diff --git a/PROTOCOL.md b/PROTOCOL.md
index ab3a6f2..209754c 100644
--- a/PROTOCOL.md
+++ b/PROTOCOL.md
@@ -26,6 +26,9 @@ Nodes MUST NOT have a public key with the broadcast address or null
 address as hash. Additionally, nodes MUST NOT connect to a node with
 either address.
 
+All integer fields are in network byte order, and unsigned (unless 
+specified otherwise).
+
 
 Crypto
 ------
@@ -40,22 +43,15 @@ private key, and the result written to the 'Encryption Data' part.
 
 Routing
 -------
-A simple flood routing protocol is currently used. Every node forwards
-all messages, unless a message with the same Origin and Sequence Number
-has already been received.
+The routing protocol is based on 
+[AODVv2](https://datatracker.ietf.org/doc/draft-ietf-manet-aodvv2/),
+with various features left out.
 
-Nodes MUST store pairs of (Origin, Sequence Number) for all received
-messages. After receiving a new message, entries with the same Origin
-and Sequence Number between _received_ + 1 and _received_ + 32767 MUST
-be removed (with a wrap around at the maximum value). The entries MUST
-NOT be cleared while the program is running. They MAY be cleared when
-the program is exited.
+TODO: Add Documentation for routing protocol.
 
 There is currently no support for offline messages. If sender and
 receiver are not in the same mesh, the message will not arrive.
 
-Nodes are free implement different routing algorithms.
-
 
 Messages
 --------
@@ -84,9 +80,7 @@ AES key is wrapped with the recipient's public RSA key.
 ### Header
 
 Every message starts with one 74 byte header indicating the message
-version, type and ID, followed by the length of the message. The
-header is in network byte order, i.e. big endian. The header may have
-6 bytes of additional data.
+version, type and ID, followed by the length of the message.
 
      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
@@ -220,6 +214,74 @@ After this message has been received, communication with normal messages
 may start.
 
 
+### Route Request (Protocol-Type = 2)
+
+Sent to request a route to a specific Target Address.
+
+     0                   1                   2                   3
+     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    |                                                               |
+    |                      Address (32 bytes)                       |
+    |                                                               |
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    |           OrigSeqNum          |         OriginMetric          |
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    |                          TargMetric                           |
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+Equivalent to the Sequence Number in the message header.
+
+Set OrigMetric = RouterClient.Cost for the Router Client entry
+which includes OrigAddr.
+
+If an Invalid route exists in the Local Route Set matching
+TargAddr using longest prefix matching and has a valid
+sequence number, set TargSeqNum = LocalRoute.SeqNum.
+Otherwise, set TargSeqNum = -1. This field is signed.
+
+### Route Reply (Protocol-Type = 3)
+
+Sent as a reply when a Route Request arrives, to inform other nodes
+about a route.
+
+     0                   1                   2                   3
+     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    |           TargSeqNum          |          TargMetric           |
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+Set TargMetric = RouterClient.Cost for the Router Client entry
+which includes TargAddr.
+
+### Route Error (Protocol-Type = 4)
+
+Notifies other nodes of routes that are no longer available. The target
+address MUST be set to the broadcast address.
+
+     0                   1                   2                   3
+     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    |                                                               |
+    |                   Packet Source (32 bytes)                    |
+    |                                                               |
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    |                                                               |
+    |                      Address (32 bytes)                       |
+    |                                                               |
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+    |                           SeqNum                              |
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+Packet Source is the source address of the message triggering this
+Route Error. If the route error is not triggered by a message,
+this MUST be set to the null address.
+
+Address is the address that is no longer reachable.
+
+SeqNum is the sequence number of the route that is no longer available
+(if known). Otherwise, set TargSeqNum = -1. This field is signed.
+
 Content Messages
 ----------------
 
diff --git a/README.md b/README.md
index 6ffb875..2bbddf6 100644
--- a/README.md
+++ b/README.md
@@ -18,10 +18,20 @@ To setup a development environment, just install [Android Studio](https://develo
 and import the project.
 
 Alternatively, you can use the command line. To create a debug apk, run `./gradlew assembleDevDebug`.
-This requires at least Android Lollipop on your development device. If you don't have Lollipop, you
-can alternatively use `./gradlew assembleRelDebug`. However, this results in considerably slower
+This requires at least Android Lollipop on your development device. If you don't have 5.0 or higher,
+you have to use `./gradlew assembleRelDebug`. However, this results in considerably slower
 incremental builds. To create a release apk, run `./gradlew assembleRelRelease`.
 
+Testing
+-------
+
+You can run the unit tests with `./gradlew test`. After connecting an Android device, you can run
+the Android tests with `./gradlew connectedDevDebugAndroidTest` (or
+`./gradlew connectedRelDebugAndroidTest` if your Android version is  lower than 5.0).
+
+To run integration tests for the core module, use `./gradlew integration:run`. If this fails (or
+is very slow), try changing the value of Crypto#PublicKeySize to 512 (in the core module).
+
 License
 -------
 
diff --git a/android/build.gradle b/android/build.gradle
index 5dfb5f8..22e783e 100644
--- a/android/build.gradle
+++ b/android/build.gradle
@@ -11,7 +11,7 @@ buildscript {
 }
 
 dependencies {
-    compile 'com.android.support:design:23.1.1'
+    compile 'com.android.support:design:23.4.0'
     compile 'com.android.support:multidex:1.0.1'
     compile 'org.scala-lang:scala-library:2.11.7'
     compile 'com.mobsandgeeks:adapter-kit:0.5.3'
@@ -46,9 +46,18 @@ android {
         testInstrumentationRunner "com.android.test.runner.MultiDexTestRunner"
     }
 
-    buildTypes.debug {
-        applicationIdSuffix ".debug"
-        testCoverageEnabled true
+    buildTypes {
+        debug {
+            applicationIdSuffix ".debug"
+            testCoverageEnabled true
+        }
+        release {
+            // HACK: This shouldn't be needed, but multidex isn't working correctly.
+            // https://code.google.com/p/android/issues/detail?id=206131
+            // https://code.google.com/p/android/issues/detail?id=209084
+            minifyEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), file('proguard-rules.txt')
+        }
     }
 
     // Increasing minSdkVersion reduces compilation time for MultiDex.
diff --git a/android/proguard-rules.txt b/android/proguard-rules.txt
new file mode 100644
index 0000000..450c62d
--- /dev/null
+++ b/android/proguard-rules.txt
@@ -0,0 +1,36 @@
+# Add project specific ProGuard rules here.
+# By default, the flags in this file are appended to flags specified
+# in /home/sg/adt/sdk/tools/proguard/proguard-android.txt
+# You can edit the include path and order by changing the ProGuard
+# include property in project.properties.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# Add any project specific keep options here:
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+-dontobfuscate
+
+-keep class scala.** { *; }
+-keep class slick.** { *; }
+-keep class org.joda.time.** { *; }
+-keep class org.h2.** { *; }
+-keep class java.util.** { *; }
+-keepclassmembers class java.util.Comparator {
+    public *;
+}
+
+-dontwarn scala.**
+-dontwarn slick.**
+-dontwarn org.joda.time.**
+-dontwarn org.h2.**
+-dontwarn java.util.function.**
+
+-ignorewarnings
diff --git a/android/src/main/scala/com/nutomic/ensichat/bluetooth/BluetoothInterface.scala b/android/src/main/scala/com/nutomic/ensichat/bluetooth/BluetoothInterface.scala
index 46a2937..42d37e1 100644
--- a/android/src/main/scala/com/nutomic/ensichat/bluetooth/BluetoothInterface.scala
+++ b/android/src/main/scala/com/nutomic/ensichat/bluetooth/BluetoothInterface.scala
@@ -170,10 +170,11 @@ class BluetoothInterface(context: Context, mainHandler: Handler,
    * Removes device from active connections.
    */
   def onConnectionClosed(device: Device, socket: BluetoothSocket): Unit = {
+    val address = getAddressForDevice(device.id)
     devices -= device.id
     connections -= device.id
-    connectionHandler.onConnectionClosed()
     addressDeviceMap = addressDeviceMap.filterNot(_._2 == device.id)
+    connectionHandler.onConnectionClosed(address)
   }
 
   /**
@@ -192,15 +193,18 @@ class BluetoothInterface(context: Context, mainHandler: Handler,
       if (!connectionHandler.onConnectionOpened(msg))
         addressDeviceMap -= address
     case _ =>
-      connectionHandler.onMessageReceived(msg)
+      connectionHandler.onMessageReceived(msg, getAddressForDevice(device))
   }
 
+  private def getAddressForDevice(device: Device.ID) =
+    addressDeviceMap.find(_._2 == device).get._1
+
   /**
    * Sends the message to nextHop.
    */
   override def send(nextHop: Address, msg: Message): Unit = {
     addressDeviceMap
-      .find(_._1 == nextHop)
+      .find(_._1 == nextHop || Address.Broadcast == nextHop)
       .map(i => connections.get(i._2))
       .getOrElse(None)
       .foreach(_.send(msg))
@@ -210,11 +214,6 @@ class BluetoothInterface(context: Context, mainHandler: Handler,
    * Returns all active Bluetooth connections.
    */
   override def getConnections: Set[Address] =
-    connections.flatMap { x =>
-        addressDeviceMap
-          .find(_._2 == x._1)
-          .map(_._1)
-      }
-      .toSet
+    connections.map( c => getAddressForDevice(c._1)).toSet
 
 }
diff --git a/core/build.gradle b/core/build.gradle
index ff6916c..7cb01d1 100644
--- a/core/build.gradle
+++ b/core/build.gradle
@@ -5,6 +5,7 @@ dependencies {
     compile 'com.h2database:h2:1.4.191'
     compile 'com.typesafe.slick:slick_2.11:3.1.1'
     compile 'com.typesafe.scala-logging:scala-logging_2.11:3.4.0'
+    compile 'joda-time:joda-time:2.9.3'
     testCompile 'junit:junit:4.12'
 }
 
diff --git a/core/src/main/resources/logback.xml b/core/src/main/resources/logback.xml
index 42b3acb..3087979 100644
--- a/core/src/main/resources/logback.xml
+++ b/core/src/main/resources/logback.xml
@@ -3,7 +3,7 @@
     <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
         <target>System.out</target>
         <encoder>
-            <pattern>%d{HH:mm:ss} [%thread] %-5level %logger{36} - %msg%n</pattern>
+            <pattern>%d{HH:mm:ss} %level/%logger{0}: %msg%n</pattern>
         </encoder>
     </appender>
 
