Create "internal" VLAN for Xen Virtual Machines

1) Add the dummy interface driver to the auto-load modules:

echo dummy >> /etc/modules

2) Configure network interface  ( /etc/network/interfaces)

auto dummy0
iface dummy0 inet static
address 192.168.100.1
netmask 255.255.255.0

3) Bring up the dummy interface

ifup dummy0

4) Add line in : /etc/xen/xend-config.sxp

(network-script 'network-bridge netdev=dummy0')

5) Run the command:

/etc/xen/scripts/network-bridge start netdev=dummy0 antispoof=no

6) Check if pdummy interface is present:

ifconfig pdummy0

pdummy0   Link encap:Ethernet  HWaddr b6:a5:b4:35:a7:1a 
          inet6 addr: fe80::b4a5:b4ff:fe35:a71a/64 Scope:Link
          UP BROADCAST RUNNING NOARP PROMISC  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:532 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:28928 (28.2 KiB)

8) Attach new interface to guest domain :

xm network-attach  example.domain.guest bridge=dummy0 script=vif-bridge mac=00:16:3E:40:22:12

9) Log in to guest domain console and add new interface:

root@debian-xen:/home/shamrock# xm console example.domain.guest


Debian GNU/Linux 6.0 debian hvc0

debian login: root
Password:

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
root@debian:~# ifconfig eth1 192.168.100.200 netmask 255.255.255.0
root@debian:~# ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 00:16:3E:40:22:12 
          inet addr:192.168.100.200  Bcast:192.168.100.255  Mask:255.255.255.0
          inet6 addr: fe80::216:3eff:fe40:2212/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:10 errors:0 dropped:0 overruns:0 frame:0
          TX packets:7 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:608 (608.0 B)  TX bytes:510 (510.0 B)
          Interrupt:244

And add this to /etc/network/interfaces

auto eth1
iface eth1 inet static
 address 192.168.100.200
 gateway 192.168.100.1
 netmask 255.255.255.0

10) In Dom0 edit DomU config and add ew interface:

i.e.: /etc/xen/example.domain.guest

vif         = [ 'ip=212.85.34.12,mac=00:16:3E:0B:0A:83,bridge=eth0', 'ip=192.168.100.100,mac=00:16:3E:D7:9C:F6,bridge=dummy0' ]

11) Last thing is to set the ip_forwarding in the kernel of Dom0 and create NAT rules.

root@debian-xen:/# echo 1 >/proc/sys/net/ipv4/ip_forward
root@debian-xen:/# iptables -t nat -A POSTROUTING -s 192.168.100.0/24 -d 0.0.0.0/0 -j MASQUERADE