From 0a56a0742030517f3726d5222ae6417a24b20e0a Mon Sep 17 00:00:00 2001 From: Rahul Joshi Date: Thu, 22 Feb 2024 12:52:07 -0500 Subject: [PATCH] Add API spec for FQDN selector --- mkdocs.yml | 4 +- npeps/npep-133-fqdn-egress-selector.md | 440 +++++++++++++++++++++++++ npeps/npep-133.md | 173 ---------- 3 files changed, 442 insertions(+), 175 deletions(-) create mode 100644 npeps/npep-133-fqdn-egress-selector.md delete mode 100644 npeps/npep-133.md diff --git a/mkdocs.yml b/mkdocs.yml index 82fe9f8f..28dff59c 100644 --- a/mkdocs.yml +++ b/mkdocs.yml @@ -64,10 +64,10 @@ nav: - Template: npeps/npep-95.md - Provisional: - npeps/npep-122.md - - npeps/npep-133.md # - Implementable: - Experimental: - npeps/npep-126-egress-traffic-control.md + - npeps/npep-133-fqdn-egress-selector.md - Standard: - npeps/npep-137-conformance-profiles.md # - Declined: @@ -83,4 +83,4 @@ plugins: post_excerpt: required post_excerpt_max_authors: 2 - search - - mike \ No newline at end of file + - mike diff --git a/npeps/npep-133-fqdn-egress-selector.md b/npeps/npep-133-fqdn-egress-selector.md new file mode 100644 index 00000000..550dac44 --- /dev/null +++ b/npeps/npep-133-fqdn-egress-selector.md @@ -0,0 +1,440 @@ +# NPEP-133: FQDN Selector for Egress Traffic + +* Issue: + [#133](https://github.com/kubernetes-sigs/network-policy-api/issues/133) +* Status: Provisional + +## TLDR + +This enhancement proposes adding a new optional selector to specify egress peers +using [Fully Qualified Domain +Names](https://www.wikipedia.org/wiki/Fully_qualified_domain_name) (FQDNs). + +## Goals + +* Provide a selector to specify egress peers using a Fully Qualified Domain Name + (for example `kubernetes.io`). +* Support basic wildcard matching capabilities when specifying FQDNs (for + example `*.cloud-provider.io`) +* Currently only `ALLOW` type rules are proposed. + * Safely enforcing `DENY` rules based on FQDN selectors is difficult as there + is no guarantee a Network Policy plugin is aware of all IPs backing a FQDN + policy. If a Network Policy plugin has incomplete information, it may + accidentally allow traffic to an IP belonging to a denied domain. This would + constitute a security breach. + + By contrast, `ALLOW` rules, which may also have an incomplete list of IPs, + would not create a security breach. In case of incomplete information, valid + traffic would be dropped as the plugin believes the destination IP does not + belong to the domain. While this is definitely undesirable, it is at least + not an unsafe failure. + +* Currently only AdminNetworkPolicy is the intended scope for this proposal. + * Since Kubernetes NetworkPolicy does not have a FQDN selector, adding this + capability to BaselineAdminNetworkPolicy could result in writing baseline + rules that can't be replicated by an overriding NetworkPolicy. For example, + if BANP allows traffic to `example.io`, but the namespace admin installs a + Kubernetes Network Policy, the namespace admin has no way to replicate the + `example.io` selector using just Kubernetes Network Policies. + +## Non-Goals + +* This enhancement does not include a FQDN selector for allowing ingress + traffic. +* This enhancement only describes enhancements to the existing L4 filtering as + provided by AdminNetworkPolicy. It does not propose any new L7 matching or + filtering capabilities, like matching HTTP traffic or URL paths. + * This selector should not control what DNS records are resolvable from a + particular workload. + * This selector provides no capability to detect traffic destined for + different domains backed by the same IP (e.g. CDN or load balancers). +* This enhancement does not add any new mechanisms for specifying how traffic is + routed to a destination (egress gateways, alternative SNAT IPs, etc). It just + adds a new way of specifying packets to be allowed or dropped on the normal + egress data path. +* This enhancement does not require any mechanism for securing DNS resolution + (e.g. DNSSEC or DNS-over-TLS). Unsecured DNS requests are expected to be + sufficient for looking up FQDNs. + +## Introduction + +FQDN-based egress controls are a common enterprise security practice. +Administrators often prefer to write security policies using DNS names such as +“www.kubernetes.io” instead of capturing all the IP addresses the DNS name might +resolve to. Keeping up with changing IP addresses is a maintenance burden, and +hampers the readability of the network policies. + +## User