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/Address.scala b/core/src/main/scala/com/nutomic/ensichat/core/Address.scala
index cab8638..b71141a 100644
--- a/core/src/main/scala/com/nutomic/ensichat/core/Address.scala
+++ b/core/src/main/scala/com/nutomic/ensichat/core/Address.scala
@@ -56,4 +56,9 @@ final case class Address(bytes: Array[Byte]) {
       .grouped(Address.GroupLength)
       .reduce(_ + "-" + _)
 
+  /**
+    * Returns shortened address, useful for debugging.
+    */
+  def short = toString.split("-").head
+
 }
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/ConnectionHandler.scala b/core/src/main/scala/com/nutomic/ensichat/core/ConnectionHandler.scala
index 10b2143..dc22815 100644
--- a/core/src/main/scala/com/nutomic/ensichat/core/ConnectionHandler.scala
+++ b/core/src/main/scala/com/nutomic/ensichat/core/ConnectionHandler.scala
@@ -1,15 +1,18 @@
 package com.nutomic.ensichat.core
 
+import java.security.InvalidKeyException
 import java.util.Date
 
-import com.nutomic.ensichat.core.body.{ConnectionInfo, MessageBody, UserInfo}
-import com.nutomic.ensichat.core.header.ContentHeader
+import com.nutomic.ensichat.core.body._
+import com.nutomic.ensichat.core.header.{ContentHeader, MessageHeader}
 import com.nutomic.ensichat.core.interfaces._
 import com.nutomic.ensichat.core.internet.InternetInterface
-import com.nutomic.ensichat.core.util.{Database, FutureHelper}
+import com.nutomic.ensichat.core.util.{Database, FutureHelper, LocalRoutesInfo, RouteMessageInfo}
 import com.typesafe.scalalogging.Logger
 
 import scala.concurrent.ExecutionContext.Implicits.global
+import scala.concurrent.Future
+import scala.concurrent.duration._
 
 /**
  * High-level handling of all message transfers and callbacks.
@@ -19,16 +22,33 @@ import scala.concurrent.ExecutionContext.Implicits.global
  */
 final class ConnectionHandler(settings: SettingsInterface, database: Database,
                               callbacks: CallbackInterface, crypto: Crypto,
-                              maxInternetConnections: Int) {
+                              maxInternetConnections: Int,
+                              port: Int = InternetInterface.DefaultPort) {
 
   private val logger = Logger(this.getClass)
 
+  private val MissingRouteMessageTimeout = 5.minutes
+
   private var transmissionInterfaces = Set[TransmissionInterface]()
 
-  private lazy val router = new Router(connections, sendVia)
-
   private lazy val seqNumGenerator = new SeqNumGenerator(settings)
 
+  private val localRoutesInfo = new LocalRoutesInfo(connections)
+
+  private val routeMessageInfo = new RouteMessageInfo()
+
+  private lazy val router = new Router(localRoutesInfo,
+                                       (a, m) => transmissionInterfaces.foreach(_.send(a, m)),
+                                       noRouteFound)
+
+  /**
+    * Contains messages that couldn't be forwarded because we don't know a route.
+    *
+    * These will be buffered until we receive a [[RouteReply]] for the target, or when until the
+    * message has couldn't be forwarded after [[MissingRouteMessageTimeout]].
+    */
+  private var missingRouteMessages = Set[(Message, Date)]()
+
   /**
    * Holds all known users.
    *
@@ -42,14 +62,15 @@ final class ConnectionHandler(settings: SettingsInterface, database: Database,
    * @param additionalInterfaces Instances of [[TransmissionInterface]] to transfer data over
    *                             platform specific interfaces (eg Bluetooth).
    */
-  def start(additionalInterfaces: Set[TransmissionInterface] = Set()): Unit = {
+  def start(additionalInterfaces: Set[TransmissionInterface] = Set()): Future[Unit] = {
     additionalInterfaces.foreach(transmissionInterfaces += _)
     FutureHelper {
       crypto.generateLocalKeys()
       logger.info("Service started, address is " + crypto.localAddress)
       logger.info("Local user is " + settings.get(SettingsInterface.KeyUserName, "none") +
         " with status '" + settings.get(SettingsInterface.KeyUserStatus, "") + "'")
-      transmissionInterfaces += new InternetInterface(this, crypto, settings, maxInternetConnections)
+      transmissionInterfaces +=
+        new InternetInterface(this, crypto, settings, maxInternetConnections, port)
       transmissionInterfaces.foreach(_.create())
     }
   }
@@ -63,6 +84,7 @@ final class ConnectionHandler(settings: SettingsInterface, database: Database,
    * Sends a new message to the given target address.
    */
   def sendTo(target: Address, body: MessageBody): Unit = {
+    assert(body.contentType != -1)
     FutureHelper {
       val messageId = settings.get("message_id", 0L)
       val header = new ContentHeader(crypto.localAddress, target, seqNumGenerator.next(),
@@ -76,23 +98,165 @@ final class ConnectionHandler(settings: SettingsInterface, database: Database,
     }
   }
 
-  private def sendVia(nextHop: Address, msg: Message) =
-    transmissionInterfaces.foreach(_.send(nextHop, msg))
+  private def requestRoute(target: Address): Unit = {
+    assert(localRoutesInfo.getRoute(target).isEmpty)
+    val seqNum = seqNumGenerator.next()
+    val targetSeqNum = localRoutesInfo.getRoute(target).map(_.seqNum).getOrElse(-1)
+    val body = new RouteRequest(target, seqNum, targetSeqNum, 0)
+    val header = new MessageHeader(body.protocolType, crypto.localAddress, Address.Broadcast, seqNum)
+
+    val signed = crypto.sign(new Message(header, body))
+    router.forwardMessage(signed)
+  }
+
+  private def replyRoute(target: Address, replyTo: Address): Unit = {
+    val seqNum = seqNumGenerator.next()
+    val body = new RouteReply(seqNum, 0)
+    val header = new MessageHeader(body.protocolType, crypto.localAddress, replyTo, seqNum)
+
+    val signed = crypto.sign(new Message(header, body))
+    router.forwardMessage(signed)
+  }
+
+  private def routeError(address: Address, packetSource: Option[Address]): Unit =  {
+    val destination = packetSource.getOrElse(Address.Broadcast)
+    val header = new MessageHeader(RouteError.Type, crypto.localAddress, destination,
+                                   seqNumGenerator.next())
+    val seqNum = localRoutesInfo.getRoute(address).map(_.seqNum).getOrElse(-1)
+    val body = new RouteError(address, seqNum)
+
+    val signed = crypto.sign(new Message(header, body))
+    router.forwardMessage(signed)
+  }
+
+  /**
+   * Force connect to a sepcific internet.
+   *
+   * @param address An address in the format IP;port or hostname:port.
+   */
+  def connect(address: String): Unit = {
+    transmissionInterfaces
+      .find(_.isInstanceOf[InternetInterface])
+      .map(_.asInstanceOf[InternetInterface])
+      .foreach(_.openConnection(address))
+  }
 
   /**
    * Decrypts and verifies incoming messages, forwards valid ones to [[onNewMessage()]].
    */
-  def onMessageReceived(msg: Message): Unit = {
+  def onMessageReceived(msg: Message, previousHop: Address): Unit = {
     if (router.isMessageSeen(msg)) {
       logger.trace("Ignoring message from " + msg.header.origin + " that we already received")
-    } else if (msg.header.target == crypto.localAddress) {
-      crypto.verifyAndDecrypt(msg) match {
-        case Some(m) => onNewMessage(m)
-        case None => logger.info("Ignoring message with invalid signature from " + msg.header.origin)
-      }
-    } else {
-      router.forwardMessage(msg)
+      return
     }
+
+    msg.body match {
+      case rreq: RouteRequest =>
+        localRoutesInfo.addRoute(msg.header.origin, rreq.originSeqNum, previousHop, rreq.originMetric)
+        // TODO: Respecting this causes the RERR test to fail. We have to fix the implementation
+        //       of isMessageRedundant() without breaking the test.
+        if (routeMessageInfo.isMessageRedundant(msg)) {
+          logger.info("Sending redundant RREQ")
+          //return
+        }
+
+        if (crypto.localAddress == rreq.requested)
+          replyRoute(rreq.requested, msg.header.origin)
+        else {
+          val body = rreq.copy(originMetric = rreq.originMetric + 1)
+
+          val forwardMsg = crypto.sign(new Message(msg.header, body))
+          localRoutesInfo.getRoute(rreq.requested) match {
+            case Some(route) => router.forwardMessage(forwardMsg, Option(route.nextHop))
+            case None => router.forwardMessage(forwardMsg, Option(Address.Broadcast))
+          }
+        }
+        return
+      case rrep: RouteReply =>
+        localRoutesInfo.addRoute(msg.header.origin, rrep.originSeqNum, previousHop, 0)
+        // TODO: See above (in RREQ handler).
+        if (routeMessageInfo.isMessageRedundant(msg)) {
+          logger.debug("Sending redundant RREP")
+          //return
+        }
+
+        resendMissingRouteMessages()
+
+        if (msg.header.target == crypto.localAddress)
+          return
+
+        val existingRoute = localRoutesInfo.getRoute(msg.header.target)
+        val states = Set(LocalRoutesInfo.RouteStates.Active, LocalRoutesInfo.RouteStates.Idle)
+        if (existingRoute.isEmpty || !states.contains(existingRoute.get.state)) {
+          routeError(msg.header.target, Option(msg.header.origin))
+          return
+        }
+
+        val body = rrep.copy(originMetric = rrep.originMetric + 1)
+
+        val forwardMsg = crypto.sign(new Message(msg.header, body))
+        router.forwardMessage(forwardMsg)
+        return
+      case rerr: RouteError =>
+        localRoutesInfo.getRoute(rerr.address).foreach { route =>
+          if (route.nextHop == msg.header.origin && (rerr.seqNum == 0 || rerr.seqNum > route.seqNum)) {
+            localRoutesInfo.connectionClosed(rerr.address)
+              .foreach(routeError(_, None))
+          }
+        }
+      case _ =>
+    }
+
+    if (msg.header.target != crypto.localAddress) {
+      router.forwardMessage(msg)
+      return
+    }
+
+    val plainMsg =
+      try {
+        if (!crypto.verify(msg)) {
+          logger.warn(s"Received message with invalid signature from ${msg.header.origin}")
+          return
+        }
+
+        if (msg.header.isContentMessage)
+          crypto.decrypt(msg)
+        else
+          msg
+      } catch {
+        case e: InvalidKeyException =>
+          logger.warn(s"Failed to verify or decrypt message $msg", e)
+          return
+      }
+
+    onNewMessage(plainMsg)
+  }
+
+  /**
+    * Tries to send messages in [[missingRouteMessages]] again, after we acquired a new route.
+    *
+    * Before checking [[missingRouteMessages]], those older than [[MissingRouteMessageTimeout]]
+    * are removed.
+    */
+  private def resendMissingRouteMessages(): Unit = {
+    // resend messages if possible
+    val date = new Date()
+    missingRouteMessages = missingRouteMessages.filter { e =>
+      val removeTime = new Date(e._2.getTime + MissingRouteMessageTimeout.toMillis)
+      removeTime.after(date)
+    }
+
+    val m = missingRouteMessages.filter(m => localRoutesInfo.getRoute(m._1.header.target).isDefined)
+    m.foreach( m => router.forwardMessage(m._1))
+    missingRouteMessages --= m
+  }
+
+  private def noRouteFound(message: Message): Unit = {
+    if (message.header.origin == crypto.localAddress) {
+      missingRouteMessages += ((message, new Date()))
+      requestRoute(message.header.target)
+    } else
+      routeError(message.header.target, Option(message.header.origin))
   }
 
