Networking – How to Fix Networking Issues After Reboot

12.04networkingserver

I powered down my headless, no gui file server to replace a seized fan and now the eth0 interface isn't picking up an IP address via DHCP; during boot it just sits there "Waiting for network configuration" and eventually times out.

/etc/network/interfaces

# 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

$grep eth0 /var/log/syslog

Sep  9 18:14:27 server kernel: [    1.921881] e1000 0000:02:00.0: eth0: (PCI:33MHz:32-bit) 00:07:e9:08:02:17
Sep  9 18:14:27 server kernel: [    1.921894] e1000 0000:02:00.0: eth0: Intel(R) PRO/1000 Network Connection
Sep  9 18:14:27 server kernel: [    9.657153] ADDRCONF(NETDEV_UP): eth0: link is not ready
Sep  9 18:14:27 server kernel: [   10.140090] ADDRCONF(NETDEV_UP): eth0: link is not ready
Sep  9 18:14:29 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 4
Sep  9 18:14:33 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 11
Sep  9 18:14:44 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 14
Sep  9 18:14:58 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 8
Sep  9 18:15:06 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 9
Sep  9 18:15:15 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 12
Sep  9 18:15:27 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 19
Sep  9 18:15:46 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7
Sep  9 18:15:53 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 12
Sep  9 18:16:05 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 16
Sep  9 18:16:21 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 20
Sep  9 18:16:41 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 15
Sep  9 18:16:56 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 14
Sep  9 18:17:10 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 21
Sep  9 18:17:31 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 13
Sep  9 18:17:44 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 19
Sep  9 18:18:03 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7
Sep  9 18:18:10 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7
Sep  9 18:18:17 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 12
Sep  9 18:18:29 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 14
Sep  9 18:18:43 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 20
Sep  9 18:19:03 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 13
Sep  9 18:19:16 server dhclient: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 11

The DHCP server is my ADSL modem which is working and assigning addresses to other network devices.

Ideas?

Update 1: Booted with an earlier, known-working, kernel; still not working.
Update 2: Tried different Ethernet cables; still not working.

Best Answer

Found a fix, though it makes no sense to me why it worked. I'd be interested to hear, in the comments, how this may have fixed the problem.

I disabled the on-board Ethernet adapter in the BIOS and booted the server (so no eth0, only loopback device). I rebooted, re-enabled the Ethernet adapter in the BIOS and this time it worked.

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