NetworkPolicies allow you to specify rules for traffic flow within your cluster, and also between Pods and the outside world. Your cluster must use a network plugin that supports NetworkPolicy enforcement. --- <!-- overview --> <del> If you want to control traffic flow at the IP address or port level (OSI layer 3 or 4), then you might consider using Kubernetes NetworkPolicies for particular applications in your cluster.  NetworkPolicies are an application-centric construct which allow you to specify how a {{< glossary_tooltip text="pod" term_id="pod">}} is allowed to communicate with various network "entities" (we use the word "entity" here to avoid overloading the more common terms such as "endpoints" and "services", which have specific Kubernetes connotations) over the network. NetworkPolicies apply to a connection with a pod on one or both ends, and are not relevant to other connections. </del> <ins> If you want to control traffic flow at the IP address or port level (OSI layer 3 or 4), then you might consider using Kubernetes NetworkPolicies for particular applications in your cluster. NetworkPolicies are an application-centric construct which allow you to specify how a {{< glossary_tooltip text="pod" term_id="pod">}} is allowed to communicate with various network "entities" (we use the word "entity" here to avoid overloading the more common terms such as "endpoints" and "services", which have specific Kubernetes connotations) over the network. NetworkPolicies apply to a connection with a pod on one or both ends, and are not relevant to other connections. </ins> <del> The entities that a Pod can communicate with are identified through a combination of the following 3 identifiers: </del> <ins> The entities that a Pod can communicate with are identified through a combination of the following 3 identifiers: </ins> 1. Other pods that are allowed (exception: a pod cannot block access to itself) 2. Namespaces that are allowed <del> 3. IP blocks (exception: traffic to and from the node where a Pod is running is always allowed, regardless of the IP address of the Pod or the node) </del> <ins> 3. IP blocks (exception: traffic to and from the node where a Pod is running is always allowed, regardless of the IP address of the Pod or the node) </ins> <del> When defining a pod- or namespace- based NetworkPolicy, you use a {{< glossary_tooltip text="selector" term_id="selector">}} to specify what traffic is allowed to and from the Pod(s) that match the selector. </del> <ins> When defining a pod- or namespace- based NetworkPolicy, you use a {{< glossary_tooltip text="selector" term_id="selector">}} to specify what traffic is allowed to and from the Pod(s) that match the selector. </ins> Meanwhile, when IP based NetworkPolicies are created, we define policies based on IP blocks (CIDR ranges). <!-- body --> ## Prerequisites <del> Network policies are implemented by the [network plugin](/docs/concepts/extend-kubernetes/compute-storage-net/network-plugins/). To use network policies, you must be using a networking solution which supports NetworkPolicy. Creating a NetworkPolicy resource without a controller that implements it will have no effect. </del> <ins> Network policies are implemented by the [network plugin](/docs/concepts/extend-kubernetes/compute-storage-net/network-plugins/). To use network policies, you must be using a networking solution which supports NetworkPolicy. Creating a NetworkPolicy resource without a controller that implements it will have no effect. </ins> ## The Two Sorts of Pod Isolation <del> There are two sorts of isolation for a pod: isolation for egress, and isolation for ingress.  They concern what connections may be established.  "Isolation" here is not absolute, rather it means "some restrictions apply".  The alternative, "non-isolated for $direction", means that no restrictions apply in the stated direction.  The two sorts of isolation (or not) are declared independently, and are both relevant for a connection from one pod to another. By default, a pod is non-isolated for egress; all outbound connections are allowed.  A pod is isolated for egress if there is any NetworkPolicy that both selects the pod and has "Egress" in its `policyTypes`; we say that such a policy applies to the pod for egress.  When a pod is isolated for egress, the only allowed connections from the pod are those allowed by the `egress` list of some NetworkPolicy that applies to the pod for egress.  The effects of those `egress` lists combine additively. By default, a pod is non-isolated for ingress; all inbound connections are allowed.  A pod is isolated for ingress if there is any NetworkPolicy that both selects the pod and has "Ingress" in its `policyTypes`; we say that such a policy applies to the pod for ingress.  When a pod is isolated for ingress, the only allowed connections into the pod are those from the pod's node and those allowed by the `ingress` list of some NetworkPolicy that applies to the pod for ingress.  