Prerequisites

2 ubuntu servers in various projects (not in a private network) having floating IPs assigned.

Host: 185.52.195.1
Client: 185.52.195.2

On the host

eouser@host:~$ sudo apt-get update
eouser@host:~$ sudo apt-get install nfs-kernel-server
eouser@host:~$ sudo mkdir /xdata
eouser@host:~$ sudo chown nobody:nogroup /xdata
eouser@host:~$ sudo nano /etc/exports

add line:

/xdata 185.52.195.2(rw,sync,no_subtree_check)

save file

start the server:

eouser@host:~$ sudo systemctl restart nfs-kernel-server

for Ubuntu 14.04 start the server with this command:

eouser@host:~$ sudo service nfs-kernel-server start

Now go to https://cf2.cloudferro.com/project/security_groups/

Create new security group.
Give it a name (eg. allow_nfs) and save by clicking "Create security group" button.
Click "manage rules".
Click "add rule"
Choose:
Rule: Custom TCP Rule

Direction: Ingress
Openport: Port
Port: 2049
Remote: CIDR
CIDR: 185.52.195.2

Click "Add"

Go to https://cf2.cloudferro.com/project/instances/

From the drop-down menu on the right of the "Host" instance, choose "Edit Security Groups"

Click on the "plus" sign on the "allow_nfs" group.
This will move the group from "All Security Groups" to "Instance Security Groups".
Click "Save".

On the Client

eouser@client:~$ sudo apt-get update
eouser@client:~$ sudo apt-get install nfs-common
eouser@client:~$ sudo mkdir /xdata
eouser@client:~$ sudo mount 185.52.195.1:/xdata /xdata

You can check if the directory is mounted:

eouser@client:~$ df -h