我有两个操作系统，当连接电缆时，计算机上的以太网灯不亮，我无法连接到互联网。这不是硬件问题，因为我的第二个操作系统很容易连接到互联网。
的输出lspci为：
00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09)
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
00:16.0 Communication controller: Intel Corporation 6 Series/C200 Series Chipset Family MEI Controller #1 (rev 04)
00:1a.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2 (rev 04)
00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 04)
00:1c.0 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1 (rev b4)
00:1c.1 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 2 (rev b4)
00:1c.2 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 3 (rev b4)
00:1c.3 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 4 (rev b4)
00:1c.5 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 6 (rev b4)
00:1d.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1 (rev 04)
00:1f.0 ISA bridge: Intel Corporation HM65 Express Chipset Family LPC Controller (rev 04)
00:1f.2 SATA controller: Intel Corporation 6 Series/C200 Series Chipset Family 6 port SATA AHCI Controller (rev 04)
23:00.0 System peripheral: JMicron Technology Corp. SD/MMC Host Controller (rev 30)
23:00.2 SD Host controller: JMicron Technology Corp. Standard SD Host Controller (rev 30)
23:00.3 System peripheral: JMicron Technology Corp. MS Host Controller (rev 30)
24:00.0 Network controller: Qualcomm Atheros AR9285 Wireless Network Adapter (PCI-Express) (rev 01)
25:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06)
输出lshw -C network：
*-network
description: Wireless interface
product: AR9285 Wireless Network Adapter (PCI-Express)
vendor: Qualcomm Atheros
physical id: 0
bus info: pci@0000:24:00.0
logical name: wlan0
version: 01
serial: 74:de:2b:02:0b:da
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
configuration: broadcast=yes driver=ath9k driverversion=3.18.2-031802-generic firmware=N/A latency=0 link=no multicast=yes wireless=IEEE 802.11bgn
resources: irq:19 memory:d4600000-d460ffff
*-network
description: Ethernet interface
product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0
bus info: pci@0000:25:00.0
logical name: eth0
version: 06
serial: 10:1f:74:e3:50:5a
size: 10Mbit/s
capacity: 1Gbit/s
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress msix vpd bus_master cap_list 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=half firmware=rtl_nic/rtl8168e-2.fw ip=192.168.0.100 latency=0 link=no multicast=yes port=MII speed=10Mbit/s
resources: irq:29 ioport:2000(size=256) memory:d4404000-d4404fff memory:d4400000-d4403fff
输出ifup eth0：
Internet Systems Consortium DHCP Client 4.2.4
Copyright 2004-2012 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Listening on LPF/eth0/10:1f:74:e3:50:5a
Sending on LPF/eth0/10:1f:74:e3:50:5a
Sending on Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 3 (xid=0x78a08d03)
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 8 (xid=0x78a08d03)
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 21 (xid=0x78a08d03)
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 19 (xid=0x78a08d03)
...
(infinite, continue for ever)
输出ifconfig -a：
eth0 Link encap:Ethernet HWaddr 10:1f:74:e3:50:5a
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)
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:298 errors:0 dropped:0 overruns:0 frame:0
TX packets:298 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:23133 (23.1 KB) TX bytes:23133 (23.1 KB)
wlan0 Link encap:Ethernet HWaddr 74:de:2b:02:0b:da
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)
我有一个/etc/network/interfaces包含以下内容的文件：
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet dhcp
输出cat /etc/resolv.conf：
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 127.0.1.1
输出route -n：
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
我也尝试了静态 IP 地址，但问题仍然存在。请帮帮我，我真的没有其他主意了！
更新
当我运行时ifup eth0，syslog输出是：
Jan 16 22:42:34 DEMON kernel: [16477.474586] r8169 0000:25:00.0 eth0: link down
Jan 16 22:42:34 DEMON avahi-daemon[1167]: Joining mDNS multicast group on interface eth0.IPv4 with address 192.168.1.100.
Jan 16 22:42:34 DEMON avahi-daemon[1167]: New relevant interface eth0.IPv4 for mDNS.
Jan 16 22:42:34 DEMON avahi-daemon[1167]: Registering new address record for 192.168.1.100 on eth0.IPv4.
Jan 16 22:42:34 DEMON kernel: [16477.475316] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
因此我尝试了 Linux 内核版本 14 和 18，但都存在同样的问题。有什么想法吗？
更新2
我尝试使用静态 IP 地址，因此我更改了接口：
auto lo
iface lo inet loopback
auto dsl-provider
iface dsl-provider inet ppp
pre-up /sbin/ifconfig eth1 up # line maintained by pppoeconf
dns-nameservers 8.8.8.8 8.8.4.4
provider dsl-provider
auto eth0
iface eth0 inet static
address 192.168.1.100
netmask 255.255.255.0
gateway 192.168.1.1
dns-nameservers 8.8.8.8 8.8.4.4
然后ifconfig -a：
eth0 Link encap:Ethernet HWaddr 10:1f:74:e3:50:5a
inet addr:192.168.1.100 Bcast:192.168.1.255 Mask:255.255.255.0
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)
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:439 errors:0 dropped:0 overruns:0 frame:0
TX packets:439 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:34837 (34.8 KB) TX bytes:34837 (34.8 KB)
ppp0 Link encap:Point-to-Point Protocol
inet addr:37.254.165.125 P-t-P:37.254.128.1 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1492 Metric:1
RX packets:7259 errors:0 dropped:0 overruns:0 frame:0
TX packets:8600 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:4900816 (4.9 MB) TX bytes:1303955 (1.3 MB)
wlan0 Link encap:Ethernet HWaddr 74:de:2b:02:0b:da
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)
输出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
Supported pause frame use: No
Supports auto-negotiation: Yes
Advertised link modes: 100baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Speed: 10Mb/s
Duplex: Half
Port: MII
PHYAD: 0
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: pumbg
Wake-on: d
Current message level: 0x00000033 (51)
drv probe ifdown ifup
Link detected: no
更新 3
我的笔记本电脑有问题，所以我将笔记本电脑连接到 PC（而不是将笔记本电脑连接到 ADSL 调制解调器），目前一切正常。但是我该如何将笔记本电脑连接到 ADSL 调制解调器呢？
这个问题与 Ubuntu 有关，因为我在 Windows 8 上检查了几次，没有问题。
我重置了 ADSL 调制解调器路由器，但仍然存在同样的问题。
更新 4
我可以检测到以太网一次，一切正常，但当我重新启动时仍然有同样的问题。应该有一个命令可以解决这个问题。
答案1
尝试执行以下步骤并根据您的网卡将 BaseT 更改为 10、100 或 1000：
识别物理 eth0 端口：ethtool --identify eth0
查看配置eth0：ethtool eth0
强制以太网为全双工 100Tx：ethtool -s eth0 speed 100 duplex full autoneg off
ifdown eth0 && ifup eth0
service network restart