I've lost my wired network connection

[devnulljp]

So, I've lost my wired network connection in network Manager. Used to be, when I plugged in an Ethernet cable, it would just connect. Now, Nothing. Nada. Zip.
Tried recreating a Wired connection, but still no go.
All the wifi connections still show up, just Wired ain't working. If I turn off wifi, I get ... nothing.

Any ideas?

ifconfig shows my eth0 just fine.

ifconfig
eth0      Link encap:Ethernet  HWaddr ##:##:##:##:##:## 
          UP BROADCAST MULTICAST  MTU:1500  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:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:20 Memory:fc000000-fc020000

[Simon]

This happened to me once, I had to download the network manager onto a thumb drive at work and reinstalled it. You can also use a live CD (which I assume you are at the present) to get it on the thumb drive.

http://packages.ubuntu.com/search?ke...etwork-manager

Good luck!

[devnulljp]

Thanks for the suggestion. I'm running over wifi atm. Just weird that wired disappeared. Normally we all have trouble with wifi. I just tried reinstalling network-manager from synaptic and still no wired connection. Damn!

[Simon]

Well then I hate to even suggest it... hardware issue? If you can boot the Live CD and use the wired connection, it is definitely a software issue. If you cannot connect after that, the best method to try is another LAN card assuming you are not on a laptop.

[oshunluvr]

First thing to do is try a different cable then a different router port.

[devnulljp]

First thing to do is try a different cable then a different router port.

Done and done and ... nada.
I tried recreating the wired connection too and got nowhere.

Ran rfkill to see if it ws locked somewhere and ... well this is odd

rfkill list
1: tpacpi_bluetooth_sw: Bluetooth
        Soft blocked: no
        Hard blocked: no
2: phy0: Wireless LAN
        Soft blocked: no
        Hard blocked: no
4: hci0: Bluetooth
        Soft blocked: no
        Hard blocked: no

No #3? No physical ethernet?
This is a Thinkpad T500.

ifconfig shows eth0 though

ifconfig -a
eth0      Link encap:Ethernet  HWaddr ##:##:##:##:##:##  
          UP BROADCAST MULTICAST  MTU:1500  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:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:20 Memory:fc000000-fc020000 

lo        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:65536  Metric:1
          RX packets:13711 errors:0 dropped:0 overruns:0 frame:0
          TX packets:13711 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:5438267 (5.4 MB)  TX bytes:5438267 (5.4 MB)

wlan0     Link encap:Ethernet  HWaddr ##:##:##:##:##:##  
          inet addr:192.168.1.4  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::221:6aff:fe51:3ace/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:252502 errors:0 dropped:0 overruns:0 frame:0
          TX packets:275706 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:193265682 (193.2 MB)  TX bytes:49920474 (49.9 MB)

[devnulljp]

cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback

sudo ifdown eth0
ifdown: interface eth0 not configured
sudo ifup eth0
Ignoring unknown interface eth0=eth0.

hmmmm

Changes /etc/network/interfaces to

auto eth0
iface eth0 inet dhcp

and now ifup eth0 works!

[oshunluvr]

Yeah, network manager must be the culprit. It doesn't require entries in interfaces to work, but something must have messed with it's config. Hopefully, your edit will fix it for good.

I usually just remove network manager from my desktop and server and manually configure my ethernet ports because I'm not using wifi there so it's not needed.

[SteveRiley]

Ran rfkill to see if it ws locked somewhere and ... well this is odd
...
No #3? No physical ethernet?

rfkill only applies to wireless interfaces.

Changes /etc/network/interfaces to

auto eth0
iface eth0 inet dhcp

and now ifup eth0 works!

This means you've told NetworkManager to ignore eth0. But let's verify something: what's inside /etc/NetworkManager/NetworkManager.conf?

[xennex81]

Managed is probably set to false, which is why the interfaces entry works. If managed is set to true it also works but NM keeps destroying your connection (removes your IP from the interface). Unfortunately you cannot set "managed" per interface and you cannot programmatically (e.g. through nmcli) turn this management on and off at will, which I believe is NM's biggest problem (at first encounter) apart from the bug that destroys your wifi (or prevents you from connecting to anything).