Networking

Christina Angstadt Karlie Meyer Kait Sharer

     ◦ ◦ Internet Protocol Address: exclusive number all information technology devices use which identifies and allows them the ability to communicate with each other on a computer network Dynamic IP Address ◦ Can change at any time Issued from a pool of IP addresses allocated by ISP or DCHP Server Computer automatically gets this number as it logs on to the network Static IP Address ◦ Fixed and never changes ◦ ISP provides a single static IP or a block of static IP’s IP version 4 ◦ Currently used by most network devices ◦ Limited to 4,294,967,296 addresses IP version 6 ◦ Estimated number of unique addresses = 340,282,366,920,938,463,463,374,607,431,768,211,456 ◦ Can be written in the following formats:   1080:0000:0000:0000:0000:0034:0000:417A 1080:0:0:0:0:34:0:417A  1080::34:0:417a

  Domain Name System (DNS): Allows the IP address to be translated to words ◦ ◦ ◦ Dynamic Host Configuration Protocol (DHCP): A computer networking protocol used by hosts to retrieve IP address assignments and other configuration information.

Client-server architecture The client sends a broadcast request for configuration information. The DHCP server receives the request and responds with configuration information from its configuration database

  ◦ ◦ ◦ ◦ ◦ Public IP address: Avoid online bans ISP may assign you an invalid address due to some technical glitch in their equipment Private IP address: Accidentally configured an invalid address Using a malfunctioning router that is providing bad addresses Installing a new router and re-configuring your home network to use its default IP address range

  ◦ ◦ To change a static IP address, contact the ISP and work with their technical support to have them assign a new one To change a dynamic IP address: If your computer is directly connected to the Internet, you can attempt to release and renew the address using ipconfig or a similar utility Often, you will need to disconnect your modem from the Internet for a long period of time (many hours or a few days) before the ISP will assign a different dynamic IP address.

   ◦ ◦ ◦ Easier Static address: directly set a new IP address on the device Dynamic Address: release and renew the DHCP address on the client Or set up the router to use a different IP address range Or change one or more devices on the network from dynamic to static addressing

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Control Panel Network Connections Find Network Connection to Internet (LAC) Right Click and select Properties Click Internet Protocol (TCP/IP) item in list

6. Click Properties Button 7. Click Use the following IP address: and enter the IP address, subnet mask, and default gateway information 8. Enter the same info for DNS servers 9.

Click OK until done All information is provided by ISP

• • •  BUT if you are behind a router it gets more complicating….

Static IP address should be assigned to the router.

Configuring the router to to not get an IP address dynamically, but instead you'll enter the IP, gateway, subnet, and possibly DNS information by hand, using whatever approach your router uses for configuration.

Port-forwarding Configure it to accept requests on certain "ports" and direct them to certain computers on your LAN.

  ◦ ◦ ◦ ◦ Bandwidth: the volume of information per unit of time that a transmission medium (like an Internet connection) can handle.

Latency: refers to any of several kinds of delays typically incurred in processing of network data.

Low latency network experiences small delay times High latency connection suffers from long delays Actual bandwidth is affected by high latencies.

Excessive latency creates bottlenecks that prevent data from filling the network pipe, thus decreasing effective bandwidth

   A set of rules which is used by computers to communicate with each other across a network governing the syntax, semantics, and synchronization of communication. A protocol is a convention or standard that controls or enables the connection, communication, and data transfer between computing endpoints. Implemented by hardware, software, or a combination of the two.

    ◦ ◦ ◦ Set of communications protocols used for the Internet Two-layer program Transmission Control Protocol (TCP): Higher layer Manages the assembling of a message or file into smaller packets that are transmitted over the Internet Messages are received by a TCP layer that reassembles the packets into the original message ◦ ◦ Internet Protocol (IP): Lower layer Handles the address part of each packet so that it gets to the right destination

  ◦ ◦ Program that allows applications on different computers to communicate within a local area network (LAN).

Two communication modes: Session mode lets two computers establish a connection for a "conversation," allows larger messages to be handled, and provides error detection and recovery Datagram mode is "connectionless" messages must be smaller, and the application is responsible for error detection and recovery. Also supports the broadcast of a message to every computer on the LAN.

   Full-duplex data can be transmitted in both directions on a signal carrier at the same time Half-duplex data can be transmitted in both directions on a signal carrier, but not at the same time.

