diff --git a/openbsc/configure.ac b/openbsc/configure.ac
index 00d1b70..394972f 100644
--- a/openbsc/configure.ac
+++ b/openbsc/configure.ac
@@ -179,6 +179,7 @@
     src/libmsc/Makefile
     src/libmgcp/Makefile
     src/libcommon/Makefile
+    src/libfilter/Makefile
     src/osmo-nitb/Makefile
     src/osmo-bsc/Makefile
     src/osmo-bsc_nat/Makefile
diff --git a/openbsc/src/Makefile.am b/openbsc/src/Makefile.am
index db7603b..6f6174e 100644
--- a/openbsc/src/Makefile.am
+++ b/openbsc/src/Makefile.am
@@ -2,7 +2,7 @@
 AM_CFLAGS=-Wall $(LIBOSMOCORE_CFLAGS) $(LIBOSMOGSM_CFLAGS) $(LIBOSMOGSM_CFLAGS) $(LIBOSMOVTY_CFLAGS) $(COVERAGE_CFLAGS)
 AM_LDFLAGS = $(LIBOSMOCORE_LIBS) $(LIBOSMOGSM_LIBS) $(COVERAGE_LDFLAGS)
 
-SUBDIRS = libcommon libmgcp libbsc libmsc libtrau osmo-nitb osmo-bsc_mgcp utils ipaccess gprs
+SUBDIRS = libcommon libmgcp libbsc libmsc libtrau libfilter osmo-nitb osmo-bsc_mgcp utils ipaccess gprs
 
 # Conditional modules
 if BUILD_NAT
diff --git a/openbsc/src/libfilter/Makefile.am b/openbsc/src/libfilter/Makefile.am
new file mode 100644
index 0000000..e24ec5f
--- /dev/null
+++ b/openbsc/src/libfilter/Makefile.am
@@ -0,0 +1,9 @@
+AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include -I$(top_builddir)
+AM_CFLAGS=-Wall $(LIBOSMOCORE_CFLAGS) $(LIBOSMOGSM_CFLAGS) \
+	$(LIBOSMOVTY_CFLAGS) $(LIBOSMOABIS_CFLAGS) $(COVERAGE_CFLAGS)
+
+noinst_LIBRARIES = libfilter.a
+
+libfilter_a_SOURCES = \
+	bsc_msg_filter.c
+
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_filter.c b/openbsc/src/libfilter/bsc_msg_filter.c
similarity index 100%
rename from openbsc/src/osmo-bsc_nat/bsc_nat_filter.c
rename to openbsc/src/libfilter/bsc_msg_filter.c
diff --git a/openbsc/src/osmo-bsc_nat/Makefile.am b/openbsc/src/osmo-bsc_nat/Makefile.am
index ca103a4..7a38430 100644
--- a/openbsc/src/osmo-bsc_nat/Makefile.am
+++ b/openbsc/src/osmo-bsc_nat/Makefile.am
@@ -7,12 +7,13 @@
 
 osmo_bsc_nat_SOURCES = bsc_filter.c bsc_mgcp_utils.c bsc_nat.c bsc_nat_utils.c \
 		  bsc_nat_vty.c bsc_sccp.c bsc_ussd.c bsc_nat_ctrl.c \
-		  bsc_nat_rewrite.c bsc_nat_filter.c bsc_nat_rewrite_trie.c
+		  bsc_nat_rewrite.c bsc_nat_rewrite_trie.c
 osmo_bsc_nat_LDADD = \
 		$(top_builddir)/src/libmgcp/libmgcp.a \
 		$(top_builddir)/src/libbsc/libbsc.a \
 		$(top_builddir)/src/libtrau/libtrau.a \
 		$(top_builddir)/src/libcommon/libcommon.a \
+		$(top_builddir)/src/libfilter/libfilter.a \
 		-lrt $(LIBOSMOSCCP_LIBS) $(LIBOSMOCORE_LIBS) \
 		$(LIBOSMOGSM_LIBS) $(LIBOSMOVTY_LIBS) $(LIBOSMOCTRL_LIBS) \
 		$(LIBOSMOABIS_LIBS) $(LIBOSMONETIF_LIBS)
diff --git a/openbsc/tests/bsc-nat/Makefile.am b/openbsc/tests/bsc-nat/Makefile.am
index b620d96..64cd9ac 100644
--- a/openbsc/tests/bsc-nat/Makefile.am
+++ b/openbsc/tests/bsc-nat/Makefile.am
@@ -10,11 +10,12 @@
 			$(top_srcdir)/src/osmo-bsc_nat/bsc_filter.c \
 			$(top_srcdir)/src/osmo-bsc_nat/bsc_sccp.c \
 			$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_utils.c \
-			$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_filter.c \
 			$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_rewrite.c \
 			$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_rewrite_trie.c \
 			$(top_srcdir)/src/osmo-bsc_nat/bsc_mgcp_utils.c
-bsc_nat_test_LDADD = $(top_builddir)/src/libbsc/libbsc.a \
+bsc_nat_test_LDADD = \
+			$(top_builddir)/src/libfilter/libfilter.a \
+			$(top_builddir)/src/libbsc/libbsc.a \
 			$(top_builddir)/src/libmgcp/libmgcp.a \
 			$(top_builddir)/src/libtrau/libtrau.a \
 			$(top_builddir)/src/libcommon/libcommon.a \