused a downside that all connected devices have to share all the bandwidth o Extremely rare unless used for specialized equipment o Replaced by the common switch Switches: o Most common device to connect everything o Looks like a hub but automatically creates point to point connections between two computers. 2

3 o This means it doesn t share the bandwidth across the board. Bridges: o Transfers Ethernet into a different medium. EG.: Fiber to Ethernet and the other way round o A bridge will always have at least two interfaces. NAS (Network Attached Storage) o Dedicated network storage. o Can most of the time run in RAID o Plugs directly in to the network o Doesn t have any keyboard, mouse or screen. o Normally configured using web browser interface. Routers o A router connects local area networks together using the TCP/IP protocol o A router must have at least two connections o Normally connects computers to a WAN. o May contain software firewall Hardware Firewall o Device to protect unauthorized access into a network o Allows forwarding of ports to direct traffic to certain machines etc. o They use SPI (Stateful Packet Inspection) o Gives the ability to completely disable ports o Allows creation of a DMZ zone. Demilitarized Zone. o Allows the use of Mac filtering to only allow certain computers to connect to the firewall / router Please note that it s easy to spoof a mac address. DNS server o Tells a computer on what IP address a server / computer is. o This is done by using a domain name once typed in to the computer and clicked, it ll look up the ip address of a domain name and tell the computer where to go DHCP server o Delegates IP addresses automatically on a network. Domain Server o Allows a user to have one single account to login with which will allow his files to be saved on to the server and accessed at any computer within that domain network. Note: Remember all NIC s in a LAN get a Broadcast Frame 3

4 Some Command Line Commands ipconfig : Shows information on the network adapters on the system, it shows the physical mac address of the card (This is 48 bit), as well as the auto or manually configured IP address s ping: Sends a packet on the network that bounces off a certain computer and is sent back to the computer that sent it, this is a handy tool to check if a computer is running or not or has access to the network. net view \\server: This command net view shows multiple things but adding a \\ devicename it will show the shared folders / drives on the certain device tracert: This commands trace s the route / network path used to connect to a certain device. It s calculated in a thing called hops, each hop is a ping off a device to another device. If you tracert a web address you will see several hops as you are going through multiple switches and routers to get to the webserver. net view: on it s own will show all the devices on your current network Protocols HTTP: Port 80, this is the generic web server port for public web pages HTTPS: Port 443, this is used for secure websites IMAP4: Port 143, used for retrieving your POP3: Port 110, also used to retrieve SMTP: Port 25, Used to send outgoing Telnet: Port 23, Used for terminal emulation SSH: Port 22, Used for secure terminal emulation FTP: Port , Used for file transfers with an FTP client SFTP: Port 22, Used for secure file transfers RDP: Port 3389, Used for remote desktop SIP: Port 5060, Used for Voice over IP DNS: Port 53, Used for domain name addressing 4

5 Wireless The main wireless networking we use today is Wi-Fi, the fastest type of Wi-Fi today would be n. To use Wi-Fi the computer requires a Wi-Fi adapter used in conjunction with a wireless access point / wireless router. Most modern laptops come with a Wi-Fi card built in, but if it does not have one you can easily install one with a express card / PCMIA card. Type Throughput Distance Frequency Wi-Fi a 54 Mbps 120m, 5000m 5 GHz Wi-Fi b 11 Mbps 140m 2.4 GHz Wi-Fi g 54 Mbps 140m 2.4 GHz Wi-Fi n 150 Mbps 140m 2.4 GHz + 5 GHz Bluetooth Mbps 10m 2.4 GHz Bluetooth Mbps 100m 2.4 GHz Bluetooth Mbps 100m 2.4 GHz Bluetooth Mbps 100m 2.4 GHz Infrared (IrDA) 4 Mbps 1m Wireless technologies are handy to create a certain network called an adhoc network this allows two or more computers to connect together without a router to share / print files and even an internet connection. Wireless Security Don t use WEP, it s outdated and easy to bypass WPA2 is your best choice, if not available use WPA. If you don t want somebody to find a network you use, you can disable the SSID from broadcasting. IP Addressing An IP address is given by DHCP (Or configured statically) to every device on the network. In the 1970 s + we organized IP addressing with something called a class license, there was 3 classes. A, B + C Network Class Address Range No. of network address s available No of IP s (Computers) Supported Class A ,777,214 Class B ,384 65,534 Class C ,097,

6 This section is not complete, I will finish it tomorrow. I just uploaded it for now so you can follow up on the most essential parts of networking for A+ 6