   /**
@@ -163,7 +327,11 @@ final class ConnectionHandler(settings: SettingsInterface, database: Database,
     true
   }
 
-  def onConnectionClosed() = callbacks.onConnectionsChanged()
+  def onConnectionClosed(address: Address): Unit = {
+    localRoutesInfo.connectionClosed(address)
+      .foreach(routeError(_, None))
+    callbacks.onConnectionsChanged()
+  }
 
   def connections(): Set[Address] = transmissionInterfaces.flatMap(_.getConnections)
 
@@ -177,6 +345,9 @@ final class ConnectionHandler(settings: SettingsInterface, database: Database,
       .find(_.address == address)
       .getOrElse(new User(address, address.toString(), ""))
 
+  /**
+    * This method should be called when the local device's internet connection has changed in any way.
+    */
   def internetConnectionChanged(): Unit = {
     transmissionInterfaces
       .find(_.isInstanceOf[InternetInterface])
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/Crypto.scala b/core/src/main/scala/com/nutomic/ensichat/core/Crypto.scala
index 2655aa4..a6f5be3 100644
--- a/core/src/main/scala/com/nutomic/ensichat/core/Crypto.scala
+++ b/core/src/main/scala/com/nutomic/ensichat/core/Crypto.scala
@@ -119,7 +119,7 @@ class Crypto(settings: SettingsInterface, keyFolder: File) {
    * @throws RuntimeException If the key does not exist.
    */
   @throws[RuntimeException]
-  private[core] def getPublicKey(address: Address): PublicKey = {
+  def getPublicKey(address: Address): PublicKey = {
     loadKey(address.toString, classOf[PublicKey])
   }
 
@@ -129,7 +129,7 @@ class Crypto(settings: SettingsInterface, keyFolder: File) {
    * @throws RuntimeException If a key already exists for this address.
    */
   @throws[RuntimeException]
-  private[core] def addPublicKey(address: Address, key: PublicKey): Unit = {
+  def addPublicKey(address: Address, key: PublicKey): Unit = {
     if (havePublicKey(address))
       throw new RuntimeException("Already have key for " + address + ", not overwriting")
 
@@ -232,20 +232,6 @@ class Crypto(settings: SettingsInterface, keyFolder: File) {
     sign(encrypt(msg, key))
   }
 
-  private[core] def verifyAndDecrypt(msg: Message, key: Option[PublicKey] = None): Option[Message] = {
-    // Catch exception to avoid crash if we receive invalid message.
-    try {
-      if (verify(msg, key))
-        Option(decrypt(msg))
-      else
-        None
-    } catch {
-      case e: InvalidKeyException =>
-        logger.warn("Failed to verify or decrypt message", e)
-        None
-    }
-  }
-
   private def encrypt(msg: Message, key: Option[PublicKey] = None): Message = {
     // Symmetric encryption of data
     val secretKey = makeSecretKey()
@@ -263,7 +249,7 @@ class Crypto(settings: SettingsInterface, keyFolder: File) {
   }
 
   @throws[InvalidKeyException]
-  private def decrypt(msg: Message): Message = {
+  def decrypt(msg: Message): Message = {
     // Asymmetric decryption of secret key
     val asymmetricCipher = Cipher.getInstance(CipherAlgorithm)
     asymmetricCipher.init(Cipher.UNWRAP_MODE, loadKey(PrivateKeyAlias, classOf[PrivateKey]))
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/Message.scala b/core/src/main/scala/com/nutomic/ensichat/core/Message.scala
index 1487a29..65eb958 100644
--- a/core/src/main/scala/com/nutomic/ensichat/core/Message.scala
+++ b/core/src/main/scala/com/nutomic/ensichat/core/Message.scala
@@ -3,7 +3,7 @@ package com.nutomic.ensichat.core
 import java.io.InputStream
 import java.security.spec.InvalidKeySpecException
 
-import com.nutomic.ensichat.core.body.{ConnectionInfo, CryptoData, EncryptedBody, MessageBody}
+import com.nutomic.ensichat.core.body._
 import com.nutomic.ensichat.core.header.{AbstractHeader, ContentHeader, MessageHeader}
 
 object Message {
@@ -50,6 +50,9 @@ object Message {
       val body =
         header.protocolType match {
           case ConnectionInfo.Type => ConnectionInfo.read(remaining)
+          case RouteRequest.Type   => RouteRequest.read(remaining)
+          case RouteReply.Type     => RouteReply.read(remaining)
+          case RouteError.Type     => RouteError.read(remaining)
           case _                   => new EncryptedBody(remaining)
         }
 
@@ -80,6 +83,11 @@ case class Message(header: AbstractHeader, crypto: CryptoData, body: MessageBody
   def this(header: AbstractHeader, body: MessageBody) =
     this(header, new CryptoData(None, None), body)
 
-  def write = header.write(body.length + crypto.length) ++ crypto.write ++ body.write
+  def write = {
+    header.write(body.length + crypto.length) ++ crypto.write ++ body.write
+  }
+
+  override def toString =
+    s"Message(${header.origin.short}(${header.seqNum}) -> ${header.target.short}: $body)"
 
 }
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/Router.scala b/core/src/main/scala/com/nutomic/ensichat/core/Router.scala
index a487917..02159b8 100644
--- a/core/src/main/scala/com/nutomic/ensichat/core/Router.scala
+++ b/core/src/main/scala/com/nutomic/ensichat/core/Router.scala
@@ -1,18 +1,44 @@
 package com.nutomic.ensichat.core
 
+import java.util.Comparator
+
 import com.nutomic.ensichat.core.header.{ContentHeader, MessageHeader}
+import com.nutomic.ensichat.core.util.LocalRoutesInfo
+
+object Router extends Comparator[Int] {
+
+  /**
+   * Compares which sequence number is newer.
+   *
+   * @return 1 if lhs is newer, -1 if rhs is newer, 0 if they are equal.
+   */
+  override def compare(lhs: Int, rhs: Int): Int = {
+    if (lhs == rhs)
+      0
+    // True if [[rhs]] is between {{{MessageHeader.SeqNumRange.size / 2}}} and
+    // [[MessageHeader.SeqNumRange.size]].
+    else if (lhs > ContentHeader.SeqNumRange.size / 2) {
+      // True if [[rhs]] is between {{{lhs - MessageHeader.SeqNumRange.size / 2}}} and [[lhs]].
+      if (lhs - ContentHeader.SeqNumRange.size / 2 < rhs && rhs < lhs) 1 else -1
+    } else {
+      // True if [[rhs]] is *not* between [[lhs]] and {{{lhs + MessageHeader.SeqNumRange.size / 2}}}.
+      if (rhs < lhs || rhs > lhs + ContentHeader.SeqNumRange.size / 2) 1 else -1
+    }
+  }
+}
 
 /**
  * Forwards messages to all connected devices.
  */
-final private[core] class Router(activeConnections: () => Set[Address], send: (Address, Message) => Unit) {
+private[core] class Router(routesInfo: LocalRoutesInfo, send: (Address, Message) => Unit,
+                                 noRouteFound: (Message) => Unit) {
 
   private var messageSeen = Set[(Address, Int)]()
 
   /**
    * Returns true if we have received the same message before.
    */
-  def isMessageSeen(msg: Message): Boolean = {
+  private[core] def isMessageSeen(msg: Message): Boolean = {
     val info = (msg.header.origin, msg.header.seqNum)
     val seen = messageSeen.contains(info)
     markMessageSeen(info)
@@ -23,15 +49,24 @@ final private[core] class Router(activeConnections: () => Set[Address], send: (A
    * Sends message to all connected devices. Should only be called if [[isMessageSeen()]] returns
    * true.
    */
-  def forwardMessage(msg: Message): Unit = {
-    val info = (msg.header.origin, msg.header.seqNum)
-    val updated = incHopCount(msg)
-    if (updated.header.hopCount >= updated.header.hopLimit)
+  def forwardMessage(msg: Message, nextHopOption: Option[Address] = None): Unit = {
+    if (msg.header.hopCount + 1 >= msg.header.hopLimit)
       return
 
-    activeConnections().foreach(a => send(a, updated))
+    val nextHop = nextHopOption.getOrElse(msg.header.target)
 
