Index: Lib/telnetlib.py
===================================================================
--- Lib/telnetlib.py	(revision 55755)
+++ Lib/telnetlib.py	(working copy)
@@ -204,6 +204,7 @@
         self.iacseq = '' # Buffer for IAC sequence.
         self.sb = 0 # flag for SB and SE sequence.
         self.sbdataq = ''
+        self.data_filter_callback = None
         self.option_callback = None
         if host is not None:
             self.open(host, port, timeout)
@@ -409,6 +410,13 @@
         self.sbdataq = ''
         return buf
 
+    def set_data_filter_callback(self, callback):
+        """Provide a callback function called after each receipt of
+        data on the telnet session.
+
+        """
+        self.data_filter_callback = callback
+
     def set_option_negotiation_callback(self, callback):
         """Provide a callback function called after each receipt of a telnet option."""
         self.option_callback = callback
@@ -517,6 +525,8 @@
         # behavior in process_rawq() above
         buf = self.sock.recv(50)
         self.msg("recv %r", buf)
+        if self.data_filter_callback is not None:
+            buf = self.data_filter_callback(self, buf)
         self.eof = (not buf)
         self.rawq = self.rawq + buf