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    BASIC NETWORKING LAB MANUAL FOR BEGINNERSVersion 1.0

    CONTENTS :

    1. Introduction

    2. Numbering Systems and Conversion

    a. Binary numbers to decimal numbers conversion and vice versa

    b.Binary to Hexadecimal conversion and vice versa

    c. Decimal to Hexadecimal conversion and vice versa

    3. IPv4 Addressing

    4. Subnetting

    5. DHCP (Dynamic Host Configuration Protocol)

    a. Common DHCP configuration parameters

    b.Configuring TCP/IP Configuration Settings Manually Without a DHCP Server

    6. DOS Utilities for Troubleshooting Network problems

    a. PINGb.TRACERT

    c. IPCONFIG

    d.IPCONFIG/ALL

    e. NBTSTAT

    f. NETSTAT

    g. NETSH

    7. Frequently used TCP/IP Protocols

    a.HTTP

    b. FTPc. Telnet

    d. Email-Protocols (SMTP, POP, and IMAP)

    8. Connectors and Cablinga. DB9

    b.DB25

    c. USB

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    d.RJ-11

    e. RJ-45

    f. DB9 to USB

    9. Appendix

    a. Troubleshooting Network Interface Card (NIC) For Physical Connectivity

    b.Modem connectivity and Troubleshooting

    10.Additional Resources

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    1. Introduction:

    This manual provides information that was previously assumed that a candidate will have prior to workingwith Juniper router networks. The manual covers topics such as number conversion, networking connectorsand cables, and troubleshooting network connectivity.

    2. Numbering Systems and Conversion:

    We need to convert from one system to another during the process of network design and implementation.For example, when you are optimizing for subnet mask or designing a wildcard mask (you will learn it whilstudying for Cisco Certification exams) you need to convert one numbering system to another. Of course,there are calculators available for this purpose. Three important systems of numbering are:

    a. Decimal - The Decimal system is what you use everyday when you count. The system

    uses ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. These digits are what we call the symbols ofthe decimal system.

    b. Binary - The Binary system uses two symbols, 0 and 1. Basically, a computer uses binarydigits for all its operations and understands only binary values. Each symbol isrepresented by low level or high level signal.

    c. Hexadecimal - This system uses 16 symbols, these are 0 - 9, A, B, C, D, E, F. The needfor Hex system aroused because the Hex numbers can easily broken in to binary digits forconsumption by digital computers and vice versa. For example, a large binary numbersuch as 1101 1011 1110 1001 is equivalent to B7D2 H (H or h is used for hexadecimalsystem). Another advantage of hex system is that it is easy to be understood by humans.

    The following sections explain conversion from one numbering system to another.

    a. Binary Numbers to Decimal Number Conversion and Vice Versa:

    Decimal is a Base 10 system with 10 possible values (0 to 9) and Binary is a Base 2 system with onlytwo numbers 0 or 1.

    i. Converting binary to decimal - The weightage of binary digits from right most bitposition to the left most bit position is given below.

    27 26 25 24 23 22 21 20

    128 64 32 16 8 4 2 1

    Example: Convert 10011101 into a decimal value.

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    There are eight bits in the binary number. The decimal value for each bit position isgiven below:

    128 64 32 16 8 4 2 1 Decimal equivalent of the binary

    position

    1 0 0 1 1 1 0 1 Given binary number

    To convert, you simply take a value from the top row wherever there is a 1 below,and then add the values together.

    For instance, in our example we would have

    1*27 + 0*26 + 0*25 + 1*24 + 1*23 + 1*22 + 0*21 + 1*20

    =128 + 0 + 0 + 16 + 8 + 4 + 0 + 1

    = 157 (decimal value)

    ii. Converting decimal to binary

    To convert decimal to binary is also very simple, you simply divide the decimal valueby 2 and then write down the remainder, repeat this process until you cannot divideby 2 anymore.

    Forexample, take the decimal value 157:

    157 2 = 78 with a remainder of1 78 2 = 39 with a remainder of0 39 2 = 19 with a remainder of1

    19 2 = 9

    with a remainder of1

    9 2 = 4 with a remainder of1 4 2 = 2 with a remainder of0 2 2 = 1 with a remainder of0

    1 2 = 0 with a remainder of1

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    0 0000

    1 0001

    2 0010

    3 0011

    4 0100

    5 0101

    6 0110

    7 0111

    8 1000

    9 1001

    A 1010

    B 1011

    C 1100

    D 1101

    E 1110

    F 1111

    Example: To convert 11110010110001 into hexadecimal, group the numbers into 4 bits each, ifthere is shortage of numbers, we can add '0s' at the beginning so that groups of four digits areformed.

    0111 1100 1011 0001

    7 C B 1

    Therefore the hexadecimal equivalent of 111110010110001 is 7CB1.Note that we have addedone 0 bit at the left most position to make it a block of 4 bits.

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    c. Decimal to Hexadecimal Conversion and Vice Versa:

    i. Decimal to Hexadecimal

    To convert a decimal number to hexadecimal , divide the number by 16 until we get'0' . The remainders , in reverse order, are used to code the hexadecimal.

