---

- name: disable AllowAgentForwarding
  lineinfile:
    path: /etc/ssh/sshd_config
    regexp: '^#?AllowAgentForwarding'
    line: 'AllowAgentForwarding no'
    validate: "sshd -t -f %s"
  notify: restart sshd

- name: disable ChallengeResponseAuthentication
  lineinfile:
    path: /etc/ssh/sshd_config
    regexp: '^#?ChallengeResponseAuthentication'
    line: 'ChallengeResponseAuthentication no'
    validate: "sshd -t -f %s"
  notify: restart sshd

# based on mozilla recommended settings
#   https://infosec.mozilla.org/guidelines/openssh.html
#
#   * prefer aes over chacha for hardware acceleration
#   * use only ed25519 host key
#
- name: disable default crypto policy
  lineinfile:
    path: /etc/sysconfig/sshd
    regexp: '^(#\s+)?CRYPTO_POLICY='
    line: "CRYPTO_POLICY="
  notify: restart sshd
  when:
    - ansible_distribution == "CentOS"
    - ansible_distribution_version is version_compare("8", ">=")

- name: tighten ssh kex algorithm
  lineinfile:
    path: /etc/ssh/sshd_config
    line: "KexAlgorithms curve25519-sha256@libssh.org,\
     diffie-hellman-group-exchange-sha256"
    regexp: "^KexAlgorithms .*"
    validate: "sshd -t -f %s"
  notify: restart sshd

- name: tighten sshd ciphers
  lineinfile:
    path: /etc/ssh/sshd_config
    line: "Ciphers aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,\
     aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr"
    regexp: "^Ciphers .*"
    validate: "sshd -t -f %s"
  notify: restart sshd

- name: tighten sshd macs
  lineinfile:
    path: /etc/ssh/sshd_config
    line: "MACs hmac-sha2-512-etm@openssh.com,\
     hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com,\
     hmac-sha2-512,hmac-sha2-256,umac-128@openssh.com"
    regexp: "^MACs .*"
    validate: "sshd -t -f %s"
  notify: restart sshd

- name: disable ecdsa key from sshd
  lineinfile:
    path: /etc/ssh/sshd_config
    line: "#HostKey /etc/ssh/ssh_host_ecdsa_key"
    regexp: "^#?HostKey /etc/ssh/ssh_host_ecdsa_key"
    validate: "sshd -t -f %s"
  notify: restart sshd

- name: disable rsa key from sshd
  lineinfile:
    path: /etc/ssh/sshd_config
    line: "#HostKey /etc/ssh/ssh_host_rsa_key"
    regexp: "^#?HostKey /etc/ssh/ssh_host_rsa_key"
    validate: "sshd -t -f %s"
  notify: restart sshd

- name: enable ed25519 key from sshd
  lineinfile:
    path: /etc/ssh/sshd_config
    line: "HostKey /etc/ssh/ssh_host_ed25519_key"
    regexp: "^#?HostKey /etc/ssh/ssh_host_ed25519_key"
    validate: "sshd -t -f %s"
  notify: restart sshd