Setting a local network on Xenserver

Giany — Mon, 18 Apr 2011 21:18:02 +0000

After installing Xenserver 5.5 or 5.6 you will need to define additional IPs that your VMs will use. Usually your provider will give you a range that you can use. But what do you do when you do not want to pay additional $$$ just for a couple of routable ips?

In my case I only have one public IP that is set on interface xenbr0 interface (bridged from eth0). In order to make my VMs to access the Internet I had to add an alias interface, something like :


ifconfig xenbr0:0 10.0.0.1 netmask 255.255.255.0 up

I will consider 10.0.0.0/24 my private LAN from where the VMs will get IPs. Additionally I route all traffic from 10.0.0.0/24 to xenbr0 using :

ip addr add 10.0.0.0/24 dev xenbr0

Now if you add an VM and set an IP from the 10.0.0.0/24 range you should be able to ping the 10.0.0.1 address. In order to reach the internet I also had to :

iptables -t nat -A POSTROUTING -s 10.0.0.0/255.255.255.0 -j MASQUERADE


iptables -I RH-Firewall-1-INPUT -s 10.0.0.0/24 -j ACCEPT

service iptables save

Last thing is to modify /etc/sysctl.conf and enable ip_forward among other settings. This is how my config looks like:

net.ipv4.ip_forward = 1 net.ipv4.conf.default.proxy_arp = 1 net.ipv4.conf.all.send_redirects = 0 net.ipv4.conf.default.send_redirects = 0 net.ipv4.conf.lo.send_redirects = 0 net.ipv4.conf.xenbr0.send_redirects = 0 net.ipv4.conf.default.rp_filter = 1 net.ipv4.icmp_echo_ignore_broadcasts = 1 net.ipv4.conf.default.accept_source_route = 0 net.ipv4.conf.all.accept_redirects = 0 net.ipv4.conf.all.send_redirects = 0 kernel.sysrq = 1 kernel.core_uses_pid = 1 net.ipv4.tcp_syncookies = 1 kernel.msgmnb = 65536 kernel.msgmax = 65536 kernel.shmmax = 4294967295 kernel.shmall = 268435456 vm.dirty_ratio = 5 kernel.printk = 4 4 1 4

FreeBSD: GRE Tunnels

Giany — Fri, 17 Oct 2008 20:54:34 +0000

b0x# kldstat
Id Refs Address Size Name
1 5 0xc0400000 34f898 kernel
2 14 0xc0750000 56270 acpi.ko
3 1 0xc0c97000 1c000 ipl.ko
4 1 0xc15ef000 4000 if_gre.ko

# kldload if_gre.ko
# sysctl -w net.inet.ip.gre_default_mtu=1450
# ifconfig gre1 create
# ifconfig gre1 tunnel 217.154.12.2 212.25.240.34
# ifconfig gre1 mtu 1450
# ifconfig gre1 inet 10.1.12.38 10.1.12.37 netmask 255.255.255.252
# ifconfig gre1 up

And that was that!

or Lan :

# ifconfig gre1 inet 10.1.12.37 10.1.12.38 netmask 255.255.255.252 up
# /usr/sbin/greconfig -i gre1 -v -s 212.25.240.34 -d 217.154.12.2

x83.net » ifconfig

Setting a local network on Xenserver

FreeBSD: GRE Tunnels