Ethernet connection suddenly stopped working, but wifi is fine?

[erinsaurus87]

Hey guys,
So this morning I discovered that I can't browse the web when I connect to the internet using my ethernet connection, although I have been able to the past few days and I can't think of why anything would have changed. The wired connection works fine when I tested it on my Mac so its not the connection itself. Oddly enough when I go to the networking interface it shows traffic and a connection speed, so I'm at a loss for whats going on. The wifi still works fine though.

I discovered this because I tried to connect my VPN software and it wouldnt login, but we just had an account set up for me so something might have happened related to that and the VPN problem may have nothing to do with the wired connection not working. But I emailed my system admin to find out if the VPN software has to connect using a wired connection just in case.

Any ideas about the ethernet connection's problem?

[GreyGeek]

In a Konsole:
ping google.com
If you get no packets back then:
ping 74.125.113.147
If you get packet responses back from Google.com with millisecond access time then your connection is working fine and the problem is that when dhcp connects with the wired interface it fails to set up resolv.conf properly. See if /etc/network/interfaces has


allow-hotplug eth0
iface eth0 inet dhcp

[erinsaurus87]

All /etc/network/interfaces has is:


# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet dhcp



Should I add that code to the file?

Also strange is that when I first pinged google.com I got no packets and then when I tried a few minutes later it worked and I am now connected via ethernet. Why would it work intermittently?

Thanks

[GreyGeek]

"auto" doesn't necessarily mean immediately.

If it is working now I'd leave it be and save the info for a future problem.

[erinsaurus87]

Sigh.

The internet worked fine for awhile there, but today both the wifi and ethernet went unresponsive. Still shows being connected to the wifi network and traffic in the network interface. But when I did a ping command I got this:

erin@osprey:~$ ping google.com
ping: unknown host google.com
erin@osprey:~$ google.com
google.com: command not found
erin@osprey:~$ ping 74.125.113.147
PING 74.125.113.147 (74.125.113.147) 56(84) bytes of data.
From 192.168.1.1 icmp_seq=1 Destination Net Unreachable
From 192.168.1.1 icmp_seq=2 Destination Net Unreachable
From 192.168.1.1 icmp_seq=3 Destination Net Unreachable
From 192.168.1.1 icmp_seq=4 Destination Net Unreachable


I added
allow-hotplug eth0
iface eth0 inet dhcp but that didnt fix the problem.

[GreyGeek]

In a Konsole, does
sudo /etc/init.d/networking stop
sudo /etc/init.d/networking start

restart your connection?

[erinsaurus87]

Well I'm guessing when I added
allow-hotplug eth0
iface eth0 inet dhcp to /etc/network/interfaces using vi, I messed something up. Because when I tried your suggestion GreyGeek this is what I got:


erin@osprey:~$ sudo /etc/init.d/networking stop
[sudo] password for erin:
* Deconfiguring network interfaces...
/etc/network/interfaces:13: duplicate interface
ifdown: couldn't read interfaces file "/etc/network/interfaces"
[fail]
erin@osprey:~$ sudo /etc/init.d/networking start
Rather than invoking init scripts through /etc/init.d, use the service(8)
utility, e.g. service networking start

Since the script you are attempting to invoke has been converted to an
Upstart job, you may also use the start(8) utility, e.g. start networking
start: Job failed to start

[GreyGeek]

Ya, you have a typo or something in that file.

Here's mine:


auto lo
iface lo inet loopback

iface wlan0 inet dhcp
wireless-essid "GreyGeek"
channel 7
auto wlan0

allow-hotplug eth0
iface eth0 inet dhcp


and,


sudo service networking stop
sudo service networking start

I guess are now the commands to use.

[erinsaurus87]

Update. I deleted
allow-hotplug eth0
iface eth0 inet dhcp

Now when I try to stop and restart the network I get:

erin@osprey:~$ sudo /etc/init.d/networking stop
[sudo] password for erin:
* Deconfiguring network interfaces... postconf: fatal: open /etc/postfix/main.cf: No such file or directory
Ignoring unknown interface wlan0=wlan0.
[ OK ]
erin@osprey:~$ sudo /etc/init.d/networking start
Rather than invoking init scripts through /etc/init.d, use the service(8)
utility, e.g. service networking start

Since the script you are attempting to invoke has been converted to an
Upstart job, you may also use the start(8) utility, e.g. start networking
networking stop/waiting

My /etc/network/interfaces file has in it:


auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

[GreyGeek]

Has your wireless chip malfunctioned?

[erinsaurus87]

well i dont know if the wireless chip has malfunctioned, but since its now both wifi and ethernet that are disconnected, i think that must not be the issue.

[Fintan]

I am having similar issue on my HP pavilion dv6 laptop.
It started after I did an update on Friday last week.

First the wired connection went drastically slower than before (I don't have any comparison numbers).

Then when I would boot up in the morning ethernet wouldn't connect at all, so I had to delete eth0 from the network manager, reboot and add a new wired connection to network manager. After a reboot this was gone again, so I had to go through the process again.

Very Boring and I have never seen this before.

I tried Greeks commands and get this:

fintan@fintanws3:~$ sudo service networking stop
[sudo] password for fintan:
stop: Unknown instance:
fintan@fintanws3:~$ sudo /etc/init.d/networking stop
* Deconfiguring network interfaces... Ignoring unknown interface eth0=eth0.
[ OK ]
fintan@fintanws3:~$ sudo /etc/init.d/networking start
Rather than invoking init scripts through /etc/init.d, use the service(8)
utility, e.g. service networking start

Since the script you are attempting to invoke has been converted to an
Upstart job, you may also use the start(8) utility, e.g. start networking
networking stop/waiting
fintan@fintanws3:~$ sudo service networking start
networking stop/waiting
fintan@fintanws3:~$


my /network/interfaces file says:

auto lo
iface lo inet loopback

Wireless on both Kubuntu and windows and wired on my windows partition work fine.

Could this be a buggy KDE network manager?

[Fintan]

Upgrading to Oneric solved my issue

[Fintan]

Just for the record this is the answer I got from the KDE forum:



You should restart network-manager service, not network. Also, when using Network Manager - don't bother with interfaces configuration file, NM doesn't use that at all. Try looking into NM logs for details, it spits a lot of information, maybe you'll find useful information about your problem.

Hope that helps here a bit :)