diff --git a/src/as/com/threerings/presents/client/Client.as b/src/as/com/threerings/presents/client/Client.as
index 193dfad3b..bd1d8f3ec 100644
--- a/src/as/com/threerings/presents/client/Client.as
+++ b/src/as/com/threerings/presents/client/Client.as
@@ -22,7 +22,7 @@ import com.threerings.presents.net.PongResponse;
 public class Client extends EventDispatcher
 {
     /** The default port on which the server listens for client connections. */
-    public static const DEFAULT_SERVER_PORT :int = 47624;
+    public static const DEFAULT_SERVER_PORTS :Array = [ 47624 ];
 
     private static const log :Log = Log.getLog(Client);
 
@@ -84,10 +84,10 @@ public class Client extends EventDispatcher
         }
     }
 
-    public function setServer (hostname :String, port :int) :void
+    public function setServer (hostname :String, ports :Array) :void
     {
         _hostname = hostname;
-        _port = port;
+        _ports = ports;
     }
 
     /**
@@ -103,9 +103,12 @@ public class Client extends EventDispatcher
         return _hostname;
     }
 
-    public function getPort () :int
+    /**
+     * Returns the ports on which this client is configured to connect.
+     */
+    public function getPorts () :Array
     {
-        return _port;
+        return _ports;
     }
 
     public function getCredentials () :Credentials
@@ -276,6 +279,15 @@ public class Client extends EventDispatcher
         }
     }
 
+    /**
+     * Called by the {@link Communicator} if it is experiencing trouble logging
+     * on but is still trying fallback strategies.
+     */
+    internal function reportLogonTribulations (cause :LogonError) :void
+    {
+        notifyObservers(ClientEvent.CLIENT_FAILED_TO_LOGON, cause);
+    }
+
     // TODO: this should be 'internal' except for a fucking bug with AS3
     public function gotClientObject (clobj :ClientObject) :void
     {
@@ -359,7 +371,7 @@ public class Client extends EventDispatcher
     protected var _hostname :String;
 
     /** The port on which we connect to the game server. */
-    protected var _port :int;
+    protected var _ports :Array; /* of int */
 
     /** The entity that manages our network communications. */
     protected var _comm :Communicator;
diff --git a/src/as/com/threerings/presents/client/ClientObserver.as b/src/as/com/threerings/presents/client/ClientObserver.as
index 2b29f7fce..0ca721075 100644
--- a/src/as/com/threerings/presents/client/ClientObserver.as
+++ b/src/as/com/threerings/presents/client/ClientObserver.as
@@ -53,6 +53,14 @@ public interface ClientObserver extends SessionObserver
      * Called if anything fails during the logon attempt. This could be a
      * network failure, authentication failure or otherwise. The exception
      * provided will indicate the cause of the failure.
+     *
+     * @param cause an exception indicating the cause of the logon failure.
+     * <em>Note:</em> this may be a {@link LogonError} and if so, the
+     * caller <em>must</em> check {@link LogonException#isStillInProgress} to
+     * find out if the logon process has totally failed or if we are simply
+     * reporting intermediate status (we might be falling back to an
+     * alternative port or delaying our auto-retry attempt due to server
+     * overload).
      */
     function clientFailedToLogon (event :ClientEvent) :void;
 
diff --git a/src/as/com/threerings/presents/client/Communicator.as b/src/as/com/threerings/presents/client/Communicator.as
index 9f9eeb72f..3ed161145 100644
--- a/src/as/com/threerings/presents/client/Communicator.as
+++ b/src/as/com/threerings/presents/client/Communicator.as
@@ -1,5 +1,7 @@
 package com.threerings.presents.client {
 
+import flash.errors.IOError;
+
 import flash.events.Event;
 import flash.events.IOErrorEvent;
 
@@ -16,6 +18,7 @@ import com.threerings.io.ObjectInputStream;
 import com.threerings.io.ObjectOutputStream;
 import com.threerings.io.Translations;
 
