 Now you have installed Ubuntu system but to be identifiable for it on the network configuration has to be done. Network configuration means giving it your system a host name and the IP address, specifying a gateway, specifying a DNS server so that it can resolve different URLs. So how it can be done I will show now. So for setting up a network there are 3 files here are the files so we have to enter the specifics in each of these files so I will show one files one by one. You open a terminal, go to applications, accessories and terminal. For doing network configuration I am going to explain the steps, first you change the root password using passwd command. It will ask for the current password of the user from which we are running this command that is swathi. I am entering new password for the root so now the root password is changed. So for doing the network changes you do su enter it will ask for the root password now. So the password that you have just said you enter that password and the user will be changed from swathi to root. Now you open the files slash etc slash host this is the first file for the network configuration you enter the IP address with which your system will be identified you give a host name for the system like this you save this file. The second file related to networking is slash etc slash host name the same host name that you specified in the slash etc slash host is to be specified here also save and close this file where the third file for the networking is slash etc slash network slash interfaces. Open this file using WIMP I will show you the typical structure of the interfaces file I have opened one interfaces file in another terminal so you write along with me this information you already have in your interfaces file that is that this file now we have to enter IP address, net mask, gateway these things have to enter in the our interfaces file. So you write along with me auto eth0 so eth0 is the interface on which we are configuring our IP address then ifas eth0 inate space static you have to specify the IP address the IP address will be the same that you specified in the host file that is 10.105.11. you are corresponding after that you have to write the net mask net mask is same as given 255.255.0.0 so basically this is the subnet in which we are working so if you do and of the IP address and net mask you will get the domain in which we are working so ending these two will result in 10.105.0.0 so this is the domain in which the systems are placed. The next thing is we have to specify the gateway for our network the gateway is 10.105.1.250 all the traffic outside the domain is routed through this gateway you enter the same thing for this lab 10.105.1.250 after that you can specify the broadcast address the domain is 10 our domain is 10.105 and this 255.255 specifies broadcasting is to be done to all systems which are in our domain you save this file using escape shift colon WQ enter now the network configuration in all the three files are done to reflect it in the system you have to restart a service the service is there in slash etc slash init.d slash networking this is to be restarted using restart it will reconfigure the network after we starting the network it gave a warning that this result at conf file is not present so this warning is due to we have not specified the DNS server name so whenever you enter a URL in the browser it cannot resolve this URL or any host name unless we specify the name server so where do we specify it it is in the slash etc slash resolve.conf you open this file using WIM I will copy the contents of some other resolve.conf in our new file you do the same thing this is the our domain cac.itb.ac.in names are host name resolution you have to specify DNS server name so where do you specify this is in slash etc slash resolve.conf file you open this file and write this in that file here cac.itb.ac.in is our domain name and the DNS server is specified as this you have to specify the same I did this is the DNS server of our computer department after doing it save this file escape shift colon WQ enter again do restart networking slash etc slash init.d slash networking space restart now that warning is gone okay after you wrote the things in the result.conf you have to again restart the network so for restarting the network this is the command slash etc slash init.d slash networking restart after configuring a network now you have specified the DNS server IP address you can check this with using ping command host host it is cac.itb.ac.in now as you can see as we have specified a DNS server it resolved this machine to this IP address and the ping is successful as you can see from the output for stopping the print ping use control C after that we will see if config command go to the terminal and type if config enter now you will see the changes reflected in output of if config command this is the ith0 interface that we configured this is the MAC address of our system this is the IP address that we just specified the broadcast address and the net mask so that means we have configured the network for this interface and IP of our system is set to this field.