-    markMessageSeen(info)
+    if (nextHop == Address.Broadcast) {
+      send(nextHop, msg)
+      return
+    }
+
+    routesInfo.getRoute(nextHop).map(_.nextHop) match {
+      case Some(a) =>
+        send(a, incHopCount(msg))
+        markMessageSeen((msg.header.origin, msg.header.seqNum))
+      case None =>
+        noRouteFound(msg)
+    }
   }
 
   private def markMessageSeen(info: (Address, Int)): Unit = {
@@ -64,15 +99,8 @@ final private[core] class Router(activeConnections: () => Set[Address], send: (A
       if (a1 != a2)
         true
 
-      // True if [[s2]] is between {{{MessageHeader.SeqNumRange.size / 2}}} and
-      // [[MessageHeader.SeqNumRange.size]].
-      if (s1 > ContentHeader.SeqNumRange.size / 2) {
-        // True if [[s2]] is between {{{s1 - MessageHeader.SeqNumRange.size / 2}}} and [[s1]].
-        s1 - ContentHeader.SeqNumRange.size / 2 < s2 && s2 < s1
-      } else {
-        // True if [[s2]] is *not* between [[s1]] and {{{s1 + MessageHeader.SeqNumRange.size / 2}}}.
-        s2 < s1 || s2 > s1 + ContentHeader.SeqNumRange.size / 2
-      }
+      else
+        Router.compare(s1, s2) > 0
     }
   }
 
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/body/EncryptedBody.scala b/core/src/main/scala/com/nutomic/ensichat/core/body/EncryptedBody.scala
index 5c6c18d..49b13fb 100644
--- a/core/src/main/scala/com/nutomic/ensichat/core/body/EncryptedBody.scala
+++ b/core/src/main/scala/com/nutomic/ensichat/core/body/EncryptedBody.scala
@@ -12,4 +12,6 @@ final case class EncryptedBody(data: Array[Byte]) extends MessageBody {
   def write = data
 
   override def length = data.length
+
+  override def toString = "EncryptedBody"
 }
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/body/RouteError.scala b/core/src/main/scala/com/nutomic/ensichat/core/body/RouteError.scala
new file mode 100644
index 0000000..f996a3e
--- /dev/null
+++ b/core/src/main/scala/com/nutomic/ensichat/core/body/RouteError.scala
@@ -0,0 +1,39 @@
+package com.nutomic.ensichat.core.body
+
+import java.nio.ByteBuffer
+
+import com.nutomic.ensichat.core.Address
+import com.nutomic.ensichat.core.util.BufferUtils
+
+private[core] object RouteError {
+
+  val Type = 4
+
+  /**
+   * Constructs [[RouteError]] instance from byte array.
+   */
+  def read(array: Array[Byte]): RouteError = {
+    val b = ByteBuffer.wrap(array)
+    val address = new Address(BufferUtils.getByteArray(b, Address.Length))
+    val seqNum = b.getInt
+    new RouteError(address, seqNum)
+  }
+
+}
+
+private[core] case class RouteError(address: Address, seqNum: Int) extends MessageBody {
+
+  override def protocolType = RouteReply.Type
+
+  override def contentType = -1
+
+  override def write: Array[Byte] = {
+    val b = ByteBuffer.allocate(length)
+    b.put(address.bytes)
+    b.putInt(seqNum)
+    b.array()
+  }
+
+  override def length = Address.Length + 4
+
+}
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/body/RouteReply.scala b/core/src/main/scala/com/nutomic/ensichat/core/body/RouteReply.scala
new file mode 100644
index 0000000..33c23f0
--- /dev/null
+++ b/core/src/main/scala/com/nutomic/ensichat/core/body/RouteReply.scala
@@ -0,0 +1,50 @@
+package com.nutomic.ensichat.core.body
+
+import java.nio.ByteBuffer
+
+import com.nutomic.ensichat.core.util.BufferUtils
+
+private[core] object RouteReply {
+
+  val Type = 3
+
+  /**
+   * Constructs [[RouteReply]] instance from byte array.
+   */
+  def read(array: Array[Byte]): RouteReply = {
+    val b = ByteBuffer.wrap(array)
+    val targSeqNum = BufferUtils.getUnsignedShort(b)
+    val targMetric = BufferUtils.getUnsignedShort(b)
+    new RouteReply(targSeqNum, targMetric)
+  }
+
+}
+
+/**
+  * Sends information about a route.
+  *
+  * Note that the fields are named different than described in AODVv2. There, targSeqNum and
+  * targMetric are used to describe the seqNum and metric of the node sending the route reply. In
+  * Ensichat, we use originSeqNum and originMetric instead, to stay consistent with the header
+  * fields. That means header.origin, originSeqNum and originMetric all refer to the node sending
+  * this message.
+  *
+  * @param originSeqNum The current sequence number of the node sending this message.
+  * @param originMetric The metric of the current route to the sending node.
+  */
+private[core] case class RouteReply(originSeqNum: Int, originMetric: Int) extends MessageBody {
+
+  override def protocolType = RouteReply.Type
+
+  override def contentType = -1
+
+  override def write: Array[Byte] = {
+    val b = ByteBuffer.allocate(length)
+    BufferUtils.putUnsignedShort(b, originSeqNum)
+    BufferUtils.putUnsignedShort(b, originMetric)
+    b.array()
+  }
+
+  override def length = 4
+
+}
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/body/RouteRequest.scala b/core/src/main/scala/com/nutomic/ensichat/core/body/RouteRequest.scala
new file mode 100644
index 0000000..bc728c3
--- /dev/null
+++ b/core/src/main/scala/com/nutomic/ensichat/core/body/RouteRequest.scala
@@ -0,0 +1,44 @@
+package com.nutomic.ensichat.core.body
+
+import java.nio.ByteBuffer
+
+import com.nutomic.ensichat.core.Address
+import com.nutomic.ensichat.core.util.BufferUtils
+
+private[core] object RouteRequest {
+
+  val Type = 2
+
+  /**
+   * Constructs [[RouteRequest]] instance from byte array.
+   */
+  def read(array: Array[Byte]): RouteRequest = {
+    val b = ByteBuffer.wrap(array)
+    val requested  = new Address(BufferUtils.getByteArray(b, Address.Length))
+    val origSeqNum = BufferUtils.getUnsignedShort(b)
+    val originMetric = BufferUtils.getUnsignedShort(b)
+    val targSeqNum = b.getInt()
+    new RouteRequest(requested, origSeqNum, targSeqNum, originMetric)
+  }
+
+}
+
+private[core] case class RouteRequest(requested: Address, originSeqNum: Int, targSeqNum: Int, originMetric: Int)
+  extends MessageBody {
+
+  override def protocolType = RouteRequest.Type
+
+  override def contentType = -1
+
+  override def write: Array[Byte] = {
+    val b = ByteBuffer.allocate(length)
+    b.put(requested.bytes)
+    BufferUtils.putUnsignedShort(b, originSeqNum)
+    BufferUtils.putUnsignedShort(b, originMetric)
+    b.putInt(targSeqNum)
+    b.array()
+  }
+
+  override def length = 8 + Address.Length
+
+}
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/internet/InternetConnectionThread.scala b/core/src/main/scala/com/nutomic/ensichat/core/internet/InternetConnectionThread.scala
index aa36f1f..4235964 100644
--- a/core/src/main/scala/com/nutomic/ensichat/core/internet/InternetConnectionThread.scala
+++ b/core/src/main/scala/com/nutomic/ensichat/core/internet/InternetConnectionThread.scala
@@ -12,8 +12,10 @@ import com.typesafe.scalalogging.Logger
 /**
  * Encapsulates an active connection to another node.
  */
-class InternetConnectionThread(socket: Socket, crypto: Crypto, onDisconnected: (InternetConnectionThread) => Unit,
-                       onReceive: (Message, InternetConnectionThread) => Unit) extends Thread {
+private[core] class InternetConnectionThread(socket: Socket, crypto: Crypto,
+                                             onDisconnected: (InternetConnectionThread) => Unit,
+                                             onReceive: (Message, InternetConnectionThread) => Unit)
+                                             extends Thread {
 
   private val logger = Logger(this.getClass)
 
@@ -78,7 +80,6 @@ class InternetConnectionThread(socket: Socket, crypto: Crypto, onDisconnected: (
     } catch {
       case e: IOException => logger.warn("Failed to close socket", e)
     }
-    logger.debug("Connection to " + socket.getInetAddress + " closed")
     onDisconnected(this)
   }
 
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/internet/InternetInterface.scala b/core/src/main/scala/com/nutomic/ensichat/core/internet/InternetInterface.scala
index 3df31a9..f68905d 100644
--- a/core/src/main/scala/com/nutomic/ensichat/core/internet/InternetInterface.scala
+++ b/core/src/main/scala/com/nutomic/ensichat/core/internet/InternetInterface.scala
@@ -12,9 +12,9 @@ import scala.concurrent.ExecutionContext.Implicits.global
 import scala.concurrent.Future
 import scala.util.Random
 
-object InternetInterface {
+private[core] object InternetInterface {
 
-  val ServerPort = 26344
+  val DefaultPort = 26344
 
 }
 
@@ -23,14 +23,14 @@ object InternetInterface {
  *
  * @param maxConnections Maximum number of concurrent connections that should be opened.
  */
-class InternetInterface(connectionHandler: ConnectionHandler, crypto: Crypto,
-                        settings: SettingsInterface, maxConnections: Int)
+private[core] class InternetInterface(connectionHandler: ConnectionHandler, crypto: Crypto,
+                        settings: SettingsInterface, maxConnections: Int, port: Int)
   extends TransmissionInterface {
 
   private val logger = Logger(this.getClass)
 
   private lazy val serverThread =
-    new InternetServerThread(crypto, onConnected, onDisconnected, onReceiveMessage)
+    new InternetServerThread(crypto, port, onConnected, onDisconnected, onReceiveMessage)
 
   private var connections = Set[InternetConnectionThread]()
 
@@ -44,10 +44,8 @@ class InternetInterface(connectionHandler: ConnectionHandler, crypto: Crypto,
       .replace("46.101.249.188:26344", SettingsInterface.DefaultAddresses)
     settings.put(SettingsInterface.KeyAddresses, servers)
 
