diff --git a/src/capwap/sock_get_primary_if.c b/src/capwap/sock_get_primary_if.c
new file mode 100644
index 00000000..a5b101dd
--- /dev/null
+++ b/src/capwap/sock_get_primary_if.c
@@ -0,0 +1,53 @@
+/*
+    This file is part of libcapwap.
+
+    libcapwap is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    libcapwap is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with Foobar.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <ifaddrs.h>
+#include <net/if.h>
+
+#include "sock.h"
+
+
+char * sock_get_primary_if(int family)
+{
+        struct ifaddrs *ifap,*ifa;
+	char * r = 0;
+
+        getifaddrs(&ifap);
+
+        for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
+		if (ifa->ifa_flags & IFF_LOOPBACK){
+			continue;
+		}
+
+		if (ifa->ifa_addr->sa_family != family)
+			continue;
+
+		r = malloc(strlen(ifa->ifa_name)+1);
+		if (r)
+			strcpy(r,ifa->ifa_name);
+		break;
+
+        }
+        freeifaddrs(ifap);
+	return r;
+}
+
+