    Example: To convert 28436 into hexadecimal number

    28436 divided by 16 = 1777 Remainder : 41777 divided by 16 = 111 Remainder : 1111 divided by 16 = 6 Remainder : 15

    6 divided by 16 = 0 Remainder : 6

    The remainders in reverse order are : 6-15-1-4 which is 6F14 in Hexadecimal(Replace 15 by F).

    ii. Hexadecimal to Decimal

    To convert hexadecimal to decimal, just multiply the digits with 160, 161, 162 and soon from right to left, and then add the results to get the decimal number.

    Example: Convert B61F h to its equivalent decimal value.

    B61F = B*163+6*162+1*161+F*160

    = (11*4096)+(6*256)+(1*16)+(15*1)

    = 45056+1536+16+15

    = 46623 Therefore the decimal equivalent of B61F is 46623.

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    3. IPv4 Addressing:

    An IP address is a unique logical identifier for a node or host connection on an IP network.

    An IPv4 address is a 32 bit binary number, and represented as 4 decimal values of 8 bits each. The decimalvalues range from 0 to 255. This is known as "dotted decimal" notation.

    Example: 192.189.210.078

    It is sometimes useful to view the values in their binary form.

    192 .189 .210 .07811000000.10111101.11010010.1001110

    Every IP address consists of network identifier and node identifier. The IP network is divided based on Clasof network. The class of network is determined by the leading bits of the IP address as shown below.

    Address Classes

    There are 5 different address classes. You can determine which class any IP address is in by examining thefirst 4 bits of the IP address.

    Class A addresses begin with 0xxx, or1 to 126 decimal.

    Class B addresses begin with 10xx, or128 to 191 decimal.

    Class C addresses begin with 110x, or192 to 223 decimal.

    Class D addresses begin with 1110, or224 to 239 decimal.

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    Class E addresses begin with 1111, or240 to 254 decimal.

    Addresses beginning with 01111111, or127 decimal, are reserved for loopback and for internal testing on alocal machine.Class D addresses are reserved for multicasting.Class E addresses are reserved for future use. They should not be used for host addresses.

    Now we can see how the Class determines, by default, which part of the IP address belongs to the network

    (N) and which part belongs to the Host/node (H).

    Class A: NNNNNNNN.HHHHHHHH.HHHHHHHH.HHHHHHHH

    Class B: NNNNNNNN.NNNNNNNN.HHHHHHHH.HHHHHHHH

    Class C: NNNNNNNN.NNNNNNNN.NNNNNNNN.HHHHHHHH

    In the example, 192.189.210.078 is a Class C address so by default the Network part of the address (alsoknown as the Network Address) is defined by the first three octets (192.189.210.XXX) and the node part isdefined by the last one octets (XXX.XXX.XXX.078).

    In order to specify the network address for a given IP address, the node section is set to all "0"s. In ourexample, 192.189.210.0 specifies the network address for 192.189.210.078. When the node section is set toall "1"s, it specifies a broadcast that is sent to all hosts on the network. 192.189.210.255 specifies thebroadcast address.

    b. Private Subnets

    There are three IP network addresses reserved for private networks. The addresses are 10.0.0.0/8,172.16.0.0/12, and 192.168.0.0/16. They can be used by anyone setting up internal IP networks, such as anintranet. Internet routers never forward the private addresses over the public Internet.

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    4. Subnetting:

    Subnetting an IP Network is done primarily for better utilization of available IP address space, and routingpurpose. Other reasons include better organization, use of different physical media (such as Ethernet, WANetc.), and securing network resources.

    A subnet mask enables you to identify the network and node parts of the address. The network bits arerepresented by the 1s in the mask, and the node bits are represented by the 0s. A logical AND operation

    between the IP address and the subnet mask provides the Network Address.

    For example, using our test IP address and the default Class C subnet mask, we get:

    192.189.210.078: 1100 0000.1011 1101.1101 0010.0100 1110 Class C IP Address255.255.255.000: 1111 1111.1111 1111.1111 1111.0000 0000 Default Class C subnet mask192.189.210.0 1100 0000 1011 1101 1101 0010 0000 0000

    As can be seen above, by using and AND operator, we can compute the network portion of an IP address.The network portion for the IP address given in the above example is 192.189.210.0, and the host portion ofthe IP address is 078.

    CIDR Notation

    A Subnetmask normally contains the host portion of the bits also. This is called Classless Inter DomainRouting (CIDR). This will enable more networks for a given class of network address. For example,allowing 3 host bits towards subnet portion in our previous IP address, will allow us to offer 2X2X2 or 8additional subnetworks. Traditionally, all zeros, and all ones subnets are not used, and hence we are left with6 subnets.

    192.189.210.078: 1100 0000.1011 1101.1101 0010.0100 1110 Class C IP Address

    255.255.255.224: 1111 1111.1111 1111.1111 1111.1110 0000 Class C subnet mask with 3 additional bits ohost portion used for Subnetting.

