This wiki page allows you to record the results of your network configuration exercise. You may need to refer to the configuration handout to complete this document.

Answer all questions based on the host that you are configuring in the lab. Edit this wiki page directly to insert your answers. You will probably find this most convenient to do at the same time as you perform the configuration. Where requested, please include listings of the actual configuration files and command outputs directly in the document. Placeholders have been provided for this purpose. Please follow the formatting hints given in the text.

When the exercise is complete you should sign and submit it in for marking. Deadline for completion is the start of the lab on the last week of this term.

This exercise is worth 20% of the module marks.

Which Linux command gives you information about your computer's name on the network?

Answer (delete as appropriate):

hostname 

Use the command selected in Question 1 to determine your host computer's name? What is the name?

Answer:

hyperion

Which configuration file would you need to edit to change your computer's name on the network?

Your answer (one of):

/etc/hostname 

Which linux command gives you information on your host's network settings?

Answer one of:

ifconfig 

Use the command selected in Question 4 to complete the following table:

How many hosts can the sub-net defined by your host's netmask support?

Answer one of:

254 

What class of network is the sub-net to which your host has been assigned?

Answer one of:

Class C 

Answer the following questions about your network configuration. Please copy and paste the contents of the files identified in Questions 8 and 11 to your submission.

In which file is the configuration of your Network Interface Controller (NIC) configured?

Answer one of:

/etc/network/interfaces 

Please include a listing of the file chosen in answer to Question 8:

auto eth0
iface eth0 inet static
address 192.168.3.21
network 192.168.3.0
netmask 255.255.255.0
gateway 192.168.3.1 

What is the IP address of the host which serves as the default gateway for your network?

Answer:

192.168.3.1

What is the hostname of the gateway interface?

Answer:

saturn

In which file is the symbolic names of the networks, hosts and interfaces available on the network defined?

Answer one of:

/etc/hosts 

Please include a listing of the file chosen in answer to Question 11:

# /etc/hosts -- Hosts file for ICCT Private network
#
# IP
FQDN
aliases
#
127.0.0.1 localhost.localdomain localhost hyperion
#
192.168.1.1 solaris.icct.co solaris inet-gateway
192.168.1.2 venus.icct.com venus www
#
# Jupiter cluster
#
192.168.1.3 gw-jupiter.icct.com gw-planets jupiter-if1
192.168.2.1 jupiter.icct.com jupiter jupiter-if2
192.168.2.23 carme.icct.com guo carme
192.168.2.22 leda.icct.com jumana leda

#
# Saturn cluster
#
192.168.1.4 gw-saturn.icct.com gw-saturn saturn-if1
192.168.3.1 saturn.icct.com saturn saturn-if2
192.168.3.3 tethys.saturn.icct.com meg tethys
192.168.3.69 mimas.saturn.icct.com rich mimas
192.168.3.2what are classes of a network1 hyperion.saturn.icct.com jen hyperion
192.168.3.3what are classes of a network5 titan.saturn.icct.com ali titan
192.168.3.2 dione.saturn.icct.com gary dione
#
# Add other hosts/clusters below here
# (we'll use this to add virtual hosts to the web-server in a later
# lab exercise)
# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnwhat are classes of a networket
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

What is the symbolic name of your network's gateway interface?

Answer:

saturn.icct.com

What is the purpose of the Gateway interface?

Answer:

The gateway interface is a protocol that allows the secure data transfer to and from a server, and a network user, by means of a program which resides on the server and handles the transaction. An example would be if an intranet user sent a request with a Web browser for database information, a program would execute on the server, retrieve the information from the database, format it in HTML, and then send it back to the user.

Not really, it acts as a gateway to the rest of the internet. Note that the network part of the gateway's IP address matches that of your host. Any packets sent to an IP address with a different network address will be sent to the gateway. That gateway (which is a router) will forward it on to the next network [192.168.1.0 via 192.168.1.4]. The match is performed again, and if necessary, the packet will be forwarded to the next gateway (which in this context will be solaris [192.168.1.1]) which will forward it to the campus network 137.44…. and if necessary, further on through one of the Campus routers and so on.

— Chris Jobling 2012/12/06 02:49

Which linux command shows the routing table for your host?

Answer:

route

Run the command identified in Question 14 and reproduce its output here.

