ubantu无法连接外网的解决方法

ubantu无法连接外网的解决方法

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声明一下我的uabntu 和windows是用的桥接模式。
首先确定你的ubantu网卡已正确获得了ip。用ifconfig命令看一下。

book@www.100ask.org:/work/hardware/drivers/19th_i2cdev$ ifconfig
ens33     Link encap:Ethernet  HWaddr 00:03:2b:e7:34:de  
          inet addr:192.168.1.101  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::aab6:81e1:af4b:3d7b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:62347 errors:0 dropped:0 overruns:0 frame:0
          TX packets:139397 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:17841569 (17.8 MB)  TX bytes:87331075 (87.3 MB)

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:75502 errors:0 dropped:0 overruns:0 frame:0
          TX packets:75502 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:4841537 (4.8 MB)  TX bytes:4841537 (4.8 MB)

如果没有分配到IP，手动设置一个和路由在同一个网段下的IP，用ifconfig命令。
然后ping一下路由器看是否能ping通。

book@www.100ask.org:/work/hardware/drivers/19th_i2cdev$ ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=3.42 ms
64 bytes from 192.168.1.1: icmp_seq=4 ttl=64 time=3.29 ms
64 bytes from 192.168.1.1: icmp_seq=5 ttl=64 time=3.15 ms
64 bytes from 192.168.1.1: icmp_seq=6 ttl=64 time=3.05 ms
64 bytes from 192.168.1.1: icmp_seq=7 ttl=64 time=2.24 ms
^C
--- 192.168.1.1 ping statistics ---
7 packets transmitted, 5 received, 28% packet loss, time 6045ms
rtt min/avg/max/mdev = 2.241/3.034/3.422/0.415 ms
book@www.100ask.org:/work/hardware/drivers/19th_i2cdev$ 

在这里我是能ping通路由的，说明我的内网连接是没有问题的。
接下来ping一下外网

book@www.100ask.org:/work/hardware/drivers/19th_i2cdev$ ping www.baidu.com
PING www.a.shifen.com (61.135.169.125) 56(84) bytes of data.
64 bytes from 61.135.169.125: icmp_seq=1 ttl=55 time=19.0 ms
64 bytes from 61.135.169.125: icmp_seq=3 ttl=55 time=119 ms
64 bytes from 61.135.169.125: icmp_seq=4 ttl=55 time=20.2 ms
64 bytes from 61.135.169.125: icmp_seq=5 ttl=55 time=19.5 ms
64 bytes from 61.135.169.125: icmp_seq=7 ttl=55 time=120 ms
64 bytes from 61.135.169.125: icmp_seq=8 ttl=55 time=19.9 ms
^C
--- www.a.shifen.com ping statistics ---
8 packets transmitted, 6 received, 25% packet loss, time 7067ms
rtt min/avg/max/mdev = 19.006/53.124/120.240/47.306 ms
book@www.100ask.org:/work/hardware/drivers/19th_i2cdev$ 

在这里我是能ping通百度的，说明我的外部连接也是没有问题的，如果你的显示connect: Network is unreachable或者ping: unknown host www.baidu.com说明你还要设置网关，子网掩码，DNS,按如下命令设置即可。
1.设置IP和子网掩码
sudo ifconfig ens33 192.168.199.31 netmask 255.255.255.0
2.设置网关
sudo route add default gw 192.168.199.1
3.设置DNS
sudo su
echo “nameserver 192.168.199.1” >> /etc/resolv.conf
注意实际的参数需要根据自己的网络。
再ping一下百度就能ping通了 。如果ping不通检查一下参数设置的是否正确，或者重启一下网卡
sudo /etc/init.d/networking restart #使网卡配置生效
sudo /etc/init.d/resolvconf restart #使DNS生效。