-    FutureHelper {
-      serverThread.start()
-      openAllConnections(maxConnections)
-    }
+    serverThread.start()
+    openAllConnections(maxConnections)
   }
 
   /**
@@ -69,13 +67,13 @@ class InternetInterface(connectionHandler: ConnectionHandler, crypto: Crypto,
       .foreach(openConnection)
   }
 
-  private def openConnection(addressPort: String): Unit = {
+  def openConnection(addressPort: String): Unit = {
     val (address, port) =
       if (addressPort.contains(":")) {
         val split = addressPort.split(":")
         (split(0), split(1).toInt)
       } else
-        (addressPort, InternetInterface.ServerPort)
+        (addressPort, InternetInterface.DefaultPort)
 
     openConnection(address, port)
   }
@@ -100,11 +98,11 @@ class InternetInterface(connectionHandler: ConnectionHandler, crypto: Crypto,
   }
 
   private def onDisconnected(connectionThread: InternetConnectionThread): Unit = {
-    addressDeviceMap.find(_._2 == connectionThread).foreach { ad =>
-      logger.trace("Connection closed to " + ad._1)
+    getAddressForThread(connectionThread).foreach { ad =>
+      logger.trace("Connection closed to " + ad)
       connections -= connectionThread
-      addressDeviceMap -= ad._1
-      connectionHandler.onConnectionClosed()
+      addressDeviceMap -= ad
+      connectionHandler.onConnectionClosed(ad)
     }
   }
 
@@ -122,15 +120,18 @@ class InternetInterface(connectionHandler: ConnectionHandler, crypto: Crypto,
       if (!connectionHandler.onConnectionOpened(msg))
         addressDeviceMap -= address
     case _ =>
-      connectionHandler.onMessageReceived(msg)
+      connectionHandler.onMessageReceived(msg, getAddressForThread(thread).get)
   }
 
+  private def getAddressForThread(thread: InternetConnectionThread) =
+    addressDeviceMap.find(_._2 == thread).map(_._1)
+
   /**
    * Sends the message to nextHop.
    */
   override def send(nextHop: Address, msg: Message): Unit = {
     addressDeviceMap
-      .find(_._1 == nextHop)
+      .filter(_._1 == nextHop || Address.Broadcast == nextHop)
       .foreach(_._2.send(msg))
   }
 
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/internet/InternetServerThread.scala b/core/src/main/scala/com/nutomic/ensichat/core/internet/InternetServerThread.scala
index cf507b3..56eb1b1 100644
--- a/core/src/main/scala/com/nutomic/ensichat/core/internet/InternetServerThread.scala
+++ b/core/src/main/scala/com/nutomic/ensichat/core/internet/InternetServerThread.scala
@@ -6,13 +6,15 @@ import java.net.ServerSocket
 import com.nutomic.ensichat.core.{Crypto, Message}
 import com.typesafe.scalalogging.Logger
 
-class InternetServerThread(crypto: Crypto, onConnected: (InternetConnectionThread) => Unit,
-                   onDisconnected: (InternetConnectionThread) => Unit, onReceive: (Message, InternetConnectionThread) => Unit) extends Thread {
+class InternetServerThread(crypto: Crypto, port: Int,
+                           onConnected: (InternetConnectionThread) => Unit,
+                           onDisconnected: (InternetConnectionThread) => Unit,
+                           onReceive: (Message, InternetConnectionThread) => Unit) extends Thread {
 
   private val logger = Logger(this.getClass)
 
   private lazy val socket: Option[ServerSocket] = try {
-    Option(new ServerSocket(InternetInterface.ServerPort))
+    Option(new ServerSocket(port))
   } catch {
     case e: IOException =>
       logger.warn("Failed to create server socket", e)
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/util/Database.scala b/core/src/main/scala/com/nutomic/ensichat/core/util/Database.scala
index 937d57e..ec8d464 100644
--- a/core/src/main/scala/com/nutomic/ensichat/core/util/Database.scala
+++ b/core/src/main/scala/com/nutomic/ensichat/core/util/Database.scala
@@ -75,8 +75,9 @@ class Database(path: File, callbackInterface: CallbackInterface) {
   /**
    * Inserts the given new message into the database.
    */
-  def onMessageReceived(msg: Message): Unit = {
-    Await.result(db.run(messages += msg), Duration.Inf)
+  def onMessageReceived(msg: Message): Unit = msg.body match {
+    case _: Text => Await.result(db.run(messages += msg), Duration.Inf)
+    case _ =>
   }
 
   def getMessages(address: Address): Seq[Message] = {
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/util/LocalRoutesInfo.scala b/core/src/main/scala/com/nutomic/ensichat/core/util/LocalRoutesInfo.scala
new file mode 100644
index 0000000..846c8c7
--- /dev/null
+++ b/core/src/main/scala/com/nutomic/ensichat/core/util/LocalRoutesInfo.scala
@@ -0,0 +1,119 @@
+package com.nutomic.ensichat.core.util
+
+import com.nutomic.ensichat.core.Address
+import com.nutomic.ensichat.core.util.LocalRoutesInfo._
+import com.typesafe.scalalogging.Logger
+import org.joda.time.{DateTime, Duration}
+
+private[core] object LocalRoutesInfo {
+
+  private val ActiveInterval = Duration.standardSeconds(5)
+
+  /**
+    * [[RouteStates.Idle]]:
+    *     A route that is known, but has not been used in the last [[ActiveInterval.
+    * [[RouteStates.Active]]:
+    *     A route that is known, and has been used in the last [[ActiveInterval]].
+    * [[RouteStates.Invalid]]:
+    *     A route that has been expired or lost, may not be used for forwarding.
+    * RouteStates.Unconfirmed is not required as connections are always bidirectional.
+    */
+  object RouteStates extends Enumeration {
+    type RouteStates = Value
+    val Idle, Active, Invalid = Value
+  }
+
+}
+
+/**
+  * This class contains information about routes available to this node.
+  *
+  * See AODVv2-13 4.5 (Local Route Set),              -> implemented
+  *               6.9 (Local Route Set Maintenance)   -> implemented (hopefully correct)
+  */
+private[core] class LocalRoutesInfo(activeConnections: () => Set[Address]) {
+
+  import RouteStates._
+
+  private val MaxSeqnumLifetime = Duration.standardSeconds(300)
+  // TODO: this can probably be much higher because of infrequent topology changes between internet nodes
+  private val MaxIdleTime = Duration.standardSeconds(300)
+
+
+  /**
+   *  Holds information about a local route.
+   *
+   * @param destination The destination address that can be reached with this route.
+   * @param seqNum Sequence number of the last route message that updated this entry.
+   * @param nextHop The next hop on the path towards destination.
+   * @param lastUsed The time this route was last used to forward a message.
+   * @param lastSeqNumUpdate The time seqNum was last updated.
+   * @param metric The number of hops towards destination using this route.
+   * @param state The last known state of the route.
+   */
+  case class RouteEntry(destination: Address, seqNum: Int, nextHop: Address, lastUsed: DateTime,
+                        lastSeqNumUpdate: DateTime, metric: Int, state: RouteStates)
+
+  private var routes = Set[RouteEntry]()
+
+  def addRoute(destination: Address, seqNum: Int, nextHop: Address, metric: Int): Unit = {
+    val entry = RouteEntry(destination, seqNum, nextHop, new DateTime(0), DateTime.now, metric, Idle)
+    routes += entry
+  }
+
+  def getRoute(destination: Address): Option[RouteEntry] = {
+    if (activeConnections().contains(destination))
+      return Option(new RouteEntry(destination, 0, destination, DateTime.now, DateTime.now, 1, Idle))
+
+    handleTimeouts()
+    val r = routes.toList
+      .sortWith(_.metric < _.metric)
+      .find( r => r.destination == destination && r.state != Invalid)
+
+    if (r.isDefined)
+      routes = routes -- r + r.get.copy(state = Active, lastUsed = DateTime.now)
+    r
+  }
+
+  /**
+    *
+    * @param address The address which can't be reached any more.
+    * @return The set of active destinations that can't be reached anymore.
+    */
+  def connectionClosed(address: Address): Set[Address] = {
+    handleTimeouts()
+
+    val affectedDestinations =
+      routes
+        .filter(r => r.state == Active && (r.nextHop == address || r.destination == address))
+        .map(_.destination)
+
+    routes = routes.map { r =>
+      if (r.nextHop == address || r.destination == address)
+        r.copy(state = Invalid)
+      else
+        r
+    }
+
+    affectedDestinations
+  }
+
+  private def handleTimeouts(): Unit = {
+    routes = routes
+      // Delete routes after max lifetime.
+      .map { r =>
+        if (DateTime.now.isAfter(r.lastSeqNumUpdate.plus(MaxSeqnumLifetime)))
+          r.copy(seqNum = 0)
+        else
+          r
+      }
+      // Set routes to invalid after max idle time.
+      .map { r =>
+        if (DateTime.now.isAfter(r.lastSeqNumUpdate.plus(MaxIdleTime)))
+          r.copy(state = Invalid)
+        else
+          r
+      }
+  }
+
+}
\ No newline at end of file
diff --git a/core/src/main/scala/com/nutomic/ensichat/core/util/RouteMessageInfo.scala b/core/src/main/scala/com/nutomic/ensichat/core/util/RouteMessageInfo.scala
new file mode 100644
index 0000000..953a751
--- /dev/null
+++ b/core/src/main/scala/com/nutomic/ensichat/core/util/RouteMessageInfo.scala
@@ -0,0 +1,74 @@
+package com.nutomic.ensichat.core.util
+
+import com.nutomic.ensichat.core.body.{RouteReply, RouteRequest}
+import com.nutomic.ensichat.core.{Address, Message, Router}
+import org.joda.time.{DateTime, Duration}
+
+/**
+  * Contains information about AODVv2 control messages that have been received.
+  *
+  * This class handles Route Request and Route Reply messages (referred to as "route messages").
+  *
+  * See AODVv2-13 4.6 (Multicast Route Message Table),                                        -> implemented
+  *               6.8 (Surpressing Redundant Messages Using the Multicast Route Message Table) -> implemented  (hopefully correct)
+  */
+private[core] class RouteMessageInfo {
+
+  private val MaxSeqnumLifetime = Duration.standardSeconds(300)
+
+  /**
+    * @param messageType Either [[RouteRequest.Type]] or [[RouteReply.Type]].
+    * @param origAddress Source address of the route message triggering the route request.
+    * @param targAddress Destination address of the route message triggering the route request.
+    * @param origSeqNum Sequence number associated with the route to [[origAddress]], if route
+    *                   message is an RREQ.
+    * @param targSeqNum Sequence number associated with the route to [[targAddress]], if present in
+    *                   the route message.
+    * @param metric Metric value received in the route message.
+    * @param timestamp Last time this entry was updated.
+    */
+  private case class RouteMessageEntry(messageType: Int, origAddress: Address,
+                                       targAddress: Address, origSeqNum: Int, targSeqNum: Int,
+                                       metric: Int, timestamp: DateTime)
+
+  private var entries = Set[RouteMessageEntry]()
+
+  private def addEntry(msg: Message): Unit = msg.body match {
+    case rreq: RouteRequest =>
+      entries += new RouteMessageEntry(RouteRequest.Type, msg.header.origin, msg.header.target,
+                                       msg.header.seqNum, rreq.targSeqNum, rreq.originMetric,
+                                       DateTime.now)
+    case rrep: RouteReply =>
+      entries += new RouteMessageEntry(RouteReply.Type, msg.header.origin, msg.header.target,
+                                       msg.header.seqNum, rrep.originSeqNum, rrep.originMetric,
+                                       DateTime.now)
+  }
+
+  def isMessageRedundant(msg: Message): Boolean = {
+    handleTimeouts()
+    val existingEntry =
+      entries.find { e =>
+        val haveEntry = e.messageType == msg.header.protocolType &&
+          e.origAddress == msg.header.origin && e.targAddress == msg.header.target
+
+        val (metric, seqNumComparison) = msg.body match {
+          case rreq: RouteRequest => (rreq.originMetric, Router.compare(rreq.originSeqNum, e.origSeqNum))
+          case rrep: RouteReply => (rrep.originMetric, Router.compare(rrep.originSeqNum, e.targSeqNum))
+        }
+        val isMetricBetter = e.metric < metric
+        haveEntry && (seqNumComparison > 0 || (seqNumComparison == 0 && isMetricBetter))
+      }
+    if (existingEntry.isDefined)
+        entries = entries - existingEntry.get
+
+    addEntry(msg)
+
+    existingEntry.isDefined
+  }
+
+  private def handleTimeouts(): Unit = {
+    entries = entries.filter { e =>
+      DateTime.now.isBefore(e.timestamp.plus(MaxSeqnumLifetime))
+    }
+  }
+}
\ No newline at end of file
diff --git a/core/src/test/scala/com/nutomic/ensichat/core/CryptoTest.scala b/core/src/test/scala/com/nutomic/ensichat/core/CryptoTest.scala
index d08a215..cbabf95 100644
--- a/core/src/test/scala/com/nutomic/ensichat/core/CryptoTest.scala
+++ b/core/src/test/scala/com/nutomic/ensichat/core/CryptoTest.scala
@@ -41,8 +41,9 @@ class CryptoTest extends TestCase {
   def testEncryptDecrypt(): Unit = {
     MessageTest.messages.foreach{ m =>
       val encrypted = crypto.encryptAndSign(m, Option(crypto.getLocalPublicKey))
-      val decrypted = crypto.verifyAndDecrypt(encrypted, Option(crypto.getLocalPublicKey))
-      assertEquals(m.body, decrypted.get.body)
+      assertTrue(crypto.verify(encrypted, Option(crypto.getLocalPublicKey)))
+      val decrypted = crypto.decrypt(encrypted)
+      assertEquals(m.body, decrypted.body)
       assertEquals(m.header, encrypted.header)
     }
   }
diff --git a/core/src/test/scala/com/nutomic/ensichat/core/MessageTest.scala b/core/src/test/scala/com/nutomic/ensichat/core/MessageTest.scala
index 881d42f..2af4609 100644
--- a/core/src/test/scala/com/nutomic/ensichat/core/MessageTest.scala
+++ b/core/src/test/scala/com/nutomic/ensichat/core/MessageTest.scala
@@ -58,9 +58,10 @@ class MessageTest extends TestCase {
 
