How to address weak ciphers in TLS 1.2

TLS 1.2 has vulnerabilities related to weak cipher implementation. If you use TLS 1.2 and want to fortify your system's security by addressing the kube API server TLS issues, you must take the following steps:

1. Modify your cipher suite by inserting the following line into your config.yaml. The configuration line must include the parameters of the ciphers that you want to allow.

   sed  -i '/kube-apiserver-arg:/a - "tls-cipher-suites=TLS_CHACHA20_POLY1305_SHA256,TLS_AES_256_GCM_SHA384,TLS_AES_128_GCM_SHA256,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,TLS_RSA_WITH_AES_128_CBC_SHA,TLS_RSA_WITH_AES_128_GCM_SHA256,TLS_RSA_WITH_AES_256_CBC_SHA,TLS_RSA_WITH_AES_256_GCM_SHA384"' /etc/rancher/rke2/config.yaml

2. Restart the RKE2 server. Note that this step may cause temporary downtime.

   systemctl restart rke2-server