diff --git a/include/libtorrent/kademlia/dht_tracker.hpp b/include/libtorrent/kademlia/dht_tracker.hpp
index cbb11336f..ef07b1b91 100644
--- a/include/libtorrent/kademlia/dht_tracker.hpp
+++ b/include/libtorrent/kademlia/dht_tracker.hpp
@@ -90,6 +90,7 @@ namespace libtorrent { namespace dht
 		// translate bittorrent kademlia message into the generic kademlia message
 		// used by the library
 		void on_receive(udp::endpoint const& ep, char const* pkt, int size);
+		void on_unreachable(udp::endpoint const& ep);
 
 	private:
 	
diff --git a/include/libtorrent/kademlia/node.hpp b/include/libtorrent/kademlia/node.hpp
index 44341bb1a..88a1677f1 100644
--- a/include/libtorrent/kademlia/node.hpp
+++ b/include/libtorrent/kademlia/node.hpp
@@ -172,6 +172,7 @@ public:
 	void(std::vector<node_entry> const&)> f);
 	void add_router_node(udp::endpoint router);
 		
+	void unreachable(udp::endpoint const& ep);
 	void incoming(msg const& m);
 
 	void refresh();
diff --git a/include/libtorrent/kademlia/rpc_manager.hpp b/include/libtorrent/kademlia/rpc_manager.hpp
index 05bb10836..837c091dd 100644
--- a/include/libtorrent/kademlia/rpc_manager.hpp
+++ b/include/libtorrent/kademlia/rpc_manager.hpp
@@ -81,6 +81,8 @@ public:
 		, routing_table& table, send_fun const& sf);
 	~rpc_manager();
 
+	void unreachable(udp::endpoint const& ep);
+
 	// returns true if the node needs a refresh
 	bool incoming(msg const&);
 	time_duration tick();
diff --git a/src/kademlia/dht_tracker.cpp b/src/kademlia/dht_tracker.cpp
index 07ca76d04..7ce6d7fa6 100644
--- a/src/kademlia/dht_tracker.cpp
+++ b/src/kademlia/dht_tracker.cpp
@@ -372,6 +372,12 @@ namespace libtorrent { namespace dht
 		m_dht.announce(ih, listen_port, f);
 	}
 
+
+	void dht_tracker::on_unreachable(udp::endpoint const& ep)
+	{
+		m_dht.unreachable(ep);
+	}
+
 	// translate bittorrent kademlia message into the generice kademlia message
 	// used by the library
 	void dht_tracker::on_receive(udp::endpoint const& ep, char const* buf, int bytes_transferred)
diff --git a/src/kademlia/node.cpp b/src/kademlia/node.cpp
index 6ea433040..c3f1cb6e1 100644
--- a/src/kademlia/node.cpp
+++ b/src/kademlia/node.cpp
@@ -243,6 +243,11 @@ void node_impl::refresh_bucket(int bucket) try
 }
 catch (std::exception&) {}
 
+void node_impl::unreachable(udp::endpoint const& ep)
+{
+	m_rpc.unreachable(ep);
+}
+
 void node_impl::incoming(msg const& m)
 {
 	if (m_rpc.incoming(m))
diff --git a/src/kademlia/rpc_manager.cpp b/src/kademlia/rpc_manager.cpp
index 4319fc4b8..384be2eed 100644
--- a/src/kademlia/rpc_manager.cpp
+++ b/src/kademlia/rpc_manager.cpp
@@ -159,6 +159,39 @@ void rpc_manager::check_invariant() const
 }
 #endif
 
+void rpc_manager::unreachable(udp::endpoint const& ep)
+{
+#ifdef TORRENT_DHT_VERBOSE_LOGGING
+	TORRENT_LOG(rpc) << time_now_string() << " PORT_UNREACHABLE [ ip: " << ep << " ]";
+#endif
+	int num_active = m_oldest_transaction_id < m_next_transaction_id
+		? m_next_transaction_id - m_oldest_transaction_id
+		: max_transactions - m_next_transaction_id + m_oldest_transaction_id;
+	TORRENT_ASSERT((m_oldest_transaction_id + num_active) % max_transactions
+		== m_next_transaction_id);
+	int tid = m_oldest_transaction_id;
+	for (int i = 0; i < num_active; ++i, ++tid)
+	{
+		if (tid >= max_transactions) tid = 0;
+		observer_ptr const& o = m_transactions[tid];
+		if (!o) continue;
+		if (o->target_addr != ep) continue;
+		observer_ptr ptr = m_transactions[tid];
+		m_transactions[tid] = 0;
+		if (tid == m_oldest_transaction_id)
+		{
+			++m_oldest_transaction_id;
+			if (m_oldest_transaction_id >= max_transactions)
+				m_oldest_transaction_id = 0;
+		}
+#ifdef TORRENT_DHT_VERBOSE_LOGGING
+		TORRENT_LOG(rpc) << "  found transaction [ tid: " << tid << " ]";
+#endif
+		ptr->timeout();
+		return;
+	}
+}
+
 bool rpc_manager::incoming(msg const& m)
 {
 	INVARIANT_CHECK;
diff --git a/src/session_impl.cpp b/src/session_impl.cpp
index 6ca5445cc..05574ca15 100755
--- a/src/session_impl.cpp
+++ b/src/session_impl.cpp
@@ -718,6 +718,11 @@ namespace aux {
 	{
 		if (e)
 		{
+			if (e == asio::error::connection_refused
+				|| e == asio::error::connection_reset
+				|| e == asio::error::connection_aborted)
+				m_dht->on_unreachable(ep);
+
 			if (m_alerts.should_post(alert::info))
 			{
 				std::string msg = "UDP socket error from '"