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?

tethys

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

Your answer (one of):

/etc/hosts 

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:

Your network's IP address is actually 192.168.3.0 – or equivalently 192.168.3/24.

— Chris Jobling 2012/12/06 03:30

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 192.168.3.3
  network 192.168.3.0
  netmask 255.255.255.0
  gateway 192.168.3.1
  

No marks lost, but I did adjust the formatting of your answer.

— Chris Jobling 2012/12/06 03:32

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

192.168.3.1

What is the hostname of the gateway interface?

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:

# Saturn cluster
#
192.168.1.4   gw-saturn.icct.com         gw-saturn saturn-if1
192.168.3.1   saturn.icct.com            saturn saturn-if2
192.168.3.69  mimas.saturn.icct.com      mimas rich
192.168.3.3   tethys.saturn.icct.com     tethys me
192.168.3.21  hyperion.saturn.icct.com   hyperion jen
192.168.3.2   dione.saturn.icct.com      dione garry
192.168.3.35  titan0.saturn.icct.com      titan ali \

I wanted the whole file, not just the bits concerned with the saturn network.

— Chris Jobling 2012/12/06 03:34

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

saturn.icct.com

What is the purpose of the Gateway interface?

The gateway interface is simply the interface between the web page or browser and the web server that runs
the program. You must have a gatewat interface access to run programs on your web page. It ensures higher security.
   

No! In this context, the gateway is a network layer issue, it has nothing to do with application prootocols like the web and it is not explicitly concerned with network security.

Think about the Intenet Protocol and routing!

In fact all the configuration in /etc/hostname, /etc/hosts and /etc/network/* is actually all about IP and Ethernet. It has nothing to do with the higher level protocols at all. The one exception is /etc/resolv.conf which is concerned with configuring your host to use DNS

— Chris Jobling 2012/12/06 03:35

Which linux command shows the routing table for your host?

sudo route -n

Not sure that you need sudo. What does -n flag do?

— Chris Jobling 2012/12/06 04:01

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

icct@tethys:~$ sudo route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.3.1     0.0.0.0         UG    100    0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 eth0
192.168.3.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0

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?

ip_forwarding = yes

The system feature is called IP forwarding. This is the command you use to turn it on!

— Chris Jobling 2012/12/06 04:02

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

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?

icct@tethys:~$ 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!

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

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?

  up	route add -net 192.168.3.0 netmask 255.255.255.0 gw 192.168.1.4

What about down route?

— Chris Jobling 2012/12/06 04:09

icct@jupiter:~$ cat /etc/network/interfaces
# 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 04:09

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.

icct@tethys:~$ 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
169.254.0.0     *               255.255.0.0     U         0 0          0 eth0
saturn-net      *               255.255.255.0   U         0 0          0 eth0


The nestat -r command displays a Kernel IP routing table. 
The eight different headers contain different information on the network;
Destination: The destination network/host
Gateway: The gateway address "*" indicates if non has been set
Flags: Possible flags include
       U (route is up)
       H (target is a host)
       G (use gateway)
       R (reinstate route for dynamic routing)
       D (dynamically installed by daemon or redirect)
       M (modified from routing daemon or redirect)
       A (installed by addrconf)
       C (cache entry)
       ! (reject route)
MSS: Default maximum segment size for TCP connections over this route
Window: Default window size for the TCP connection
IRTT: Initial Round Trip Time, the Kernel uses this to guess about the best TCP Protocol parameters without waiting on answers.
IFace: Interface to which packets of 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 04:10

Give and explain the output of the command 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     27607      0      0 0         27095      0      0      0 BMRU
lo        16436 0         0      0      0 0             0      0      0      0 LRU

The MTU and met fields show the current MTU and metric values for that interface. The RX and TX columns show how many packets have been received or transmitted error-free(RX-OK/TX-OK) or damaged (RX-ERR/TX-ERR);
How many have been dropped (RX-DRP/TX-DRP); and how many were lost because of an overrun.


The last column shows the flags that have been set for this interface. 
These characters are one-character versions of the long flag names that are printed when you display the interface configuration with ifconfig:
B: A broadcast address has been set
L: The interface is a loopback device
M: All packets have been received
O: APR has been 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 04:11

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

icct@tethys:~$ 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     

The command -t displays all of the active TCP connections. A displays all active connections and the TCP and UDP ports on which the computer is listening. 
Combining them together gives the above output.

Good, that's what I was after for the previous two questions! Perhaps the documentation is better for netstat -ta

— Chris Jobling 2012/12/06 04:14

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.

icct@tethys:~$ traceroute hyperion.saturn.icct.com
traceroute to hyperion.saturn.icct.com (192.168.3.21), 30 hops max, 60 byte packets
1  hyperion.saturn.icct.com (192.168.3.21)  0.753 ms  0.755 ms  0.748 ms

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 04:12

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

icct@tethys:~$ traceroute hyperion.saturn.icct.com
1  hyperion.saturn.icct.com (192.168.3.21)  0.753 ms  0.755 ms  0.748 ms
icct@tethys:~$ 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)  0.273 ms  0.259 ms  0.464 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  * * *

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: M Castleton