    Broadcast address: 1100 0000.1011 1101.1101 0010.0101 1111 :192.189.210.95

    The above is the broadcast address for a given subnet (192.189.210.078). Under Classful routing, thebroadcast address would have been 192.189.210.255.

    Note that by using Subnetting, we are able to increase the number of networks available within a given IPaddress. On the otherhand, we will be loosing the number of hosts available within a subnet to 24 or 16 hosper subnet. Again, all zeros, and all ones host addresses are traditionally reserved for other purposes.

    CIDR (Classless InterDomain Routing) notation: Subnet mask is also represented as below:

    192.189.210.078/27, where 27 is the number of bits in the network portion of the IP address.

    Why use CIDR?

    Normally, ISPs allocate the IP addresses for individuals or Corporates. The reason being that it is almost

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    impossible to allocate a classful IP address to every individual or a corporate. Using CIDR, the biggest ISPsare given large pool of IP address space. The ISP's customers such as individual or Corporates are thenallocated networks from the big ISP's pool. This kind of arrangement will enable efficient management andutilization of the Internet.

    Classful addresses can easily be written in CIDR notation

    Class A = A.B.C.D/8, Class B = A.B.C.D/16, and Class C = A.B.C.D/24

    Where A,B,C,D are dotted decimal octets.

    CIDR Chart

    CIDR Block Prefix # Equivalent Class C # of Host Addresses (2-2 )

    /30 1/128th of a Class C 2 hosts

    /27 1/8th of a Class C 30 hosts

    /26 1/4th of a Class C 62 hosts

    /25 1/2 of a Class C 126 hosts

    /24 1 Class C 254 hosts

    /23 2 Class C 510 hosts

    /22 4 Class C 1022 hosts

    /21 8 Class C 2046 hosts

    /20 16 Class C 4094 hosts

    /19 32 Class C 8190 hosts

    /18 64 Class C 16382 hosts

    /17 128 Class C 32766 hosts

    /16 256 Class C = 1 Class B 65534 hosts

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    /15 512 Class C 131070 hosts

    /14 1024 Class C 262142 hosts

    /13 2048 Class C 524286 hosts

    *Important points to note:

    A subnet mask is used to determine the break between network and host subsections of an IPaddressing

    VLSM allows for conservation of address space by allowing the subnet mask to allocate bits acrossthe entire range of the IP address

    An address where all the host bits are set to 1 is the broadcast

    An address where all the host bits are set to 0 is the network

    There are 2-2 addresses in a CIDR block, where n is the number of host bits

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    5. DHCP (Dynamic Host Configuration Protocol):

    In a TCP/IP network, a host computer needs to be configured for some basic parameters such as IP address,subnet mask, default gateway, etc. There are two ways to configure these TCP/IP network parameters. One to configure them manually using the workstation's network applet or command prompt. The other is toconfigure automatically as and when the host computer is switched ON. DHCP is the term used for theautomatic configuration of host computers (or workstations). For DHCP to operate, you need a DHCP servethat was pre-configured with IP address range and other parameters for passing on to DHCP clients (host

    computers). The DHCP server provides TCP/IP configuration parameters (IP address, subnet mask, defaultgateway, etc.) to DHCP client computers. A DHCP server need not be a stand alone machine. It could be aCisco router or a Linux/Windows server working as a DHCP server as well. Note that the DHCP server itserequires that its TCP/IP network parameters (IP address, subnet mask, etc.) be configured manually.

    a. Common DHCP configuration parameters:

    Normally the DHCP server provides the client with at least this basic information:

    IP Address - This is the client computer IP address

    Subnet Mask - This is the subnet mask to be used by the client computer

    Default Gateway - This is the default gateway to be used by the client computer.

    Other information can be provided as well, such as Domain Name Service (DNS) serveraddresses and Windows Internet Name Service (WINS) server addresses. DNS resolution is theprocedure used to resolve an IP address from a domain name. It occurs when a client queries aname server to obtain the IP Address with which it wants to connect. All computers communicateby addressing each other using IP Addresses over any TCP/IP network. So every time we connectto a website or send an email, DNS resolution occurs.

    Note: Sometimes, you may want to bypass DNS look up for certain addresses. Then, you can usewhat is known as HOSTS file to map hostnames to IP addresses. The hosts file contains lines of

    text consisting of an IP address in the first text field followed by one or more hostnames, each

    field separated by white space (blanks or tabulation characters).

    It is located in " %SystemRoot%\system32\drivers\etc\" on Windows 2003/XP/Vista

    computers.

    Given below is an example of the hosts file.

    207.46.197.32 office.microsoft.com

    96.0.7.166 practicetests.info127.0.0.1 localhost loopback

    ::1 localhost

    The following sections describe the DHCP configuration for Windows 7 client computers. It isassumed that the DHCP server computer is already configured and available.

    1. Steps for configuring the workstation (DHCP Client) from the DHCP server

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    are given below: Using GUI applet

    Right-click on " Network" icon on the desktop and click properties which opens"Network and Sharing" window as shown.

    Network and Sharing window shows up the basic network information and alsoshows all the current connections.

