[nat] Let IMSI DETACH and other messages pass by.
diff --git a/openbsc/src/nat/bsc_nat_utils.c b/openbsc/src/nat/bsc_nat_utils.c
index 32301f5..ca7a4c6 100644
--- a/openbsc/src/nat/bsc_nat_utils.c
+++ b/openbsc/src/nat/bsc_nat_utils.c
@@ -378,9 +378,8 @@
 		   hdr48->msg_type == GSM48_MT_RR_PAG_RESP) {
 		return _cr_check_pag_resp(bsc, &hdr48->data[0], hdr48_len - sizeof(*hdr48));
 	} else {
-		LOGP(DNAT, LOGL_ERROR, "Unknown GSM48 content: proto: %d msg: %d\n",
-		     hdr48->proto_discr, hdr48->msg_type);
-		return -1;
+		/* We only want to filter the above, let other things pass */
+		return 0;
 	}
 }