diff -Naur -x '*~' -x '*.rej' -x '*.orig' ntop-4.0/misc/configure.in.lua ntop-4.0-system_lua/misc/configure.in.lua
--- ntop-4.0/misc/configure.in.lua	2009-08-11 10:24:46.000000000 +0200
+++ ntop-4.0-system_lua/misc/configure.in.lua	2010-07-20 10:48:50.000000000 +0200
@@ -1,21 +1,7 @@
 dnl>
 dnl> Lua - http://www.lua.org
 dnl>
-LUA_VERSION=lua-5.1.4
-if test -f "$LUA_VERSION.tar.gz"; then
-   echo "Lua already present on this machine"
-else
-   wget http://www.lua.org/ftp/$LUA_VERSION.tar.gz
-fi
-
-tar xvfz $LUA_VERSION.tar.gz
-cat $LUA_VERSION/src/Makefile | sed -e s,'MYCFLAGS=-DLUA_USE_POSIX',' MYCFLAGS="-fPIC -DLUA_USE_POSIX"',g > /tmp/lua.temp
-cat /tmp/lua.temp >  $LUA_VERSION/src/Makefile
-#rm -f /tmp/lua.temp
-cd $LUA_VERSION; make posix; cd ..
-
-LUA_LIB_DIR=$PWD/$LUA_VERSION"/src"
-LIBS="-L${LUA_LIB_DIR} -llua ${LIBS} "
-INCS="${INCS} -I${LUA_LIB_DIR}"
+# use system lua
+LIBS="${LIBS} -llua"
 AC_DEFINE_UNQUOTED(HAVE_LUA, 1, [LUA is supported])