Both imply a bidirectional line, or one that can move data in both directions

  Windows has two modes of operation – Workgroup and Domain Workgroup: ◦ Peer-to-peer network, or each computer is sustainable on its own ◦ ◦ ◦ In order for a user to access resources on another workgroup computer, that exact user must be setup on the other computer Workgroups offer little security outside of basic access control.

Workgroups are more than adequate for most small business and home use Domain: ◦ Trusted group of computers that share security, access control and have data passed down from a centralized domain controller server or servers ◦ ◦ ◦ Domain Controllers handle all aspects of granting users permission to login Use Active Directory which allows and even more centralized point for software distribution, user management and computer controls Most mid to large businesses will run in Domain mode

  HTTP (Hypertext Transfer Protocol): ◦ Set of rules for transferring files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. ◦ ◦ Application protocol that runs on top of the TCP/IP suite of protocols Web browser is an HTTP client, sending requests to server machines. When the browser user enters file requests by either "opening" a Web file (typing in a URL) or clicking on a hypertext link, the browser builds an HTTP request and sends it to the IP address indicated by the URL. The HTTP daemon in the destination server machine receives the request and sends back the requested file or files associated with the request.

FTP: ◦ simplest way to exchange files between computers on the Internet ◦ ◦ Used to transfer Web page files from their creator to the computer that acts as their server for everyone on the Internet Used to download programs and other files to your computer from other servers.

   POP3 (Post Office Protocol 3): ◦ Client/server protocol in which e-mail is received and held for you by your Internet server ◦ Built into most popular e-mail products, such as Eudora and Outlook Express. Also built into the Netscape and Microsoft Internet Explorer browsers “Store-and-forward” service ◦ IMAP (Internet Message Access Protocol): ◦ Provides the user more capabilities for retaining e-mail on the server and for organizing it in folders on the server ◦ POP and IMAP both deal with the receiving of e-mail SMTP (Simple Mail Transfer Protocol): ◦ Protocol for transferring e-mail across the Internet  You send e-mail with SMTP and a mail handler receives it on your recipient's behalf. Then the mail is read using POP or IMAP.

  TELENET: ◦ User command and an underlying TCP/IP protocol for accessing remote computers ◦ ◦ ◦ An administrator or another user can access someone else's computer remotely You log on as a regular user with whatever privileges you may have been granted to the specific application and data on that computer. Telnet is most likely to be used by program developers and anyone who has a need to use specific applications or data located at a particular host computer. HTTPS: ◦ Use of Secure Socket Layer (SSL) or Transport Layer Security (TLS) as a sublayer under regular HTTP application layering ◦ Encrypts and decrypts user page requests as well as the pages that are returned by the Web server

  ◦ ◦ ◦ LAN (Local Area Network): ◦ ◦ ◦ Group of computers and associated devices that share a common communications line or wireless link Connected devices share the resources of a single processor or server within a small geographic area Server has applications and data storage that are shared in common by multiple computer users. A local area network may serve as few as two or three users or as many as thousands of users WAN (Wide Area Network): Geographically dispersed telecommunications network May be privately owned or rented Inclusion of public (shared user) networks

   Hub: ◦ Place of convergence where data arrives from one or more directions and is forwarded out in one or more other directions ◦ ◦ Switch: ◦ Device that channels incoming data from any of multiple input ports to the specific output port that will take the data toward its intended destination ◦ Place where data comes together One or more switches are used to set up a dedicated though temporary connection or circuit for an exchange between two or more parties a switch determines from the physical device (MAC) address in each incoming message frame which output port to forward it to and out of Router: ◦ A device or, in some cases, software in a computer, that determines the next network point to which a packet should be forwarded toward its destination ◦ ◦ Connected to at least two networks and decides which way to send each information packet based on its current understanding of the state of the networks it is connected to Often included as part of a network switch

   A virtual private network (VPN) is a network that uses a public telecommunication infrastructure, to provide remote offices or individual users with secure access to their organization's network The goal of a VPN is to provide the organization with the same capabilities, but at a much lower cost The protocols, by encrypting data at the sending end and decrypting it at the receiving end, send the data through a "tunnel" that cannot be "entered" by data that is not properly encrypted

  Plenum ◦ In buildings with computer installations, the plenum space is often used to house connecting communication cables ◦ ◦ ◦ ◦ ◦ ◦ Often made of Teflon and is more expensive than ordinary cabling In the event of fire, its outer material is more resistant to flames and, when burning, produces less smoke than ordinary cabling Both twisted pair and coaxial cable are made in plenum cable versions.

