diff --git a/src/main/java/envoy/server/ConnectionManager.java b/src/main/java/envoy/server/ConnectionManager.java
index 9dfd56b..73985bd 100644
--- a/src/main/java/envoy/server/ConnectionManager.java
+++ b/src/main/java/envoy/server/ConnectionManager.java
@@ -1,8 +1,10 @@
 package envoy.server;
 
+import java.util.ArrayList;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
@@ -98,4 +100,14 @@ public class ConnectionManager implements ISocketIdListener {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public boolean isOnline(long userId) { return sockets.containsKey(userId); }
+
+	/**
+	 * @return the userId of all users who are currently online
+	 * @since Envoy Server Standalone v0.1-alpha
+	 */
+	public List<Long> getOnlineUsers() {
+		List<Long> onlineUsers = new ArrayList<>();
+		sockets.forEach((userId, unimportant) -> onlineUsers.add(userId));
+		return onlineUsers;
+	}
 }
diff --git a/src/main/java/envoy/server/database/PersistenceManager.java b/src/main/java/envoy/server/database/PersistenceManager.java
index 84587e6..c7b6f11 100644
--- a/src/main/java/envoy/server/database/PersistenceManager.java
+++ b/src/main/java/envoy/server/database/PersistenceManager.java
@@ -1,11 +1,14 @@
 package envoy.server.database;
 
+import java.util.Date;
 import java.util.List;
 
 import javax.persistence.EntityManager;
 import javax.persistence.EntityTransaction;
 import javax.persistence.Persistence;
 
+import envoy.data.User.UserStatus;
+import envoy.server.ConnectionManager;
 import envoy.server.data.ConfigItem;
 import envoy.server.data.Message;
 import envoy.server.data.User;
@@ -32,7 +35,14 @@ public class PersistenceManager {
 	 */
 	private PersistenceManager() {
 		transaction.begin();
-		Runtime.getRuntime().addShutdownHook(new Thread(() -> transaction.commit()));
+		Runtime.getRuntime().addShutdownHook(new Thread(() -> {
+			ConnectionManager.getInstance()
+				.getOnlineUsers()
+				.stream()
+				.map(this::getUserById)
+				.forEach(user -> { user.setStatus(UserStatus.OFFLINE); user.setLastSeen(new Date()); updateUser(user); });
+			transaction.commit();
+		}));
 	}
 
 	/**
diff --git a/src/main/java/envoy/server/processors/LoginCredentialProcessor.java b/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
index 9020937..31ddbbd 100644
--- a/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
+++ b/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
@@ -44,7 +44,7 @@ public class LoginCredentialProcessor implements ObjectProcessor<LoginCredential
 		UserStatusChangeProcessor.setWriteProxy(writeProxy);
 		System.out.println(String.format("Received login credentials %s from socket ID %d", input, socketId));
 
-		envoy.server.data.User user = getUser(input, writeProxy);
+		envoy.server.data.User user = getUser(input, socketId, writeProxy);
 
 		// Not logged in successfully
 		if (user == null) return;
@@ -76,8 +76,8 @@ public class LoginCredentialProcessor implements ObjectProcessor<LoginCredential
 		}
 	}
 
-	private envoy.server.data.User getUser(LoginCredentials credentials, ObjectWriteProxy writeProxy) throws IOException {
-		return credentials.isRegistration() ? newUser(credentials) : checkForExistingUser(credentials, writeProxy);
+	private envoy.server.data.User getUser(LoginCredentials credentials, long socketId, ObjectWriteProxy writeProxy) throws IOException {
+		return credentials.isRegistration() ? newUser(credentials, socketId, writeProxy) : checkForExistingUser(credentials, socketId, writeProxy);
 	}
 
