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James B. Byrne
Asked: 2015-04-17 12:27:30 +0800 CST

Routing private IPv4 addresses internally

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I have the following set-up involving two KVM hosts and numerous virtual machine guests on each. The guests communicate to each other on both hosts via [192.168.216.0/24]. [192.168.216.42] is connected to [192.168.216.41] via a cross-over cable. Traffic between [192.168.216.0/24] addresses should not escape out onto the LAN. However, I want to ping [x.y.A.2] from [192.168.216.25].:

   ISP ethx[x.y.A.2/30] >-----< eth0[x.y.A.3/30]              |
              ISP                      GWAY                   |
                                eth1[x.y.z.1/24] >----------< |
                                       GWAY                   |
                                                              |
         br0[x.y.z.42/24] >---------------------------------< |
               KVM2                                           |
                                     br0[x.y.z.41/24] >-----< |
                                             KVM1             ~
      br1[192.168.216.42] >-----X-----< br1[192.168.216.41]
          |    KVM2                          KVM1        |
          |                                              |
          | >-----< eth1[192.168.216.21]                 |
          | >-----< eth1[192.168.216.25]                 |
                                                         |
                           eth1[192.168.216.221] >-----< |
                           eth1[192.168.216.223] >-----< |

IPTABLES on GWAY is set-up to masquerade outgoing 198.168.0.0/16.

I believe I will need to add a virtual i/f eth1[192.168.0.1/16] to GWAY:

ifcfg-eth1:192168
BOOTPROTO=none
BROADCAST=192.168.255.255
DEVICE=eth1:192168
IPADDR=192.168.0.1
IPV6INIT=no
NETMASK=255.255.0.0
NETWORK=192.168.0.0
#ONBOOT=yes
ONPARENT=yes

As well as a static route similar to:

route-eth1
192.168.216.0/24  via  x.y.z.42  dev  eth1

And on KVM2 I would need:

ifcfg-br0
BOOTPROTO="none"
DEFROUTE="yes"
DEVICE="br0"
GATEWAY="x.y.z.1"
IPADDR="x.y.z.42"
IPV4_FAILURE_FATAL="no"
IPV6INIT="no"
NAME="System br0"
NETMASK="255.255.255.0"
NETWORK="x.y.z.0"
NM_CONTROLLED="no"
ONBOOT="yes"
TYPE="Bridge"
USERCTL="no

ifcfg-br1
BOOTPROTO="none"
DEVICE="br1"
GATEWAY="x.y.z.42"
IPADDR="192.168.216.42"
IPV4_FAILURE_FATAL="no"
IPV6INIT="no"
NAME="System br1"
NETMASK="255.255.255.0"
NETWORK="192.168.216.0"
NM_CONTROLLED="no"
ONBOOT="yes"
TYPE="Bridge"
USERCTL="no

Am I anywhere close to what actually needs to be done?

kvm-virtualization

0 Answers