我最近双启动了 Windows 7 和 12.04 系统。尽管插座中插有 LAN 电缆，但我无法通过有线连接访问互联网。它显示网络电缆已拔出，但我可以从 Windows 7 访问互联网。
在 Ubuntu 的安装阶段，当它尝试检查网络连接，它给出相同的消息“网线已拔出”。
以前，我使用的是 10.04 和 Windows XP，运行良好。
以下是一些您可能觉得有用的信息。
ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:21:70:e7:cc:93
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:44 Base address:0xa000
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:16436 Metric:1
RX packets:1328 errors:0 dropped:0 overruns:0 frame:0
TX packets:1328 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:105328 (105.3 KB) TX bytes:105328 (105.3 KB)
wlan0 Link encap:Ethernet HWaddr 00:24:2b:dc:04:ed
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)
sudo lshw -class network
*-network
description: Network controller
product: BCM4312 802.11b/g LP-PHY
vendor: Broadcom Corporation
physical id: 0
bus info: pci@0000:06:00.0
version: 01
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list
configuration: driver=b43-pci-bridge latency=0
resources: irq:19 memory:f4000000-f4003fff
*-network DISABLED
description: Ethernet interface
product: RTL8111/8168B PCI Express Gigabit Ethernet controller
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0
bus info: pci@0000:07:00.0
logical name: eth0
version: 02
serial: 00:21:70:e7:cc:93
size: 1Gbit/s
capacity: 1Gbit/s
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress msix vpd bus_master cap_list rom ethernet physical
tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI
duplex=full firmware=N/A latency=0 link=no multicast=yes port=MII speed=1Gbit/s
resources: irq:44 ioport:5000(size=256) memory:f8610000-f8610fff memory:f8600000-
f860ffff memory:f8620000-f862ffff
*-network DISABLED
description: Wireless interface
physical id: 2
logical name: wlan0
serial: 00:24:2b:dc:04:ed
capabilities: ethernet physical wireless
configuration: broadcast=yes driver=b43 driverversion=3.2.0-23-generic-pae firmware=N/A
link=no multicast=yes wireless=IEEE 802.11bg
sudo ethtool eth0
Settings for eth0:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Link partner advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Link partner advertised pause frame use: Symmetric Receive-only
Link partner advertised auto-negotiation: Yes
Speed: 1000Mb/s
Duplex: Full
Port: MII
PHYAD: 0
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: pumbg
Wake-on: pumbg
Current message level: 0x00000033 (51)
Link detected: no