PVC ◦ Software-defined logical connection in a network such as a frame relay network Feature of frame relay that makes it a highly flexible network technology is that users can define logical connections and required bandwidth between end points and let the frame relay network technology worry about how the physical network is used to achieve the defined connections and manage the traffic The end points and a stated bandwidth called a Committed Information Rate (CIR) constitute a PVC Multiple PVCs share the same physical paths at the same time

  ◦ ◦ ◦ ◦ ◦ UTP (Unshielded Twisted Pair): Most common kind of copper telephone wiring Ordinary copper wire that connects home and many business computers to the telephone company Each signal on twisted pair requires both wires Twisted pair is sometimes installed in two or more pairs, all within a single cable.

Although twisted pair is often associated with home use, a higher grade of twisted pair is often used for horizontal wiring in LAN installations because it is less expensive than coaxial cable ◦ ◦ STP (Shielded Twisted Pair): Special kind of copper telephone wiring used in some business installations Twisted pair is enclosed in a shield that functions as a ground

  Fiber to the home (FTTH): ◦ Installation and use of optical fiber from a central point directly to individual buildings such as residences, apartment buildings and businesses to provide unprecedented high-speed Internet access. FTTH dramatically increases the connection speeds available to computer users ◦ Implementing FTTH on a large scale will be costly because it will require installation of new cable sets over the "last links" from existing optical fiber cables to individual users Coaxial Cable: ◦ Copper cable widely installed for use in business and corporation Ethernet and other types of local area network ◦ ◦ ◦ “Coaxial" because it includes one physical channel that carries the signal surrounded (after a layer of insulation) by another concentric physical channel, both running along the same axis Outer channel serves as a ground Can be placed in a single outer sheathing and, with repeaters, can carry information for a great distance

  ◦ ◦ RJ45: ◦ Single-line jack for digital transmission over ordinary phone wire, either untwisted or twisted Eight pins or positions Two varieties of RJ-45: keyed and unkeyed  Keyed has a small bump on its end  Both jack and plug must match ◦ ◦ RJ11: ◦ Most common telephone jack ◦ ◦ Can have six conductors but usually is implemented with four Likely to be the jack that your household or office phones are plugged into from the ordinary "untwisted" wire people are most familiar with Four wires are usually characterized as a red and green pair and a black and white pair   Red and green pair typically carry voice or data Black and white pair may be used for low-voltage signals such as phone lights A computer that uses a dial-up modem to connect to a network is usually plugged into an RJ-11 jack

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Server:

◦  Web, ftp, email, application server Provides service to client(s)  email exchange  web / database access

Client:

◦  browser, email, online chat Initiates request for some service

All communication through server Clients do

not

communicate directly

+ + + Maintenance Security Centralized server / data – – Overload Centralized server

   No dedicated server End systems directly communicate ◦ Switch roles of client & server More peers = better performance + + – –

Shared resources No Single point of failure High Bandwidth usage Security

P2P Client / Server

  Centralized server ◦ ◦ Find IP address of remote party / peer “controls” communication ◦ Direct client – client connection not through server  

Skype Instant messaging

     High-speed Internet access ◦ exceeding 200 Kbps “Always On” More reliable Wider range of frequencies Simultaneous access to voice & data communication ◦ splitter       Access limited to phone line bandwidth ◦ 56 Kbps max Initiate connection Dynamic IP address Less vulnerable to attacks Difficult to download multimedia files Less cost

    DSL (Digital Subscriber Line) ◦ existing copper telephone lines ◦ Kbps – Mbps Cable ◦ Coaxial cables ◦ ◦ ◦ 1.5 Mbps + Fiber to the Home (FTTH) ◦ Converts data signals to light & sends them through glass fibers ◦ Speeds exceed DSL / Cable by hundreds of Mbps Satellite ◦ Provides wireless broadband to remote areas 500 Kbps (download) & 80 Kbps (upload) Extreme weather can disrupt service

  ◦ ◦ High-speed Internet service via wireless technology Radio waves / signals Speeds roughly equivalent to wired broadband access 1.5 Mbps data rate

Standard Speed Range Frequency Security 802.11a

54Mbps 150ft

Compatibility Spread Spectrum method Mode

802.11a

DSSS

802.11b

11Mbps 300ft

802.11g

54Mbps (108) 300ft 5GHz 2.4GHz

2.4GHz

2.4-5GHz SSID, MAC Filtering, WEP, WPA (TKIP), WPA2 (AES) 802.11b

802.11g/b DSSS OFDM Ad Hoc or Infrastructure

802.11n

100Mbps (600Mbps) 300ft 802.11n/g/b OFDM

  ◦ ◦ WEP (Wired Equivalent Privacy) Algorithm used to secure wireless networks  Authentication ◦  Data encryption WPA (WiFi Protected Access) Encrypts wireless traffic  Protects against eavesdropping More secure than WEP