+import com.threerings.presents.data.AuthCodes;
 import com.threerings.presents.net.AuthRequest;
 import com.threerings.presents.net.AuthResponse;
 import com.threerings.presents.net.AuthResponseData;
@@ -32,24 +35,77 @@ public class Communicator
 
     public function logon () :void
     {
-        // create the socket and set up listeners
-        _socket = new Socket();
-        _socket.endian = Endian.BIG_ENDIAN;
-        _socket.addEventListener(Event.CONNECT, socketOpened);
-        _socket.addEventListener(IOErrorEvent.IO_ERROR, socketError);
-        _socket.addEventListener(Event.CLOSE, socketClosed);
-
         // create our input/output business
         _outBuffer = new ByteArray();
         _outBuffer.endian = Endian.BIG_ENDIAN;
         _outStream = new ObjectOutputStream(_outBuffer);
 
-        _frameReader = new FrameReader(_socket);
-        _frameReader.addEventListener(FrameAvailableEvent.FRAME_AVAILABLE,
-            inputFrameReceived);
         _inStream = new ObjectInputStream();
 
-        _socket.connect(_client.getHostname(), _client.getPort());
+        _portIdx = 0;
+        logonToPort();
+    }
+
+    /**
+     * This method is strangely named, and it does two things which is
+     * bad style. Either log on to the next port, or save that the port
+     * we just logged on to was a good one.
+     */
+    protected function logonToPort (logonWasSuccessful :Boolean = false) :Boolean
+    {
+        var ports :Array = _client.getPorts();
+
+        if (!logonWasSuccessful) {
+            if (_portIdx >= ports.length) {
+                return false;
+            }
+            if (_portIdx != 0) {
+                _client.reportLogonTribulations(
+                    new LogonError(AuthCodes.TRYING_NEXT_PORT, true));
+
+                removeListeners();
+            }
+
+            // create the socket and set up listeners
+            _socket = new Socket();
+            _socket.endian = Endian.BIG_ENDIAN;
+            _socket.addEventListener(Event.CONNECT, socketOpened);
+            _socket.addEventListener(IOErrorEvent.IO_ERROR, socketError);
+            _socket.addEventListener(Event.CLOSE, socketClosed);
+
+            _frameReader = new FrameReader(_socket);
+            _frameReader.addEventListener(FrameAvailableEvent.FRAME_AVAILABLE,
+                inputFrameReceived);
+        }
+
+        var host :String = _client.getHostname();
+        var pportKey :String = host + ".preferred_port";
+        // TODO: extract preferred port from saved prefs
+        var pport :int = /** TODO Prefs.getValue(pportKey, **/ (ports[0] as int);
+        var ppidx :int = Math.max(0, ports.indexOf(pport));
+        var port :int = (ports[(_portIdx + ppidx) % ports.length] as int);
+
+        if (logonWasSuccessful) {
+            _portIdx = -1; // indicate that we're no longer trying new ports
+            // TODO: Prefs.setValue(pportKey, port);
+
+        } else {
+            Log.getLog(this).info(
+                "Connecting [host=" + host + ", port=" + port + "].");
+            _socket.connect(host, port);
+        }
+
+        return true;
+    }
+
+    protected function removeListeners () :void
+    {
+        _socket.removeEventListener(Event.CONNECT, socketOpened);
+        _socket.removeEventListener(IOErrorEvent.IO_ERROR, socketError);
+        _socket.removeEventListener(Event.CLOSE, socketClosed);
+
+        _frameReader.removeEventListener(FrameAvailableEvent.FRAME_AVAILABLE,
+            inputFrameReceived);
     }
 
