解决：linux 固定ip 导致ping 外网unknown host
首先说下问题产生场景：最近搞jenkins搭建持续集成，搞完后发现服务器ip(ifconfig 红色）老是变化，一怒之下果断修改ip
[root@bogon etc]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:0C:29:F4:A4:5A
inet addr:192.168.229.129 Bcast:192.168.229.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fef4:a45a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:544599 errors:0 dropped:0 overruns:0 frame:0
TX packets:230155 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:661731467 (631.0 MiB) TX bytes:54607105 (52.0 MiB)
Interrupt:19 Base address:0x2024
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:15743 errors:0 dropped:0 overruns:0 frame:0
TX packets:15743 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:67040869 (63.9 MiB) TX bytes:67040869 (63.9 MiB)
改完ping 了下github.com 和百度外网一直显示unknown host
[root@bogon etc]# ping www.baidu.com
ping: unknown host www.baidu.com
我就纳闷了找找博客看了一圈整理下思路：
问题分析过程如下：
首先检查windows 网络中心配置尤其是v8的：
cmd检查也可以：主要看网关和虚拟机在不在一个网段，ip windows不可以和虚拟机的ifconfig ip相同但要在一个网段
虚拟机网关查看centos6如下：
虚拟机网关查看：注意这个网关必须和windows v8适配器网关保持一致
以上如果出现不一致应该修改保持一致：windows修改在
此外虚拟机修改如下文件见标红，这个地方网关必须和虚拟机网卡v8网关一致，ip设置成你要的固定ip但是要和windows 适配器v8在同网段不同ip，DNS1填这个谷歌的就可以：
[root@bogon etc]# vi /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE="eth0"
BOOTPROTO=static
IPADDR=192.168.229.129
GATEWAY=192.168.229.2
NETMASK=255.255.255.0
HWADDR="00:0C:29:F4:A4:5A"
IPV6INIT="yes"
NM_CONTROLLED="yes"
ONBOOT="yes"
TYPE="Ethernet"
UUID="32f46724-9e38-4712-b088-29be2ae53bc4"
DNS1=8.8.8.8
设置永久默认网关添加GATEWAY
[root@bogon sysconfig]# vi /etc/sysconf/network
NETWORKING=yes
HOSTNAME=bogon
GATEWAY=192.168.229.2
然后重启网络适配器：service network restart
检查route 路由网关：route
[root@bogon etc]# route ,default 开头是默认网关Gateway
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.229.0 * 255.255.255.0 U 1 0 0 eth0
default bogon 0.0.0.0 UG 0 0 0 eth0
ping www.baidu.com 检查如下成功：
[root@bogon etc]# ping www.baidu.com
PING www.a.shifen.com (163.177.151.110) 56(84) bytes of data.
64 bytes from 163.177.151.110: icmp_seq=1 ttl=128 time=11.1 ms
64 bytes from 163.177.151.110: icmp_seq=2 ttl=128 time=10.5 ms
64 bytes from 163.177.151.110: icmp_seq=3 ttl=128 time=11.0 ms
