我最近安装了 Ubuntu 12.04。自从安装以来，我一直无法 ping 到我的默认本地网关，更不用说连接到互联网了。
下面是我对 ifconfig 的输出：
ifconfig 的输出：
eth0 Link encap:Ethernet HWaddr 00:26:b9:e2:3d:20
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:e9600000-e9620000
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:1362 errors:0 dropped:0 overruns:0 frame:0
TX packets:1362 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:142670 (142.6 KB) TX bytes:142670 (142.6 KB)
wlan0 Link encap:Ethernet HWaddr 00:27:10:0c:9b:50
inet addr:192.168.1.103 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::227:10ff:fe0c:9b50/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:463 errors:0 dropped:0 overruns:0 frame:0
TX packets:1234 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:146587 (146.5 KB) TX bytes:86383 (86.3 KB
以下是我对 /etc/network/interfaces 的输出
/etc/network/interfaces:
auto lo
iface lo inet loopback
下面是我对 cat /etc/resolv.conf 的输出
nameserver 75.75.75.75
nameserver 75.75.76.76
search hsd1.il.comcast.net
以下是 /etc/NetworkManager/NetworkManager.conf 的内容：
[main]
plugins=ifupdown,keyfile
[ifupdown]
managed=false
下面是我的输出：nmcli dev list iface wlan0 | grep IP4：
IP4.ADDRESS[1]: ip = 192.168.1.103/24, gw = 192.168.1.1
IP4.DNS[1]: 75.75.75.75
IP4.DNS[2]: 75.75.76.76
IP4.DOMAIN[1]: hsd1.il.comcast.net.
路线-n的输出：
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 wlan0
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 wlan0
192.168.1.0 0.0.0.0 255.255.255.0 U 2 0 0 wlan0
我已经验证 /etc/resolv.conf 已正确符号链接到 /run/resolvconf/resolv.conf
当我 ping 到本地网关时，结果是这样的：
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
From 192.168.1.103 icmp_seq=1 Destination Host Unreachable
我可以正常 ping 通 localhost、127.0.0.1 和 192.168.1.103（我的 IP 地址）。