       val read = Message.read(new ByteArrayInputStream(bytes))
       assertEquals(encrypted.crypto, read.crypto)
-      val decrypted = crypto.verifyAndDecrypt(read, Option(crypto.getLocalPublicKey))
-      assertEquals(m.header, decrypted.get.header)
-      assertEquals(m.body, decrypted.get.body)
+      assertTrue(crypto.verify(read, Option(crypto.getLocalPublicKey)))
+      val decrypted = crypto.decrypt(read)
+      assertEquals(m.header, decrypted.header)
+      assertEquals(m.body, decrypted.body)
     }
   }
 
diff --git a/core/src/test/scala/com/nutomic/ensichat/core/RouterTest.scala b/core/src/test/scala/com/nutomic/ensichat/core/RouterTest.scala
index 0441212..88ca751 100644
--- a/core/src/test/scala/com/nutomic/ensichat/core/RouterTest.scala
+++ b/core/src/test/scala/com/nutomic/ensichat/core/RouterTest.scala
@@ -1,34 +1,45 @@
 package com.nutomic.ensichat.core
 
+import java.util.concurrent.{CountDownLatch, TimeUnit}
 import java.util.{Date, GregorianCalendar}
 
 import com.nutomic.ensichat.core.body.{Text, UserInfo}
 import com.nutomic.ensichat.core.header.ContentHeader
+import com.nutomic.ensichat.core.util.LocalRoutesInfo
 import junit.framework.TestCase
 import org.junit.Assert._
 
 class RouterTest extends TestCase {
 
-  private def neighbors() = Set[Address](AddressTest.a1, AddressTest.a2, AddressTest.a3)
+  private def neighbors() = Set[Address](AddressTest.a1, AddressTest.a2, AddressTest.a4)
 
-  private val msg = generateMessage(AddressTest.a1, AddressTest.a4, 1)
+  def testNoRouteFound(): Unit = {
+    val msg = generateMessage(AddressTest.a2, AddressTest.a3, 1)
+    val latch = new CountDownLatch(1)
+    val router = new Router(new LocalRoutesInfo(neighbors),
+      (_, _) => fail("Message shouldn't be forwarded"), m => {
+        assertEquals(msg, m)
+        latch.countDown()
+      })
+    router.forwardMessage(msg)
+    assertTrue(latch.await(1, TimeUnit.SECONDS))
+  }
 
-  /**
-   * Messages should be sent to all neighbors.
-   */
-  def testFlooding(): Unit = {
+  def testNextHop(): Unit = {
+    val msg = generateMessage(AddressTest.a1, AddressTest.a4, 1)
     var sentTo = Set[Address]()
-    val router: Router = new Router(neighbors,
+    val router = new Router(new LocalRoutesInfo(neighbors),
       (a, m) => {
         sentTo += a
-      })
+      }, _ => ())
 
     router.forwardMessage(msg)
-    assertEquals(neighbors(), sentTo)
+    assertEquals(Set(AddressTest.a4), sentTo)
   }
 
   def testMessageSame(): Unit = {
-    val router: Router = new Router(neighbors,
+    val msg = generateMessage(AddressTest.a1, AddressTest.a4, 1)
+    val router = new Router(new LocalRoutesInfo(neighbors),
       (a, m) => {
         assertEquals(msg.header.origin,       m.header.origin)
         assertEquals(msg.header.target,       m.header.target)
@@ -38,7 +49,7 @@ class RouterTest extends TestCase {
         assertEquals(msg.header.hopLimit,     m.header.hopLimit)
         assertEquals(msg.body, m.body)
         assertEquals(msg.crypto, m.crypto)
-      })
+      }, _ => ())
     router.forwardMessage(msg)
   }
 
@@ -47,26 +58,32 @@ class RouterTest extends TestCase {
    */
   def testDifferentSenders(): Unit = {
     var sentTo = Set[Address]()
-    val router: Router = new Router(neighbors, (a, m) => sentTo += a)
+    val router = new Router(new LocalRoutesInfo(neighbors), (a, m) => sentTo += a, _ => ())
 
-    router.forwardMessage(msg)
-    assertEquals(neighbors(), sentTo)
+    router.forwardMessage(generateMessage(AddressTest.a1, AddressTest.a4, 1))
+    assertEquals(Set(AddressTest.a4), sentTo)
 
     sentTo = Set[Address]()
     router.forwardMessage(generateMessage(AddressTest.a2, AddressTest.a4, 1))
-    assertEquals(neighbors(), sentTo)
+    assertEquals(Set(AddressTest.a4), sentTo)
+  }
+
+  def testSeqNumComparison(): Unit = {
+    Router.compare(1, ContentHeader.SeqNumRange.last)
+    Router.compare(ContentHeader.SeqNumRange.last / 2, ContentHeader.SeqNumRange.last)
+    Router.compare(ContentHeader.SeqNumRange.last / 2, 1)
   }
   
   def testDiscardOldIgnores(): Unit = {
     def test(first: Int, second: Int) {
       var sentTo = Set[Address]()
-      val router: Router = new Router(neighbors, (a, m) => sentTo += a)
-      router.forwardMessage(generateMessage(AddressTest.a1, AddressTest.a3, first))
-      router.forwardMessage(generateMessage(AddressTest.a1, AddressTest.a3, second))
+      val router = new Router(new LocalRoutesInfo(neighbors), (a, m) => sentTo += a, _ => ())
+      router.forwardMessage(generateMessage(AddressTest.a1, AddressTest.a4, first))
+      router.forwardMessage(generateMessage(AddressTest.a1, AddressTest.a4, second))
 
       sentTo = Set[Address]()
-      router.forwardMessage(generateMessage(AddressTest.a1, AddressTest.a3, first))
-      assertEquals(neighbors(), sentTo)
+      router.forwardMessage(generateMessage(AddressTest.a1, AddressTest.a4, first))
+      assertEquals(Set(AddressTest.a4), sentTo)
     }
 
