Index: boto/boto/connection.py
===================================================================
--- boto.orig/boto/connection.py
+++ boto/boto/connection.py
@@ -891,8 +891,8 @@ class AWSAuthConnection(object):
                 # the port info. All others should be now be up to date and
                 # not include the port.
                 if 's3' not in self._required_auth_capability():
-                    self.set_host_header(request)
-
+                    if not getattr(self, 'anon', False):
+                        self.set_host_header(request)
                 if callable(sender):
                     response = sender(connection, request.method, request.path,
                                       request.body, request.headers)