WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-users

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

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Help creating virtual networks of domU guests
From: David Richardson <daverich04@xxxxxxxxx>
Date: Mon, 18 Jul 2005 14:12:07 -0700 (PDT)
Delivery-date: Mon, 18 Jul 2005 21:10:46 +0000
Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:Received:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=pwGZHqUhjcRszqjRVpXVWpoTmMPpY/6LZormnsVbhZVgN8qj/5jC6VBkShfoUvWyzdzJJMgrlkJpxQnuaPUzRtvqeD4NXbIBaZF3BWDCt3zc+RNoWn1dAK+VzPVT2hRv1oKm+3eW0UFCdVnd1hkFaSqMjWpmSn/aj07R5k5PSRc= ;
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <200507180928.07390.e.bachmann@xxxxxxxx>
List-help: <mailto:xen-users-request@lists.xensource.com?subject=help>
List-id: Xen user discussion <xen-users.lists.xensource.com>
List-post: <mailto:xen-users@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
Thanks for your help everyone.  I think I'm close now
(hopefully).  Here's what I've got:  In dom0, I
execute the following to set up the bridge xenbr1 with
address 192.168.1.1  

#brctl addbr xenbr1
#brctl stp xenbr1 off
#brctl setfd xenbr1 0
#ifconfig xenbr1 192.168.1.1 netmask 255.255.255.0 up

Then, in my domU's config file, I add:
vif = [ 'bridge=xenbr1']

So that eth0 in domU will bridge to my xenbr1.  I also
modify /etc/network/interfaces in my domU filesystem
(it's a debian guest) with:

auto eth0
iface eth0 inet static
        address 192.168.1.5
        netmask 255.255.255.0

To assign the address 192.168.1.5 to the domU guest. 
Finally, I try to set up the nat by doing (in dom0):

#iptables --flush
#iptables --delete-chain
#iptables --table nat --delete-chain
#iptables --table nat --append POSTROUTING /
--out-interface eth0 -j MASQUERADE
#iptables --append FORWARD --in-interface xenbr1 -j /
ACCEPT
#echo 1 > /proc/sys/net/ipv4/ip_forward

#route add  -net 192.168.1.0 netmask 255.255.255.0 /
dev xenbr1

When I boot up domU, I am able to ping 192.168.1.1
from domU, and likewise ping 192.168.1.5 from dom0. 
However, I can't get to the outside world from domU,
suggesting that my nat'ing (or something else) isn't
quite right...  Any suggestions?  Thanks again for all
the help.

~Dave




--- Ernst Bachmann <e.bachmann@xxxxxxxx> wrote:

> 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
> 


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