解决VM中配置多网卡多IP只能有一个网卡工作

VM Server 已经配置好了多个网卡，可以连接多个不同的IP段，但是创建的VM如果配置了多个网卡，只能有一个网卡连能ping通。

国内的百度搜了不少的答案根本没有用，Google到了这篇文章解决了我的问题：

https://stackoverflow.com/questions/14583984/multiple-ip-configuration-on-multiple-nic-on-same-server

简略说重点：

1) edit the file "/etc/sysctl.conf"

change the value from 1 to 2 in the following line:

net.ipv4.conf.default.rp_filter = 1

2）Add this line:

net.ipv4.conf.all.rp_filter = 2

After edit, it should look like this:

net.ipv4.conf.default.rp_filter = 2

net.ipv4.conf.all.rp_filter = 2

3）reload the configuration by typing

sysctl -p

Now you should be able to ping both IPs