Stories + +* As a cluster admin, I want to allow all Pods in the cluster to send traffic to + an external service specified by a well-known domain name. For example, all + Pods must be able to talk to `my-service.com`. + +* As a cluster admin, I want to allow Pods in the "monitoring" namespace to be + able to send traffic to a logs-sink, hosted at `logs-storage.com` + +* As a cluster admin, I want to allow all Pods in the cluster to send traffic to + any of the managed services provided by my Cloud Provider. Since the cloud + provider has a well known parent domain, I want to allow Pods to send traffic + to all sub-domains using a wild-card selector -- `*.my-cloud-provider.com` + +* As a cluster admin, I want to allow Pods in the cluster to send traffic to a + entire tree of domains. For example, our CDN has domains of the format + `...my-app.cdn.com`. I want to be able to use a + wild-card selector toallow the full tree of subdomains below + `**.my-app.cdn.com`. + +### Future User Stories + +These are some user stories we want to keep in mind, but due to limitations of +the existing Network Policy API, cannot be implemented currently. The design +goal in this case is to ensure we do not make these unimplementable down the +line. + +* As a cluster admin, I want to switch the default disposition of the cluster to + be default deny. This is enforced using a `BaselineAdminNetworkPolicy`. I also + want individual namespace owners to be able to specify their egress peers. + Namespace admins would then use a FQDN selector in the Kubernetes + `NetworkPolicy` objects to allow `my-service.com`. + +## API + +This NPEP proposes adding a new type of `AdminNetworkPolicyEgressPeer` called +`FQDNPeerSelector` which allows specifying domain names. + +```golang + +// Domain describes one or more DNS names to be used as a peer. +// +// Domain can be an exact match, or use the wildcard specifier '*' to match one +// or more labels. +// +// '*', the wildcard specifier, matches one or more entire labels. It does not +// support partial matches. '*' may only be specified as a prefix. +// +// Examples: +// - `kubernetes.io` matches only `kubernetes.io`. +// It does not match "www.kubernetes.io", "blog.kubernetes.io", +// "my-kubernetes.io", or "wikipedia.org". +// - `blog.kubernetes.io` matches only "blog.kubernetes.io". +// It does not match "www.kubernetes.io" or "kubernetes.io". +// - `*.kubernetes.io` matches subdomains of kubernetes.io. +// "www.kubernetes.io", "blog.kubernetes.io", and +// "latest.blog.kubernetes.io" match, however "kubernetes.io", and +// "wikipedia.org" do not. +// +// +kubebuilder:validation:Pattern=`^(\*\.)?([a-zA-z0-9]([-a-zA-Z0-9_]*[a-zA-Z0-9])?\.)+[a-zA-z0-9]([-a-zA-Z0-9_]*[a-zA-Z0-9])?\.?$` +type Domain string + +type AdminNetworkPolicyEgressPeer struct { + + // Domains provides a way to specify domain names as peers. + // + // Domains is only supported for ALLOW rules. In order to control access, + // Domain ALLOW rules should be used with a lower priority egress deny -- + // this allows the admin to maintain an explicit "allowlist" of reachable + // domains. + // + // Support: Extended + // + // + // +optional + // +listType=set + // +kubebuilder:validation:MinItems=1 + Domains []Domain `json:"domains,omitempty"` +} +``` + +### Examples + +#### Pods in `monitoring` namespace can talk to `my-service.com` and `*.cloud-provider.io` + +```yaml +apiVersion: policy.networking.k8s.io/v1alpha1 +kind: AdminNetworkPolicy +metadata: + name: allow-my-service-egress +spec: + priority: 55 + subject: + namespaces: + matchLabels: + kubernetes.io/metadata.name: "monitoring" + egress: + - name: "allow-to-my-service" + action: "Allow" + to: + - domains: + - "my-service.com" + - "*.cloud-provider.io" + ports: + - portNumber: + protocol: TCP + port: 443 +``` + +#### Maintaining an allowlist of domains + +There are a couple ways to maintain an allowlist: + +This example, includes the DENY rule in the same ANP object. It's also possible +to use another ANP object with a lower priority (e.g. `100` in this example): +```yaml +apiVersion: policy.networking.k8s.io/v1alpha1 +kind: AdminNetworkPolicy +metadata: + name: allow-my-service-egress +spec: + priority: 55 + subject: + namespaces: + matchLabels: + kubernetes.io/metadata.name: "monitoring" + egress: + - name: "allow-to-my-service" + action: "Allow" + to: + - domains: + - "my-service.com" + - "*.cloud-provider.io" + ports: + - portNumber: + protocol: TCP + port: 443 + - name: "default-deny" + action: "Deny" + to: + - networks: + - "0.0.0.0/0" +``` + +This example uses a default-deny BaselineAdminNetworkPolicy to create the +allowlist: +```yaml +apiVersion: policy.networking.k8s.io/v1alpha1 +kind: AdminNetworkPolicy +metadata: + name: allow-my-service-egress +spec: + priority: 55 + subject: + namespaces: + matchLabels: + kubernetes.io/metadata.name: "monitoring" + egress: + - name: "allow-to-my-service" + action: "Allow" + to: + - domains: + - "my-service.com" + - "*.cloud-provider.io" + ports: + - portNumber: + protocol: TCP + port: 443 +--- +apiVersion: policy.networking.k8s.io/v1alpha1 +kind: BaselineAdminNetworkPolicy +metadata: + name: default +spec: + subject: + namespaces: {} + ingress: + - action: Deny + to: + - networks: + - "0.0.0.0/0" +``` + +### Expected Behavior + +1. A FQDN egress policy does not grant the workload permission to communicate + with any in-cluster DNS services (like `kube-dns`). A separate rule needs to + be configured to allow traffic to any DNS servers. +1. FQDN policies should not affect the ability of workloads to resolve domains, + only their ability to communicate with the IP backing them. Put another way, + FQDN policies should not result in any form of DNS filtering. + * For example, if a policy allows traffic to `kubernetes.io`, any selected + Pods can still resolve `wikipedia.org` or + `my-services.default.svc.cluster.local`, but can not send traffic to them + unless allowed by a different rule. +1. Each implementation will provide guidance on which DNS name-server is + considered authoritative for resolving domain names. This could be the + `kube-dns` Service or potentially some other DNS provider specified in the + implementation's configuration. +1. DNS record querying and lifetimes: + * Pods are expected to make a DNS query for a domain before sending traffic + to it. If the Pod fails to send a DNS request and instead just sends + traffic to the IP (either because of caching or a static config), traffic + is not guaranteed to flow. + * Pods should respect the TTL of DNS records they receive. Trying to + establish new connection using DNS records that are expired is not + guaranteed to work. + * When the TTL for a DNS record expires, the implementor should stop + allowing new connections to that IP. Existing connection will still be + allowed (that's consistent with NetworkPolicy behavior on long-running + connections). +1. Implementations must support at least 100 unique IPs (either IPv4 or IPv6) + for each domain. This is true for both explicitly specified domains, as well + as for each domain selected by a wild-card rule. For example, the rule + `*.kubernetes.io` supports 100 IPs each for both `docs.kubernetes.io` and + `blog.kubernetes.io`. +1. PTR records are not required to properly configure a FQDN selector. For + example, as long as an A record exists mapping `my-hostname` to `1.2.3.4`, + the Network Policy implementation should allow traffic to `1.2.3.4`. There is + no requirement that a PTR record for `1.2.3.4.in-addr.arpa` exist or that it + points to `my-hostname` (it is allowed to point to `other-host`). +1. Targeting in-cluster endpoints with FQDN selector is not recommended. There + are other selectors which can more precisely capture intent. However, if + in-cluster endpoints are selected: + * ✅︎ Supported: + * Selecting Pods using their [generated DNS + record](https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/#pods) + (for example `pod-ip-address.my-namespace.pod.cluster.local`). This is + analogous to selecting the Pod by its IP address using the Network + selector. + * Headless Services can be selected using their [generated DNS + record](https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/#services) + because the generated DNS records contain a list of all the Pod IPs that + back the service. + * ❌ Not Supported: + * ClusterIP Services can not be selected using their [generated DNS + record](https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/#services) + (for example `my-svc.my-namespace.svc.cluster.local`). This is + consistent with the behavior when selecting the Service VIP using the + Network selector. + * ExternalName Services return a `CNAME` record. See the entry below + about CNAME support. + * Any record which points to the IPs used for `LoadBalancer` type + services. This includes the `externalIPs` and the + `.status.loadBalancer.ingress` fields +1. If the specified domain in a FQDN selector resolves to a [CNAME + record](#cname-records) the behavior of the implementor depends on the + returned response. + + If the upstream resolver used [CNAME chasing](#cname-chasing) to fully + resolve the domain to a A/AAAA record and returns the resulting chain, the + implementor can use this information to allow traffic to the specified IPs. + However the implementor does not need to perform their own CNAME chasing or + to understand resolutions across multiple DNS requests. + + For example, if the FQDN selector is allowing traffic to `www.kubernetes.io`: + * If a DNS query to the upstream resolver returns *a single response* with + the following records: + ``` + www.kubernetes.io -- CNAME to kubernetes.io + kubernetes.io -- A to 1.2.3.4 + ``` + The implementor can use this response to allow traffic to `1.2.3.4` + * If DNS query only responds with a CNAME record, the resolver is not + required to allow traffic even if subsequent requests resolve the full + chain: + ``` + # REQUEST 1 + + www.kubernetes.io -- CNAME to kubernetes.io + + # REQUEST 2 + + kubernetes.io -- A to 1.2.3.4 + ``` + The implementer can still deny traffic to `1.2.3.4` because no single + response contained the full chain required to resolve the domain. + +## Alternatives + +### IP Block Selector + +IP blocks are an important tool for specifying Network Policies. However, they +do not address all user needs and have a few short-comings when compared to FQDN +selectors: + +* IP-based selectors can become verbose if a single logical service has numerous + IPs backing it. +* IP-based selectors pose an ongoing maintenance burden for administrators, who + need to be aware of changing IPs. +* IP-based selectors can result in policies that are difficult to read and + audit. + +### L4 Proxy + +Users can also configure a L4 Proxy (e.g. using SOCKS) to inspect their traffic +and implement egress firewalls. They present a few trade-ofs when compared to a +FQDN selector: + +* Additional configuration and maintenance burden of the proxy application + itself +* Configuring new routes to direct traffic leaving the application to the L4 + proxy. + +### L7 Policy + +Another alternative is to provide a L7 selector, similar to the policies +provided by Service Mesh providers. While L7 selectors can offer more +expressivity, they often come trade-offs that are not suitable for all users: + +* L7 selectors necessarily support a select set of protocols. Users may be + using a custom protocol for application-level communication, but still want + the ability to specify endpoints using DNS. +* L7 selectors often require proxies to perform deep packet inspection and + enforce the policies. These proxies can introduce un-desireable latencies in + the datapath of applications. + +## References + +* [NPEP #126](https://github.com/kubernetes-sigs/network-policy-api/issues/126): + Egress Control in ANP + +### Implementations + +* [Antrea](https://antrea.io/docs/main/docs/antrea-network-policy/#fqdn-based-filtering) +* [Calico](https://docs.tigera.io/calico-enterprise/latest/network-policy/domain-based-policy) +* [Cilium](https://docs.cilium.io/en/latest/security/policy/language/#dns-based) +* [OpenShift](https://docs.openshift.com/container-platform/latest/networking/openshift_sdn/configuring-egress-firewall.html) + +The following is a best-effort breakdown of capabilities of different +NetworkPolicy providers, as of 2023-09-25. This information may be out-of-date, +or inaccurate. + +| | Antrea | Calico | Cilium | OpenShift
(current) | OpenShift
(future) | +| -------------- | ------------------------------ | ------------ | ------------ | ------------------------- | ------------------------ | +| Implementation | DNS Snooping