     test(1, ContentHeader.SeqNumRange.last)
@@ -77,7 +94,7 @@ class RouterTest extends TestCase {
   def testHopLimit(): Unit = Range(19, 22).foreach { i =>
     val msg = new Message(
       new ContentHeader(AddressTest.a1, AddressTest.a2, 1, 1, Some(1), Some(new Date()), i), new Text(""))
-    val router: Router = new Router(neighbors, (a, m) => fail())
+    val router = new Router(new LocalRoutesInfo(neighbors), (a, m) => fail(), _ => ())
     router.forwardMessage(msg)
   }
 
diff --git a/core/src/test/scala/com/nutomic/ensichat/core/body/RouteErrorTest.scala b/core/src/test/scala/com/nutomic/ensichat/core/body/RouteErrorTest.scala
new file mode 100644
index 0000000..51b2002
--- /dev/null
+++ b/core/src/test/scala/com/nutomic/ensichat/core/body/RouteErrorTest.scala
@@ -0,0 +1,16 @@
+package com.nutomic.ensichat.core.body
+
+import com.nutomic.ensichat.core.AddressTest
+import junit.framework.TestCase
+import org.junit.Assert._
+
+class RouteErrorTest extends TestCase {
+
+  def testWriteRead(): Unit = {
+    val rerr = new RouteError(AddressTest.a2, 62000)
+    val bytes = rerr.write
+    val parsed = RouteError.read(bytes)
+    assertEquals(rerr, parsed)
+  }
+
+}
diff --git a/core/src/test/scala/com/nutomic/ensichat/core/body/RouteReplyTest.scala b/core/src/test/scala/com/nutomic/ensichat/core/body/RouteReplyTest.scala
new file mode 100644
index 0000000..06149d0
--- /dev/null
+++ b/core/src/test/scala/com/nutomic/ensichat/core/body/RouteReplyTest.scala
@@ -0,0 +1,16 @@
+package com.nutomic.ensichat.core.body
+
+import com.nutomic.ensichat.core.AddressTest
+import junit.framework.TestCase
+import org.junit.Assert._
+
+class RouteReplyTest extends TestCase {
+
+  def testWriteRead(): Unit = {
+    val rrep = new RouteReply(61000, 123)
+    val bytes = rrep.write
+    val parsed = RouteReply.read(bytes)
+    assertEquals(rrep, parsed)
+  }
+
+}
diff --git a/core/src/test/scala/com/nutomic/ensichat/core/body/RouteRequestTest.scala b/core/src/test/scala/com/nutomic/ensichat/core/body/RouteRequestTest.scala
new file mode 100644
index 0000000..b726c2b
--- /dev/null
+++ b/core/src/test/scala/com/nutomic/ensichat/core/body/RouteRequestTest.scala
@@ -0,0 +1,16 @@
+package com.nutomic.ensichat.core.body
+
+import com.nutomic.ensichat.core.AddressTest
+import junit.framework.TestCase
+import org.junit.Assert._
+
+class RouteRequestTest extends TestCase {
+
+  def testWriteRead(): Unit = {
+    val rreq = new RouteRequest(AddressTest.a2, 60000, 60001, 60002)
+    val bytes = rreq.write
+    val parsed = RouteRequest.read(bytes)
+    assertEquals(rreq, parsed)
+  }
+
+}
diff --git a/core/src/test/scala/com/nutomic/ensichat/core/util/LocalRoutesInfoTest.scala b/core/src/test/scala/com/nutomic/ensichat/core/util/LocalRoutesInfoTest.scala
new file mode 100644
index 0000000..f5ebba6
--- /dev/null
+++ b/core/src/test/scala/com/nutomic/ensichat/core/util/LocalRoutesInfoTest.scala
@@ -0,0 +1,45 @@
+package com.nutomic.ensichat.core.util
+
+import com.nutomic.ensichat.core.AddressTest
+import junit.framework.TestCase
+import org.joda.time.{DateTime, DateTimeUtils, Duration}
+import org.junit.Assert._
+
+class LocalRoutesInfoTest extends TestCase {
+
+  private def connections() = Set(AddressTest.a1, AddressTest.a2)
+
+  def testRoute(): Unit = {
+    val routesInfo = new LocalRoutesInfo(connections)
+    routesInfo.addRoute(AddressTest.a3, 0, AddressTest.a1, 1)
+    val route = routesInfo.getRoute(AddressTest.a3)
+    assertEquals(AddressTest.a1, route.get.nextHop)
+  }
+
+  def testBestMetric(): Unit = {
+    val routesInfo = new LocalRoutesInfo(connections)
+    routesInfo.addRoute(AddressTest.a3, 0, AddressTest.a1, 1)
+    routesInfo.addRoute(AddressTest.a3, 0, AddressTest.a2, 2)
+    val route = routesInfo.getRoute(AddressTest.a3)
+    assertEquals(AddressTest.a1, route.get.nextHop)
+  }
+
+  def testConnectionClosed(): Unit = {
+    val routesInfo = new LocalRoutesInfo(connections)
+    routesInfo.addRoute(AddressTest.a3, 0, AddressTest.a1, 1)
+    routesInfo.addRoute(AddressTest.a4, 0, AddressTest.a1, 1)
+    // Mark the route as active, because only active routes are returned.
+    routesInfo.getRoute(AddressTest.a3)
+    val unreachable = routesInfo.connectionClosed(AddressTest.a1)
+    assertEquals(Set(AddressTest.a3), unreachable)
+  }
+
+  def testTimeout(): Unit = {
+    DateTimeUtils.setCurrentMillisFixed(new DateTime().getMillis)
+    val routesInfo = new LocalRoutesInfo(connections)
+    routesInfo.addRoute(AddressTest.a3, 0, AddressTest.a1, 1)
+    DateTimeUtils.setCurrentMillisFixed(DateTime.now.plus(Duration.standardSeconds(400)).getMillis)
+    assertEquals(None, routesInfo.getRoute(AddressTest.a3))
+  }
+
+}
\ No newline at end of file
diff --git a/core/src/test/scala/com/nutomic/ensichat/core/util/RouteMessageInfoTest.scala b/core/src/test/scala/com/nutomic/ensichat/core/util/RouteMessageInfoTest.scala
new file mode 100644
index 0000000..bc6e2b5
--- /dev/null
+++ b/core/src/test/scala/com/nutomic/ensichat/core/util/RouteMessageInfoTest.scala
@@ -0,0 +1,79 @@
+package com.nutomic.ensichat.core.util
+
+import com.nutomic.ensichat.core.body.{RouteReply, RouteRequest}
+import com.nutomic.ensichat.core.header.MessageHeader
+import com.nutomic.ensichat.core.{AddressTest, Message}
+import junit.framework.TestCase
+import org.joda.time.{DateTime, DateTimeUtils, Duration}
+import org.junit.Assert._
+
+class RouteMessageInfoTest extends TestCase {
+
+  /**
+    * Test case in which we have an entry with the same type, origin and target.
+    */
+  def testSameMessage(): Unit = {
+    val header = new MessageHeader(RouteRequest.Type, AddressTest.a1, AddressTest.a2, 1)
+    val msg = new Message(header, new RouteRequest(AddressTest.a3, 2, 3, 1))
+    val rmi = new RouteMessageInfo()
+    assertFalse(rmi.isMessageRedundant(msg))
+    assertTrue(rmi.isMessageRedundant(msg))
+  }
+
+  /**
+    * Forward a message with a seqnum that is older than the latest.
+    */
+  def testSeqNumOlder(): Unit = {
+    val header1 = new MessageHeader(RouteRequest.Type, AddressTest.a1, AddressTest.a2, 1)
+    val msg1 = new Message(header1, new RouteRequest(AddressTest.a3, 0, 0, 0))
+    val rmi = new RouteMessageInfo()
+    assertFalse(rmi.isMessageRedundant(msg1))
+
+    val header2 = new MessageHeader(RouteRequest.Type, AddressTest.a1, AddressTest.a2, 3)
+    val msg2 = new Message(header2, new RouteRequest(AddressTest.a3, 2, 0, 0))
+    assertTrue(rmi.isMessageRedundant(msg2))
+  }
+
+  /**
+    * Announce a route with a metric that is worse than the existing one.
+    */
+  def testMetricWorse(): Unit = {
+    val header1 = new MessageHeader(RouteRequest.Type, AddressTest.a1, AddressTest.a2, 1)
+    val msg1 = new Message(header1, new RouteRequest(AddressTest.a3, 1, 0, 2))
+    val rmi = new RouteMessageInfo()
+    assertFalse(rmi.isMessageRedundant(msg1))
+
+    val header2 = new MessageHeader(RouteRequest.Type, AddressTest.a1, AddressTest.a2, 2)
+    val msg2 = new Message(header2, new RouteRequest(AddressTest.a3, 1, 0, 4))
+    assertTrue(rmi.isMessageRedundant(msg2))
+  }
+
+  /**
+    * Announce route with a better metric.
+    */
+  def testMetricBetter(): Unit = {
+    val header1 = new MessageHeader(RouteRequest.Type, AddressTest.a1, AddressTest.a2, 1)
+    val msg1 = new Message(header1, new RouteReply(0, 4))
+    val rmi = new RouteMessageInfo()
+    assertFalse(rmi.isMessageRedundant(msg1))
+
+    val header2 = new MessageHeader(RouteRequest.Type, AddressTest.a1, AddressTest.a2, 2)
+    val msg2 = new Message(header2, new RouteReply(0, 2))
+    assertFalse(rmi.isMessageRedundant(msg2))
+  }
+
+  /**
+    * Test that entries are removed after [[RouteMessageInfo.MaxSeqnumLifetime]].
+    */
+  def testTimeout(): Unit = {
+    val rmi = new RouteMessageInfo()
+    DateTimeUtils.setCurrentMillisFixed(DateTime.now.getMillis)
+    val header = new MessageHeader(RouteRequest.Type, AddressTest.a1, AddressTest.a2, 1)
+    val msg = new Message(header, new RouteRequest(AddressTest.a3, 0, 0, 0))
+    assertFalse(rmi.isMessageRedundant(msg))
+
+    DateTimeUtils.setCurrentMillisFixed(DateTime.now.plus(Duration.standardSeconds(400)).getMillis)
+    assertFalse(rmi.isMessageRedundant(msg))
+  }
+
+}
\ No newline at end of file
diff --git a/integration/.gitignore b/integration/.gitignore
new file mode 100644
index 0000000..796b96d
--- /dev/null
+++ b/integration/.gitignore
@@ -0,0 +1 @@
+/build
diff --git a/integration/build.gradle b/integration/build.gradle
new file mode 100644
index 0000000..6736632
--- /dev/null
+++ b/integration/build.gradle
@@ -0,0 +1,12 @@
+apply plugin: 'scala'
+apply plugin: 'application'
+
+dependencies {
