diff --git a/network.hpp b/network.hpp
index 1c03a81..1a1d873 100644
--- a/network.hpp
+++ b/network.hpp
@@ -80,6 +80,7 @@ namespace Network {
 
     int port( void );
     string get_key( void ) { return key.printable_key(); }
+    bool get_attached( void ) { return attached; }
   };
 }
 
diff --git a/networktransport.cpp b/networktransport.cpp
index 04e38dc..03f4ee3 100644
--- a/networktransport.cpp
+++ b/networktransport.cpp
@@ -77,11 +77,19 @@ void Transport<MyState, RemoteState>::send_to_receiver( void )
      sequence of diffs (this time limited by MTU) that bring us to
      that state. */
 
+  if ( !connection.get_attached() ) {
+    return;
+  }
+
   MyState target_receiver_state( assumed_receiver_state->state );
   target_receiver_state.apply_string( current_state.diff_from( target_receiver_state, -1 ) );
 
   if ( assumed_receiver_state->state == target_receiver_state ) {
     /* send empty ack */
+    if ( timestamp() - sent_states.back().timestamp < int64_t( ACK_INTERVAL ) ) {
+      return;
+    }
+
     Instruction inst( assumed_receiver_state->num,
 		      assumed_receiver_state->num,
 		      received_states.back().num,
@@ -221,7 +229,7 @@ void Transport<MyState, RemoteState>::recv( void )
   }
 
   if ( !found ) {
-    fprintf( stderr, "Ignoring out-of-order packet. Reference state %d has been discarded.\n", int(inst.old_num) );
+    //    fprintf( stderr, "Ignoring out-of-order packet. Reference state %d has been discarded or hasn't yet been received.\n", int(inst.old_num) );
     return;
   }
 
diff --git a/networktransport.hpp b/networktransport.hpp
index bb7cbe3..0a32d0f 100644
--- a/networktransport.hpp
+++ b/networktransport.hpp
@@ -50,7 +50,8 @@ namespace Network {
   private:
     static const int INITIAL_TIMEOUT = 1000; /* ms, same as TCP */
     static const int SEND_INTERVAL = 20; /* ms between frames */
-    static const int HEADER_LEN = 80;
+    static const int ACK_INTERVAL = 1000; /* ms between empty acks */
+    static const int HEADER_LEN = 100;
 
     /* helper methods for tick() */
     void update_assumed_receiver_state( void );
diff --git a/ntester.cpp b/ntester.cpp
index abd3a47..a626b4f 100644
--- a/ntester.cpp
+++ b/ntester.cpp
@@ -52,16 +52,32 @@ int main( int argc, char *argv[] )
   fprintf( stderr, "Port bound is %d, key is %s\n", n->port(), n->get_key().c_str() );
 
   if ( server ) {
+    struct pollfd my_pollfd;
+    my_pollfd.fd = n->fd();
+    my_pollfd.events = POLLIN;
+    uint64_t last_num = n->get_remote_state_num();
     while ( true ) {
       try {
-	n->recv();
 	n->tick();
-	fprintf( stderr, "Num: %d. Contents: ",
-		 (int)n->get_remote_state_num() );
-	for ( size_t i = 0; i < n->get_remote_state().user_bytes.size(); i++ ) {
-	  fprintf( stderr, "%c", n->get_remote_state().user_bytes[ i ] );
+
+	if ( poll( &my_pollfd, 1, 10 ) < 0 ) {
+	  perror( "poll" );
+	  exit( 1 );
+	}
+	
+	if ( my_pollfd.revents & POLLIN ) {
+	  n->recv();
+
+	  if ( n->get_remote_state_num() != last_num ) {
+	    fprintf( stderr, "Num: %d. Contents: ",
+		     (int)n->get_remote_state_num() );
+	    for ( size_t i = 0; i < n->get_remote_state().user_bytes.size(); i++ ) {
+	      fprintf( stderr, "%c", n->get_remote_state().user_bytes[ i ] );
+	    }
+	    fprintf( stderr, "\n" );
+	    last_num = n->get_remote_state_num();
+	  }
 	}
-	fprintf( stderr, "\n" );
       } catch ( CryptoException e ) {
 	fprintf( stderr, "Cryptographic error: %s\n", e.text.c_str() );
       }
@@ -84,16 +100,29 @@ int main( int argc, char *argv[] )
       exit( 1 );
     }
 
+    struct pollfd fds[ 2 ];
+    fds[ 0 ].fd = STDIN_FILENO;
+    fds[ 0 ].events = POLLIN;
+
+    fds[ 1 ].fd = n->fd();
+    fds[ 1 ].events = POLLIN;
+
     while( true ) {
-      char x = getchar();
-      
-      n->get_current_state().key_hit( x );
-      
       try {
-	if ( readable( n->fd() ) ) {
+	n->tick();
+
+	if ( poll( fds, 2, 10 ) < 0 ) {
+	  perror( "poll" );
+	}
+
+	if ( fds[ 0 ].revents & POLLIN ) {
+	  char x = getchar();
+	  n->get_current_state().key_hit( x );
+	}
+
+	if ( fds[ 1 ].revents & POLLIN ) {
 	  n->recv();
 	}
-	n->tick();
       } catch ( Network::NetworkException e ) {
 	fprintf( stderr, "%s: %s\r\n", e.function.c_str(), strerror( e.the_errno ) );
 	break;