The effects of those `ingress` lists combine additively. Network policies do not conflict; they are additive. If any policy or policies apply to a given pod for a given direction, the connections allowed in that direction from that pod is the union of what the applicable policies allow. Thus, order of evaluation does not affect the policy result. For a connection from a source pod to a destination pod to be allowed, both the egress policy on the source pod and the ingress policy on the destination pod need to allow the connection. If either side does not allow the connection, it will not happen. </del> <ins> There are two sorts of isolation for a pod: isolation for egress, and isolation for ingress. They concern what connections may be established. "Isolation" here is not absolute, rather it means "some restrictions apply". The alternative, "non-isolated for $direction", means that no restrictions apply in the stated direction.  The two sorts of isolation (or not) are declared independently, and are both relevant for a connection from one pod to another. By default, a pod is non-isolated for egress; all outbound connections are allowed. A pod is isolated for egress if there is any NetworkPolicy that both selects the pod and has "Egress" in its `policyTypes`; we say that such a policy applies to the pod for egress. When a pod is isolated for egress, the only allowed connections from the pod are those allowed by the `egress` list of some NetworkPolicy that applies to the pod for egress. The effects of those `egress` lists combine additively. By default, a pod is non-isolated for ingress; all inbound connections are allowed. A pod is isolated for ingress if there is any NetworkPolicy that both selects the pod and has "Ingress" in its `policyTypes`; we say that such a policy applies to the pod for ingress. When a pod is isolated for ingress, the only allowed connections into the pod are those from the pod's node and those allowed by the `ingress` list of some NetworkPolicy that applies to the pod for ingress. The effects of those `ingress` lists combine additively. Network policies do not conflict; they are additive. If any policy or policies apply to a given pod for a given direction, the connections allowed in that direction from that pod is the union of what the applicable policies allow. Thus, order of evaluation does not affect the policy result. For a connection from a source pod to a destination pod to be allowed, both the egress policy on the source pod and the ingress policy on the destination pod need to allow the connection. If either side does not allow the connection, it will not happen. </ins> ## The NetworkPolicy resource {#networkpolicy-resource} <del> See the [NetworkPolicy](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#networkpolicy-v1-networking-k8s-io) reference for a full definition of the resource. </del> <ins> See the [NetworkPolicy](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#networkpolicy-v1-networking-k8s-io) reference for a full definition of the resource. </ins> An example NetworkPolicy might look like this: {{< codenew file="service/networking/networkpolicy.yaml" >}} {{< note >}} <del> POSTing this to the API server for your cluster will have no effect unless your chosen networking solution supports network policy. </del> <ins> POSTing this to the API server for your cluster will have no effect unless your chosen networking solution supports network policy. </ins> {{< /note >}} <del> __Mandatory Fields__: As with all other Kubernetes config, a NetworkPolicy needs `apiVersion`, `kind`, and `metadata` fields.  For general information about working with config files, see </del> <ins> __Mandatory Fields__: As with all other Kubernetes config, a NetworkPolicy needs `apiVersion`, `kind`, and `metadata` fields.  For general information about working with config files, see </ins> [Configure a Pod to Use a ConfigMap](/docs/tasks/configure-pod-container/configure-pod-configmap/), and [Object Management](/docs/concepts/overview/working-with-objects/object-management). <del> __spec__: NetworkPolicy [spec](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/api-conventions.md#spec-and-status) has all the information needed to define a particular network policy in the given namespace. </del> <ins> **spec**: NetworkPolicy [spec](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/api-conventions.md#spec-and-status) has all the information needed to define a particular network policy in the given namespace. </ins> <del> __podSelector__: Each NetworkPolicy includes a `podSelector` which selects the grouping of pods to which the policy applies. The example policy selects pods with the label "role=db". An empty `podSelector` selects all pods in the namespace. </del> <ins> **podSelector**: Each NetworkPolicy includes a `podSelector` which selects the grouping of pods to which the policy applies. The example policy selects pods with the label "role=db". An empty `podSelector` selects all pods in the namespace. </ins> <del> __policyTypes__: Each NetworkPolicy includes a `policyTypes` list which may include either `Ingress`, `Egress`, or both. The `policyTypes` field indicates whether or not the given policy applies to ingress traffic to selected pod, egress traffic from selected pods, or both. If no `policyTypes` are specified on a NetworkPolicy then by default `Ingress` will always be set and `Egress` will be set if the NetworkPolicy has any egress rules. </del> <ins> **policyTypes**: Each NetworkPolicy includes a `policyTypes` list which may include either `Ingress`, `Egress`, or both. The `policyTypes` field indicates whether or not the given policy applies to ingress traffic to selected pod, egress traffic from selected pods, or both. If no `policyTypes` are specified on a NetworkPolicy then by default `Ingress` will always be set and `Egress` will be set if the NetworkPolicy has any egress rules. </ins> <del> __ingress__: Each NetworkPolicy may include a list of allowed `ingress` rules.  