Configure ssh

machine.yml

@@ -7,7 +7,29 @@
   tasks:
 
     # ----------------------------------------------------------------------------------------------
-    # NTP.
+    # SSH configuration.
+    # ----------------------------------------------------------------------------------------------
+
+    # SSH must be installed and enabled for ansible to even connect so we don't bother with
+    # installing and starting it.
+
+    - name: Configure sshd
+      template:
+        src: ./root/etc/ssh/sshd_config.d/00-yggdrasil.conf.j2
+        dest: /etc/ssh/sshd_config.d/00-yggdrasil.conf
+        mode: 0600
+      register: sshd_cfg
+
+    - name: Restart sshd
+      service:
+        name: sshd
+        enabled: yes
+        state: restarted
+      when:
+        sshd_cfg is changed
+
+    # ----------------------------------------------------------------------------------------------
+    # NTP configuration.
     # ----------------------------------------------------------------------------------------------
 
     - name: Install systemd-timesyncd

root/etc/ssh/sshd_config

@@ -1,123 +0,0 @@
-#	$OpenBSD: sshd_config,v 1.103 2018/04/09 20:41:22 tj Exp $
-
-# This is the sshd server system-wide configuration file.  See
-# sshd_config(5) for more information.
-
-# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin
-
-# The strategy used for options in the default sshd_config shipped with
-# OpenSSH is to specify options with their default value where
-# possible, but leave them commented.  Uncommented options override the
-# default value.
-
-Include /etc/ssh/sshd_config.d/*.conf
-
-#Port 22
-#AddressFamily any
-#ListenAddress 0.0.0.0
-#ListenAddress ::
-
-#HostKey /etc/ssh/ssh_host_rsa_key
-#HostKey /etc/ssh/ssh_host_ecdsa_key
-#HostKey /etc/ssh/ssh_host_ed25519_key
-
-# Ciphers and keying
-#RekeyLimit default none
-
-# Logging
-#SyslogFacility AUTH
-#LogLevel INFO
-
-# Authentication:
-
-#LoginGraceTime 2m
-#PermitRootLogin prohibit-password
-#StrictModes yes
-#MaxAuthTries 6
-#MaxSessions 10
-
-#PubkeyAuthentication yes
-
-# Expect .ssh/authorized_keys2 to be disregarded by default in future.
-#AuthorizedKeysFile	.ssh/authorized_keys .ssh/authorized_keys2
-
-#AuthorizedPrincipalsFile none
-
-#AuthorizedKeysCommand none
-#AuthorizedKeysCommandUser nobody
-
-# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
-#HostbasedAuthentication no
-# Change to yes if you don't trust ~/.ssh/known_hosts for
-# HostbasedAuthentication
-#IgnoreUserKnownHosts no
-# Don't read the user's ~/.rhosts and ~/.shosts files
-#IgnoreRhosts yes
-
-# To disable tunneled clear text passwords, change to no here!
-#PasswordAuthentication yes
-#PermitEmptyPasswords no
-
-# Change to yes to enable challenge-response passwords (beware issues with
-# some PAM modules and threads)
-ChallengeResponseAuthentication no
-
-# Kerberos options
-#KerberosAuthentication no
-#KerberosOrLocalPasswd yes
-#KerberosTicketCleanup yes
-#KerberosGetAFSToken no
-
-# GSSAPI options
-#GSSAPIAuthentication no
-#GSSAPICleanupCredentials yes
-#GSSAPIStrictAcceptorCheck yes
-#GSSAPIKeyExchange no
-
-# 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'.
-UsePAM yes
-
-#AllowAgentForwarding yes
-#AllowTcpForwarding yes
-#GatewayPorts no
-X11Forwarding yes
-#X11DisplayOffset 10
-#X11UseLocalhost yes
-#PermitTTY yes
-PrintMotd no
-#PrintLastLog yes
-#TCPKeepAlive yes
-#PermitUserEnvironment no
-#Compression delayed
-#ClientAliveInterval 0
-#ClientAliveCountMax 3
-#UseDNS no
-#PidFile /var/run/sshd.pid
-#MaxStartups 10:30:100
-#PermitTunnel no
-#ChrootDirectory none
-#VersionAddendum none
-
-# no default banner path
-#Banner none
-
-# Allow client to pass locale environment variables
-AcceptEnv LANG LC_*
-
-# override default of no subsystems
-Subsystem	sftp	/usr/lib/openssh/sftp-server
-
-# Example of overriding settings on a per-user basis
-#Match User anoncvs
-#	X11Forwarding no
-#	AllowTcpForwarding no
-#	PermitTTY no
-#	ForceCommand cvs server

root/etc/ssh/sshd_config.d/00-yggdrasil.conf.j2

@@ -0,0 +1,17 @@
+# Yggdrasil SSH daemon configuration. Note that sshd_config(5) states "For each keyword, the first
+# obtained value will be used." This is why, despite files > 00 being read later, settings
+# configured in this file are retained.
+
+Port {{ ansible_port }}
+
+# Completely disable root login via ssh.
+PermitRootLogin no
+
+# Explicitly set the list of allowed ssh users.
+AllowUsers {{ ssh_user }}
+
+# SSH enabled only via ssh-key.
+PasswordAuthentication no
+
+# No X window forwarding.
+X11Forwarding no

secrets.def.yml

@@ -2,6 +2,9 @@
 ansible_port:
 ansible_become_password:
 
+# SSH variables
+ssh_user:
+
 # Machine variables
 hostname:
 domain: