Add network interface check

src/sysinfo/network-interface.js

@@ -31,5 +31,9 @@ function testConfig(config, callback) {
 
     if (typeof config.ifname !== 'string') return callback(new BoxError(BoxError.BAD_FIELD, 'ifname is not a string'));
 
-    callback(null);
+    getServerIp(config, function (error) {
+        if (error) return callback(error);
+
+        callback(null);
+    });
 }