diff --git a/bacnet-stack/ports/linux/bip-init.c b/bacnet-stack/ports/linux/bip-init.c
index 8ccd2d5f..2aad427c 100644
--- a/bacnet-stack/ports/linux/bip-init.c
+++ b/bacnet-stack/ports/linux/bip-init.c
@@ -180,3 +180,18 @@ bool bip_init(
 
     return true;
 }
+
+/** Get the netmask of the BACnet/IP's interface via an ioctl() call.
+ * @param netmask [out] The netmask, in host order.
+ * @return 0 on success, else the error from the ioctl() call.
+ */
+int bip_get_local_netmask(
+    struct in_addr *netmask )
+{
+	int rv;
+    char *ifname = getenv("BACNET_IFACE");		/* will probably be null */
+    if ( ifname == NULL )
+    	ifname = "eth0";
+    rv = get_local_address_ioctl(ifname, netmask, SIOCGIFNETMASK);
+    return rv;
+}
diff --git a/bacnet-stack/ports/linux/net.h b/bacnet-stack/ports/linux/net.h
index e4cf610a..99b04f85 100644
--- a/bacnet-stack/ports/linux/net.h
+++ b/bacnet-stack/ports/linux/net.h
@@ -94,6 +94,12 @@
 #include <sys/ioctl.h>
 #include <netdb.h>
 
+/** @file linux/net.h  Includes Linux network headers. */
+
+/* Local helper functions for this port */
+extern int bip_get_local_netmask(
+			struct in_addr *netmask );
+
+
 #endif
 
-/** @file linux/net.h  Includes Linux network headers. */
diff --git a/bacnet-stack/ports/linux/timer.h b/bacnet-stack/ports/linux/timer.h
index 8cee552d..153bb1c4 100644
--- a/bacnet-stack/ports/linux/timer.h
+++ b/bacnet-stack/ports/linux/timer.h
@@ -26,7 +26,7 @@
 
 #include <stdbool.h>
 #include <stdint.h>
-#include <sys/time.h>		// for timeval
+#include <sys/time.h>		/* for timeval */
 
 /* Timer Module */
 #ifndef MAX_MILLISECOND_TIMERS