[CentOS] KVM/NAT issue SOLVED

[david]

At 12:40 PM 2/21/2014, you wrote:
>On Fri, Feb 21, 2014 at 1:55 PM, david <david at daku.org> wrote:
> > Dear Linux Gurus
> >
> > I'm having problems with KVM and networking.  My guest cannot use NAT
> > through the host's connection.  This is what I've done:
> >
> > I installed a new version of Centos 6.5 on the hardware.  Starting
> > with a Net-Install, I selected the Virtual Hosting, and later added
> > "Desktop".  I ran "yum update" with some reboots until nothing 
> needed updating.
> >
> > The host networking is IPV4 only, using DHCP.  (A different box on my
> > home network provides DHCP and is a gateway to the internet.  I have
> > a reservation in that DHCP so that the host always gets a known IP address)
> >
> > Using a Gnome desktop, as a non-root user, I installed Windows 7 Pro
> > from an image of an ISO I had copied onto the host.  In the
> > "Networking" configuration, I chose "DEFAULT".  The documentation of
> > KVM seems to imply that it should give me a NAT'ted interface to my
> > host's connection (I wasn't worried about performance at this point).
> >
> > When the installation was complete, Windows tries to configure the
> > network.  Running the Windows command line "IPCONFIG" program, the
> > Windows guest program does get an IP address from the host
> > (192.168.122.xxx), but the guest cannot communicate to the outside
> > world.  I can ping the host, but nothing else.
> >
> > Is there some other magic sauce, perhaps in the IPTABLES of the host,
> > that will allow the guest to use the internet?  I'm baffled.
>
>Do you have ip_forwarding enabled in sysctl?
>
>https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Security_Guide/sect-Security_Guide-Firewalls-FORWARD_and_NAT_Rules.html
>
>--
>    Les


OOOPS
<Putting that white pointy hat on my head and sitting in the corner>

It's so obvious, I forgot.  In my "normal" installations, that's 
taken care of by my scripts so I forgot to do it by hand.