 ◦ ◦ ◦ ◦ Dynamic Host Configuration Protocol Retrieve IP address assignments Configuration information Client / server architecture   Client broadcast request for configuration info  Server responds from configuration database  Configure DHCP Add new machines to network Given unique IP Address

     ◦ ◦ Wireless technology Exchanges data over short distances PANs Uses frequency-hopping spread spectrum Transmits data into chunks 2402-2480 MHz range ◦ Communicate with up to 7 devices Mobile phones, laptops, GPA, digital cameras, printers, PCs, video game consoles

  Network type ◦ DSL, cable, Fiber, etc ◦ ◦ ◦ Hardware requirements ◦ Network adapters ◦ ◦ Desired speed   Connect computers to network to communicate Hubs & switches  Ethernet Routers & Access Points  Share single connection between multiple computers Modems  Send / receive information over telephone & cable Network Cables Connect computers & hardware

   provides networked computers with the ability to share a single connection to the Internet If you have multiple computers, you can use ICS to allow you and others on your local area network (LAN) to perform different tasks simultaneously For example, one person can send and receive e-mail messages, while another person downloads a file, and another person browses the Internet

    Multiple users can gain access to the Internet through a single connection by using Dial-Up Networking and local networking.

Connected devices receive transparent network configuration by using Domain Name System (DNS) and Dynamic Host Configuration Protocol (DHCP) to resolve Internet names Any IP-attached device can connect, including older Windows based clients, non-Windows-based clients, Microsoft Windows 98-based clients, and Microsoft Windows 2000-based clients, with no additional client software required.

Connected devices and software have comprehensive protocol support. For example, you can play Internet games without additional configuration, or you can use Point-to-Point Tunneling Protocol (PPTP) and Virtual Private Networking (VPN) to gain access to your corporate network.

     DHCP Allocator - A simplified DHCP service that assigns the IP address, gateway, and name server on the local network.

DNS Proxy - Resolves names on behalf of local network clients and forwards queries.

Network Address Translation (NAT) - Maps a set of private addresses to a set of public addresses. NAT tracks private-source IP addresses and public destination IP addresses for outbound flows. It changes the IP address information and edits the required IP header information dynamically.

Auto-dial - Automatically dials connections.

Application programming interfaces (APIs) - For configuration, status, and dial control for programs.

 Your ICS network is a type of local area network that relies on a single computer called a gateway, through which all other computers and TCP/IP-capable devices connect to the Internet.

 ◦ ◦ ◦ The hardware and software needed to set up a home network includes: ◦ A primary computer, called a gateway, that provides network connectivity to the Internet. This computer must be running Windows 98 Second Edition, Windows 2000, or Windows Me with Internet Connection Sharing enabled.

◦ ◦ ◦ One or more computers running Windows 95, Windows 98, Microsoft Windows NT 4.0, Windows 2000, or other TCP-IP enabled client software.

Devices that are capable of connecting to the Internet.

A network connection device for each computer .Cabling and hubs, depending on the type of connection devices you use.

A single modem (or an ISDN or ADSL line) for the entire network.

Internet browser software and TCP/IP drivers installed on each device that shares the connection.

 ◦ ◦ ◦ ◦ You can enable Internet Connection Sharing by using the Add/Remove Programs tool in Windows 98 Second Edition or Windows Me: Click Start, point to Settings, click Control Panel, and then double-click Add/Remove Programs.

On the Windows Setup tab, double-click Internet Tools.

Click to select the Internet Connection Sharing check box, and then click OK.

Click OK, and then follow the instructions on the screen to run the Internet Connection Sharing wizard.

    Basic tools: Network Diagnostics in Help and Support ◦ Contains detailed information about the network configuration and the results of automated tests.

Network Connections folder ◦ Contains information and configuration for all network connections on the computer. To locate the Network Connections folder, click Start, click Control Panel, and then click Network and Internet Connections.

IPConfig command ◦ Displays current TCP/IP network configuration values, updates, or releases, Dynamic Host Configuration Protocol (DHCP) allocated leases, and display, register, or flush Domain Name System (DNS) names.

