//module included in the following assembly:
//
// * networking/multiple_networks/primary_networks/about-user-defined-networks.adoc

:_mod-docs-content-type: REFERENCE
[id="opening-default-network-ports-udn_{context}"]
= Opening default network ports on user-defined network pods

[role="_abstract"]
To allow default network pods to connect to a user-defined network pod, you can use the `k8s.ovn.org/open-default-ports` annotation. This annotation opens specific ports on the user-defined network pod for access from the default network.

By default, pods on a user-defined network (UDN) are isolated from the default network. This means that default network pods, such as those running monitoring services (Prometheus or Alertmanager) or the {product-title} image registry, cannot initiate connections to UDN pods.

The following pod specification allows incoming TCP connections on port `80` and UDP traffic on port `53` from the default network:
[source,yaml]
----
apiVersion: v1
kind: Pod
metadata:
  annotations:
    k8s.ovn.org/open-default-ports: |
      - protocol: tcp
        port: 80
      - protocol: udp
        port: 53
# ...
----

[NOTE]
====
Open ports are accessible on the pod's default network IP, not its UDN network IP.
====