adsl connection troubles with ubuntu

[Chanchao]

Hi, I'm in Thailand as well.. And since last week happily connecting
through my new ADSL router in Ubuntu. 

First things first:

* Are you connecting by network cable or wireless? You say 'a 4 port
adsl router' so that means you connect through a cable right? I'll
assume it's cable from here on.

* Switch the cables. On some hubs/routers there's one port that's
'uplink' or otherwise not available. Switch the cable that goes into
your Ubuntu box from one of the other PC's that you know works. This
also rules out anything being wrong with the cable itself. (you never
know. :)

* Now, Ubuntu uses the EXACT same protocols as Windows for Internet. On
Windows, is it picking up things automatically?  This is the most
common: The router assigns IP addresses automatically.  In Windows you
can check this by going Start->Control Panel->Networking and then
right-clicking your LAN connection and selext 'properties', then double
click 'TCP/IP'.  It will likely say 'automatically obtain ...' for
everything.  let me know if it doesn't. 

* While still on your working windows box, check what network address
the windows PC got. This is useful because you can then check that your
basic local network works, never mind the internet (yet).  So in
windows, click 'Start' -> 'Run'  then type 'CMD' and click OK. You will
get a command prompt. Type 'ipconfig' <enter> and note the IP address
you see. Chances are this will look something like " 192.168.1.3 "
Remember it.

* Now back to your Ubuntu box.  Ubuntu should work exactly the same, it
will also automatically pick up the network address. If you see the
network icon in the title bar on the top right hand side (looks like 2
computer monitors), then just click it, a window will pop up. Click the
'Support' tab. It will show the IP address it received (if any).
Something like 192.168.x.x usually.

Or if you DONT see that icon, Ubuntu has a similar command to Windows
'ipconfig' except that it's called 'ifconfig' with an 'f'.  Click
'Applications' -> 'Accessories' -> 'Terminal'. Then type 'ifconfig'
<enter>.  In all that you will see the ip address (if indeed assigned)
for your LAN network connection which is usually called 'eth0'.
Something like this:

eth0      Link encap:Ethernet  HWaddr 00:16:36:69:C2:E7  
          inet addr:192.168.1.102  Bcast:192.168.1.255   ...etc.
          ......

(Lots more stuff before and after this, but from this you can see the IP
address the Ubuntu box got, in this case above it's 192.168.1.102. (If
you DONT see an IP address but you know that Windows DID get one, then
something is wrong with your network (card), chances are Ubuntu is not
picking it up properly.  If you DO see an IP address then continue:

* Next we will check if your local network works or not.  Remember your
Windows PC address? Let's see if we can reach it.  On your Ubuntu box,
click System -> Administration -> Network Tools.   Then click the 'Ping'
tab.  In here, fill in the address of your Windows box in 'Network
Address' and 'ping' it by clicking the Ping button.  If you see a reply
then you can rejoice that your network is basically working.   

Note that you can do it the other way around too, from windows you can
ping the Ubuntu address you saw above. Windows however doesn't come with
a neat graphical tool so you would need to use the windows command
prompt again.  (Start->Run->'CMD' <Enter>) and then manually type 'ping
192.168.1.102' where the address is the address of your Ubuntu box. 

* So, did that work so far?  If yes then there's no real reason why
Internet shouldn't work.  If it did NOT work, then it may be a case of
your network card not being picked up by Ubuntu properly.  In that case
most people end up Googling for the brand & model of the network
hardware in combination with 'ubuntu' or 'linux' to hunt for a solution.
Or they end up replacing the network card altogether with one that 'just
works'.

Let me know!

Cheers,
Chanchao (in Chiang Mai)