diff --git a/utils/auxiliary_functions.py b/utils/auxiliary_functions.py
new file mode 100644
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--- /dev/null
+++ b/utils/auxiliary_functions.py
@@ -0,0 +1,227 @@
+# -*- coding: utf-8 -*-
+
+##
+# Copyright 2015 Telefónica Investigación y Desarrollo, S.A.U.
+# This file is part of openmano
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact with: nfvlabs@tid.es
+##
+
+'''
+Common usuful functions 
+'''
+
+__author__="Alfonso Tierno, Pablo Montes"
+__date__ ="$10-jul-2014 12:07:15$"
+
+
+import yaml
+import paramiko 
+from definitionsClass import definitionsClass
+from definitionsClass import Units
+import random
+from jsonschema import validate as js_v, exceptions as js_e
+
+def check_and_convert_units(value, value_type):
+    """TODO: Update description
+    This method receives a text with 2 fields using a blank as separator and a list of valid units. The first field must represent a number
+    and the second one units. 
+    In case the second field is not one of valid_units (False, <error description>) is returned.
+    In case the second field is a valid unit the first number is converted in the following way:
+    Gbps, Mbps, kbps -> Mbps
+    GB,MB,KB,B,GiB,MiB,KiB -> B
+    GHz,MHz,KHz,Hz -> Hz
+    If conversion is done successfully (True, <converted value>) is returned"""
+    try:
+        if value_type == Units.no_units:
+            if not isinstance(value,int) and not isinstance(value,float):
+                return (False, 'When no units are used only an integer or float must be used')
+        elif value_type == Units.name:
+            if not isinstance(value,str):
+                return (False, 'For names str must be used')
+        elif value_type == Units.boolean:
+            if not isinstance(value,bool):
+                return (False, 'A boolean or Yes/No mut be used')
+        else:
+            splitted  = value.split(' ')
+            if len(splitted) != 2:
+                return (False, 'Expected format: <value> <units>')
+            (value, units) = splitted 
+            if ',' in value or '.' in value:
+                return (False, 'Use integers to represent numeric values')
+                
+            value = int(value)
+            
+#            if not isinstance(value_type, Units):
+#                return (False, 'Not valid value_type')
+            
+            valid_units = definitionsClass.units[value_type]
+            
+            #Convert everything to upper in order to make comparations easier
+            units = units.upper()
+            for i in range(0, len(valid_units)):
+                valid_units[i] = valid_units[i].upper()
+            
+            #Check the used units are valid ones
+            if units not in valid_units:
+                return (False, 'Valid units are: '+', '.join(valid_units))
+
+            if units.startswith('GI'):
+                value = value *1024*1024*1024
+            elif units.startswith('MI'):
+                value = value *1024*1024
+            elif units.startswith('KI'):
+                value = value *1024
+            elif units.startswith('G'):
+                value = value *1000000000
+            elif units.startswith('M'):
+                value = value *1000000
+            elif units.startswith('K'):
+                value = value *1000
+    except Exception,e:
+        return (False, 'Unexpected error in auxiliary_functions.py - check_and_convert_units:\n'+str(e))
+
+    return (True, value)
+        
+def get_ssh_connection(machine, user=None, password=None):
+    """Stablishes an ssh connection to the remote server. Returns (True, paramiko_ssh) in case of success or (False, <error message>) in case of error"""
+    try:
+        s = paramiko.SSHClient()
+        s.set_missing_host_key_policy(paramiko.AutoAddPolicy())
+        s.load_system_host_keys()
+        s.connect(machine, 22, user, password, timeout=10)
+    except Exception,e:
+        return (False, 'It was not possible to connect to '+machine+str(e))
+        
