Linux used to have internet

J_K9 · 07-07-2005, 02:50 AM

Hi,

Just this morning, I was looking around LQ on my lovely Ubuntu laptop. My ISP had a small tech problem (again!) and so my router automatically reconnected when the ISP went back up. All my other computers work, i.e the Windows and my Mac (which I am currently posting this from), but even though I can access my router's settings from Ubuntu and ping the router, my Hoary laptop is unable to acces the internet. A "ping google.com" returns "ping: unknown host google.com", and as you could expect, typing the URL into Firefox does absolutely nothing. I find it very strange that my laptop can't connect to the internet, even though it can see my router, but my other computers can. I didn't alter any settings while the ISP was down, so I'm really not sure how this has happened. Any help would be appreciated.

J_K9

P.S I am connected via ethernet to a Linksys router/modem which is connected to an ADSL line, just for those of you who want to know!

bathory · 07-07-2005, 03:33 AM

Quote:

ping: unknown host google.com

That means you cannot resolve the domain. Possible reasons:
You have the wrong dns settings in /etc/resolv.conf.
Or most likely you have lost your gateway. Check with "route -n" to find out what is your default gateway.

J_K9 · 07-07-2005, 03:46 AM

The result of "route -n":

Code:

Kernel IP Routing Table
Destination         Gateway            Genmask                Flags     Metric  Ref  Use  Iface
192.168.1.0        0.0.0.0              255.255.255.0          U        0         0      0    eth1
192.168.1.0        0.0.0.0              255.255.255.0          U        0         0      0    eth0
0.0.0.0               192.168.1.1       0.0.0.0                UG       0         0      0    eth0
0.0.0.0           192.168.1.1           0.0.0.0                UG       0         0      0    eth1

My router is at 192.168.1.1, my default ethernet (PCMCIA) card is eth1 and the Subnet mask should be 255.255.255.0.

My resolv.conf:

Quote:

nameserver 195.244.192.66
nameserver 195.244.192.6

I'm not really sure about the DNS stuff....is that correct? Thanks,

J_K9

bathory · 07-07-2005, 03:58 AM

If you are not sure about your nameservers, check with your other boxes that work, or contact your ISP

J_K9 · 07-07-2005, 04:11 AM

Cool, but my Windows laptop is on "Obtain DNS address automatically" and I have no idea how to find out my dns on my Mac (because of different filesystem)! Oh, just checked router and it says that the primary DNS server is 195.244.192.66. Any more ideas? Thanks for your help so far!

[edit]
Don't think I mentioned this: I have a DHCP network.

J_K9

|Congrats Bathory on 666 posts |

pingu · 07-07-2005, 04:46 AM

That routing-table doesn't look good, you have same entries for eth0 and eth1. This means some traffic goes out correct way, some traffic goes wrong way.
Now do you have two nic's?
If not, maybe one is 1394/USB - I have noticed Debian-based distros often wants to activate that.
I have broken my Debian, so I can't really check where to change that. I have to do some guessing:
Take a look in /etc/network/interface (or whatever there might be in /etc/network directory, could be /etc/networking/ also)
If you have a nic not used somewhere, put a '#' in front of the line thus disabling it.

Or simply test:
First of all check
# ifconfig
It will show you what network-cards you have configured. Then
# ifdown eth0
Can you connect? Then do
# ifdown eth1
# ifup eth0
Can you connect now?

If you have 2 nic's and mean to use both, you will have to manually edit routing-table. This is not that difficult, but as I assume you don't need it I'll leave it out for now.
Just return with results!

J_K9 · 07-07-2005, 05:12 AM

Hi,

Sorry for not explaining myself properly before! I have two NICs: the first one (inbuilt) is eth0 - this one is broken, physically broken, for an unknown reason- and eth1 is a PCMCIA NIC which I have plugged into my laptop (a Netgear FA511 to be precise).

Thank you Pingu!!!! THANK YOU! "sudo ifdown eth0" made it work immediately!

Thank you very much. I guess eth0 was interfering with eth1 somehow, or maybe Ubuntu just "got confused"

. Thanks for helping me fix it though!

edit: In order to stop this happening when I next reboot, should I disable eth0 in /etc/network/interface? Thanks,

J_K9

pingu · 07-07-2005, 05:22 AM

Glad it helped!

I don't know if you have to remove that line manually or not, maybe just wait and see.
I guess what happened was that when ISP went down, ubuntu tried to find some other way out, therefore enbled eth0.

J_K9 · 07-07-2005, 05:39 AM

Yep, thanks for everything! Except that I kinda have another problem now! lol. It's got nothing to do with anything I've done in this thread, it's just something with Samba I want to fix...Thanks,

J_K9