diff --git a/src/main/java/org/gcube/portal/ldapexport/LDAPSync.java b/src/main/java/org/gcube/portal/ldapexport/LDAPSync.java
index 55d9d47..047e480 100644
--- a/src/main/java/org/gcube/portal/ldapexport/LDAPSync.java
+++ b/src/main/java/org/gcube/portal/ldapexport/LDAPSync.java
@@ -35,6 +35,8 @@ public class LDAPSync implements Runnable {
 
 	private static final String LDAP_ORG_FILTER = "(objectClass=organizationalUnit)";
 	private static final String LDAP_GROUP_FILTER = "(objectClass=posixGroup)";
+	private static final String USER_CONTEXT = ",ou=People,o=D4Science,ou=Organizations,dc=d4science,dc=org";
+	private static final String DEFAULT_GID_NUMBER = "1000";
 
 	private String ldapUrl;
 	private String filter; 
@@ -102,12 +104,13 @@ public class LDAPSync implements Runnable {
 		try {
 			DirContext ctx = new InitialDirContext(env);
 			_log.debug("Initiating LDAP Sync ...");
-			//update the whole list of users (uid="+username+",ou=People,o=Liferay,ou=Organizations,dc=d4science,dc=org")
-			exportSingleUsers(ctx, env, users);
+			createUsersOrganizationalUnit(ctx);
 
 			//crate or update the whole list of organizations (objectClass=organizationalUnit, ou="+orgName+",dc=d4science,dc=org) and groups ( objectClass=top and POSIXGroup)
+			
 			updateGroups(ctx, rootVO);
-
+			//and update the users list
+			exportSingleUsers(ctx, env, users);
 		} catch (NamingException e) {
 			_log.error("Something went Wrong during LDAP Sync in Exporting to LDAP");
 			e.printStackTrace();
@@ -116,7 +119,50 @@ public class LDAPSync implements Runnable {
 			es.printStackTrace();
 		}
 	}
+	
+	/**
+	 * create the following: ou=People,o=D4Science,ou=Organizations,dc=d4science,dc=org
+	 * @param ctx
+	 * @throws NamingException
+	 */
+	private void createUsersOrganizationalUnit(DirContext ctx) throws NamingException 	{
+		if (!checkIfLDAPOrganizationalUnitExists(ctx, "ou=Organizations,dc=d4science,dc=org")) {
+			Attributes attributes = new BasicAttributes();
+			Attribute objectClass = new BasicAttribute("objectClass");
+			objectClass.add("organizationalUnit");
+			attributes.put(objectClass);
 
+			Attribute description = new BasicAttribute("description");
+			description.add("Where to find users");		
+			attributes.put(description);		
+			//	private static final String USER_CONTEXT = ",";
+			ctx.createSubcontext("ou=Organizations,dc=d4science,dc=org", attributes);
+
+			attributes = new BasicAttributes();
+			objectClass = new BasicAttribute("objectClass");
+			objectClass.add("Organization");
+			attributes.put(objectClass);
+			description.add("Default Organization");		
+			ctx.createSubcontext("o=D4Science,ou=Organizations,dc=d4science,dc=org", attributes);	
+
+			attributes = new BasicAttributes();
+			objectClass = new BasicAttribute("objectClass");
+			objectClass.add("organizationalUnit");
+			attributes.put(objectClass);
+			description.add("People Org Unit");		
+			ctx.createSubcontext("ou=People,o=D4Science,ou=Organizations,dc=d4science,dc=org", attributes);	
+		}
+		else
+			_log.info("ou=Organizations,dc=d4science,dc=org already present, skip");
+	}
+
+	/**
+	 * 
+	 * @param ctx
+	 * @param root
+	 * @throws NamingException
+	 * @throws SystemException
+	 */
 	private void updateGroups(DirContext ctx, Organization root) throws NamingException, SystemException {
 		String subCtx = getOrgSubContext(root.getName());
 		if (!checkIfLDAPOrganizationalUnitExists(ctx, subCtx))
@@ -134,7 +180,14 @@ public class LDAPSync implements Runnable {
 			}
 		}			
 	}
-	
+	/**
+	 * 
+	 * @param ctx
+	 * @param vreSubCtx
+	 * @param vre
+	 * @throws NamingException
+	 * @throws SystemException
+	 */
 	private void updateUsersInGroup(DirContext ctx, String vreSubCtx, Organization vre) throws NamingException, SystemException {
 		List<User> users = UserLocalServiceUtil.getOrganizationUsers(vre.getOrganizationId());
 		for (User userObj : users) {
@@ -206,7 +259,7 @@ public class LDAPSync implements Runnable {
 		attributes.put(cn);
 