+    compile 'org.scala-lang:scala-library:2.11.7'
+    compile 'com.github.scala-incubator.io:scala-io-file_2.11:0.4.3'
+    compile project(path: ':core')
+}
+
+mainClassName = 'com.nutomic.ensichat.integration.Main'
+version = "0.2.3"
+applicationName = 'ensichat-server'
diff --git a/integration/src/main/scala/com.nutomic.ensichat.integration/LocalNode.scala b/integration/src/main/scala/com.nutomic.ensichat.integration/LocalNode.scala
new file mode 100644
index 0000000..58c58af
--- /dev/null
+++ b/integration/src/main/scala/com.nutomic.ensichat.integration/LocalNode.scala
@@ -0,0 +1,84 @@
+package com.nutomic.ensichat.integration
+
+import java.io.File
+import java.util.concurrent.{LinkedBlockingDeque, LinkedBlockingQueue}
+
+import com.nutomic.ensichat.core.body.{RouteError, RouteRequest, RouteReply}
+import com.nutomic.ensichat.core.interfaces.{CallbackInterface, SettingsInterface}
+import com.nutomic.ensichat.core.util.Database
+import com.nutomic.ensichat.core.{ConnectionHandler, Crypto, Message}
+import com.nutomic.ensichat.integration.LocalNode._
+
+import scala.concurrent.Await
+import scala.concurrent.duration.Duration
+import scalax.file.Path
+
+object LocalNode {
+
+  private final val StartingPort = 21000
+
+  object EventType extends Enumeration {
+    type EventType = Value
+    val MessageReceived, ConnectionsChanged, ContactsUpdated = Value
+  }
+
+  class FifoStream[A]() {
+    private val queue = new LinkedBlockingQueue[Option[A]]()
+    def toStream: Stream[A] = queue.take match {
+      case Some(a) => Stream.cons(a, toStream)
+      case None => Stream.empty
+    }
+    def close() = queue add None
+    def enqueue(a: A) = queue.put(Option(a))
+  }
+
+}
+
+/**
+  * Runs an ensichat node on localhost.
+  *
+  * Received messages can be accessed through [[eventQueue]].
+  *
+  * @param index Number of this node. The server port is opened on port [[StartingPort]] + index.
+  * @param configFolder Folder where keys and configuration should be stored.
+  */
+class LocalNode(val index: Int, configFolder: File) extends CallbackInterface {
+
+  import com.nutomic.ensichat.integration.LocalNode.EventType._
+  private val databaseFile = new File(configFolder, "database")
+  private val keyFolder    = new File(configFolder, "keys")
+
+  private val database = new Database(databaseFile, this)
+  private val settings = new SettingsInterface {
+    private var values = Map[String, Any]()
+    override def get[T](key: String, default: T): T = values.get(key).map(_.asInstanceOf[T]).getOrElse(default)
+    override def put[T](key: String, value: T): Unit = values += (key -> value.asInstanceOf[Any])
+  }
+
+  val crypto            = new Crypto(settings, keyFolder)
+  val connectionHandler = new ConnectionHandler(settings, database, this, crypto, 0, port)
+  val eventQueue        = new FifoStream[(EventType.EventType, Option[Message])]()
+
+  configFolder.mkdirs()
+  keyFolder.mkdirs()
+  settings.put(SettingsInterface.KeyAddresses, "")
+  Await.result(connectionHandler.start(), Duration.Inf)
+
+  def port = StartingPort + index
+
+  def stop(): Unit = {
+    connectionHandler.stop()
+    Path(configFolder).deleteRecursively()
+  }
+
+  def onMessageReceived(msg: Message): Unit = {
+    eventQueue.enqueue((EventType.MessageReceived, Option(msg)))
+  }
+
+  def onConnectionsChanged(): Unit =
+    eventQueue.enqueue((EventType.ConnectionsChanged, None))
+
+  def onContactsUpdated(): Unit =
+    eventQueue.enqueue((EventType.ContactsUpdated, None))
+
+}
diff --git a/integration/src/main/scala/com.nutomic.ensichat.integration/Main.scala b/integration/src/main/scala/com.nutomic.ensichat.integration/Main.scala
new file mode 100644
index 0000000..65ccc90
--- /dev/null
+++ b/integration/src/main/scala/com.nutomic.ensichat.integration/Main.scala
@@ -0,0 +1,135 @@
+package com.nutomic.ensichat.integration
+
+import java.io.File
+import java.util.concurrent.{CountDownLatch, TimeUnit}
+
+import com.nutomic.ensichat.core.Crypto
+import com.nutomic.ensichat.core.body.Text
+
+import scala.concurrent.ExecutionContext.Implicits.global
+import scala.concurrent.duration.Duration
+import scala.concurrent.{Await, Future}
+import scala.util.Try
+
+/**
+ * Creates some local nodes, connects them and sends messages between them.
+ *
+ * If the test runs slow or fails, changing [[Crypto.PublicKeySize]] to 512 should help.
+ */
+object Main extends App {
+
+  val nodes = createMesh()
+  System.out.println("\n\nAll nodes connected!\n\n")
+
+  sendMessages(nodes)
+  System.out.println("\n\nAll messages sent!\n\n")
+
+  // Stop node 1, forcing route errors and messages to use the (longer) path via nodes 7 and 8.
+  nodes(1).connectionHandler.stop()
+  System.out.println("node 1 stopped")
+  sendMessages(nodes)
+
+  /**
+    * Creates a new mesh with a predefined layout.
+    *
+    * Graphical representation:
+    *     8 —— 7
+    *    /      \
+    *   0———1———3———4
+    *    \ /    |   |
+    *     2     5———6
+    *
+    * @return List of [[LocalNode]]s, ordered from 0 to 7.
+    */
+  private def createMesh(): Seq[LocalNode] = {
+    val nodes = Await.result(Future.sequence(0.to(8).map(createNode)), Duration.Inf)
+    sys.addShutdownHook(nodes.foreach(_.stop()))
+
+    connectNodes(nodes(0), nodes(1))
+    connectNodes(nodes(0), nodes(2))
+    connectNodes(nodes(1), nodes(2))
+    connectNodes(nodes(1), nodes(3))
+    connectNodes(nodes(3), nodes(4))
+    connectNodes(nodes(3), nodes(5))
+    connectNodes(nodes(4), nodes(6))
+    connectNodes(nodes(5), nodes(6))
+    connectNodes(nodes(3), nodes(7))
+    connectNodes(nodes(0), nodes(8))
+    connectNodes(nodes(7), nodes(8))
+    nodes.foreach(n => System.out.println(s"Node ${n.index} has address ${n.crypto.localAddress}"))
+
+    nodes
+  }
+
+  private def createNode(index: Int): Future[LocalNode] = {
+    val configFolder = new File(s"build/node$index/")
+    assert(!configFolder.exists(), s"stale config exists in $configFolder")
+    Future(new LocalNode(index, configFolder))
+  }
+
+  private def connectNodes(first: LocalNode, second: LocalNode): Unit = {
+    first.connectionHandler.connect(s"localhost:${second.port}")
+
+    first.eventQueue.toStream.find(_._1 == LocalNode.EventType.ConnectionsChanged)
+    second.eventQueue.toStream.find(_._1 == LocalNode.EventType.ConnectionsChanged)
+
+    val firstAddress      = first.crypto.localAddress
+    val secondAddress     = second.crypto.localAddress
+    val firstConnections  = first.connectionHandler.connections()
+    val secondConnections = second.connectionHandler.connections()
+
+    assert(firstConnections.contains(secondAddress),
+      s"${first.index} is not connected to ${second.index}")
+    assert(secondConnections.contains(firstAddress),
+      s"${second.index} is not connected to ${second.index}")
+
+    System.out.println(s"${first.index} and ${second.index} connected")
+  }
+
+  private def sendMessages(nodes: Seq[LocalNode]): Unit = {
+    sendMessage(nodes(0), nodes(2))
+    sendMessage(nodes(2), nodes(0))
+    sendMessage(nodes(4), nodes(3))
+    sendMessage(nodes(3), nodes(5))
+    sendMessage(nodes(4), nodes(6))
+    sendMessage(nodes(2), nodes(3))
+    sendMessage(nodes(0), nodes(3))
+    sendMessage(nodes(3), nodes(6))
+    sendMessage(nodes(3), nodes(2))
+  }
+
+
+  private def sendMessage(from: LocalNode, to: LocalNode): Unit = {
+    addKey(to.crypto, from.crypto)
+    addKey(from.crypto, to.crypto)
+
+    System.out.println(s"sendMessage(${from.index}, ${to.index})")
+    val text = s"${from.index} to ${to.index}"
+    from.connectionHandler.sendTo(to.crypto.localAddress, new Text(text))
+
+    val latch = new CountDownLatch(1)
+    Future {
+      val exists =
+        to.eventQueue.toStream.exists { event =>
+          if (event._1 != LocalNode.EventType.MessageReceived)
+            false
+          else {
+            event._2.get.body match {
+              case t: Text => t.text == text
+              case _ => false
+            }
+          }
+        }
+      assert(exists, s"message from ${from.index} did not arrive at ${to.index}")
+      latch.countDown()
+    }
+    assert(latch.await(1000, TimeUnit.MILLISECONDS))
+  }
+
+  private def addKey(addTo: Crypto, addFrom: Crypto): Unit = {
+    if (Try(addTo.getPublicKey(addFrom.localAddress)).isFailure)
+      addTo.addPublicKey(addFrom.localAddress, addFrom.getLocalPublicKey)
+
+  }
+
+}
\ No newline at end of file
diff --git a/settings.gradle b/settings.gradle
index 65899c0..e61120e 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1 +1 @@
-include ':android', ':core', ':server'
+include ':android', ':core', ':server', ':integration'