- When client certificate files are provided, reload files for new connections, and close connections when a certificate changes. ([#79083](https://github.com/kubernetes/kubernetes/pull/79083), [@jackkleeman](https://github.com/jackkleeman)) [SIG API Machinery, Auth, Node and Testing]

* Add conntrack as a dependency of kubelet and kubeadm when building rpms and debs. Both require conntrack to handle cleanup of connections. ([#71540](https://github.com/kubernetes/kubernetes/pull/71540), [@mauilion](https://github.com/mauilion))
* UDP connections now support graceful termination in IPVS mode ([#71515](https://github.com/kubernetes/kubernetes/pull/71515), [@lbernail](https://github.com/lbernail))

## Changelog since v1.13.5

### Other notable changes

* Connections from Pods to Services with 0 endpoints will now ICMP reject immediately, rather than blackhole and timeout. ([#72534](https://github.com/kubernetes/kubernetes/pull/72534), [@thockin](https://github.com/thockin))

- Don't use a custom dialer for the kubelet if is not rotating certificates, so we can reuse TCP connections and have only one between the apiserver and the kubelet.

## Changelog since v1.12.7

### Other notable changes

* Connections from Pods to Services with 0 endpoints will now ICMP reject immediately, rather than blackhole and timeout. ([#72534](https://github.com/kubernetes/kubernetes/pull/72534), [@thockin](https://github.com/thockin))

- New metrics: `apiserver_kube_aggregator_x509_missing_san_total` and `apiserver_webhooks_x509_missing_san_total`. This metric measures a number of connections to webhooks/aggregated API servers that use certificates without Subject Alternative Names. It being non-zero is a warning sign that these connections will stop functioning in the future since Golang is going to deprecate x509 certificate subject Common Names for server hostname verification. ([#95396](https://github....

### Other (Cleanup or Flake)

- Kube-apiserver: sets an upper-bound on the lifetime of idle keep-alive connections and time to read the headers of incoming requests ([#103958](https://github.com/kubernetes/kubernetes/pull/103958), [@liggitt](https://github.com/liggitt)) [SIG API Machinery and Node]

## Dependencies

### Added

  // serving certificate of the backend it is connecting to.  This will make the HTTPS connection between the apiserver
  // and the backend insecure. This means the apiserver cannot verify the log data it is receiving came from the real
  // kubelet.  If the kubelet is configured to verify the apiserver's TLS credentials, it does not mean the

### Other (Cleanup or Flake)

- Kube-apiserver: sets an upper-bound on the lifetime of idle keep-alive connections and time to read the headers of incoming requests ([#103958](https://github.com/kubernetes/kubernetes/pull/103958), [@liggitt](https://github.com/liggitt)) [SIG API Machinery and Node]

## Dependencies

### Added

- The kubelet no longer forcefully closes active connections on heartbeat failures, using the HTTP2 health check mechanism to detect broken connections. Users can force the previous behavior of the kubelet by setting the environment variable DISABLE_HTTP2. ([#108107](https://github.com/kubernetes/kubernetes/pull/108107), [@aojea](https://github.com/aojea))...