can't connect through cable modem

You are connecting your Ubuntu box with an Ethernet (normal Network-Cable) to your modem, right?

So the only reason I see is that your Ubuntu is set on DHCP and your modem doesn't have a DHCP-Server (The router will have one). Try turning the modem's DHCP-Server on or set your IP-Address manually in Ubuntu.

Many thanks for your reply. I'm kind of a novice at this so please bear
with me. The cable modem is provided by my ISP and accepts DHCP requests
from my Windows system with no problem. I assume that it works when I
connect through a router because the router sends a valid DHCP request.
Does that sound right? I tried changing the DHCP address in my Linux system
to the same as that in my Windows system to no avail. How would I determine
what my IP address is to set it manually? My ISP tech support people say
they don't support Linux and that it won't work but I don't understand why
it won't. I may be beating a dead horse. Thanks again for any help or
insight
you can provide.

Regards,
John Oliver

----- Original Message -----
From: "dei" <email address hidden>
To: <email address hidden>
Sent: Wednesday, August 20, 2008 10:51 AM
Subject: Re: [Question #42631]: can't connect through cable modem

Your question #42631 on Ubuntu changed:
https://answers.launchpad.net/ubuntu/+question/42631

    Status: Open => Answered

dei proposed the following answer:
You are connecting your Ubuntu box with an Ethernet (normal Network-
Cable) to your modem, right?

So the only reason I see is that your Ubuntu is set on DHCP and your
modem doesn't have a DHCP-Server (The router will have one). Try turning
the modem's DHCP-Server on or set your IP-Address manually in Ubuntu.

--
If this answers your question, please go to the following page to let us
know that it is solved:
https://answers.launchpad.net/ubuntu/+question/42631/+confirm?answer_id=0

If you still need help, you can reply to this email or go to the
following page to enter your feedback:
https://answers.launchpad.net/ubuntu/+question/42631

You received this question notification because you are a direct
subscriber of the question.

I'm not currently connected through a router (which works OK) so I switched
off the cable modem, switched off the Ubuntu PC, switched the modem back on
and then switched the Ubuntu PC on and did an ifconfig -a with the following
result:

Link encap:Ethernet HWaddr 00:10:a4:ff:9c:8a
inet addr: 66.67.173.52 Bcast:255.255.255.255 Mask:255.255.254.0
inet6 addr: fe80::210:a4ff:feff:9c8a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1046 errors:0 dropped:0 overruns:0 frame:0
TX packets: 41 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:69570 (67.9 KB) TX bytes:6018 (5.8 KB)
Interrupt:3 Base address:0x300

Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0B)

I then did sudo /etc/init.d/networking restart with the following result:

* Reconfiguring network interfaces......

IT NOW WORKS PERFECTLY. I previously talked to a number of people who are
knowledgeable about networking and they gave me various ideas and
suggestions, none of which worked. You are the first person who has
recommended anything that worked and I suspect the first really
knowledgeable Unix/Linux person I've worked with. Thank you very, very much
for your help. I am setting up Linux systems for a charitable organization
so you will have helped many other people in addition to myself. Thank you
again.

John

----- Original Message -----
From: "marcobra" <email address hidden>
To: <email address hidden>
Sent: Wednesday, August 20, 2008 4:21 PM
Subject: Re: [Question #42631]: can't connect through cable modem

Your question #42631 on Ubuntu changed:
https://answers.launchpad.net/ubuntu/+question/42631

    Status: Open => Answered

marcobra proposed the following answer:
Also try:
- switch your router off
- switch Ubuntu pc off
- switch router on
- switch ubuntu on

-- Please open a Terminal from the menu
Applications->Accessories->Terminal and type or better copy and paste:

ifconfig -a

copy and paste result here

Then pleas also restart your netwirk layer:

sudo /etc/init.d/networking restart

-- give your user password when requested, you don't see nothing when
you type it, then press enter.

Copy and paste result here.

Thank you

--
If this answers your question, please go to the following page to let us
know that it is solved:
https://answers.launchpad.net/ubuntu/+question/42631/+confirm?answer_id=2

If you still need help, you can reply to this email or go to the
following page to enter your feedback:
https://answers.launchpad.net/ubuntu/+question/42631

You received this question notification because you are a direct
subscriber of the question.

Then now be sure your system is fully upgraded, to check:
open a Terminal from the menu Applications->Accessories->Terminal and type:

sudo dpkg --configure -a
sudo apt-get -f install
sudo apt-get clean all
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
sudo apt-get clean all
sud apt-get autoremove

give your user password when requested, you don't see nothing when you type it, then press enter.

Then please also close this question mark it as solved.

Thank you

Thanks marcobra, that solved my question.

Thank you. Will do.

John

----- Original Message -----
From: "marcobra" <email address hidden>
To: <email address hidden>
Sent: Wednesday, August 20, 2008 5:33 PM
Subject: Re: [Question #42631]: can't connect through cable modem

Your question #42631 on Ubuntu changed:
https://answers.launchpad.net/ubuntu/+question/42631

    Status: Open => Answered

marcobra proposed the following answer:
Then now be sure your system is fully upgraded, to check:
open a Terminal from the menu Applications->Accessories->Terminal and type:

sudo dpkg --configure -a
sudo apt-get -f install
sudo apt-get clean all
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
sudo apt-get clean all
sud apt-get autoremove

give your user password when requested, you don't see nothing when you
type it, then press enter.

Then please also close this question mark it as solved.

Thank you

--
If this answers your question, please go to the following page to let us
know that it is solved:
https://answers.launchpad.net/ubuntu/+question/42631/+confirm?answer_id=4

If you still need help, you can reply to this email or go to the
following page to enter your feedback:
https://answers.launchpad.net/ubuntu/+question/42631

You received this question notification because you are a direct
subscriber of the question.

HI Marco,

I have some queries regarding this. Is it always required to establish connection with dhclient on ubuntu if we are using a cable modem that assigns IP using DHCP? if yes shoudn't /sbin/dhclient be configured accordingly?

I have a similar issue with my laptop. I am pretty sure that my ethernet card is detected by the machine. lspci is good and lsmod shows the proper kernel module.

ifconfig shows eth0 with MAC address which means that kernel has accepted the card and whats left is just accept the connection from modem. I have been using this modem on another machine, so tried all these after switching off and on, both lap and modem.

/var/log/messages shows that device is ready.

I am thinking i should try after assigning a static IP and then try connecting, and maybe configure dhclient if that doesn't work. Do you have any thoughts on this? Thanks Marco!