5.2. Securing SSH & passwords

If your server accepts SSH connections, the playbooks work directly if you specify the right domain/IP, username and password. However you could consider securing SSH:

5.2.1. Enable host key checking

  • Change vault_ssh_args to ‘-o StrictHostKeyChecking=yes’

  • Add the hosts fingerprint to known_hosts in ssh:

$ ssh-keyscan -H domain >> ~/.ssh/known_hosts

  • Login to the server and make sure the fingerprints match

5.2.2. Disable password-based ssh login and root login

  • Generate a ssh key if necessary:

$ ssh-keygen -t rsa

  • Copy the public key to the server:

$ ssh-copy-id -i ~/.ssh/key_rsa.pub user@server

(check in ~/.ssh/authorized_keys at server)

  • To disable password-based login and root login edit /etc/ssh/sshd_config as sudo:

ChallengeResponseAuthentication no
PasswordAuthentication no
UsePAM no
PermitRootLogin no

  • You might need to setup ssh-agent for ansible because it does not prompt for a password to unlock the private key (or try to make it prompt for the password):

$ ssh-agent bash
$ ssh-add ~/.ssh/id_rsa
    (ssh private key path)
$ exit

  • Try connecting:

$ ansible gnuhealth -m ping -e "ansible_user='user'"

5.2.3. Handling the sudo password

If you use a password stored in vault you could at least encrypt the vault file like it is explained in the section Encryption by Ansible-Vault.

In order to avoid putting your sudo password in vault two different approaches for becoming sudo are tested:

  • Keep vault_set_sudo_pass false and run the playbook with the -K flag (default)

  • Enable passwordless sudo on the target system and set vault_set_sudo_pass to false as well. For example sudo visudo /etc/sudoers/ and change the line %sudo ALL=(ALL:ALL) ALL to %sudo ALL=(ALL:ALL) NOPASSWD: ALL on Debian. For openSUSE use wheel instead of sudo and add your user to wheel: sudo usermod -aG wheel username.

5.2.4. Prompt for SSH password

If you do not have a SSH key you have to use the -k flag when calling a playbook or executing an ad hoc command.

5.2.5. Using the SSH playbook

If you want to create and fetch a key on the Ansible controller in order to trust it on target servers, run the playbook with the following flags:

$ ansible-playbook playbooks/ssh.yml -i inventories/dev -c local -e ssh_key_create=1 -e ssh_key_user=`whoami` -e ssh_key_fetch=1 -K

Afterwards you should have the key in the fetch folder.

Now set the host(s) where the new key should get trusted in inventories/dev/hosts under [ssh]. Next open inventories/dev/group_vars/ssh/vars.yml and uncomment the lines under ssh_key_trust_local_paths, remove the [] above, set key to the path of the key in the fetch folder and user to your username. Now run the playbook again:

$ ansible-playbook playbooks/ssh.yml -i inventories/dev -K -k

Afterwards you should be able to connect using the SSH key.

Note that you need the sshpass program installed for connecting over SSH password based. It can be installed from terminal:

$ sudo apt install sshpass

If you want to disable password based authentication set ssh_disable_pw_auth to true and run the playbook again.