    Click on "Local Area Connection" on the previous screen that opens Local AreaConnection Properties window as shown below

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    .

    Double-click on Internet Protocol Version 4 (TCP/IPv4) option, the window InternetProtocol Version4(TCP/IPv4) Properties shows up as below. If your DHCP isconfigured with IPv6, please use TCP/IPv6.

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    Click on "OK" until the network dialogue boxes are closed.

    This specific adapter is now set for DHCP. Reboot your system for the changes totake effect. Further, it is assumed that the DHCP server is already configured andpresent.

    Note : These steps are with respect to Windows 7 operating system. Other operatingsystems like windows 2000/XP etc, the steps are almost the same.

    2. Using Command Prompt

    Netsh.exe, dos utility can be used to configure NIC to automatically obtain anIP address from a DHCP server. The command is given below:

    netsh interface ip set address "Local Area Connection" dhcp

    To configure DNS and WINS addresses from the Command Prompt, use

    the following command:

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    netsh interface ip set dns "Local Area Connection" static 192.168.0.200

    To configure your NIC to dynamically obtain it's DNS settings using

    DHCP:

    netsh interface ip set dns "Local Area Connection" dhcp

    b. Configuring TCP/IP Configuration Settings Manually Without a DHCPServer:

    1. Configure TCP/IP settings using Windows 2000/XP/Vista, and

    Windows7 Using GUI

    Right-click on "Network" icon on the desktop and click properties whichopens "Network and Sharing" window as shown.

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    Now click on "Local Area Connection" that opens Local Area Connection

    Properties window as shown below

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    .

    Double-click on Internet Protocol Version4(TCP/IPv4) option, thewindow Internet Protocol Version4(TCP/IPv4) Properties shows up asshown below

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    Now select the option "Use the following IP Address" and enter the IPAddress, Subnet Mask and Default Gateway. Enter the values as required.These values may be obtained from your network administrator.

    Note: In a home network environment, the Internet router acts as thedefault gateway. Therefore, you need to enter the IP address of the router

    as default gateway on your host computer. The router and your client

    work station will be in the same subnet. The subnet mask is same as thatof the router interface. DNS information is usually optional, and check

    with your service provider if you need to enter the DNS Serverinformation.

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    Click on Ok, also on "Internet Protocol Version4 (TCP/IPv4) Properties"window. Reboot the computer if prompted. Usually, rebooting is notnecessary. The settings can then be checked using DOS command"ipconfig".

    Note : These steps are with respect to Windows 7 operating system. Otheroperating systems like windows 2000/XP etc, the steps are almost thesame.

    2. Configure TCP/IP settings using Windows 2000/XP/Vista, and

    Windows7 Using Command Prompt

    The same thing can be achieved using command prompt utility callednetsh.exe. Netsh.exe is a command-line scripting utility that allows youto, either locally or remotely, display or modify the network configurationof a computer that is currently running. In order to configure TCP/IPsettings such as the IP address, Subnet Mask, Default Gateway, DNS andWINS addresses and many other options you can use Netsh.exe.

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    To view TCP/IP settings, use the below command:

    netsh interface ip show config

    Configuration is also easy. The following command configures the

    interface named Local Area Connection with the static IP address192.168.0.100, the subnet mask of 255.255.255.0, and a default gateway

    of 192.168.0.1:

    netsh interface ip set address name="Local Area Connection" static192.168.0.100 255.255.255.0 192.168.0.1 1

    6. DOS Utilities For Troubleshooting Network Problems:

    DOS (Disk Operating System) controls the computer's hardware and provides an environment for programsto run. Windows computers simulate DOS in virtual environment. There are several DOS utilities that arefrequently used for troubleshooting network problems. The subsequent sections discuss these utilities.

    When there is a network of computers connected in a LAN, then we can use DOS utilities like PING,TRACERT, etc. for testing the connectivity between the workstations and also for troubleshooting theproblems.

    Given below are some frequently used DOS utilities for troubleshooting network related problems:

    a. Ping

    b. Tracertc. Ipconfigd. NBTstate. netstat, andf. netsh

    The first ever step in troubleshooting is testing layer 1 of the OSI model, i.e, verifying the cabling. Ensurethat the network connector (usually, RJ-45) is properly connected and the network card LEDs are active.

    a. PING:

    After verifying the physical connectivity, test the functionality of NIC and the computer for itsability to communicate with networking by using ping to any address on the loopback network(127.0.0.1 to 127.255.255.254). A sample output of pinging the local host is given below:

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    Next is to test the basic connection between your workstation and default gateway using ping. Ifthe ping to the default gateway is not successful, then check the IP Address, subnet mask, and

    default gateway address on the workstation and reboot the system if necessary.

    A successful ping to default gateway is given below:

    Ping sends out a packet to a designated internet host or network computer and measures itsresponse time. The target computer will return (hopefully) a signal. It is often used to testconnections on local networks.

    b. TRACERT:

    The actual path between two computers on the internet consists of numerous segments or "hops"from one intermediate computer to another. Tracert shows each node of the path taken to reachthe destination host.

