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Chapter 31. Configuring VPN connections by using RHEL system roles

A VPN is an encrypted connection to securely transmit traffic over untrusted networks. By using the vpn RHEL system role, you can automate the process of creating VPN configurations.

Note

The vpn RHEL system role supports only Libreswan, which is an IPsec implementation, as the VPN provider.

31.1. Creating a host-to-host IPsec VPN with PSK authentication by using the vpn RHEL system role

You can use IPsec to directly connect hosts to each other through a VPN. The hosts can use a pre-shared key (PSK) to authenticate to each other. By using the vpn RHEL system role, you can automate the process of creating IPsec host-to-host connections with PSK authentication.

By default, the role creates a tunnel-based VPN.

Prerequisites

Procedure

  1. Create a playbook file, for example ~/playbook.yml, with the following content: 

    ---
- name: Configuring VPN
  hosts: managed-node-01.example.com, managed-node-02.example.com
  tasks:
    - name: IPsec VPN with PSK authentication
      ansible.builtin.include_role:
        name: redhat.rhel_system_roles.vpn
      vars:
        vpn_connections:
          - hosts:
              managed-node-01.example.com:
              managed-node-02.example.com:
            auth_method: psk
            auto: start
        vpn_manage_firewall: true
        vpn_manage_selinux: true
    Copy to Clipboard

    The settings specified in the example playbook include the following:

    hosts: <list>

    Defines a YAML dictionary with the hosts between which you want to configure a VPN. If an entry is not an Ansible managed node, you must specify its fully-qualified domain name (FQDN) or IP address in the hostname parameter, for example: 

              ...
          - hosts:
              ...
              external-host.example.com:
                hostname: 192.0.2.1
    Copy to Clipboard

    The role configures the VPN connection on each managed node. The connections are named <host_A>-to-<host_B>, for example, managed-node-01.example.com-to-managed-node-02.example.com. Note that the role can not configure Libreswan on external (unmanaged) nodes. You must manually create the configuration on these hosts.

    auth_method: psk
    Enables PSK authentication between the hosts. The role uses openssl on the control node to create the PSK.
    auto: <start-up_method>
    Specifies the start-up method of the connection. Valid values are add, ondemand, start, and ignore. For details, see the ipsec.conf(5) man page on a system with Libreswan installed. The default value of this variable is null, which means no automatic startup operation.
    vpn_manage_firewall: true
    Defines that the role opens the required ports in the firewalld service on the managed nodes.
    vpn_manage_selinux: true
    Defines that the role sets the required SELinux port type on the IPsec ports.

    For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-system-roles.vpn/README.md file on the control node.

  2. Validate the playbook syntax: 

    $ ansible-playbook --syntax-check ~/playbook.yml
    Copy to Clipboard

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook: 

    $ ansible-playbook ~/playbook.yml
    Copy to Clipboard

Verification

  • Confirm that the connections are successfully started, for example: 

    # ansible managed-node-01.example.com -m shell -a 'ipsec trafficstatus | grep "managed-node-01.example.com-to-managed-node-02.example.com"'
...
006 #3: "managed-node-01.example.com-to-managed-node-02.example.com", type=ESP, add_time=1741857153, inBytes=38622, outBytes=324626, maxBytes=2^63B, id='@managed-node-02.example.com'
    Copy to Clipboard

    Note that this command only succeeds if the VPN connection is active. If you set the auto variable in the playbook to a value other than start, you might need to manually activate the connection on the managed nodes first.

31.2. Creating a host-to-host IPsec VPN with PSK authentication and separate data and control planes by using the vpn RHEL system role

You can use IPsec to directly connect hosts to each other through a VPN. For example, to enhance the security by minimizing the risk of control messages being intercepted or disrupted, you can configure separate connections for both the data traffic and the control traffic. By using the vpn RHEL system role, you can automate the process of creating IPsec host-to-host connections with a separate data and control plane and PSK authentication.

