Internet connection problems in Ubuntu

Many users do have a lot of problems connecting to the internet in ubuntu... There could be many reasons for that, either an ip problem where your computer is not getting an ip address,or a DNS problem, where you have not set up your DNS server or you are not able to dial your internet connection properly.. etc etc etc
One of the most common reasons which can cause a problem in not connecting you to the internet is when the Ubuntu network settings are not configured properly..So try the following steps and hopefully it would help!!!
Step 1:Go to System->Adminsitration->Network and type in the password ..
Step 2:Then under the CONNECTIONS tab choose the ethernet card which is connected to your modem/router ...You will find an option called Modem Connection - this is only for dial up connections and is not used in this case...Your ethernet card would mostly be eth0 .. suppose you have two ethernet cards then you will find 2 options eth0 and eth1 ..They will be mentioned in the list as "WIRED CONNECTION(eth0)" ...If you have more than 1 ethernet card and you are not sure which one is connected to your modem/router , then just try one card first and if that doesnt work try the other one..
If you have only 1 LAN card then only one option will be there which would be "WIRED CONNECTION(eth0)" .. Once you have selected the card i.e. eth0 or eth1 etc etc... click on PROPERTIES ..
Step 3:Now if "ENABLED ROAMING MODE " is checked .. Then uncheck it and choose "AUTOMATIC CONFIGURATION (DHCP)" as the configuration type in Connection Settings if your modem/router has DHCP enabled..Otherwise select "STATIC IP ADDRESS".. and enter the ip address manually..
Some standard values are:
IP ADDRESS:192.168.1.2
Subnet Mask:255.255.255.0
Gateway Address:192.168.1.1

here 192.168.1.1 is your modem/router's ip address
These are standard values but it may vary depending on your setup..After you are done Click on OK and close other windows. .You may have to reboot...although i feel its not required..it depends...

If you want to find out whether your modem is DHCP enabled or not.. open your web browser and type your modem's ip address..by default it is http://192.168.1.1 ..then type in your modem's username and password..Default username and passwords are:-
1)username=admin and password=admin
2)username=admin and pasword=password
3)username=admin and password=(blank)

Once you have successfully logged in to your modem/router..Look for an option called DHCP.. There you would come to know whether DHCP is enabled or not...

Another reason as to why your internet connection may not work is if your DNS settings are not set.. CLICK HERE to sort that out
These are common settings which have to be checked in order to make sure you get your internet connection working in ubuntu..


NOTE: In case you want to make sure that you are getting an ip address from your modem when you enable DHCP just go to the terminal and type ifconfig ...you should find your network card either eth0(mostly) or eth1 depending on your setup.. and you should see something known as "inet addr" if there is an ip address mentioned there which is of the form 192.168.1.x .. (considering your modem's ip address to be 192.168.1.1)then you have successfully received an ip address from your modem/router...