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    As seen in the above figure, the output contains

    i. the times for each hop,ii. the IP addresses for each intermediate computer, andiii.the time taken are displayed.

    Tracert shows up to 30 hops. It is convenient for finding if there is one particularsegment that is causing a slow or bad connection.

    c. IPCONFIG:

    IPCONFIG is a command line utility available on windows that gets the IP Address informationon a computer, it is an alternative to "winipcfg" utility. The output of the default commandcontains the IP address, network mask and gateway for all physical and virtual network adapters.

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    d. IPCONFIG/ALL:

    This option displays the same IP addressing information for each adapter as the default option.Additionally, it displays DNS and WINS settings for each adapter.

    e. NBTSTAT:

    NBTSTAT is a DOS utility that displays protocol statistics and current TCP/IP connections.NBTSTAT is a useful tool for troubleshooting NetBIOS name resolution problems. In a purelyTCP/IP network, NBTSTAT is not used.

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    f. NETSTAT:

    NETSTAT is a tool that can be used for checking network configuration and utility. The netstat a command displays all connections, and netstat r displays the route table plus activeconnections. The netstat e command displays Ethernet statistics, and netstat s displays per-protocol statistics.

    g. NETSH:

    NETSH is a utility that allows you to, either locally or remotely, display or modify the networkconfiguration of a computer that is currently running. In order to configure TCP/IP settings suchas the IP address, Subnet Mask, Default Gateway, DNS and WINS addresses and many otheroptions, NETSH.exe can be used.

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    7. Frequently Used TCP/IP Protocols:There are a few frequently used TCP/IP protocols that a network administrator needs to be familiar with.Most notable among these are:

    a. HTTPb. FTPc. Telnetd. Email Protocols (SMTP, POP, and IMAP)

    a. HTTP (Hyper Text Transfer Protocol):

    This is the most widely used protocol on the web. In order to fetch a web page foryou, your web browser must "talk" to a web server on the Internet. When webbrowsers talk to web servers, they use HTTP protocol (HyperText Transfer Protocol).All browsers use this protocol whether they are Windows based or Linux based.

    b. FTP (File Transfer Protocol):

    File Transfer Program is used to transfer files from one computer to another. FTP isthe most widely used protocol by network administrators for:

    i. Taking backupsii. Uploading or downloading files to/from the server machineiii.Providing a platform for file storage among many different hosts (such as

    workstations, routers, servers, etc.)

    Note that in order to upload or download a file from FTP site, the login details, FTPusername and FTP password must be known. Once connected, files can be transferred

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    using binary or ASCII mode. However, using anonymous FTP, one can transfer fileswithout supplying login credentials.

    The following topics are discussed here:

    1. FTP to a Remote Host Using Command Prompt2. FTP to a Remote Host Using GUI based Software (FileZilla)

    1. FTP to a Remote Host Using Command Prompt

    FTP can be accessed using "ftp" command on the command prompt, theprompt changes to prompt, after which the FTP site can be openedusing the command "Open". The user will be prompted for "Username"and "Password", after which the files can be viewed, uploaded ordownloaded.

    2. FTP to a Remote Host Using GUI-based Software - FileZilla

    A software based FTP is almost inevitable for effective control over thefile transfer. There are several software based FTP programs available

    including FileZilla, CuteFTP, SmartFTP, etc. Among these, FileZilla isthe most widely used software. It is a free FTP open source solution. Itcan be downloaded here.

    A few useful options available with FileZilla are synchronous browsing(local and remote folders are synchronized with each other), multiplesessions (several FTP sessions can be opened at the same timetransferring 2 or more files at the same time), and storing connections tomultiple remote servers so that we don't need to enter the settings againfor connecting to remote servers.

    c. Telnet:

    Telnet is another most widely used application layer protocol in the TCP/IP stack.Telnet is a protocol underlying TCP/IP protocol for accessing remote computers anduse the resources present there. On the web, FTP and HTTP protocols allows torequest specific files from remote computers but not to actually be logged on as a userof that computer, with telnet it is possible to log on as a regular user with only thoseprivileges that are granted to the specific application and data on that computer.

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    Note that to telnet to a computer, Username and Password should be known.

    1. Telneting to a remote host from command prompt on local work

    station

    Syntax is : telnet open hostname [port]

    hostname : specifies the hostname or IP address of the remote computerto connect toport : Specifies the port number or service name.

    2. Telnet Software

    There are a number of third-party telnet programs (terminal emulation)available with offering features in addition to the one that comes with theoperating system.

