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Ping and traceroute

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If the destination responds, you have a good TCP/IP connection (working route) ... a TCP/IP network, including the Internet. Each host has a unique IP address. ... – PowerPoint PPT presentation

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Title: Ping and traceroute


1
Ping and traceroute
  • Lab/Homework exercise
  • Assigned 9/12/2006
  • Due 9/19/2006
  • CSIT 220 Fall, 2006Based on T. Blum Exercises

2
Exercise/Assignment
  • Assigned 9/12/2006
  • We will be doing parts of this exercise in class.
  • Some parts will require outside research and
    reference.
  • You need to submit the results of this exercise
    in a hardcopy format.
  • The lab exercise is due 9/19/2006. It will count
    as a homework grade.

3
Pinging
  • Ping is short for Packet Internet Groper
  • It is a utility that sends a message to a
    computer and waits for a response
  • A utility is part of system software that is used
    to help manage the computers resources, as
    opposed to application software
  • If the response is received, information about
    the times required and so on are reported
  • If the response is not received in a certain
    amount of time, the request is said to have
    timed out

4
Pinging (Cont.)
  • It works by sending special packets ICMP
    (Internet Control Message Protocol) echo request
    and echo reply packets to a destination, an IP
    address or domain name
  • If the destination responds, you have a good
    TCP/IP connection (working route).
  • There are many freeware and shareware PING
    utilities available for personal computers (see
    for example http//www.shareware.com)

5
Breaking it down
  • Pinging consists of the command ping followed
    by an IP address or domain name
  • ping 139.84.10.250
  • ping www.lasalle.edu
  • It sends out special packets which request a
    response (echo reply) if the destination host is
    reached

6
host
  • A computer that is connected to a TCP/IP network,
    including the Internet.
  • Each host has a unique IP address.
  • A computer may always have the same address or
    may have a different address each time it
    connects to the networks
  • Two computers on the same network or internet at
    the same time should not have the same address

7
Usual form
  • Instead of writing out a string of thirty-two 1s
    and 0s, IP addresses are usually written as four
    numbers between 0 and 255 separated by periods
    (the dotted decimal notation)
  • For example
  • 139.84.10.250

8
How many?
  • With 32 bits, 232 devices could be distinguished
  • Actually the number of valid IP addresses is less
    than 232 because certain addresses are reserved
    for special purposes (127.0.0.1 is one example
    well see later)
  • Another problem is that addresses are owned by
    people not using them

9
IP Address (cont.)
  • In an isolated network, any set of IP addresses
    can be assigned.
  • On the other hand, connecting a network to the
    Internet requires using registered IP addresses
    to avoid duplications.
  • The InterNIC Registration Service assigns
    Internet addresses.

10
Domain name
  • A domain name is a string of characters standing
    in for an IP address
  • Can have
  • One Name ? Multiple Addresses
  • One Address ? Multiple Names
  • Domain names are used in URLs to identify
    particular Web pages. For example, in the URL
    http//www.pcwebopedia.com/index.html, the domain
    name is pcwebopedia.com.

11
Packet
  • A packet is a message (protocol some data) or
    a piece of a message transmitted over a
    packet-switching network.
  • A packet must also contain an address
    (identifier) so that it can be routed to its
    destination.

12
Packet switching
  • A set of protocols (rules for communication) in
    which messages are broken into pieces called
    packets before being sent.
  • The packets are transmitted individually
    (connectionless).
  • They may follow different routes
  • They can arrive out of order
  • Share the medium with other packets from other
    transmissions
  • When the packets arrive, they are reassembled
    into the original message.

13
Pinging Start/Run
14
Pinging Type command in Run dialog box
Actually cmd is preferred
15
Pinging type ping followed by domain name
16
Pinging a host which was off at the time
Timed out
Can use IP instead of domain name
17
Pinging webopedia, also timed out
18
Webopedia ping timed out, even though site was up
19
Denial of service
  • One possibility is that some companies block
    pings because their systems could become clogged
    with ping requests.
  • Rejecting pings could make a site less vulnerable
    to a Denial of Service (DoS) attack, in which a
    site is flooded with so many requests that it
    cannot answer them all.