Answer

<cli> icct@hyperion:~$ route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default saturn.icct.com 0.0.0.0 UG 100 0 0 eth0 link-local * 255.255.0.0 U 1000 0 0 eth0 192.168.3.0 * 255.255.255.0 U 0 0 0 eth0 </cli>

How many interfaces (NICs) must a router have?

Answer one of:

2 

Which system feature must be turned on if you want a Linux host to act as a router?

Answer:

ip_forward=yes

Answer is IP forwarding. Your answer would be part of the later question.

— Chris Jobling 2012/12/06 03:09

Which run-time command can be used to make a Ubuntu Linux host act as a router?

Answer:

sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"

In which file is the setting defined in Question 17 set if you want a Ubuntu host to be configured as a router at boot-time?

Answer:

icct@hyperion:~$ ssh jupiter
icct@jupiter:~$ nano /etc/network/options

Because the question asks for the file name, a better answer would be jupiter:/etc/network/options – but in actual fact, for your network the correct answer is saturn:/etc/network/options, because the gateway router for your host is saturn!

— Chris Jobling 2012/12/06 03:07

Reproduce the contents of the file defined in Question 17 to make a Ubuntu host into a router?

Answer:

ip_forward=yes
spoofprotect=yes
syncookies=no

What setting has been added to the network configuration file to define a route to icct-net from your sub-network's cluster-server?

Answer:

up    route add -net 192.168.3.0 netmask 255.255.255.0 gw 192.168.1.4

What about down?

— Chris Jobling 2012/12/06 03:09

Contents:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# This is Jupiter

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
  address 192.168.1.3
  network 192.168.1.0
  netmask 255.255.255.0
  gateway 192.168.1.1
  # route to saturn-net
  up    route add -net 192.168.3.0 netmask 255.255.255.0 gw 192.168.1.4
  down  route del -net 192.168.3.0 netmask 255.255.255.0 gw 192.168.1.4

auto eth1
iface eth1 inet static
  address 192.168.2.1
  netmask 255.255.255.0
  network 192.168.2.0
  gateway 192.168.1.3

#iface eth0 inet dhcp
#iface eth1 inet dhcp

# Uncomment following lines to active third interface
#auto eth2
#iface eth2 inet dhcp

Yes, except, you should have reproduced the file for saturn!

— Chris Jobling 2012/12/06 03:22

The Linux command netstat gives a lot of useful information on your network. In the following 3 questions, reproduce the output of various usages of netstat. You should annotate your results with a brief explanation of what they mean. You may need to print the output and attach to the submission.

Give and explain the output of the command netstat -r.

Answer <cli prompt=“$” comment=“#”> user@host:~$ netstat -r Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface default saturn.icct.com 0.0.0.0 UG 0 0 0 eth0 link-local * 255.255.0.0 U 0 0 0 eth0 192.168.3.0 * 255.255.255.0 U 0 0 0 eth0 </cli>

This command displays the kernel routing information. The output of the kernel routing table is organized in the following columns:
  Destination: The destination network/host.
  Gateway: The gateway address(’*’ if none set).
  Genmask: The netmask for the destination net.
  Flags: The flags shown above are:
    - U (route is up) 
    - G (use gateway)
  MSS: Default maximum segment size for TCP connections over the route.
  Window: Default window size for TCP connections over the route.
  irtt: Initial RTT (Round Trip Time).
  Iface: Interface to which packets for this route will be sent.

Good idea to use the documentation for the definition, but what does it do in words that you and I could understand?

— Chris Jobling 2012/12/06 03:11

Give and explain the output of the command netstat -i.

Answer <cli prompt=“$” comment=“#”> user@host:~$ netstat -i Kernel Interface table Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg eth0 1500 0 9660 0 0 0 7084 0 0 0 BMRU lo 16436 0 0 0 0 0 0 0 0 0 LRU </cli>

This command displays statistics for the network interfaces currently configured. The output of the table is organized in 
the following columns:
  MTU and Met: show the current MTU and metric values for that interface. 
  RX and TX: shows how many packets have been received or transmitted error-free (RX-OK/TX-OK) or damaged (RX-ERR/TX-ERR), how 
  many were dropped (RX-DRP/TX-DRP) and how many were lost because of an overrun (RX-OVR/TX-OVR).
  Flg: shows the flags that have been set for the interface. The possible characters are:
    - B: A broadcast address has been set.
    - L: This interface is a loopback device.
    - M: All packets are received (promiscuous mode).
    - O: ARP is turned off for this interface.
    - P: This is a point-to-point connection.
    - R: Interface is running.
    - U: Interface is up.

