simplifying openssh-server configuration and relying more on upstream defaults

defaults/main.yml

@@ -50,7 +50,13 @@ common_scripts:
   - { dest: "/usr/local/bin/zombies", src: "scripts/zombies" }
 
 common_openssh: True
+common_openssh_ports: []
+common_openssh_host_keys: []
+common_openssh_listen_addresses: []
+common_openssh_permit_root_login: "no"
+common_openssh_password_authentication: "no"
 common_openssh_keys_root: []
+common_openssh_x11_forwarding: "no"
 
 common_aliases:
   - "mailer-daemon: postmaster"

tasks/openssh.yml

@@ -7,7 +7,13 @@
   service: name=ssh state=started enabled=yes
 
 - name: openssh - config
-  template: dest=/etc/ssh/sshd_config src=sshd_config.j2 owner=root group=root mode=0600
+  template:
+      dest: /etc/ssh/sshd_config
+      src: sshd_config.j2
+      owner: root
+      group: root
+      mode: 0600
+      validate: '/usr/sbin/sshd -T -f %s'
   notify: reload openssh
 
 - name: openssh - root keys

templates/sshd_config.j2

@@ -1,89 +1,20 @@
 # {{ ansible_managed }}
 # See the sshd_config(5) manpage for details
 
-# What ports, IPs and protocols we listen for
-Port 22
-# Use these options to restrict which interfaces/protocols sshd will bind to
-#ListenAddress ::
-#ListenAddress 0.0.0.0
-Protocol 2
-# HostKeys for protocol version 2
-HostKey /etc/ssh/ssh_host_rsa_key
-HostKey /etc/ssh/ssh_host_dsa_key
-HostKey /etc/ssh/ssh_host_ecdsa_key
-HostKey /etc/ssh/ssh_host_ed25519_key
-#Privilege Separation is turned on for security
-UsePrivilegeSeparation yes
-
-# Lifetime and size of ephemeral version 1 server key
-KeyRegenerationInterval 3600
-ServerKeyBits 1024
-
-# Logging
-SyslogFacility AUTH
-LogLevel INFO
-
-# Authentication:
-LoginGraceTime 120
-PermitRootLogin without-password
-StrictModes yes
-
-RSAAuthentication yes
-PubkeyAuthentication yes
-#AuthorizedKeysFile	%h/.ssh/authorized_keys
-
-# Don't read the user's ~/.rhosts and ~/.shosts files
-IgnoreRhosts yes
-# For this to work you will also need host keys in /etc/ssh_known_hosts
-RhostsRSAAuthentication no
-# similar for protocol version 2
-HostbasedAuthentication no
-# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication
-#IgnoreUserKnownHosts yes
-
-# To enable empty passwords, change to yes (NOT RECOMMENDED)
-PermitEmptyPasswords no
-
-# Change to yes to enable challenge-response passwords (beware issues with
-# some PAM modules and threads)
+{% for port in common_openssh_ports -%}
+Port {{ port }}
+{% endfor %}
+{% for address in common_openssh_listen_addresses -%}
+ListenAddress {{ address }}
+{% endfor %}
+{% for hostkey in common_openssh_host_keys %}
+HostKey /etc/ssh/ssh_host_{{ hostkey }}_key
+{% endfor %}
+PermitRootLogin {{ common_openssh_permit_root_login }}
 ChallengeResponseAuthentication no
-
-# Change to no to disable tunnelled clear text passwords
-PasswordAuthentication no
-
-# Kerberos options
-#KerberosAuthentication no
-#KerberosGetAFSToken no
-#KerberosOrLocalPasswd yes
-#KerberosTicketCleanup yes
-
-# GSSAPI options
-#GSSAPIAuthentication no
-#GSSAPICleanupCredentials yes
-
-X11Forwarding yes
-X11DisplayOffset 10
+PasswordAuthentication {{ common_openssh_password_authentication }}
+X11Forwarding {{ common_openssh_x11_forwarding }}
 PrintMotd no
-PrintLastLog yes
-TCPKeepAlive yes
-#UseLogin no
-
-#MaxStartups 10:30:60
-#Banner /etc/issue.net
-
-# Allow client to pass locale environment variables
 AcceptEnv LANG LC_*
-
-Subsystem sftp {{ common_openssh_subsystem_sftp | default("/usr/lib/openssh/sftp-server") }}
-
-
-# Set this to 'yes' to enable PAM authentication, account processing,
-# and session processing. If this is enabled, PAM authentication will
-# be allowed through the ChallengeResponseAuthentication and
-# PasswordAuthentication.  Depending on your PAM configuration,
-# PAM authentication via ChallengeResponseAuthentication may bypass
-# the setting of "PermitRootLogin without-password".
-# If you just want the PAM account and session checks to run without
-# PAM authentication, then enable this but set PasswordAuthentication
-# and ChallengeResponseAuthentication to 'no'.
+Subsystem sftp /usr/lib/openssh/sftp-server
 UsePAM yes