+ Async DNS | DNS Snooping | DNS Snooping | Async DNS | DNS Snooping | +| Wildcards | ✅︎ | ️✅︎ | ✅︎ | ❌ | ✅︎ | +| Egress Rules | ✅︎ | ️✅︎ | ✅︎ | ✅︎ | ✅︎ | +| Ingress Rules | ❌ | ️❌ | ❌ | ❌ | ❌ | +| Allow Rules | ✅︎ | ️✅︎ | ✅︎ | ✅︎ | ✅︎ | +| Deny Rules | ✅︎ | ️❌(?) | ❌ | ✅︎ | ❌(?) | + +## Appendix + +### CNAME Records + +CNAME records are a type of DNS record (like a `A` or `AAAA`) that direct the +resolver to query another name to retrieve actual A/AAAA records. + +For example: +``` +$ dig www.kubernetes.io + +... Omitted output ... + +;; OPT PSEUDOSECTION: +; EDNS: version: 0, flags:; udp: 4096 +;; QUESTION SECTION: +;www.kubernetes.io. IN A + +;; ANSWER SECTION: +www.kubernetes.io. 3600 IN CNAME kubernetes.io. +kubernetes.io. 3600 IN A 147.75.40.148 + +... Omitted Output ... +``` +### CNAME Chasing + +CNAME chasing refers to an optional behavior for DNS resolvers whereby they +perform subsequent lookups to resolve CNAMEs returned for a particular query. In +the above example, querying for `www.kubernetes.io.` returned a CNAME record for +`kubernetes.io.`. When CNAME chasing is enabled, the DNS server will +automatically resolve `kubernetes.io.` and return both records as the DNS +response. \ No newline at end of file diff --git a/npeps/npep-133.md b/npeps/npep-133.md deleted file mode 100644 index f9d89b58..00000000 --- a/npeps/npep-133.md +++ /dev/null @@ -1,173 +0,0 @@ -# NPEP-133: FQDN Selector for Egress Traffic - -* Issue: - [#133](https://github.com/kubernetes-sigs/network-policy-api/issues/133) -* Status: Provisional - -## TLDR - -This enhancement proposes adding a new optional selector to specify egress peers -using [Fully Qualified Domain -Names](https://www.wikipedia.org/wiki/Fully_qualified_domain_name) (FQDNs). - -## Goals - -* Provide a selector to specify egress peers using a Fully Qualified Domain Name - (for example `kubernetes.io`). -* Support basic wildcard matching capabilities when specifying FQDNs (for - example `*.cloud-provider.io`) -* Currently only `ALLOW` type rules are proposed. - * Safely enforcing `DENY` rules based on FQDN selectors is difficult as there - is no guarantee a Network Policy plugin is aware of all IPs backing a FQDN - policy. If a Network Policy plugin has incomplete information, it may - accidentally allow traffic to an IP belonging to a denied domain. This would - constitute a security breach. - - By contrast, `ALLOW` rules, which may also have an incomplete list of IPs, - would not create a security breach. In case of incomplete information, valid - traffic would be dropped as the plugin believes the destination IP does not - belong to the domain. While this is definitely undesirable, it is at least - not an unsafe failure. - -* Currently only AdminNetworkPolicy is the intended scope for this proposal. - * Since Kubernetes NetworkPolicy does not have a FQDN selector, adding this - capability to BaselineAdminNetworkPolicy could result in writing baseline - rules that can't be replicated by an overriding NetworkPolicy. For example, - if BANP allows traffic to `example.io`, but the namespace admin installs a - Kubernetes Network Policy, the namespace admin has no way to replicate the - `example.io` selector using just Kubernetes Network Policies. - -## Non-Goals - -* This enhancement does not include a FQDN selector for allowing ingress - traffic. -* This enhancement only describes enhancements to the existing L4 filtering as - provided by AdminNetworkPolicy. It does not propose any new L7 matching or - filtering capabilities, like matching HTTP traffic or URL paths. - * This selector should not control what DNS records are resolvable from a - particular workload. -* This enhancement does not provide a mechanism for selecting in-cluster - endpoints using FQDNs. To select Pods, Nodes, or the API Server, - AdminNetworkPolicy has other more specific selectors. - * Using the FQDN selector to refer to other Kubernetes endpoints, while not - explicitly disallowed, is not defined by this spec and left up to individual - providers. Trying to allow traffic to the following domains is NOT - guaranteed to work: - * `my-svc.my-namespace.svc.cluster.local` (the generated DNS record for a - Service as defined - [here](https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/#services)) - * `pod-ip-address.my-namespace.pod.cluster.local` (the generated DNS record - for a Pod as defined - [here](https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/#pods)) -* This enhancement does not add any new mechanisms for specifying how traffic is - routed to a destination (egress gateways, alternative SNAT IPs, etc). It just - adds a new way of specifying packets to be allowed or dropped on the normal - egress data path. -* This enhancement does not require any mechanism for securing DNS resolution - (e.g. DNSSEC or DNS-over-TLS). Unsecured DNS requests are expected to be - sufficient for looking up FQDNs. - -## Introduction - -FQDN-based egress controls are a common enterprise security practice. -Administrators often prefer to write security policies using DNS names such as -“www.kubernetes.io” instead