問題描述
在使用Vmware虛擬64位CentOS 7的過程中，每次新創建一個虛擬機後（網絡設置爲NAT模式），會發現網絡不可用，使用ping後會出現unknown host錯誤或者是network is unreachable等等，
[peng@localhost Desktop]$ ping baidu.com
ping: unknown host baidu.com解決方案
首先使用ifconfig查看網卡信息，發現第一個網絡適配器eno1677736沒有獲得Ipv4的地址，也就是沒有在網絡中註冊成功：
eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 ether 00:0c:29:91:5c:69 txqueuelen 1000 (Ethernet) RX packets 171 bytes 10260 (10.0 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 0 (Local Loopback) RX packets 304 bytes 25880 (25.2 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 304 bytes 25880 (25.2 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255 ether 52:54:00:59:c4:0c txqueuelen 0 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0進入etc/sysconfig/network-scripts，並找到這個網絡適配器的配置文件，使用nano或者vi編輯
[root@localhost network-scripts]# cd /etc/sysconfig/network-scripts [root@localhost network-scripts]# ls ifcfg-eno16777736 ifdown-ppp ifup-ib ifup-Team ifcfg-lo ifdown-routes ifup-ippp ifup-TeamPort ifdown ifdown-sit ifup-ipv6 ifup-tunnel ifdown-bnep ifdown-Team ifup-isdn ifup-wireless ifdown-eth ifdown-TeamPort ifup-plip init.ipv6-global ifdown-ib ifdown-tunnel ifup-plusb network-functions ifdown-ippp ifup ifup-post network-functions-ipv6 ifdown-ipv6 ifup-aliases ifup-ppp ifdown-isdn ifup-bnep ifup-routes ifdown-post ifup-eth ifup-sit [root@localhost network-scripts]# nano ifcfg-eno16777736將
ONBOOT=false改爲ONBOOT=yes：TYPE=Ethernet BOOTPROTO=dhcp DEFROUTE=yes PEERDNS=yes PEERROUTES=yes IPV4_FAILURE_FATAL=no IPV6INIT=yes IPV6_AUTOCONF=yes IPV6_DEFROUTE=yes IPV6_PEERDNS=yes IPV6_PEERROUTES=yes IPV6_FAILURE_FATAL=no NAME=eno16777736 UUID=94a36c28-dc0d-4999-bc65-334d30fff6fc DEVICE=eno16777736 ONBOOT=yes保存退出，最後使用service network restart重啓網絡
service network restart Restarting network (via systemctl): [ OK ]
檢驗
再次使用ifconfig檢查網卡情況，發現eno16777736獲得了ipv4的地址
[root@localhost network-scripts]# ifconfig
eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.124.134 netmask 255.255.255.0 broadcast 192.168.124.255
inet6 fe80::20c:29ff:fe91:5c69 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:91:5c:69 txqueuelen 1000 (Ethernet)
RX packets 276800 bytes 372561384 (355.3 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 121742 bytes 7389047 (7.0 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 476 bytes 40664 (39.7 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 476 bytes 40664 (39.7 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:59:c4:0c txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0再次使用ping檢查網絡情況，發現網絡正常：
[root@localhost network-scripts]# ping baidu.com
PING baidu.com (180.149.132.47) 56(84) bytes of data.
64 bytes from 180.149.132.47: icmp_seq=1 ttl=128 time=394 ms
64 bytes from 180.149.132.47: icmp_seq=2 ttl=128 time=390 ms
^C
--- baidu.com ping statistics ---
3 packets transmitted, 2 received, 33% packet loss, time 2000ms
rtt min/avg/max/mdev = 390.585/392.724/394.863/2.139 ms
