Index: twisted/internet/abstract.py
===================================================================
--- twisted/internet/abstract.py	(revision 12585)
+++ twisted/internet/abstract.py	(working copy)
@@ -224,6 +224,12 @@
             self._writeDisconnecting = True
             self.startWriting()
     
+    def abortConnection(self):
+        """Aborts the connection -- default implementation calls
+        self.connectionLost(main.CONNECTION_LOST). 
+        """
+        self.connectionLost(main.CONNECTION_LOST)
+
     def stopReading(self):
         """Stop waiting for read availability.
 
Index: twisted/internet/interfaces.py
===================================================================
--- twisted/internet/interfaces.py	(revision 12585)
+++ twisted/internet/interfaces.py	(working copy)
@@ -980,6 +980,12 @@
         and there is no registered producer.
         """
     
+    def abortConnection(self):
+        """Close the connection abruptly.
+        
+        Discards any buffered data, unregisters any producer, and, if
+        possible, notifies the other end of the unclean closure."""
+        
     def getTcpNoDelay(self):
         """Return if TCP_NODELAY is enabled."""
 
Index: twisted/internet/tcp.py
===================================================================
--- twisted/internet/tcp.py	(revision 12585)
+++ twisted/internet/tcp.py	(working copy)
@@ -22,6 +22,7 @@
 import select
 import operator
 import warnings
+import struct
 try:
     import fcntl
 except ImportError:
@@ -139,14 +140,22 @@
             log.err()
             return main.CONNECTION_LOST
 
-    def _closeSocket(self):
+    def _closeSocket(self, orderly):
         try:
-            self.socket.sock_shutdown(2)
-        except:
+            if orderly:
+                self.socket.sock_shutdown(2)
+            else:
+                # Set SO_LINGER to 1,0 which, by convention, causes a
+                # connection reset to be sent when close is called,
+                # instead of the standard FIN shutdown sequence.
+                self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER,
+                                       struct.pack("ii", 1, 0))
+        except (SSL.Error, socket.error):
             pass
+        
         try:
             self.socket.close()
-        except:
+        except (SSL.Error, socket.error):
             pass
 
     def _postLoseConnection(self):
@@ -367,17 +376,24 @@
             else:
                 return main.CONNECTION_LOST
 
-    def _closeSocket(self):
+    def _closeSocket(self, orderly):
         """Called to close our socket."""
-        # This used to close() the socket, but that doesn't *really* close if
-        # there's another reference to it in the TCP/IP stack, e.g. if it was
-        # was inherited by a subprocess. And we really do want to close the
-        # connection. So we use shutdown() instead, and then close() in order
-        # to release the filedescriptor.
+        # The call to shutdown() before close() isn't really necessary, because
+        # we set FD_CLOEXEC now, which will ensure this is the only process
+        # holding the FD, thus ensuring close() really will shutdown the TCP
+        # socket. However, do it anyways, just to be safe.
         try:
-            self.socket.shutdown(2)
+            if orderly:
+                self.socket.shutdown(2)
+            else:
+                # Set SO_LINGER to 1,0 which, by convention, causes a
+                # connection reset to be sent when close is called,
+                # instead of the standard FIN shutdown sequence.
+                self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER,
+                                       struct.pack("ii", 1, 0))
         except socket.error:
             pass
+
         try:
             self.socket.close()
         except socket.error:
@@ -414,7 +430,7 @@
         """See abstract.FileDescriptor.connectionLost().
         """
         abstract.FileDescriptor.connectionLost(self, reason)
-        self._closeSocket()
+        self._closeSocket(reason.value.__class__ == error.ConnectionDone)
         protocol = self.protocol
         del self.protocol
         del self.socket