 		Attribute gidNumber = new BasicAttribute("gidNumber");
-		gidNumber.add(getRandomPOSIXidentifier(ctx));
+		gidNumber.add(String.valueOf(getRandomPOSIXidentifier()));
 		attributes.put(gidNumber);
 
 		ctx.createSubcontext(subContext, attributes);
@@ -262,7 +315,7 @@ public class LDAPSync implements Runnable {
 	 * @return the single user subContext
 	 */
 	private String getSubContext(String username) {
-		return "uid="+username+",ou=People,o=Liferay,ou=Organizations,dc=d4science,dc=org";
+		return "uid="+username+USER_CONTEXT;
 	}
 	/**
 	 * 
@@ -297,6 +350,7 @@ public class LDAPSync implements Runnable {
 		Attributes attributes=new BasicAttributes();
 		Attribute objectClass=new BasicAttribute("objectClass");
 		objectClass.add("inetOrgPerson");
+		objectClass.add("posixAccount");
 		attributes.put(objectClass);
 
 		//the main ldap server uses 'givenName' for the First name, 'cn' for "first name last name', 'sn' for the last name
@@ -305,24 +359,43 @@ public class LDAPSync implements Runnable {
 		Attribute sn = new BasicAttribute("sn");		
 		Attribute mail = new BasicAttribute("mail");
 		Attribute userPassword = new BasicAttribute("userPassword");
+		Attribute gidNumber = new BasicAttribute("gidNumber");
+		Attribute homeDirectory = new BasicAttribute("homeDirectory");
+	
 
 		givenName.add(name);
 		cn.add(fullName);
 		sn.add(lastName);		
 		mail.add(email);
 		userPassword.add(passwd);
-
+		gidNumber.add(DEFAULT_GID_NUMBER);
+		homeDirectory.add("/home/"+username);
+		
 		attributes.put(givenName);
 		attributes.put(cn);
 		attributes.put(sn);		
 		attributes.put(mail);
 		attributes.put(userPassword);
+		attributes.put(gidNumber);
+		attributes.put(homeDirectory);
+	
+
 
 		if (checkIfLDAPUserExists(username, ctx, filter)) {
 			//_log.debug("User " +  username + " already exists, replacing attributes");
 			ctx.modifyAttributes(getSubContext(username), DirContext.REPLACE_ATTRIBUTE, attributes);
+			_log.debug("Updated attributes for already existing user with uid=" +  username);
 		}
 		else {
+			int n = getRandomPOSIXidentifier();
+			while (checkIfPosixUidNumberExists(ctx, n)) {
+				_log.info("Found collision on UidNumber="+n);
+				n = getRandomPOSIXidentifier();
+				_log.info("Trying newone="+n);
+			}
+			Attribute uidNumber = new BasicAttribute("uidNumber");
+			attributes.put(uidNumber);
+			uidNumber.add(String.valueOf(n));
 			ctx.createSubcontext(getSubContext(username),attributes);
 			_log.debug("New User Found with uid=" +  username + " created");
 		}
@@ -350,11 +423,28 @@ public class LDAPSync implements Runnable {
 	 * 
 	 * @return an integer between 1000 and 2147483647
 	 */
-	private String getRandomPOSIXidentifier(DirContext ctx) {
+	private int getRandomPOSIXidentifier() {
 		final int Low = 1000;
 		final int High = 2147483647;
 		Random r = new Random();
 		int toReturn = r.nextInt(High-Low) + Low;
-		return toReturn+"";
+		return toReturn;
+	}
+
+	
+	private boolean checkIfPosixUidNumberExists(DirContext ctx, int numberToCheck) {
+		SearchControls ctls = new SearchControls();
+		ctls.setSearchScope(SearchControls.SUBTREE_SCOPE);
+		NamingEnumeration<SearchResult> answer;
+		try {
+			answer = ctx.search("ou=People,o=D4Science,ou=Organizations,dc=d4science,dc=org", "(uidNumber="+numberToCheck+")", ctls);
+		} catch (NamingException e) {
+			_log.info("exception");
+			return false;
+		}
+
+		boolean toReturn = answer.hasMoreElements();
+		_log.info("return " + toReturn);
+		return toReturn;
 	}
 }