diff --git a/java/org/servalproject/servaldna/AbstractMdpProtocol.java b/java/org/servalproject/servaldna/AbstractMdpProtocol.java
index aa35ce8f..c489eefc 100644
--- a/java/org/servalproject/servaldna/AbstractMdpProtocol.java
+++ b/java/org/servalproject/servaldna/AbstractMdpProtocol.java
@@ -35,6 +35,15 @@ public abstract class AbstractMdpProtocol<T>  extends ChannelSelector.Handler {
 		socket.close();
 	}
 
+	public void rebind() throws IOException {
+		selector.unregister(this);
+		try{
+			socket.rebind();
+		}finally{
+			selector.register(this);
+		}
+	}
+
 	protected abstract void parse(MdpPacket response);
 
 	@Override
diff --git a/java/org/servalproject/servaldna/MdpSocket.java b/java/org/servalproject/servaldna/MdpSocket.java
index 41a28123..dd868643 100644
--- a/java/org/servalproject/servaldna/MdpSocket.java
+++ b/java/org/servalproject/servaldna/MdpSocket.java
@@ -51,6 +51,8 @@ public class MdpSocket{
 	public synchronized void bind(SubscriberId sid, int port) throws IOException {
 		if (loopbackMdpPort==0)
 			throw new IOException("Loopback MDP port has not been set");
+		if (sid==null)
+			throw new NullPointerException();
 		if (sid.equals(this.sid) && this.port == port)
 			return;
 		if (this.sid!=null)
@@ -80,6 +82,14 @@ public class MdpSocket{
 		this.port = packet.getLocalPort();
 	}
 
+	public void rebind() throws IOException{
+		if (this.sid==null)
+			return;
+		SubscriberId sid = this.sid;
+		this.sid=null;
+		bind(sid, this.port);
+	}
+
 	public SelectableChannel getChannel() throws IOException {
 		if (channel == null){
 			channel = DatagramChannel.open();
@@ -114,6 +124,7 @@ public class MdpSocket{
 				// ignore errors due to servald stopping.
 				e.printStackTrace();
 			}
+			sid = null;
 		}
 		if (channel!=null){
 			try {