Prerequisites

Procedure

  1. Create a playbook file, for example ~/playbook.yml, with the following content: 

    ---
- name: Configuring VPN
  hosts: managed-node-01.example.com, managed-node-02.example.com
  tasks:
    - name: IPsec VPN with PSK authentication
      ansible.builtin.include_role:
        name: redhat.rhel_system_roles.vpn
      vars:
        vpn_connections:
          - name: control_plane_vpn
            hosts:
              managed-node-01.example.com:
                hostname: 203.0.113.1  # IP address for the control plane
              managed-node-02.example.com:
                hostname: 198.51.100.2 # IP address for the control plane
            auth_method: psk
            auto: start
          - name: data_plane_vpn
            hosts:
              managed-node-01.example.com:
                hostname: 10.0.0.1   # IP address for the data plane
              managed-node-02.example.com:
                hostname: 172.16.0.2 # IP address for the data plane
            auth_method: psk
            auto: start
        vpn_manage_firewall: true
        vpn_manage_selinux: true
    Copy to Clipboard

    The settings specified in the example playbook include the following:

    hosts: <list>

    Defines a YAML dictionary with the hosts between which you want to configure a VPN. The connections are named <name>-<IP_address_A>-to-<IP_address_B>, for example control_plane_vpn-203.0.113.1-to-198.51.100.2.

    The role configures the VPN connection on each managed node. Note that the role can not configure Libreswan on external (unmanaged) nodes. You must manually create the configuration on these hosts.

    auth_method: psk
    Enables PSK authentication between the hosts. The role uses openssl on the control node to create the pre-shared key.
    auto: <start-up_method>
    Specifies the start-up method of the connection. Valid values are add, ondemand, start, and ignore. For details, see the ipsec.conf(5) man page on a system with Libreswan installed. The default value of this variable is null, which means no automatic startup operation.
    vpn_manage_firewall: true
    Defines that the role opens the required ports in the firewalld service on the managed nodes.
    vpn_manage_selinux: true
    Defines that the role sets the required SELinux port type on the IPsec ports.

    For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-system-roles.vpn/README.md file on the control node.

  2. Validate the playbook syntax: 

    $ ansible-playbook --syntax-check ~/playbook.yml
    Copy to Clipboard

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  3. Run the playbook: 

    $ ansible-playbook ~/playbook.yml
    Copy to Clipboard

Verification

  • Confirm that the connections are successfully started, for example: 

    # ansible managed-node-01.example.com -m shell -a 'ipsec trafficstatus | grep "control_plane_vpn-203.0.113.1-to-198.51.100.2"'
...
006 #3: "control_plane_vpn-203.0.113.1-to-198.51.100.2", type=ESP, add_time=1741860073, inBytes=0, outBytes=0, maxBytes=2^63B, id='198.51.100.2'
    Copy to Clipboard

    Note that this command only succeeds if the VPN connection is active. If you set the auto variable in the playbook to a value other than start, you might need to manually activate the connection on the managed nodes first.

31.3. Creating an IPsec mesh VPN among multiple hosts with certificate-based authentication by using the vpn RHEL system role

Libreswan supports creating an opportunistic mesh to establish IPsec connections among a large number of hosts with a single configuration on each host. Adding hosts to the mesh does not require updating the configuration on existing hosts. For enhanced security, use certificate-based authentication in Libreswan.

By using the vpn RHEL system role, you can automate configuring a VPN mesh with certificate-based authentication among managed nodes.

Prerequisites

  • You have prepared the control node and the managed nodes.
  • You are logged in to the control node as a user who can run playbooks on the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions on them.

  • You prepared a PKCS #12 file for each managed node:

    • Each file contains:

      • The certificate authority (CA) certificate
      • The node’s private key
      • The node’s client certificate
    • The files are named <managed_node_name_as_in_the_inventory>.p12.
    • The files are stored in the same directory as the playbook.

Procedure

  1. Edit the ~/inventory file, and append the cert_name variable: 

    managed-node-01.example.com cert_name=managed-node-01.example.com
managed-node-02.example.com cert_name=managed-node-02.example.com
managed-node-03.example.com cert_name=managed-node-03.example.com
    Copy to Clipboard

    Set the cert_name variable to the value of the common name (CN) field used in the certificate for each host. Typically, the CN field is set to the fully-qualified domain name (FQDN).

  2. Store your sensitive variables in an encrypted file:

    1. Create the vault: 

      $ ansible-vault create ~/vault.yml
New Vault password: <vault_password>
Confirm New Vault password: <vault_password>
      Copy to Clipboard

    2. After the ansible-vault create command opens an editor, enter the sensitive data in the <key>: <value> format: 

      pkcs12_pwd: <password>
      Copy to Clipboard
    3. Save the changes, and close the editor. Ansible encrypts the data in the vault.