of capturing all the IP addresses the DNS name might -resolve to. Keeping up with changing IP addresses is a maintenance burden, and -hampers the readability of the network policies. - -## User Stories - -* As a cluster admin, I want to allow all Pods in the cluster to send traffic to - an external service specified by a well-known domain name. For example, all - Pods must be able to talk to `my-service.com`. - -* As a cluster admin, I want to allow Pods in the "monitoring" namespace to be - able to send traffic to a logs-sink, hosted at `logs-storage.com` - -* As a cluster admin, I want to allow all Pods in the cluster to send traffic to - any of the managed services provided by my Cloud Provider. Since the cloud - provider has a well known parent domain, I want to allow Pods to send traffic - to all sub-domains using a wild-card selector -- `*.my-cloud-provider.com` - -### Future User Stories - -These are some user stories we want to keep in mind, but due to limitations of -the existing Network Policy API, cannot be implemented currently. The design -goal in this case is to ensure we do not make these unimplementable down the -line. - -* As a cluster admin, I want to block all cluster egress traffic by default, and - require namespace admins to create NetworkPolicies explicitly allowing egress - to the domains they need to talk to. - - The Cluster admin would use a `BaselineAdminNetworkPolicy` object to switch - the default disposition of the cluster. Namespace admins would then use a FQDN - selector in the Kubernetes `NetworkPolicy` objects to allow `my-service.com`. - -## API - -TODO: https://github.com/kubernetes-sigs/network-policy-api/issues/133 - -## Alternatives - -### IP Block Selector - -IP blocks are an important tool for specifying Network Policies. However, they -do not address all user needs and have a few short-comings when compared to FQDN -selectors: - -* IP-based selectors can become verbose if a single logical service has numerous - IPs backing it. -* IP-based selectors pose an ongoing maintenance burden for administrators, who - need to be aware of changing IPs. -* IP-based selectors can result in policies that are difficult to read and - audit. - -### L4 Proxy - -Users can also configure a L4 Proxy (e.g. using SOCKS) to inspect their traffic -and implement egress firewalls. They present a few trade-ofs when compared to a -FQDN selector: - -* Additional configuration and maintenance burden of the proxy application - itself -* Configuring new routes to direct traffic leaving the application to the L4 - proxy. - -### L7 Policy - -Another alternative is to provide a L7 selector, similar to the policies -provided by Service Mesh providers. While L7 selectors can offer more -expressivity, they often come trade-offs that are not suitable for all users: - -* L7 selectors necessarily support a select set of protocols. Users may be - using a custom protocol for application-level communication, but still want - the ability to specify endpoints using DNS. -* L7 selectors often require proxies to perform deep packet inspection and - enforce the policies. These proxies can introduce un-desireable latencies in - the datapath of applications. - -## References - -* [NPEP #126](https://github.com/kubernetes-sigs/network-policy-api/issues/126): - Egress Control in ANP - -### Implementations - -* [Antrea](https://antrea.io/docs/main/docs/antrea-network-policy/#fqdn-based-filtering) -* [Calico](https://docs.tigera.io/calico-enterprise/latest/network-policy/domain-based-policy) -* [Cilium](https://docs.cilium.io/en/latest/security/policy/language/#dns-based) -* [OpenShift](https://docs.openshift.com/container-platform/latest/networking/openshift_sdn/configuring-egress-firewall.html) - -The following is a best-effort breakdown of capabilities of different -NetworkPolicy providers, as of 2023-09-25. This information may be out-of-date, -or inaccurate. - -| | Antrea | Calico | Cilium | OpenShift
(current) | OpenShift
(future) | -| -------------- | ------------------------------ | ------------ | ------------ | ------------------------- | ------------------------ | -| Implementation | DNS Snooping
+ Async DNS | DNS Snooping | DNS Snooping | Async DNS | DNS Snooping | -| Wildcards | ✔ | ️✔ | ✔ | ❌ | ✔ | -| Egress Rules | ✔ | ️✔ | ✔ | ✔ | ✔ | -| Ingress Rules | ❌ | ️❌ | ❌ | ❌ | ❌ | -| Allow Rules | ✔ | ️✔ | ✔ | ✔ | ✔ | -| Deny Rules | ✔ | ️❌(?) | ❌ | ✔ | ❌(?) | \ No newline at end of file