NETWORKING IN GNS3

January 19, 2014

NETWORKING IN GNS3

INTRODUCTION
GNS3 is a simulator which provide you a real environment as you are going to see in this tutorial .It gives you a feel of real router , PC’s etc .
The requirement of this tutorial is real operating system installed on virtual box . This tutorial is just for your knowledge , what you can do if you know networking .So keep following www.hackingdna.com

In this tutorial you are going to learn how to work in GNS3 .
We create a small network by just adding 1 Router , 1 Switch and 1 PC.
See the below image of our network scenario –

START YOUR NETWORK

To start your network click on the play button .As you start your network , your windows xp is started .
See the below image , our windows xp is started on virtual box , it shows that we add a real operating system in our network with the help of GNS3.
See the below image for more help -

GIVE ROUTER IP VIA CONSOLE

To give ip address to a router , right click on a router and click on console .
Then a black window will pop up , now enter the commands as shown below
See the below image for more details –

COMMANDS
Connected to Dynamips VM "R1" (ID 0, type c7200) - Console port
Press ENTER to get the prompt.

R1#
R1#config t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#int f1/0
R1(config-if)#ip add 10.0.0.1 255.0.0.0
R1(config-if)#no shut
R1(config-if)#exit
*Oct 1 00:27:25.963: %LINK-3-UPDOWN: Interface FastEthernet1/0, changed state to up
R1(config-if)#exit
R1(config)#
CONFIGURE ROUTER IP

CONFIGURE DHCP SERVER ON ROUTER R1

DHCP Server is used to assign ip addresses to the clients who is requested for ip addresses.
To configure dhcp server , you have to enter the command as shown below –

COMMANDS

R1(config)#ip dhcp pool hackingDNA
R1(dhcp-config)#network 10.0.0.0
R1(dhcp-config)#default-router 10.0.0.1
R1(dhcp-config)#exit
R1(config)#exit
R1#
*Oct 1 00:33:22.591: %SYS-5-CONFIG_I: Configured from console by console
R1#
CONFIGURE DHCP SERVER

WINDOWS XP GET IP ADDRESS AUTOMATICALLY BY DHCP SERVER

As soon you configure DHCP server on router , your windows xp will receive the ip address as shown below .
See the below image it shows the windows xp ip address, subnet mask and gateway address.
See the below image for more help -

CONFIGURE TELNET ON ROUTER

Now in this step , we configure line-vty for accessing router from windows xp via TELNET .
Enter the commands as shown below -

COMMAND

R1#config t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#line vty 0 4
R1(config-line)#password 12345
R1(config-line)#login
R1(config-line)#exit
R1(config)#enable secret cisco123
R1(config)#exit
R1#
*Oct 1 00:46:47.139: %SYS-5-CONFIG_I: Configured from console by console
R1#

configure line vty

ACCESS ROUTER WITH TELNET

Once you configure on router and set passwords , now open command prompt on windows xp and enter the telnet command .
Command : telnet 10.0.0.1
As you press enter , it ask you for the password enter 12345.This is a login level password .
Now enter the command : enable or en .
Now again you have to enter the password that you set is : cisco123
Bingo ! , you are in hackingDNA router .
See the below image for more details -