fixing position for docker

src/iptables_wrapper.rs

@@ -121,6 +121,13 @@ pub fn secure_port(
         return Err("Err gathering secure port rule".into());
     }
 
+    let position = if docker && position.is_none() {
+        let all_docker_rules = iptables.list("filter", &chain).unwrap();
+        Some(all_docker_rules.len() as i32 - 1)
+    } else {
+        position
+    };
+
     let rule = rule.unwrap();
     if let Some(position) = position {
         insert_unique(&iptables, table, &chain, &rule, position)