Each rule allows traffic which matches both the `from` and `ports` sections. The example policy contains a single rule, which matches traffic on a single port, from one of three sources, the first specified via an `ipBlock`, the second via a `namespaceSelector` and the third via a `podSelector`. </del> <ins> **ingress**: Each NetworkPolicy may include a list of allowed `ingress` rules. Each rule allows traffic which matches both the `from` and `ports` sections. The example policy contains a single rule, which matches traffic on a single port, from one of three sources, the first specified via an `ipBlock`, the second via a `namespaceSelector` and the third via a `podSelector`. </ins> <del> __egress__: Each NetworkPolicy may include a list of allowed `egress` rules.  Each rule allows traffic which matches both the `to` and `ports` sections. The example policy contains a single rule, which matches traffic on a single port to any destination in `10.0.0.0/24`. </del> <ins> **egress**: Each NetworkPolicy may include a list of allowed `egress` rules. Each rule allows traffic which matches both the `to` and `ports` sections. The example policy contains a single rule, which matches traffic on a single port to any destination in `10.0.0.0/24`. </ins> So, the example NetworkPolicy: <del> 1. isolates "role=db" pods in the "default" namespace for both ingress and egress traffic (if they weren't already isolated) 2. (Ingress rules) allows connections to all pods in the "default" namespace with the label "role=db" on TCP port 6379 from: </del> <ins> 1. isolates `role=db` pods in the `default` namespace for both ingress and egress traffic (if they weren't already isolated) 1. (Ingress rules) allows connections to all pods in the `default` namespace with the label `role=db` on TCP port 6379 from: * any pod in the `default` namespace with the label `role=frontend` * any pod in a namespace with the label `project=myproject` * IP addresses in the ranges `172.17.0.0`–`172.17.0.255` and `172.17.2.0`–`172.17.255.255` (ie, all of `172.17.0.0/16` except `172.17.1.0/24`) </ins> <del> * any pod in the "default" namespace with the label "role=frontend" * any pod in a namespace with the label "project=myproject" * IP addresses in the ranges 172.17.0.0–172.17.0.255 and 172.17.2.0–172.17.255.255 (ie, all of 172.17.0.0/16 except 172.17.1.0/24) 3. (Egress rules) allows connections from any pod in the "default" namespace with the label "role=db" to CIDR 10.0.0.0/24 on TCP port 5978 </del> <ins> 1. (Egress rules) allows connections from any pod in the `default` namespace with the label `role=db` to CIDR `10.0.0.0/24` on TCP port 5978 </ins> <del> See the [Declare Network Policy](/docs/tasks/administer-cluster/declare-network-policy/) walkthrough for further examples. </del> <ins> See the [Declare Network Policy](/docs/tasks/administer-cluster/declare-network-policy/) walkthrough for further examples. </ins> ## Behavior of `to` and `from` selectors <del> There are four kinds of selectors that can be specified in an `ingress` `from` section or `egress` `to` section: </del> <ins> There are four kinds of selectors that can be specified in an `ingress` `from` section or `egress` `to` section: </ins> <del> __podSelector__: This selects particular Pods in the same namespace as the NetworkPolicy which should be allowed as ingress sources or egress destinations. </del> <ins> **podSelector**: This selects particular Pods in the same namespace as the NetworkPolicy which should be allowed as ingress sources or egress destinations. </ins> <del> __namespaceSelector__: This selects particular namespaces for which all Pods should be allowed as ingress sources or egress destinations. </del> <ins> **namespaceSelector**: This selects particular namespaces for which all Pods should be allowed as ingress sources or egress destinations. </ins> <del> __namespaceSelector__ *and* __podSelector__: A single `to`/`from` entry that specifies both `namespaceSelector` and `podSelector` selects particular Pods within particular namespaces. Be careful to use correct YAML syntax; this policy: </del> <ins> **namespaceSelector** *and* **podSelector**: A single `to`/`from` entry that specifies both `namespaceSelector` and `podSelector` selects particular Pods within particular namespaces. Be careful to use correct YAML syntax. For example: </ins> ```yaml ...