  3. Create a playbook file, for example ~/playbook.yml, with the following content: 

    - name: Configuring VPN
  hosts: managed-node-01.example.com, managed-node-02.example.com, managed-node-03.example.com
  vars_files:
    - ~/vault.yml
  tasks:
    - name: Install LibreSwan
      ansible.builtin.package:
        name: libreswan
        state: present

    - name: Identify the path to IPsec NSS database
      ansible.builtin.set_fact:
        nss_db_dir: "{{ '/etc/ipsec.d/' if
          ansible_distribution in ['CentOS', 'RedHat']
          and ansible_distribution_major_version is version('8', '=')
          else '/var/lib/ipsec/nss/' }}"

    - name: Locate IPsec NSS database files
      ansible.builtin.find:
        paths: "{{ nss_db_dir }}"
        patterns: "*.db"
      register: db_files

    - name: Remove IPsec NSS database files
      ansible.builtin.file:
        path: "{{ item.path }}"
        state: absent
      loop: "{{ db_files.files }}"
      when: db_files.matched > 0

    - name: Initialize IPsec NSS database
      ansible.builtin.command:
        cmd: ipsec initnss

    - name: Copy PKCS #12 file to the managed node
      ansible.builtin.copy:
        src: "~/{{ inventory_hostname }}.p12"
        dest: "/etc/ipsec.d/{{ inventory_hostname }}.p12"
        mode: 0600

    - name: Import PKCS #12 file in IPsec NSS database
      ansible.builtin.shell:
        cmd: 'pk12util -d {{ nss_db_dir }} -i /etc/ipsec.d/{{ inventory_hostname }}.p12 -W "{{ pkcs12_pwd }}"'

    - name: Remove PKCS #12 file
      ansible.builtin.file:
        path: "/etc/ipsec.d/{{ inventory_hostname }}.p12"
        state: absent

    - name: Opportunistic mesh IPsec VPN with certificate-based authentication
      ansible.builtin.include_role:
        name: redhat.rhel_system_roles.vpn
      vars:
        vpn_connections:
          - opportunistic: true
            auth_method: cert
            policies:
              - policy: private
                cidr: default
              - policy: private
                cidr: 192.0.2.0/24
              - policy: clear
                cidr: 192.0.2.1/32
        vpn_manage_firewall: true
        vpn_manage_selinux: true
    Copy to Clipboard

    The settings specified in the example playbook include the following:

    opportunistic: true
    Enables an opportunistic mesh among multiple hosts. The policies variable defines for which subnets and hosts traffic must or or can be encrypted and which of them should continue using clear text connections.
    auth_method: cert
    Enables certificate-based authentication. This requires that you specified the nickname of each managed node’s certificate in the inventory.
    policies: <list_of_policies>

    Defines the Libreswan policies in YAML list format.

    The default policy is private-or-clear. To change it to private, the above playbook contains an according policy for the default cidr entry.

    To prevent a loss of the SSH connection during the execution of the playbook if the Ansible control node is in the same IP subnet as the managed nodes, add a clear policy for the control node’s IP address. For example, if the mesh should be configured for the 192.0.2.0/24 subnet and the control node uses the IP address 192.0.2.1, you require a clear policy for 192.0.2.1/32 as shown in the playbook.

    For details about policies, see the ipsec.conf(5) man page on a system with Libreswan installed.

    vpn_manage_firewall: true
    Defines that the role opens the required ports in the firewalld service on the managed nodes.
    vpn_manage_selinux: true
    Defines that the role sets the required SELinux port type on the IPsec ports.

    For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-system-roles.vpn/README.md file on the control node.

  4. Validate the playbook syntax: 

    $ ansible-playbook --ask-vault-pass --syntax-check ~/playbook.yml
    Copy to Clipboard

    Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

  5. Run the playbook: 

    $ ansible-playbook --ask-vault-pass ~/playbook.yml
    Copy to Clipboard

Verification

  1. On a node in the mesh, ping another node to activate the connection: 

    [root@managed-node-01]# ping managed-node-02.example.com
    Copy to Clipboard

  2. Confirm that the connections is active: 

    [root@managed-node-01]# ipsec trafficstatus
006 #2: "private#192.0.2.0/24"[1] ...192.0.2.2, type=ESP, add_time=1741938929, inBytes=372408, outBytes=545728, maxBytes=2^63B, id='CN=managed-node-02.example.com'
    Copy to Clipboard
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