tighten sshd settings (ciphers, kex, macs)

roles/base/tasks/main.yml

@@ -14,6 +14,49 @@
     owner: root
     group: "{{ ansible_wheel }}"
 
+# use openbsd kex algorithms but drop ssh-audit errors
+- name: tighten sshd kex algorithms
+  lineinfile:
+    path: /etc/ssh/sshd_config
+    line: "KexAlgorithms curve25519-sha256,curve25519-sha256@libssh.org,\
+     diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,\
+     diffie-hellman-group14-sha256"
+    regexp: "^KexAlgorithms .*"
+  notify: restart sshd
+# use openbsd ciphers but in mozilla recommended order (kind of)
+- 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 .*"
+  notify: restart sshd
+# use openbsd macs but drop ssh-audit errors
+- name: tighten sshd macs
+  lineinfile:
+    path: /etc/ssh/sshd_config
+    line: "MACs hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com"
+    regexp: "^MACs .*"
+  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"
+  notify: restart sshd
+- name: enable 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"
+  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"
+  notify: restart sshd
+
 - name: install basic roles
   include_role:
     name: "{{ role }}"