    Examples to this are Van Dyke CRT program, Putty, etc.

    d. Email Protocols (SMTP, POP, and IMAP):

    After HTTP, arguably, the most widely used web resource is email. A networkadministrator configures an email client on host computers quite often, and thereforeneed to know the functioning and configuration of email client software. Theprotocols that are commonly used when accessing email over the Internet or intranetare given below:

    SMTP,

    POP3, and IMAP

    SMTP is the protocol used for accessing the Email Server for sending email messagesfrom client computer to the Server, whereas POP and IMAP are used for receivingemail messages from the Email Server to the client computer. Note that an EmailServer may be a Web Server doing the additional duty of Email Server.

    i. SMTP: SMTP stands for Simple Mail Transfer Protocol. It is an "outgoingmail" server that is used for sending email messages from the client computerto the remote mail server. You need to configure your email client with properSMTP server information for sending messages. SMTP uses port 25.

    ii. POP3 and IMAP: POP and IMAP are protocols that are used for fetching

    email from an Email Server. The main difference between POP and IMAP arethat the former does not keep a copy of email messages on the server, whereasIMAP can synchronize with the email folders on the server and maintain acopy of the same locally. The advantage of using IMAP is the ability to roan.You can access the the email server from home as well as office and keepyour INBOX, OUTBOX and other folders synchronized using IMAP. POP3uses port number 110 where as IMAP uses port number 143.

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    For fetching emails from a remote server, you need to configure an emailclient such as Outlook or Mozilla Thunderbird.

    8. Connectors And Cabling:

    Connectors are interfaces for linking devices by using cables. The pins and holes in connectors are usuallylinked to the electric wires which form the cable. The pin layout describes which pins couple with whichwires.

    a. DB9:

    DB9 connector is an analog 9-pin plug of the D-Subminiature connector family, mainly used forserial connections. The connector is "D" shaped, and easy to recognize.

    Actual DB-9 Connector (both Male and Female) Pin Diagram of DB9 Connector

    PIN Details

    Pin number Name

    1 CD - Carrier Detect

    2 RXD - Receive Data

    3 TXD - Transmit Data

    4DTR - Data TerminalReady

    5 GND - Signal Ground

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    6 DSR - Data Set Ready

    7 RTS - Request To Send

    8 CTS - Clear To Send

    9 RI - Ring Indicator

    Shield

    b. DB25:

    DB25 connector is an analog 25-pin plug of the D-Subminiature connector family, mainly usedfor serial connections, also used for parallel port connections. DB25 serial ports on computergenerally have male connectors, while parallel port connectors are DB25 female plugs.

    DB-25 Physical Connector (Male) DB-25 Connector Pin Out

    Pins (Serial Connection)

    Pin number Name

    2 TXD - Transmit Data

    3 RXD - Receive Data

    4 RTS - Request To Send

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    5 CTS - Clear To Send

    6 DSR - Data Set Ready

    7 GND - Signal Ground

    8 CD - Carrier Detect

    20DTR - Data TerminalReady

    22 RI - Ring Indicator

    c. USB:

    Universal Serial Bus (USB) is an input-output interface which is much faster than standard serialports.

    USB Connectors (Physical) USB Connector Pin Outs

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    PIN Details

    Pin number Function

    1Power supply +5V (VBUS) 100mAmaximum

    2 Data (D-)

    3 Data (D+)

    4 Ground (GND)

    Two kinds of USB connectors:

    1. "Type A" connectors, rectangular in shape, generally used for devices which consume little

    bandwidth2. "Type B" connectors, square-shaped , generally used for devices with heavy bandwidthrequirements

    The difference between the two is in the physical layout of pins in the connector. USB "A" plugsare used towards the host system and USB "B" plugs are used towards the USB device.

    d. RJ-11:

    RJ-11 is a 4-wire connector, commonly used with a modem. It should not be confused with

    bigger RJ-45 cable and connector. RJ-45 is commonly used for Ethernet network interface card(NIC).

    RJ-11 Connector with Cable RJ-11 Connector Pin Out

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    PIN Details

    Pin # Function

    A1 Ground

    A2 Rx (Data Input)

    A3 Tx (Data Output)

    A4 Vc (Power)

    e. RJ-45:

    The RJ-45 connector is commonly used for network cabling and for telephony applications. An

    RJ-45 connector has 4 pairs of wires as shown in the schematic diagram below. RJ-45 connectoris commonly used for Ethernet Networking ports. Devices that normally use RJ-45 ports includeNICs, Hubs, Switches, and Routers. It's also used for serial connections in special cases.

    RF-45 Connector with Cable RJ-45 Connector Pin Out Diagram

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    PIN Details

    Pin Name Description

    1 TX_D1+ Transceive data +

    2 TX_D1- Transceive data -

    3 RX_D2+ Receive data +

    4 BI_D3+ Bi-directional Data+

    5 BI_D3- Bi-directional Data-

    6 RX_D2- Receive data -

    7 BI_D4+ Bi-directional Data+

    8 BI_D4- Bi-directional Data-

    CABLING

    Cisco routers either have RJ-45 based or DB-25 DCE/DTE console and AUX ports.

    RJ-45 cabling types are

    i. Straight-through : Straight-through cable is used for connecting a work station to a hubii. Crossover : Cross cable is used for connecting two hubs or switchesiii. Rolled : Rollover cable is used to connect console port of cisco router to a pc

    Identifying a RJ-45 Cable

    Hold the two ends of the cable next to one another such that the colored wires can be seen. Thereare eight colored strips or pins at each end. If the order of the colored pins is same at each end,the cable is straight and if the order of the colors is reversed at each end, the cable is rolled.

    i. Straight-Through Cable

    In this, the colored wires are in the same sequence at both ends of the cable.

