- Kube-proxy: Added dual-stack IPv4/IPv6 support to the iptables proxier. ([#82462](https://github.com/kubernetes/kubernetes/pull/82462), [@vllry](https://github.com/vllry)) [SIG Network]

		},
	})

	// On macOS, if a process already listens on LOCALIPADDR:PORT, net.Listen() falls back
	// to IPv6 address ie minio will start listening on IPv6 address whereas another
	// (non-)minio process is listening on IPv4 of given port.
	// To avoid this error situation we check for port availability.
	logger.FatalIf(xhttp.CheckPortAvailability(globalMinioHost, globalMinioPort, globalTCPOptions), "Unable to start the server")
}

### IPv4/IPv6 run

* The pod annotation `security.alpha.kubernetes.io/sysctls` now allows customization of namespaced and well isolated kernel parameters (sysctls), starting with `kernel.shm_rmid_forced`, `net.ipv4.ip_local_port_range` and `net.ipv4.tcp_syncookies` for Kubernetes 1.4. ([#27180](https://github.com/kubernetes/kubernetes/pull/27180), [@sttts](https://github.com/sttts))

 *  Fix: Don't leak connections if web sockets have malformed responses or if `onOpen()` throws.
 *  Fix: Don't retry when request bodies fail due to `FileNotFoundException`.
 *  Fix: Don't crash when URLs have IPv4-mapped IPv6 addresses.
 *  Fix: Don't crash when building `HandshakeCertificates` on Android API 28.
 *  Fix: Permit multipart file names to contain non-ASCII characters.
 *  New: API to get MockWebServer's dispatcher.

  slightly stricter about what values will be accepted as IP addresses and network
  address ranges (“CIDR blocks”).
  
  In particular, octets within IPv4 addresses are not allowed to have any leading
  `0`s, and IPv4-mapped IPv6 values (e.g. `::ffff:192.168.0.1`) are forbidden.
  These sorts of values can potentially cause security problems when different

- PodLifecycleSleepAction is graduated to GA ([#128046](https://github.com/kubernetes/kubernetes/pull/128046), [@AxeZhan](https://github.com/AxeZhan)) [SIG Architecture, Node and Testing]
- Pods were allowed to use the `net.ipv4.tcp_rmem` and `net.ipv4.tcp_wmem` sysctl by default
  when the kernel version was 4.15 or higher. With the kernel 4.15 the sysctl became namespaced.

- Kube-proxy doesn't set the sysctl `net.ipv4.conf.all.route_localnet=1` if no IPv4 loopback address is selected by the `nodePortAddresses` configuration parameter. ([#107684](https://github.com/kubernetes/kubernetes/pull/107684), [@aojea](https://github.com/aojea))

- IPVS proxier now set net/ipv4/vs/conn_reuse_mode to 0 by default, which will highly improve IPVS proxier performance. ([#71114](https://github.com/kubernetes/kubernetes/pull/71114), [@Lion-Wei](https://github.com/Lion-Wei))

### OpenStack

* Fixed a bug in the OpenStack cloud provider where dual stack deployments (IPv4 and IPv6) did not work well when using kubenet as the network plugin. ([#59749](https://github.com/kubernetes/kubernetes/pull/59749), [@zioproto](https://github.com/zioproto))