openssh

Install and configure an openssh server.

Table of Contents

General notes

See the full SaltStack Formulas installation and usage instructions.

If you are interested in writing or contributing to formulas, please pay attention to the Writing Formula Section.

If you want to use this formula, please pay attention to the FORMULA file and/or git tag, which contains the currently released version. This formula is versioned according to Semantic Versioning.

See Formula Versioning Section for more details.

Contributing to this repo

Commit message formatting is significant!!

Please see How to contribute <CONTRIBUTING> for more details.

Available states

openssh

Installs the openssh server package and service.

openssh.auth

Manages SSH certificates for users.

openssh.auth_map

Same functionality as openssh.auth but with a simplified Pillar syntax. Plays nicely with Pillarstack.

openssh.banner

Installs a banner that users see when SSH-ing in.

openssh.client

Installs the openssh client package.

openssh.config

Installs the ssh daemon configuration file included in this formula (under "openssh/files"). This configuration file is populated by values from pillar. pillar.example results in the generation of the default sshd_config file on Debian Wheezy.

It is highly recommended PermitRootLogin is added to pillar so root login will be disabled.

openssh.config_ini

Version of managing sshd_config that uses the ini_managed.option_present state module, so it enables to override only one or multiple values and keeping the defaults shipped by your distribution.

openssh.known_hosts

Manages /etc/ssh/ssh_known_hosts and fills it with the public SSH host keys of your minions (collected via the Salt mine) and of hosts listed in you pillar data. It's possible to include minions managed via salt-ssh by using the known_hosts_salt_ssh renderer.

You can restrict the set of minions whose keys are listed by using the pillar data openssh:known_hosts:target and openssh:known_hosts:tgt_type (those fields map directly to the corresponding attributes of the mine.get function).

The Salt mine is used to share the public SSH host keys, you must thus configure it accordingly on all hosts that must export their keys. Two mine functions are required, one that exports the keys (one key per line, as they are stored in /etc/ssh/ssh_host_*_key.pub) and one that defines the public hostname that the keys are associated to. Here's the way to setup those functions through pillar:

# Required for openssh.known_hosts
mine_functions:
  public_ssh_host_keys:
    mine_function: cmd.run
    cmd: cat /etc/ssh/ssh_host_*_key.pub
    python_shell: True
  public_ssh_hostname:
    mine_function: grains.get
    key: id

The above example assumes that the minion identifier is a valid DNS name that can be used to connect to the host. If that's not the case, you might want to use the fqdn grain instead of the id one. The above example also uses the default mine function names used by this formula. If you have to use other names, then you should indicate the names to use in pillar keys openssh:known_hosts:mine_keys_function and openssh:known_hosts:mine_hostname_function.

You can also integrate alternate DNS names of the various hosts in /etc/ssh/ssh_known_hosts. You just have to specify all the alternate DNS names as a list in the openssh:known_hosts:aliases pillar key. Whenever the IPv4 or IPv6 behind one of those DNS entries matches an IPv4 or IPv6 behind the official hostname of a minion, the alternate DNS name will be associated to the minion's public SSH host key.

To include minions managed via salt-ssh install the known_hosts_salt_ssh renderer:

# in pillar.top:
'*':
  - openssh.known_hosts_salt_ssh

# In your salt/ directory:
# Link the pillar file:
mkdir pillar/openssh
ln -s ../../formulas/openssh-formula/_pillar/known_hosts_salt_ssh.sls pillar/openssh/known_hosts_salt_ssh.sls

You'll find the cached pubkeys in Pillar openssh:known_hosts:salt_ssh.

It's possible to define aliases for certain hosts:

openssh:
  known_hosts:
    cache:
      public_ssh_host_names:
        minion.id:
          - minion.id
          - alias.of.minion.id

The cache is populated by applying openssh.gather_host_keys to the salt master:

salt 'salt-master.example.test' state.apply openssh.gather_host_keys

The state tries to fetch the SSH host keys via salt-ssh. It calls the command as user salt-master by default. The username can be changed via Pillar:

openssh:
  known_hosts:
    cache:
      user: salt-master

Use a cronjob to populate a host key cache:

# crontab -e -u salt-master
0 1 * * * salt 'salt-master.example.test' state.apply openssh.gather_host_keys

If you must have the latest pubkeys, run the state before all others:

# states/top.sls:
base:
  salt:
    # slooooow!
    - openssh.gather_host_keys

You can also use a "golden" known hosts file. It overrides the keys fetched by the cronjob. This lets you re-use the trust estabished in the salt-ssh user's known_hosts file:

# In your salt/ directory: (Pillar expects the file here.)
ln -s /home/salt-master/.ssh/known_hosts ./known_hosts

# Test it:
salt-ssh 'minion' pillar.get 'openssh:known_hosts:salt_ssh'

To add public keys of hosts not among your minions list them under the pillar key openssh:known_hosts:static:

openssh:
  known_hosts:
    static:
      github.com: 'ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAq[...]'
      gitlab.com: 'ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABA[...]'

Pillar openssh:known_hosts:static overrides openssh:known_hosts:salt_ssh.

To include localhost and local IP addresses (127.0.0.1 and ::1) use this Pillar:

openssh:
  known_hosts:
    include_localhost: True

openssh.moduli

Manages the system wide /etc/ssh/moduli file.

Testing

Linux testing is done with kitchen-salt.

Requirements

• Ruby
• Docker

$ gem install bundler
$ bundle install
$ bin/kitchen test [platform]

Where [platform] is the platform name defined in kitchen.yml, e.g. debian-9-2019-2-py3.

bin/kitchen converge

Creates the docker instance and runs the template main state, ready for testing.

bin/kitchen verify

Runs the inspec tests on the actual instance.

bin/kitchen destroy

Removes the docker instance.

bin/kitchen test

Runs all of the stages above in one go: i.e. destroy + converge + verify + destroy.

bin/kitchen login

Gives you SSH access to the instance for manual testing.