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    RJ-45 Straight-Through Cable Pinouts

    Signal RJ-45 Pin RJ-45 Pin Signal

    Tx+ 1 1 Tx+

    Tx 2 2 Tx

    Rx+ 3 3 Rx+

    4 4

    5 5

    Rx 6 6 Rx

    7 7

    8 8

    ii. Crossover cable

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    In this, the first (far left) colored wire at one end of the cable is the third colored wireat the other end of the cable.

    RJ-45 Crossover Cable Pinouts

    Signal RJ-45 Pin RJ-45 Pin Signal

    Tx+ 1 3 Rx+

    Tx 2 6 Rx

    Rx+ 3 1 Tx+

    4 4

    5 5

    Rx 6 2 Tx

    7 7

    8 8

    iii. Rolled Cable

    In this, the colored wires at one end of the cable are in the reverse sequence of thecolored wires at the other end of the cable.

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    RJ-45 Rolled Cable Pinouts

    Signal RJ-45 Pin RJ-45 Pin Signal

    1 8

    2 7

    3 6

    4 5

    5 4

    6 3

    7 2

    8 1

    f. DB9 to USB:

    DB9 connectors are used to link external peripheral devices using serial communication. Somecomputers, such as laptops do not have DB9/DB25 ports. You may need to convert theDB9/DB25 to USB for communicating to a router using a laptop computer. Therefore, an adaptercable is required to convert DB9 (or DB25) to USB. Note that, the conversion requires a signal

    adapter so that DB9 (or DB25) signals are made compatible to USB pinout. It is important toknow that the conversion is not a passive process (matching the pinouts) like DB9 to DB25 orRJ-45. This adapter, powered by the USB 2.0 port, takes care of converting from the old serialcommunications to USB and vice versa. Each USB-RS232 cable contains a small internalelectronic circuit board, which is encapsulated into the USB/DB-9 connector.

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    Connecting a USB to DB9 is a simple task that you can perform with an adapter cable.

    Steps are given below

    1. Purchase a USB to DB9 cable. Remember to note if the cable ends are either male or female. Amale cable inserts into a female cable. A male cable has the pins while the female cable has the

    slots.2. Plug the male end of the USB adapter cable into the female end of the device you'reconnecting. Plug and then screw the DB9 end of the adapter cable into the next device.3. Check the connection by checking the data that you are transferring over the cable. There arenumerous applications for using a USB to DB9 adapter cable.

    9. Appendix:

    a. Troubleshooting Network Interface Card (NIC) For Physical Connectivity:

    NIC is the interface between the computer Operating System and the external network, andtherefore a critical element in the networking of computers. Typically, an NIC consists of MACaddress, and driver software. The driver software is controlled by the TCP/IP protocol residing inthe Operating System.

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    As shown in the above diagram, a Network Interface Card consists of a PCI connector (Edgeconnector) to connect to one of the PC expansion slots, and an RJ-45 connector to connect toexternal Ethernet. Note that the interface connectors may differ depending upon the expansionbus being used (for example, PCI, ISA, EISA, USB etc.), and the networking media being used(for example, Token Ring, 100BaseT, etc.). The LED indicators provide information about thestatus of communication.

    The D-Link DGE-550SX 1000Base SX Network adapter has two LED indicators:

    1. Link indicator (Link: Link up/down). This indicator goes green when the fiber port isconnected to the Ethernet network successfully.

    2. Activity indicator (ACT - Transmitting/Receiving): When this indicator is blinking green, thenetwork adapter is either transmitting or receiving data to/from the Ethernet network.

    b. Modem connectivity and Troubleshooting:

    A MODEM (MOdulator-DEModulator) is typically used to send digital data over a phone line. Itis a DCE device and connects a computer ( or any other DTE device) to the voice channel (dial-up line). While transmitting the data, modem modulates the data into a signal that is compatiblewith the phone line, and while receiving the data, the modem demodulates the signal back intodigital data.

    There are primarily two types of modems. These are:

    i. Analog modemii. Digital modem

    i. Analog modems:

    The analog modem is the one commonly used for connecting remotely to a router or switch. The

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    diagram below shows an analog modem.

    As seen from the above figure, you can use an external modem, internal modem that sits on theinternal extension bus such as PCI bus, or and USB modem. For installing an analog modem, youwill be needing modem driver software. This software will be different for different OperatingSystems and you need to make sure that you have the right version of the driver software loadedon to the computer before attempting to connect to any external host. Usually, the software willalso have self testing abilities that can be used for troubleshooting any problems with theinstallation.

    The following features are configured frequently for communicating between hostsusing a modem:

    1. Speed : The speed at which the modem can send data in bps (bits per second).Typically modem speeds are: 300, 600, 1200, 2400, 4800, 9600, 14.4K, 19.2K, 28.8Kbps

    2. Auto Dial /Redial : Smart Modems can dial the phone number and & auto redial ifa busy signal is received.

    3. Auto Answer : Most modems can automatically answer the phone when anincoming call comes in. They have Ring Detect capability.