If anything, the official documentation of netstat -i is even more opaque. What does it really show us?

— Chris Jobling 2012/12/06 03:12

Give and explain the output of the command netstat -ta.

Answer <cli prompt=“$” comment=“#”> user@host:~$ netstat -ta Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 *:http *:* LISTEN tcp 0 0 *:ssh *:* LISTEN tcp 0 0 localhost.localdoma:ipp *:* LISTEN tcp 0 0 localhost.localdo:mysql *:* LISTEN tcp 0 0 hyperion.saturn.i:51272 50.97.210.35-stati:http TIME_WAIT tcp 0 0 hyperion.saturn.i:51276 50.97.210.35-stati:http TIME_WAIT tcp 0 0 hyperion.saturn.i:51271 50.97.210.35-stati:http TIME_WAIT tcp 0 0 hyperion.saturn.i:51277 50.97.210.35-stati:http TIME_WAIT tcp 1 0 hyperion.saturn.i:46254 mistletoe.canonica:http CLOSE_WAIT tcp 0 0 hyperion.saturn.i:51270 50.97.210.35-stati:http TIME_WAIT tcp6 0 0 [::]:ssh [::]:* LISTEN tcp6 0 0 ip6-localhost:ipp [::]:* LISTEN </cli>

The option -t shows active TCP connections. Providing the -a also shows sockets that are waiting for a connection. The command netstat -ta will display a list of all servers that are currently running on your system.

Good, that's what I was after for the previous two questions!

— Chris Jobling 2012/12/06 03:13

Install, if necessary, the traceroute command then answer the following two questions.

Give the output of traceroute from your host to any host on one of the other ICCT networks.

Answer <cli prompt=“$” comment=“#”> user@host:~$ traceroute tethys.saturn.icct.com traceroute to tethys.saturn.icct.com (192.168.3.3), 30 hops max, 60 byte packets 1 tethys.saturn.icct.com (192.168.3.3) 0.969 ms 0.974 ms 0.969 ms </cli>

The question asks you to provide a route to another network. You should have used something on jupiter.icct.com or icct.com. There would then have been at least 2 hops.

— Chris Jobling 2012/12/06 03:14

Give the output of traceroute from your host to www.swan.ac.uk

Answer <cli prompt=“$” comment=“#”> user@host:~$ traceroute www.swan.ac.uk traceroute to www.swan.ac.uk (137.44.1.7), 30 hops max, 60 byte packets 1 saturn.icct.com (192.168.3.1) 0.267 ms 0.487 ms 0.476 ms 2 * * * 3 * * * 4 * * * 5 * * * 6 * * * 7 * * * 8 * * * 9 * * * 10 * * * 11 * * * 12 * * * 13 * * * 14 * * * 15 * * * 16 * * * 17 * * * 18 * * * 19 * * * 20 * * * 21 * * * 22 * * * 23 * * * 24 * * * 25 * * * 26 * * * 27 * * * 28 * * * 29 * * * 30 * * * </cli>

When you connect to another computer, your traffic does not go directly to the machine you are attempting to connect to. Instead it goes through multiple machines on the Internet known as routers. These machines serve the sole purpose of controlling how your traffic gets to your destination. If any one connection fails, you will not be able to connect to the intended destination.

How do you explain the no-reply status of hops 2-30? Do you think that there are there really 30 networks between hyperion.saturn.icct.com and www.swan.ac.uk?

— Chris Jobling 2012/12/06 04:15

A new sub-network engineering-net (192.168.10.0/24) is to be added to the ICCT network. Host engineering (192.168.10.1/32) is a cluster server for this new network. Give the settings needed to set up this host as a router to icct-net, jupiter-net, and saturn-net and a gateway for engineering-net.

Answer

Which other files would you need to modify to correctly set up this new router?

Answer

Summarize the changes that you would you need to make to your host's network configuration to have the new engineering sub-network recognized?

Answer

Which other files would you need to modify to fully configure your host to recognizes the new engineering sub-network?

Answer

I hereby submit this work for marking.

Your signature here: J. Thomas