how do I set the, DHCP to assign a addresses for the newer computer

Where is the other end of the cable plugged to? A router?

yes a router it work on my old computer but not on the HP

Most routers have an in built DHCP server. Its usually enabled by default but may not be.

With your old computer let it connect to the internet and in a terminal enter the following command

route -n

You should see something similar to this

warren@dell:~$ route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.0.1 0.0.0.0 UG 0 0 0 eth2
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth2
192.168.0.0 0.0.0.0 255.255.255.0 U 2 0 0 eth2
warren@dell:~$

The gateway address in my case 192.168.0.1 is the address of your router.

In a web page enter this address. You will probably be asked for a user name and password.

You will need to look in the documentation that came with your router for these. On this web page interface you can set up the DHCP server.

If you let us know the make and model of your router then there is probably at least one of us who can give you step by step instructions.

rob@rob-desktop:~$ route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
71.237.208.0 0.0.0.0 255.255.248.0 U 1 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth0
0.0.0.0 71.237.208.1 0.0.0.0 UG 0 0 0 eth0

it is a motorola SB5100 SURFboard Cable Modem

step by step instructions is what I will need. I'm new to this and don't know much about computers .

Can you give the output of:

lsb_release -a; uname -a; lsusb

Thanks

How are you connecting to this router? USB or LAN cable?

I'm not personally experienced with this router but we will try to help.

For everybody else's benefit I've found a pdf of the manual here
http://www.google.co.uk/url?sa=t&rct=j&q=motorola%20sb5100%20surfboard%20cable%20modem&source=web&cd=1&ved=0CCMQFjAA&url=http%3A%2F%2Fwww.firstmedia.com%2Fdownload%2Ffastnet%2FPanduan%2520Pelanggan%2520FastNet%2520Cable%2520Modem%2520Motorola%2520SB5101.pdf&ei=qaRgUO-JAaet0QWJnoDADg&usg=AFQjCNHIAnn8XlvaO5kaENZRNYLVpxnUxw&cad=rja

no LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 12.04 LTS
Release 12.04
Codename: precise
Linux bob-desktop 3.2.0-23-generic-pae #36-Ubuntu SMP Tue Arp 10 22:19:09 UTC 20
12 i686 i686 GNU/Linux
bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

is that good or bad the first line (no LSB modules are available)?

connecting to router with a LAN cable

Bob can you give us the output of

cat /etc/network/interfaces

mine looks like this is yours similar

warren@dell:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback

bob@bobdesktop:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback

Sorry Bob,

I'm confusing my self here. Is this the old or new machine and can you compare it with what was on the other?

that was the newer one this is the old one
rob@rob-desktop:~$ cat /etc/network/interfaces
auto lo
iface lo inet loopback

could it have something to do with the address in the newer computer

what if I got another LAN cable and plugged it into the old computer? would that be a defiant set up?

you can go to Question #209387 to see more info about what is happening but everyone just stopped on that one

I found the fix turn off modem and unplug the power cord. Wait a minute plug power back in. it's the modem this model needs to reset for other computers to work off it.
I thank everyone that tried to help and was beating there head against the wall with me :)

Glad to here you are sorted now. I was running out ideas. I think everybody else was too. But now its working so that's the important thing