- Kubelet allows pods to use the `net.ipv4.ip_local_reserved_ports` sysctl by default and the minimal kernel version is 3.16; Pod Security admission allows this sysctl in v1.27+ versions of the baseline and restricted policies. ([#115374](https://github.com/kubernetes/kubernetes/pull/115374), [@pacoxu](https://github.com/pacoxu)) [SIG Auth, Network and Node]

## Urgent Upgrade Notes 

### (No, really, you MUST read this before you upgrade)

* Add RBAC support to fluentd-elasticsearch cluster addon ([#46203](https://github.com/kubernetes/kubernetes/pull/46203), [@simt2](https://github.com/simt2))
* Avoid redundant copying of tars during kube-up for gce if the same file already exists ([#46792](https://github.com/kubernetes/kubernetes/pull/46792), [@ianchakeres](https://github.com/ianchakeres))

- Changes behaviour of kube-proxy start; does not attempt to set specific `sysctl` values (which does not work in recent Kernel versions anymore in non-init namespaces), when the current sysctl values are already set higher. ([#103174](https://github.com/kubernetes/kubernetes/pull/103174), [@Napsty](https://github.com/Napsty))

  
  When the feature gate is enabled, kubelet ignores errors that happens during setting the following sysctl values: `vm.overcommit_memory`, `vm.panic_on_oom`, `kernel.panic`, `kernel.panic_on_oops`, `kernel.keys.root_maxkeys`, `kernel.keys.root_maxbytes`. (These sysctl values for the host, not for the containers)
  
  kubelet also ignores an error during opening `/dev/kmsg`.

- Pod SecurityContext and PodSecurityPolicy supports slash as sysctl separator. ([#106834](https://github.com/kubernetes/kubernetes/pull/106834), [@mengjiao-liu](https://github.com/mengjiao-liu)) [SIG Apps, Architecture, Auth, Node, Security and Testing]

- Improved algorithm for selecting `best` non-preferred hint in the TopologyManager ([#108154](https://github.com/kubernetes/kubernetes/pull/108154), [@klueska](https://github.com/klueska))
- 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))

  and “net.ipv4.tcp_keepalive_probes“ sysctl by default; Pod Security Admission
  allows this sysctl in `v1.29+` versions of the baseline and restricted policies. ([#121240](https://github.com/kubernetes/kubernetes/pull/121240), [@HirazawaUi](https://github.com/HirazawaUi))
- `kubelet` now allows pods to use the `net.ipv4.tcp_keepalive_time` sysctl by default