在Ubuntu 14.04 LTS上没有以太网
我的以太网已停止工作，只留下无线网络：
这似乎是一个常见的问题，但我还没有找到解决办法。
标准诊断
$ ifconfig -a
eth0 Link encap:Ethernet HWaddr 68:f7:28:39:71:5d 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) eth0:avahi Link encap:Ethernet HWaddr 68:f7:28:39:71:5d inet addr:169.254.6.136 Bcast:169.254.255.255 Mask:255.255.0.0 UP BROADCAST MULTICAST MTU:1500 Metric:1 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:2208 errors:0 dropped:0 overruns:0 frame:0 TX packets:2208 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:190071 (190.0 KB) TX bytes:190071 (190.0 KB) wlan0 Link encap:Ethernet HWaddr 74:29:af:29:9b:09 inet addr:192.168.1.94 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::7629:afff:fe29:9b09/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:689 errors:0 dropped:0 overruns:0 frame:0 TX packets:570 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:268689 (268.6 KB) TX bytes:135063 (135.0 KB) $ sudo lshw -C network
*-network description: Ethernet interface product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:01:00.0 logical name: eth0 version: 10 serial: 68:f7:28:39:71:5d 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=rtl8168g-3_0.0.1 04/23/13 latency=0 link=no multicast=yes port=MII speed=10Mbit/s resources: irq:61 ioport:5000(size=256) memory:c3504000-c3504fff memory:c3500000-c3503fff *-network description: Wireless interface product: RTL8723BE PCIe Wireless Network Adapter vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:02:00.0 logical name: wlan0 version: 00 serial: 74:29:af:29:9b:09 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=rtl8723be driverversion=3.16.0-59-generic firmware=N/A ip=192.168.1.94 latency=0 link=yes multicast=yes wireless=IEEE 802.11bgn resources: irq:19 ioport:4000(size=256) memory:c3400000-c3403fff
$ lspci | grep以太网
01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 10)
$ cat / etc / network / interfaces
# interfaces(5) file used by ifup(8) and ifdown(8) auto lo iface lo inet loopback
$ cat /etc/NetworkManager/NetworkManager.conf
[main] plugins=ifupdown,keyfile,ofono dns=dnsmasq [ifupdown] managed=false
$ 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 search home
$ netstat -rn
Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface 0.0.0.0 192.168.1.254 0.0.0.0 UG 0 0 0 wlan0 0.0.0.0 0.0.0.0 0.0.0.0 U 0 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 wlan0
试图解决方案
我已经排除了显而易见的事情（重新启动，更换线路，路由器端口），我已经尝试了以下所有但是无济于事（因此已经逆转了它们）：
我尝试添加这些行：
auto eth0 iface eth0 inet dhcp
到/ etc / network / interfaces，然后重启服务：
$ sudo service network-manager restart
我尝试在/etc/NetworkManager/NetworkManager.conf中将’false’更改为’true’并重新启动
我跑了这个（无论它做什么）：
$ sudo ethtool -s eth0 speed 100 duplex full
编辑
回应Jeff Sereno的建议：
$ sudo ifconfig eth0 up
$ sudo dhclient
RTNETLINK answers: File exists
没有变化（即使重启）。
$ cat /etc/udev/rules.d/70-persistent-net.rules
# PCI device 0x10ec:0x8168 (r8169) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="68:f7:28:39:71:5d", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0" # PCI device 0x10ec:0xb723 (rtl8723be) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="74:29:af:29:9b:09", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="wlan*", NAME="wlan0"
只有一个以太网条目。
我不知道这些是否提供了新的线索，但我也跑了：
$ dmesg | grep eth0
[ 0.749460] r8169 0000:01:00.0 eth0: RTL8168g/8111g at 0xffffc9000001e000, 68:f7:28:39:71:5d, XID 10900880 IRQ 61 [ 0.749463] r8169 0000:01:00.0 eth0: jumbo features [frames: 9200 bytes, tx checksumming: ko] [ 20.811216] r8169 0000:01:00.0 eth0: link down [ 20.811261] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready [ 539.016509] r8169 0000:01:00.0 eth0: link down [ 539.016602] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
$ sudo nm-tool
... - Device: eth0 ----------------------------------------------------------------- Type: Wired Driver: r8169 State: unavailable Default: no HW Address: 68:F7:28:39:71:5D Capabilities: Carrier Detect: yes Wired Properties Carrier: off
它说eth0状态是“不可用”而有线属性“关闭”……？
在谷歌搜索时，我遇到了一些其他人遇到与我相同的问题只是发现他们的以太网电缆无法工作，或者同样微不足道的事情。 哈！ 什么白痴！ 当然，这是你检查的第一件事！ ……好吧，事实certificate电源线已经从我的网络交换机中轻微滑落了 。
我会羞愧地低下头。
将您的/etc/NetworkManager/NetworkManager.conf文件恢复原样 – 您将无缘无故地破坏网络管理器。 同时从/ etc / network / interfaces中删除eth0条目，因为Network Manager正在管理它。
您的以太网卡绝对不会被禁用，请尝试：
sudo ifconfig eth0 up sudo dhclient
看看你是否得到了这样分配的地址。
还要检查/etc/udev/rules.d/70-persistent-net.rules文件以确保没有定义多个“eth0”适配器（在用新硬件替换旧硬件时常见，但不重新安装操作系统）。 如果这样做，我建议删除所有显示的适配器，重启并让Ubuntu重新检测并重新填充此文件。