Lab 19. Using Ifconfig to View and
Modify Network Information on
Linux
Lab Objective:
Learn how to use ifconfig to view and modify network information on Linux.
Lab Purpose:
Ifconfig is a system administration utility in Linux operating systems, used
for network interface configuration. It is a command line interface tool and is
used in the system start-up scripts of many operating systems.
Ifconfig is the equivalent of the ipconfig tool used on Windows.
Lab Tool:
Kali Linux
Lab Topology:
You can use Kali Linux for this lab.
Lab Walkthrough:
Task 1:
We will begin by viewing the help information screen by executing the
following command:
Ifconfig -h
Open a terminal to begin, and type “ifconfig” to view your networking
information.
As you will see, there will be a lot of information, including your local IP
addresses. New Linux distributions do not have the “ifconfig” command
installed. In this case, you can use the “ip addr” command.
Task 2:
To display a short list output, we can use the following command:
ifconfig -s
Task 3:
We can display information about a specific interface by using the following
command:
ifconfig [interface-name]
This is useful for determining interface information and for debugging.
Task 4:
We can disable or enable a network interface using an ifconfig flag. For
example:
ifconfig eth0 down
This command will disable our local connection to the Wi-Fi card. To enable
it, enter the following command:
ifconfig eth0 up
Task 5:
We can use ifconfig to enable promiscuous mode on an interface. This will
allow the interface to receive all packets on the network. You will need a
compatible network card for this to work correctly:
ifconfig eth0 promisc
This can be disabled using the following command:
ifconfig eth0 -promisc
Task 6:
The ifconfig tool also enables you to change the MAC address associated
with a network interface. This can be done with the following command:
ifconfig [network-name] hw [class] [hardware-address]
Eg. ifconfig eth0 hw ether 66:3e:7f:60:f2:1f
There are actually 4 sets of Locally Administered Address Ranges that can be
used on your network without fear of conflict, assuming no one else has
assigned these on your network:
x2-xx-xx-xx-xx-xx
x6-xx-xx-xx-xx-xx
xA-xx-xx-xx-xx-xx
xE-xx-xx-xx-xx-xx
To make the changes permanent, open the file below and add the following
lines in it:
nano /etc/network/interfaces
pre-up ifconfig eth0 hw ether AA:22:33:44:55:66
Reboot the system. The new MAC address will appear.
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