 	/**
@@ -87,28 +87,28 @@ public class LoginCredentialProcessor implements ObjectProcessor<LoginCredential
 	 * @throws IOException if sending the failed login back to the client failed
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	private envoy.server.data.User checkForExistingUser(LoginCredentials credentials, ObjectWriteProxy writeProxy) throws IOException {
+	private envoy.server.data.User checkForExistingUser(LoginCredentials credentials, long socketId, ObjectWriteProxy writeProxy) throws IOException {
 		envoy.server.data.User	user;
 		ConnectionManager		connectionManager	= ConnectionManager.getInstance();
-		long					userId				= credentials.getId();
-		long					socketId			= connectionManager.getSocketId(userId);
+		String					userIdentifier		= credentials.getIdentifier();
 		try {
+			//TODO will need to be replaced with the Identifier once implemented
+			user = persistenceManager.getUserByName(userIdentifier);
 			// Checking if user is already online
-			if (connectionManager.isOnline(userId)) {
+			if (connectionManager.isOnline(user.getId())) {
 				writeProxy.write(socketId, new HandshakeRejectionEvent(HandshakeRejectionEvent.ALREADY_ONLINE));
 				return null;
 			}
-			user = persistenceManager.getUserById(userId);
 			// Evaluating the correctness of the password hash
 			if (!Arrays.equals(credentials.getPasswordHash(), user.getPasswordHash()))
-				throw new InputMismatchException("User " + credentials.getName() + "tried logging in using a wrong password");
+				throw new InputMismatchException("User " + credentials.getIdentifier() + "tried logging in using a wrong password");
 			return user;
 		} catch (NoResultException e) {
 			// Checking if user exists
 			writeProxy.write(socketId, new HandshakeRejectionEvent(HandshakeRejectionEvent.USER_DOES_NOT_EXIST));
 		} catch (InputMismatchException e) {
 			// Checking if the given password hash is correct
-			writeProxy.write(socketId, new HandshakeRejectionEvent(HandshakeRejectionEvent.INCORRECT_PASSWORD));
+			writeProxy.write(socketId, new HandshakeRejectionEvent(HandshakeRejectionEvent.WRONG_PASSWORD));
 		}
 		return null;
 	}
@@ -116,12 +116,18 @@ public class LoginCredentialProcessor implements ObjectProcessor<LoginCredential
 	/**
 	 * @param credentials the credentials upon which to create the new {@link User}
 	 * @return the newly created {@link User}
+	 * @throws IOException if sending the failed login back to the client failed
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	private envoy.server.data.User newUser(LoginCredentials credentials) {
+	private envoy.server.data.User newUser(LoginCredentials credentials, long socketId, ObjectWriteProxy writeProxy) throws IOException {
+		// Checking that no user already has this identifier TODO change to identifier once implemented
+		if (PersistenceManager.getPersistenceManager().getUserByName(credentials.getIdentifier()) != null)
+			writeProxy.write(socketId, new HandshakeRejectionEvent(HandshakeRejectionEvent.USER_EXISTS_ALREADY));
+		// Creation of a new user
 		envoy.server.data.User user;
 		user = new envoy.server.data.User();
-		user.setName(credentials.getName());
+		//TODO needs to be replaced later on
+		user.setName(credentials.getIdentifier());
 		user.setLastSeen(new Date());
 		user.setStatus(User.UserStatus.ONLINE);
 		user.setPasswordHash(credentials.getPasswordHash());
diff --git a/src/main/java/envoy/server/processors/MessageProcessor.java b/src/main/java/envoy/server/processors/MessageProcessor.java
index 0d9a7e6..23a9b43 100644
--- a/src/main/java/envoy/server/processors/MessageProcessor.java
+++ b/src/main/java/envoy/server/processors/MessageProcessor.java
@@ -37,7 +37,7 @@ public class MessageProcessor implements ObjectProcessor<Message> {
 			// Update the message status to RECEIVED
 			message.setReceivedDate(new Date());
 			message.nextStatus();
-			writeProxy.write(connectionManager.getSocketId(message.getSenderId()), new MessageStatusChangeEvent(message));
+			writeProxy.write(socketId, new MessageStatusChangeEvent(message));
 		} catch (IOException e) {
 			System.err.println("Recipient online. Failed to send message" + message.getId());
 			e.printStackTrace();