基本信息

宿主机： 172.28.12.2
KVM: 172.28.56.8 
添加的别名： 172.28.56.18 

操作实例

# 网卡上添加 ip:
$ ifconfig eth0:1 172.28.56.18 netmask 255.255.255.0 up

# 网卡上删除 ip:
$ ip addr del 172.28.56.18 dev eth0


$ ifconfig
eth0      Link encap:Ethernet  HWaddr FA:16:3E:AB:3E:B2
          inet addr:172.28.56.8  Bcast:172.28.56.255  Mask:255.255.255.0
          inet6 addr: fe80::f816:3eff:feab:3eb2/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:929 errors:0 dropped:0 overruns:0 frame:0
          TX packets:649 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:87345 (85.2 KiB)  TX bytes:79252 (77.3 KiB)

eth0:1    Link encap:Ethernet  HWaddr FA:16:3E:AB:3E:B2
          inet addr:172.28.56.18  Bcast:172.28.56.255  Mask:255.255.255.0
          UP BROADCAST RUNNING 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:16436  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:0
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

# 用原有 IP ping 一个外部ip
$ ping -I 172.28.56.8  172.28.12.2
PING 172.28.12.2 (172.28.12.2) from 172.28.56.8: 56 data bytes
64 bytes from 172.28.12.2: seq=0 ttl=63 time=0.278 ms
64 bytes from 172.28.12.2: seq=1 ttl=63 time=0.271 ms
^C
--- 172.28.12.2 ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 0.271/0.274/0.278 ms

# 用添加的虚拟IP ping 一个外部 IP 
$ ping -I 172.28.56.18  172.28.12.2
PING 172.28.12.2 (172.28.12.2) from 172.28.56.18: 56 data bytes
^C
--- 172.28.12.2 ping statistics ---
24 packets transmitted, 0 packets received, 100% packet loss

扩展阅读：

Openstack镜像和密码

http://www.chenshake.com/openstack-mirror-and-password/