    4. Self-Testing : New modems have self-testing features. They can test the digitalconnection to the terminal /computer and the analog connection to a remote modem.They can also check the modem's internal electronics.

    5. Voice over Data : Voice over Data modems allow a voice conversation to takeplace while data is being transmitted. This requires both the source and destinationmodems to have this feature.

    6. Synchronous or Asynchronous Transmission : Newer modems allow a choice ofsynchronous or asynchronous transmission of data. Normally, modem transmission isasynchronous. We send individual characters with just start and stop bits.

    Synchronous transmission or packet transmission is used in specific applications.

    Analog Modems - AT command set and Modem scripts

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    Analog Modems are used for dial-up connections. Modem configurations vary bymanufacturer. They use their own language for communication. The commonalphabets of modem speak is given below:

    a-z -->alphabet* -->asterisk^ -->carat- -->hyphen

    $ -->dollar sign: -->colon% -->percent sign@ -->character command set& -->ampersand\ -->backslash)--> parenthesis#--> character command set

    1. AT Command Set

    AT commands allows to control many of the functions of modem. ATcommands can be used by typing them at the command line of anyTerminal program.

    See Appendix for AT command set.

    2. Writing Modem Scripts

    Scripts are those where-in we combine modem-speak commands.

    Ex: AT&FS0=1&C1&D3&K3&Q9&W

    AT&F load factory defaults and settingsS0=1 set modem to answer on first ring&C1&D3 set modem up for action (cd/dtr)&K3 set hardware flow control&Q9 set compression&W save configuration to modem

    Connecting to a telephone line

    When the modem is turned on or after reset, the modem

    always goes to command state. It enters on-line state aftersuccessfully making a connection with a remote modem,either when answering or originating a call. When you returnto command state from on-line state, the modem goes to localcommand state, which allows you to maintain the connectionand enter commands.

    To go to local command state, type the escape sequence +++

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    AT refers to the command prefix (attention sequence) thatprecedes each command to the modem.

    D Dial (Originate mode) : This command signals the modemthat the numbers, letters, and commas that follow are all partof a telephone number that it should dial.

    T Touch-Tone dialing / Enable tone (DTMF dialing) : When

    "T" is used as a subcommand of the "D" command (ATDT12345) this causes all following numbers to be Touch-Tonedialed (default).

    When it is used as ATT it sets the default dialing mode toTouch-Tone mode. Can be used in dial string (default).

    Ex: ATDT15551235

    ATDT is the command for dial and enable tone i.e,connecting to a telephone line.

    Disconnecting a telephone line

    Hn Hook (hang up) When the modem is on-line, you mustfirst enter the +++ escape sequence to take the modem back tocommand state before issuing the hang up command, ATH. 0- Forces the modem on-hook. Hangs up the modemsconnection to the telephone line and place modem incommand state. 1 - Forces the modem off-hook. After goingoff hook, operate auxiliary relay.

    Ex:ATH 1

    ii. Digital Modems :

    A digital modem is faster than a analog modem, it does not have to convert betweenanalog and digital signals. The types of digital modems are :

    1.ISDN Modem : An ISDN (Integrated Services Digital Network) modem allowsthe user to connect to the Internet via a dedicated telephone line.

    2.DSL Modem : DSL (Digital Subscriber Line) modem uses a copper wire

    transmission technology to access high speed broadband Internet over telephonelines. For more details on how to install and set up a DSL modem, clickhere.

    3.Cable Modem : Cable modems use fiber optic technology to access the Internet.Cable modems are primarily used to deliver broadband Internet access in the form ofcable Internet.

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    10. Additional Resources:

    1. For configuring telnet and ftp on Linux workstation please refer to http://www.cae.wisc.edu/linconftcpip.

    2. Modem AT Command Set and Router Configuration Guide:

    http://www.cisco.com/en/US/docs/routers/access/modem/AT/Command/reference/atnextpt.html

    Disclaimer

    CertExams.com is neither affiliated with Juniper Systems, Inc., Microsoft Corporation, Inc., CompTIA, Check Point Software Corp., Prosoft or any other company. All trademarks are trademarks of theirrespective owners and duly acknowledged.

    http://www.idevelopment.info/data/Unix/Linux/LINUX_TelnetFTPAsRoot.shtml#Red%20Hat%20(RHEL3%20/%20RHEL4)http://www.idevelopment.info/data/Unix/Linux/LINUX_TelnetFTPAsRoot.shtml#Red%20Hat%20(RHEL3%20/%20RHEL4)http://www.cisco.com/en/US/docs/routers/access/modem/AT/Command/reference/atnextpt.htmlhttp://www.idevelopment.info/data/Unix/Linux/LINUX_TelnetFTPAsRoot.shtml#Red%20Hat%20(RHEL3%20/%20RHEL4)http://www.cisco.com/en/US/docs/routers/access/modem/AT/Command/reference/atnextpt.html

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