[CentOS] Basic KVM networking question

Steve Thompson smt at vgersoft.com
Sat Sep 15 08:49:19 EDT 2012


On Mon, 10 Sep 2012, Steve Thompson wrote:

> On Mon, 10 Sep 2012, Steve Thompson wrote:
>
>> On Mon, 10 Sep 2012, Dale Dellutri wrote:
>>
>>> This looks like it should work for Client A, but maybe not for Client B (see
>>> below).  So maybe it's a firewall problem (iptables chain FORWARD) on the
>>> host?
>
> Let me expand on this. There is no issue with a client on net1
> communicating with a client on net2; the host passes packets from one
> subnet to the other as it should. The only issue is when the client is a
> virtual machine on the host.

For those following along at home, the solution to this turned out to be 
related to the change in the function of the net.ipv4.conf.default.rp_filter
parameter in the CentOS 6 kernels; it had nothing to do with KVM. Changing 
the value of rp_filter from 1 to 2 resolved all issues.

Steve


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