1.1 Which is the IP address of the Google site
(www.google.com)? Explain why you have several IP addresses.
1.2 What is the name of the server 134.214.100.6?
1.3 Find out name of the IP address 127.0.0.1. What is special
about this IP address?
2.1 What is the IP address of your station?
2.2 What are the interfaces on your station?
3.1 Are the following machines reachable from your machine:
wasal.epfl.ch, www.zurich.ibm.com, www.microsoft.com,dns.univ-lyon1.fr
www.hoola.hp, www.20min.ch? Check if the addresses unreachable by the command ping are
reachable from the Web browser.
3.2 What is the minimal, average, and maximum round trip time
for the site www.fiu.edu?
4.1 How many routers are there between your station and
www.ttbt.cn? Which ones are between your workstation and the SWITCH network?
4.2 Between which routers does a packet cross the Atlantic?
Pacific? Hint: compare the round trip times from your station to the routers.
4.3 Make traceroute to the site www.trustmymail.com. Where is it situated? HINT: You can find out the location of a server by using this Visual Trace Route Tool.
4.4 The www.traceroute.org
provides with a list of servers distributed around the world from which using a
web interface you can perform a traceroute to any other host in the Internet.
Choose the server in www.washington.edu
(USA) and/or www.ipartners.pl
(Poland). Make traceroute from a server towards your station and conversely. Repeat it for the
two traceroute servers only, i.e., traceroute from USA to Poland and back. Try
out other traceroute servers from the list at www.traceroute.org. What are the IP
addresses of the servers in USA and in Poland? Are the paths travelled by a
packet from one host to another and vice versa symmetrical?
Let enable ssh by uncommenting in /etc/ssh/sshd_config the line #passwordAuthentication no and by replacing no by yes. After that, restart ssh by \verb"/etc/rc.d/ssh restart".
5.1 Open a session on another station in the room. Which is
the default ssh port number?
Check in the file /etc/services. The /etc/services file contains a list of Internet services and the port numbers to be
used if the relevant server is set up on the computer on which you are looking
at the file. The content of this file is more or less self-explanatory.
6.1 Print TCP connections that are up and running on your
system. Start an ssh connection to your neighbor station. Using netstat find the
TCP connection that you just established and print out the information for that
connection. Which TCP connections are now up?
Launch the tcpdump tool by typing tcpdump in the command
line. Let ping www.google.fr and simultaneously, inspect the traffic
(before capturing the traffic, let flush the arp cache with arp -d -a)
7.1 Since a lot of traffic can be received, let filter it to
receive only the traffic from www.google.fr.
7.2 Let take a look on the content of the packet (the payload,
i.e. the information it carries). You can use the -A mode of tcpdump. Change
the length of the ping and verify that the payload length changes also.
Launch the wireshark tool by typing ethereal in the command
line. Clear the cache of your web browser and start capturing packets on your
network interface. Then enter the following URL: www.ub.edu.bz.
Once the whole page is loaded in your web browser save the wireshark traces.
8.1 From the saved trace view the HTTP traffic only. Wireshark
allows you to see the encapsulation where the data from an upper layer protocol
is included in a lower layer protocol. Which protocols encapsulate others?
8.2 What type of transport protocol is used by HTTP protocol?
8.3 Now view only DNS protocol messages from the saved traces.
What type of transport protocol is used by DNS?
8.4 Now view only ARP protocol messages from the saved traces.
Are these protocol messages related to the HTTP traffic issued by your web
browser? Why?
9.1 Let take a look on the owner of google.fr. Why
could it be useful?
Let take a look on the Renater topology (the core of the
network you are currently using): http://www.renater.fr/Metrologie/map-Renater4/
http://www.renater.fr/spip.php?rubrique153
http://www.renater.fr/spip.php?article530
http://pasillo.renater.fr/metrologie/IPv4.html
http://cicg.grenet.fr/ (in menu infrastructure/amplivia) and Geant: http://www.geant2.net/server/show/nav.00d007009
10.2 What are the typical bandwidth for each type of network?
The delay? What do you conclude about the traffic pattern (local, distant,
etc)?
10.3 What is the GIX?
10.4 let try to ping an european university. Did you succeed
to find correspondences between the path and the map?