20
Ping Exercise Part 1 (30 points)
  • Pick the address of a site you visit. You are
    going to use it to test some network diagnostics.
    What happened when you ping your site?
  • Try it with a few more examples. What is
    happening?
  • How can ping be useful?

21
Type ping /? To find the various options there
are
22
Using the count request option to send 5 instead
of 4
23
Useful or not?
  • Simply pinging a remote host (a computer that is
    on ones internet but not on ones network)
    usually has an all or nothing outcome and as such
    can provide somewhat limited information
  • A sequence of pinging can provide more
    information (see MCSE TCP/IP for Dummies)

24
Pinging yourself using localhost or 127.0.0.1
verifies that TCP/IP has been installed and
started correctly
Reserved IP address
25
Pinging yourself using your IP, checks that the
IP is valid
26
You can use another utility ipconfig to find your
IP if you dont know it
27
  • Go to the start command
  • Select the option run and type
  • command.com
  • You now have the black window and we are going to
    use this to check our connection.
  • Run ipconfigwhat is your address? What can you
    tell from your about your connection?

28
Pinging the Gateway timing out here may
indicate a problem with the router
29
Gateway
  • Recall that one gets an internet by connecting
    more networks
  • The point at which data leaves one (local)
    network and enters another is known as a gateway
  • A node (a device on the Internet) can be either a
    gateway, router, or a host (end-point).

30
Host/Gateway
  • When you are looking at some site on the net,
    your computer and the one containing the site are
    hosts
  • On the other hand, the computers that direct the
    traffic, for example your Internet service
    provider (ISP) are gateway/router nodes.

31
Traceroute
  • A utility that traces (determines the route taken
    by) a packet from your computer (the local host)
    to some other host on the network
  • It doesnt actually follow a single packet but
    sends out a series of packets
  • The packets are restricted in the number of
    hops they can take
  • It is limited by the time-to-live (TTL) field
  • When the limit is reached, information about the
    node is (should be) returned
  • Each consecutive packet is allowed one more hop

32
hop
  • A hop is when a packet is transmitted from one
    node to the next.
  • Some Internet Service Providers (ISPs) advertise
    how many hops away from Internet backbone they
    are. Theoretically, the fewer hops it takes to
    get your data onto the backbone, the faster your
    access will be. (webopedia)

33
Traceroute (Cont.)
  • Traceroute shows how many hops were required to
    reach the destination as well as the length of
    time for each hop.
  • When the web is sluggish, you can use traceroute
    to determine where the congestion lies.

34
Traceroute (Cont.)
  • The original traceroute was for UNIX utility
  • Windows has a traceroute utility called tracert.
  • Go to Start/Run, type cmd, and then type
    tracert followed by the domain name of the
    host.
  • For example
  • tracert www.webopedia.com

35
tracert www.whatis.com
36
Tracert Exercise Part 2 (40 points)
  • Using the command.com and tracert command, find
    the command to
  • www.whatis.com
  • 139.84.19.200
  • Ask your neighbor for their ip addresstrace the
    route to them.

37
Other TCP/IP diagnostic commands
  • Nbtstat
  • Netstat
  • Ipconfig
  • Arp
  • Hostname
  • Route
  • Look up these commands and see what they mean.
    Prepare a table with the list and the job of each
    command.site your sources.

38
Another Exercise part 3 (30 points)
  • Find the ipconfig for your machine.
  • Open the command window
  • Look at the options for the NBTSTAT command.
  • Run the NBTSTAT command using your ip address for
    your machine. Use the A option. What did you
    find out?

39
Other sources
  • http//www.webopedia.com
  • http//www.whatis.com
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