Ping command ◦ Sends ICMP Echo Request messages to verify that TCP/IP is configured correctly and that a TCP/IP host is available.

 ◦ ◦ ◦ Make Sure You Have Correct IP Information: Make sure you have the correct IP scheme for your network. This would include the:    IP Address Subnet Mask Default Gateway  DNS Servers IP Config Command   Displays current TCP/IP network configuration values, updates, or releases, Dynamic Host Configuration Protocol (DHCP) allocated leases, and display, register, or flush Domain Name System (DNS) names.

FOR: Win9x - Start / Run / command; Windows2000/XP/Vista - Start / Run / cmd Then run IPCONFIG /ALL.

 IP Config Command

 ◦ ◦ Possible causes for not getting an IP address assigned are: Defective cable, network card or port on the router. Make sure you are using all known working components.

Your router is not configured for DHCP (which would automatically be assigning IP addresses).

 Basic ping tests: Using the command prompt ◦ Try pinging the router's IP address ◦ ◦  e.g. ping 192.168.1.1

If you get a reply, then your connection to the router is working.

If you don't get a reply, then you need to double check your network card, cable, port on the router. You might also see if any other computers on the network can do the same.

   Basic ping tests: Try pinging an external site by IP address ◦ ◦ ◦ e.g. ping 4.2.2.1

If you get a reply, then you have a connection to the Internet.

If you don't get a reply, there are several things you can try: Double check that the router is connecting to the Internet. Typically you can access the router through your web browser and check it's status.

Take the power off your DSL/Cable modem and Router. Plug the modem back in a wait a minute or so. Plug the router back in and wait a minute or so. Then restart your computer.

   Basic ping tests: Try pinging an external site by Name ◦ ◦ ◦ ◦ e.g. ping www.yahoo.com

If you get a reply, then you have a connection to the Internet and DNS is working If you don't get a reply, there are several things you can try: Double check your DNS entries You many need to use the same DNS IP address that your ISP or Router is using.

On rare occasions your ISP has problems with their DNS servers. But that is rare in comparison to misconfigured computers.

      Advanced tools: Hostname command ◦ Displays the name of the host computer.

Nbtstat command ◦ Displays the status of current NetBIOS over TCP/IP connections, updates the NetBIOS name cache, and displays the registered names and scope ID.

PathPing command ◦ Displays a path of a TCP/IP host and packet losses at each router along the way.

Route command ◦ Displays the IP routing table and adds or deletes IP routes.

Tracert command ◦ Displays the path of a TCP/IP host.

To view the correct command syntax to use with each of these tools, type -? at a command prompt after the name of the tool.

 Automated troubleshooting For most issues that involve Internet connectivity, start by using the Network Diagnostics tool to identify the source of the issue. To use Network Diagnostics, follow these steps: ◦ ◦ ◦ ◦ Click Start, and then click Help and Support.

Click the link to Use Tools to view your computer information and diagnose problems, and then click Network Diagnostics in the list on the left.

When you click Scan your system, Network Diagnostics gathers configuration information and performs automated troubleshooting of the network connection.

When the process is completed, look for any items that are marked "FAILED" in red, expand those categories, and then view the additional details about what the testing showed.

          Start by rechecking your physical connections verify that your client's wireless adapter is installed and working properly verify that your wireless router's LAN settings are correct verify your client's TCP/IP settings Once your client has a valid IP address, use "ping" to verify network connectivity If your wireless client still cannot connect, get a valid IP address, or ping your router, it's time to consider wireless-specific problems If a matched wireless client and router can "hear" each other but still cannot connect or exchange traffic, look for a security mismatch Ensure RADIUS is working If RADIUS is working but the client's access requests are rejected, look for an 802.1X Extensible Authentication Protocol (EAP) or user login problem If your wireless client connects and pings successfully, but encounters intermittent network connectivity problems (e.g., some pings work, some fail), you may be experiencing poor signal strength, RF interference, or disconnection caused by AP roaming.

      Microsoft Support ◦ http://support.microsoft.com/kb/314067 ◦ ◦ http://support.microsoft.com/kb/306126 http://support.microsoft.com/kb/234815 Bob Cerelli’s Windows Page ◦ http://www.onecomputerguy.com/networking/troubleshoo t_internet.htm

Wireless network troubleshooting: Connectivity By Lisa Phifer ◦ http://searchnetworking.techtarget.com/news/article/0,28 9142,sid7_gci945257,00.html

Wikipedia ◦ http://www.wikipedia.org

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