+    return (True, s)
+
+def run_in_remote_server(s,command):
+    """Runs in the remote server the specified command. Returns (True, stdout) in case of success or (False, <error message>) in case of error"""
+    try:
+        (_, stdout, stderr) = s.exec_command(command)
+        error_msg = stderr.read()
+        if len(error_msg) > 0:
+            return (False, error_msg)
+    except Exception,e:
+        return (False, str(e))
+    
+    return (True, stdout)
+
+def read_file(file_):
+    """Reads a file specified by 'file' and returns (True,<its content as a string>) in case of success or (False, <error message>) in case of failure"""
+    try:
+        f = open(file_, 'r')
+        read_data = f.read()
+        f.close()
+    except Exception,e:
+        return (False, str(e))
+      
+    return (True, read_data)
+
+def check_contains(element, keywords):
+    """Auxiliary function used to check if a yaml structure contains or not
+    an specific field. Returns a bool"""
+    for key in keywords:
+        if not key in element:
+            return False      
+    return True
+
+def check_contains_(element, keywords):
+    """Auxiliary function used to check if a yaml structure contains or not
+    an specific field. Returns a bool,missing_variables"""
+    for key in keywords:
+        if not key in element:
+            return False, key      
+    return True, None
+
+def write_file(file_, content):
+    """Generates a file specified by 'file' and fills it using 'content'"""
+    f = open(file_, 'w')
+    f.write(content)
+    f.close()
+
+def nice_print(yaml_element):
+    """Print a yaml structure. Used mainly for debugging"""
+    print(yaml.dump(yaml_element, default_flow_style=False))
+    
+def new_random_mac():
+    mac = (0xE2, random.randint(0x00, 0xff), random.randint(0x00, 0xff), random.randint(0x00, 0xff), random.randint(0x00, 0xff), random.randint(0x00, 0xff) )
+    return ':'.join(map(lambda x: "%02X" % x, mac)) 
+
+def parse_dict(var, template):
+    if type(var) is not dict: return -1, 'not a dictionary'
+    for _,tv in template.items():
+        if type(tv) is list:
+            return
+    
+def delete_nulls(var):
+    if type(var) is dict:
+        for k in var.keys():
+            if var[k] is None: del var[k]
+            elif type(var[k]) is dict or type(var[k]) is list or type(var[k]) is tuple: 
+                if delete_nulls(var[k]): del var[k]
+        if len(var) == 0: return True
+    elif type(var) is list or type(var) is tuple:
+        for k in var:
+            if type(k) is dict: delete_nulls(k)
+        if len(var) == 0: return True
+    return False
+
+def get_next_2pow(var):
+    if var==0: return 0
+    v=1
+    while v<var: v=v*2
+    return v        
+
+def check_valid_uuid(uuid):
+    id_schema = {"type" : "string", "pattern": "^[a-fA-F0-9]{8}(-[a-fA-F0-9]{4}){3}-[a-fA-F0-9]{12}$"}
+    try:
+        js_v(uuid, id_schema)
+        return True
+    except js_e.ValidationError:
+        return False
+
+def DeleteNone(var):
+    '''Removes recursively empty dictionaries or lists
+    return True if var is an empty dict or list '''
+    if type(var) is dict:
+        for k in var.keys():
+            if var[k] is None: del var[k]
+            elif type(var[k]) is dict or type(var[k]) is list or type(var[k]) is tuple: 
+                if DeleteNone(var[k]): del var[k]
+        if len(var) == 0: return True
+    elif type(var) is list or type(var) is tuple:
+        for k in var:
+            if type(k) is dict: DeleteNone(k)
+        if len(var) == 0: return True
+    return False
+    
+def gen_random_mac():
+    '''generates a random mac address. Avoid multicast, broadcast, etc
+    '''
+    mac = (
+        #52,54,00,
+        #2 + 4*random.randint(0x00, 0x3f), #4 multiple, unicast local mac address
+        0x52,
+        random.randint(0x00, 0xff),
+        random.randint(0x00, 0xff),
+        random.randint(0x00, 0xff),
+        random.randint(0x00, 0xff),
+        random.randint(0x00, 0xff) 
+    )
+    return ':'.join(map(lambda x: "%02x" % x, mac))
+