Setting up a Dedibox Failover-IP

tested on NetBSD, Slackware, Ubuntu

Introduction

It is much easier to use a Failover-IP from the host, as an alias. But if you are sure you want that for e.g. XEN or LXC, ok here is how it goes. We are assuming a bridge here, without any NAT nor routing trick from the host. Therefore no proxy_arp nor ip_forward is neededi (as xen-routing would otherwise require).

Hardcode your MAC

Dedibox requires you to define your guest’s MAC in their management console. Then hardcode it as such

vif = [ 'bridge=xenbr0,vifname=GUEST.0,mac=00:16:3e:xx:xx:xx' ]

Check that the bridge is in good state

brctl show

GNU/Linux guest system setup

the new school

ip l show eth0 # check MAC address
    ip addr add $failover/32 dev eth0

    ip route add 62.210.0.1 dev eth0
ping -c1 62.210.0.1

    ip route add default via 62.210.0.1 dev eth0

    ip route add HOST-IP dev eth0
ping -c1 HOST-IP

if you had net-tools already, you could have done it the old way

ifconfig eth0 # check MAC address
    ifconfig eth0 $failover/32
    route add -host 62.210.0.1 dev eth0
    route add default gw 62.210.0.1

or as such step by step

ifconfig eth0 $failover/32 up
route add -host 62.210.0.1 dev eth0
ping -c1 62.210.0.1
route add default gw 62.210.0.1
ping -c1 1.1.1.1

as for slackware’s rc.inet1, that would look like

    echo -n eth0...
    failover=x.x.x.x
    ifconfig eth0 $failover/32 up && echo done || echo FAIL
    #ifconfig eth0 $failover/32 pointopoint 62.210.0.1 up && echo done || echo FAIL
unset failover

    echo -n custom route for non-subnet gateway...
    route add -host 62.210.0.1 dev eth0 && echo done || echo FAIL

    echo -n default route...
    route add default gw 62.210.0.1 && echo done || echo FAIL

Note: no much success with the pointopoint argument

NetBSD guest system setup

Once the guest has booted-up, check your MAC address

ifconfig xennet0 | grep address

Ping from the outside and validate step-by-step first

fo=FAILOVER-IP
fogw=62.210.0.1
xenhost=HOST-IP
#xenhostgw=HOST-GW

ifconfig xennet0 inet $fo/32 up
route add -net $fogw/32 -link -cloning -iface xennet0
ping -c1 $fogw
route add default $fogw
#route add default $fogw -iface $fo
netstat -rn -f inet
ping -c1 62.210.16.6
ping -c1 62.210.16.7

And your box should now respond from the public network.

Besides, you can also make a shortcut to reach the XEN host (if you want the return path to be also direct, you will need to tweak the XEN host itself)

route add -net $xenhost/32 -link -cloning -iface xennet0
traceroute $xenhost
ping -c1 $xenhost

While there is really no point of reaching its gateway, though. Otherwise add a route to the whole subnet (both $xenhost and $xenhostgw).

#route add -net $xenhostgw/32 -link -cloning -iface xennet0
#traceroute $xenhostgw
#ping -c1 $xenhostgw

You’re now ready to proceed with this at boot-time

cat > /etc/ifconfig.xennet0 <<-EOF
inet $fo/32 up
!/sbin/route add -net $fogw/32 -link -cloning -iface xennet0
!/sbin/route add default $fogw
!/sbin/route add -net $xenhost/32 -link -cloning -iface xennet0
EOF
cat /etc/ifconfig.xennet0
shutdown -r now

Resources

fip

Failover IP - Scaleway Dedibox https://www.scaleway.com/en/docs/manage-failover-ip-scaleway-dedibox/

FAILOVER IP https://documentation.online.net/en/dedicated-server/network/ip-failover/ip-failover

Network configuration on a virtual machine https://documentation.online.net/en/dedicated-server/network/ip-failover/virtual-machine

MAC virtuelles multi-IP https://documentation.online.net/fr/dedicated-server/network/ip-failover/multi-ip-virtual-mac

Virtualisation Xen https://documentation.online.net/en/dedicated-server/network/ip-failover/xen

IP Failover https://www.scaleway.com/en/dedibox/ip-address/

routing tricks

Networking with a gateway not on the local subnet https://www.netbsd.org/docs/network/#nonsubnetgateway

Add static routes and keep them across boots on NetBSD https://ezunix.org/index.php?title=Add_static_routes_and_keep_them_across_boots_on_NetBSD

Can I prevent a default route being added when bringing up an interface? https://unix.stackexchange.com/questions/182967/can-i-prevent-a-default-route-being-added-when-bringing-up-an-interface

does the gateway have to be on the subnet? https://unix.stackexchange.com/questions/98344/does-the-gateway-have-to-be-on-the-subnet

How to add a route for a specific subnet? https://serverfault.com/questions/597736/how-to-add-a-route-for-a-specific-subnet

Соединение point-to-point в Debian и CentOS http://blog.102web.ru/howto/point-to-point/