     public function logoff () :void
@@ -77,6 +133,7 @@ public class Communicator
                 Log.getLog(this).warning(
                     "Error closing failed socket [error=" + err + "].");
             }
+            removeListeners();
             _socket = null;
             _outStream = null;
             _inStream = null;
@@ -169,6 +226,7 @@ public class Communicator
      */
     protected function socketOpened (event :Event) :void
     {
+        logonToPort(true);
         // well that's great! let's logon
         var req :AuthRequest = new AuthRequest(_client.getCredentials(),
             _client.getVersion());
@@ -180,6 +238,16 @@ public class Communicator
      */
     protected function socketError (event :IOErrorEvent) :void
     {
+        _socket.close();
+        // if we're trying ports, try the next one.
+        if (_portIdx != -1) {
+            _portIdx++;
+            if (logonToPort()) {
+                return;
+            }
+        }
+
+        // total failure
         Log.getLog(this).warning("socket error: " + event);
         shutdown(new Error("socket closed unexpectedly."));
     }
@@ -206,5 +274,8 @@ public class Communicator
     protected var _socket :Socket;
 
     protected var _lastWrite :uint;
+
+    /** The current port we'll try to connect to. */
+    protected var _portIdx :int = -1;
 }
 }
diff --git a/src/as/com/threerings/presents/client/LogonError.as b/src/as/com/threerings/presents/client/LogonError.as
new file mode 100644
index 000000000..0550d4a55
--- /dev/null
+++ b/src/as/com/threerings/presents/client/LogonError.as
@@ -0,0 +1,55 @@
+//
+// $Id: LogonException.java 4158 2006-05-30 22:12:15Z mdb $
+//
+// Narya library - tools for developing networked games
+// Copyright (C) 2002-2004 Three Rings Design, Inc., All Rights Reserved
+// http://www.threerings.net/code/narya/
+//
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.threerings.presents.client {
+
+/**
+ * A logon exception is used to indicate a failure to log on to the
+ * server. The reason for failure is encoded as a string and stored in the
+ * message field of the exception.
+ */
+public class LogonError extends Error
+{
+    /**
+     * Constructs a logon exception with the supplied logon failure code.
+     */
+    public function LogonError (msg :String, stillInProgress :Boolean = false)
+    {
+        super(msg);
+        _stillInProgress = stillInProgress;
+    }
+
+    /**
+     * Returns true if this exception is reporting an intermediate status
+     * rather than total logon failure. The client may be falling back to an
+     * alternative port or delaying an auto-retry attempt due to server
+     * overload. If this method returns true, the client <em>should not</em>
+     * allow additional calls to {@link Client#logon} as the current attempt is
+     * still in progress.
+     */
+    public function isStillInProgress () :Boolean
+    {
+        return _stillInProgress;
+    }
+
+    protected var _stillInProgress :Boolean;
+}
+}
diff --git a/src/as/com/threerings/presents/data/AuthCodes.as b/src/as/com/threerings/presents/data/AuthCodes.as
new file mode 100644
index 000000000..6d0379609
--- /dev/null
+++ b/src/as/com/threerings/presents/data/AuthCodes.as
@@ -0,0 +1,47 @@
+//
+// $Id: AuthCodes.java 4158 2006-05-30 22:12:15Z mdb $
+//
+// Narya library - tools for developing networked games
+// Copyright (C) 2002-2004 Three Rings Design, Inc., All Rights Reserved
+// http://www.threerings.net/code/narya/
+//
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.threerings.presents.data {
+
+/**
+ * Basic authentication response codes.
+ */
+public class AuthCodes
+{
+    /** A code indicating that no user exists with the specified
+     * username. */
+    public static const NO_SUCH_USER :String = "m.no_such_user";
+
+    /** A code indicating that the supplied password was invalid. */
+    public static const INVALID_PASSWORD :String = "m.invalid_password";
+
+    /** A code indicating that an internal server error occurred while
+     * trying to log the user on. */
+    public static const SERVER_ERROR :String = "m.server_error";
+
+    /** A code indicating that the server is not available at the moment. */
+    public static const SERVER_UNAVAILABLE :String = "m.server_unavailable";
+
+    /** A code indicating that we failed to connect to the server on a port and
+     * are trying the next port in the list. */
+    public static const TRYING_NEXT_PORT :String = "m.trying_next_port";
+}
+}