+#################################################################################
+#
+# hide-tor-exit-notation: Header filter to remove the Tor exit node notation
+# in Host and Referer headers.
+#
+# Note: If Privoxy and Tor are chained and Privoxy is configured to
+# use socks4a, one can use http://www.example.org.foobar.exit/
+# to access the host www.example.org through Tor exit node foobar.
+#
+# As the HTTP client isn't aware of this notation, it treats the
+# whole string "www.example.org.foobar.exit" as host and uses it
+# for the "Host" and "Referer" headers. From the server's point of
+# view the resulting headers are invalid and can cause problems.
+#
+# An invalid "Referer" header can trigger "hot-linking" protections,
+# an invalid "Host" header will make it impossible for the server to
+# find the right vhost (several domains hosted on the same IP address).
+#
+# This filter removes the "foo.exit" part in those headers
+# to prevent the mentioned problems. Note that it only modifies
+# the HTTP headers, it doesn't make it impossible for the server
+# to detect your Tor exit node based on the IP address the request is
+# coming from.
+#
+#################################################################################
+FILTER: hide-tor-exit-notation Header filter to remove the Tor exit node notation in Host and Referer headers.
+s@^((?:Referer|Host):\s*(?:https?://)?[^/]*)\.[^\./]*?\.exit@$1@i
+
+