Re: [Xen-users] Help creating virtual networks of domU guests

[Ernst Bachmann <e.bachmann@xxxxxxxx>]

On Monday 18 July 2005 03:25, David Richardson wrote:
> Hey guys,
> I'm still having problems getting this to work
> correctly.  Maybe I should be more clear in my setup.
> I only have 1 nic, eth0.  My dom0 gets its IP address
> from a dhcp server on eth0.  However, the dhcp server
> always gives me the same IP address based on my MAC
> address.  As such, my domU guests are unable to use
> this dhcp server to obtain IPs. 

Simply assign a different MAC address to your domU.
You can run with standard bridging, don't need alias devices and whatnot.
For the DHCP Server it looks like a second computer with different MAC is 
behind an ethernet bridge, so it'll assign a different IP to it.

> Therefore, what I 
> want to do (I think...) is to create a vpn of domU
> guests that bridge to a virtual interface eth0:1 in
> dom0. 

Bridging only accepts real interfaces AFAIK. After all, virtual eth0:1 style 
interfaces are just alias IP adresses, and the bridge works on ethernet level 
and doesn't care about IP at all.

> Outside traffic can then be routed between the 
> real eth0 and the virtual eth0:1 to reach the domU
> guests.  Then, I can run a dhcp server in dom0 for
> eth0:1 to assign made-up addresses to the domU guests
> when they boot.

with VPN you mean NAT?

> I've never done anything like this before, so any help
> would be great.  My first attempts have started out by
> doing the following:
>
> Create the virtual ethernet interface:
> #ifconfig eth0:1 192.168.1.1 netmask 255.255.255.0
>
> Create a bridge in dom0, attach it to eth0:1:
> #brctl addbr xen-br1
> #brctl stp xen-br1 off
> #brctl setfd xen-br1 0
> #ip link set xen-br1 up
> #brctl addif xen-br1 eth0:1

More like:
# no eth0:1 iface!

brctl addbr xen-br1
brctl stp xen-br1 off
brctl setfd xen-br1 0
# no brctl addif!
ifconfig xen-br1 192.168.1.1 netmask 255.255.255.0 up
# connect  domUs to xen-br1
# set "192.168.1.1" as default route inside domU

#setup NAT in dom0:
iptables -t nat -I POSTROUTING -i xen-br1 -j SNAT --to <insert IP of eth0 
here>
...
(the nat rules will need more work, maybe your distribution comes with premade 
scripts there)

/Ernst

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users