IP Floater tries to help to implement OpenStack-like floating IPs for general purpose.

On one side, in an on-premises Cloud we may have a lot of private IP addresses but we usually have few public IP addresses. On the other side, not all the VMs in a Cloud need a public accessible IP address, as they usually have a gateway for registered users.

IP Floater consists of a server that enables associating a public accessible IP address managed by the IP Floater host to a private IP in the LAN. Later this IP can be associated to other private IP in the LAN.

The use case is shown in the figure 

In that use case, we have multiple Virtual Machines, but in particular we have a web server (with private IP 192.168.1.40) and the front-end of a virtual cluster that is connected to its working nodes (with private IP 192.168.1.32). We need to access the web server and the front-end from the internet, but we do not need to access to the working nodes. The most common way is to access to the working nodes from the front-end.

In case that we had two public IP addresses (216.58.211.227 and 216.58.211.228) IPFloater could assign them to the private IP addresses and the private IPs will act as if they were these public IPs.

OpenStack implements a mechanism of Floating IP addresses that (in brief) consist in a set of Public IP addresses that can be associated to private IP addresses. This is very similar to the IP address mechanism introduced in Amazon EC2.

But such Floating IPs are not available for a general case or other platforms such as OpenNebula.

IP Floater is based in iptables and implements pretty much the same rules that are implemented by the OpenStack's Floating IP, to make that the router host redirect the traffic directed to a public IP to a private IP in the LAN.

Appart from using the ipfloater by itself, you can try the integration with OpenNebula, that enables to deploy any VM using a private range of IPs. Then it is possible to attach floating IPs to them, in order to be able to access to them from the outern internet. Instead of using the concept of attaching IPs in ONE (i.e. creating an extra network device), the implementation manages the floating IPs concept from OpenStack and Amazon AWS by mapping public IPs to the private IPs.

IPFloater has to be installed in a server that is connected to the internet and to the internal LAN that in which are the private IPs.

We'll assume eth0 for the interface that has access to the public network and eth1 for the interface that has access to the private network.

You have to assign the floating IP addresses to the public interface eth0. The most easy way of assigning them is by using the ip command:

$ ip addr add 216.58.211.227/32 dev eth0
$ ip addr add 216.58.211.228/32 dev eth0

Then, it is advisable to include a rule to drop any packet that is directed to these IP addresses in the INPUT chain.

$ iptables -I INPUT -d 216.58.211.227/32 -j DROP

$ apt-get install python python-pip iptables
$ pip install --upgrade python-iptables cpyutils bottle
$ git clone https://github.com/dealfonso/ipfloater
$ cd ipfloater
$ python setup.py install --record installed-files.txt

Now you have to create a configuration file in /etc/ipfloater.conf. You can start from the /etc/default/ipfloater.conf file

$ cp /etc/default/ipfloaterd.conf /etc/ipfloaterd.conf

And you must edit the IP_POOL variable to set the comma separated pool of IP addresses.

Finally you can start the daemon:

$ ipfloaterd start

IPFloater has a command line application whose help is self-contained

This the client for ipfloaterd, which is a server that deals with iptables to enable floating IPs in private networks

Usage: ipfloater [-h] [--server-ip <value>] [--server-port <value>] [getip|redirect|releaseip|status|version|ippool|arp]

	[-h|--help] - Shows this help
	[--server-ip|-i] <value> - The ip adress in which ipfloater listens
	[--server-port|-p] <value> - The ip port in which ipfloater listens
	* Requests a floating IP for a private IP
	  Usage: getip <private ip>
		<private ip> - private ip address to which is requested the floating ip

	* Redirects a floating IP to a private IP
	  Usage: redirect <public ip> <private ip>
		<public ip> - floating ip address
		<private ip> - private ip address to which is requested the floating ip

	* Releases a floating IP
	  Usage: releaseip <public ip>
		<public ip> - public ip address (the floating ip)

	* Gets the status of the redirections
	  Usage: status 

	* Gets the version of the client and the server
	  Usage: version 

	* Gets the public ip addresses in the pool
	  Usage: ippool 

	* Requests the IP for a MAC address
	  Usage: arp <mac>
		<mac> - the mac address for which is requested the ip