VPN System Role

A Role for managing setup and configuration of VPN tunnels.

Basic usage:

all:
  hosts:
    bastion1.example.com: {...}
    bastion2.example.com: {...}
    bastion3.example.com: {...}
  vars:
    vpn_connections:
      - hosts:
          bastion1.example.com:
          bastion2.example.com:
          bastion3.example.com:

The role will set up a vpn tunnel between each pair of hosts in the list of vpn_connections, using the default parameters, including generating keys as needed. This role assumes that the names of the hosts under hosts are the same as the names of the hosts used in the Ansible inventory, and that you can use those names to configure the tunnels (i.e. they are real FQDNs that resolve correctly).

Variables

These global variables should be applied to the configuration for every tunnel (unless the user overrides them in the configuration of a particular tunnel).

vpn_auth_method

Acceptable values are psk for shared secrets (PSK) authentication or cert for authentication using certificates.

vpn_connections

vpn_connections is a list of tunnels. Each tunnel specifies two or more hosts. The role creates tunnels between each pair of hosts. At least one tunnel must be defined in this list.

The user may provide a number of other variables that should be applied to the configuration for each tunnel. The list of these tunnel-specific options is outlined in the table below.

name

By default, the role will generate a descriptive name for each tunnel it creates. For example, when creating a tunnel between bastion1 and bastion2, the descriptive name of this connection on bastion1 will be bastion1-to-bastion2. Similarly, the name of the connection associated with this tunnel on bastion2 will be bastion2-to-bastion1. The user may choose to prefix these auto-generated names by specifying a value in the name field.

auth_method

The user can define an authentication method to use at the tunnel level, however this is optional. If this parameter is not defined, the role will default to using the global variable vpn_auth_method. The value specified in this parameter will infer the value to be used in the authby field for a Libreswan tunnel. Acceptable values are the same as for vpn_auth_method (see vpn_auth_method).

auto

What operation, if any, should be done automatically at IPsec startup. Currently-accepted values are add, ondemand, start, and ignore (also the default, signifies no automatic startup operation).

hosts

Each key in this dictionary is the unique name of a host. If a host is listed here and is not part of the inventory list of hosts, it will be assumed that this host is not managed by our own inventory. In this case, the hostname parameter is required because it is necessary for setting up the local ends of such a tunnel. For each host key in this dictionary, the following host-specific parameters can be specified.

hostname

Can hold an IP address or FQDN. Specified only when overriding hostnames used by Ansible for SSH. Note that if a domain name is specified, it must be fully-qualified to ensure that DNS resolution will work correctly on host machines. This parameter is required when the host is not part of the inventory list of hosts.

cert_name

It is assumed that the cert_name provided by the user exists in the IPSec NSS cert database. Users may use the certificate system role to issue these certificates.

Verifying a successful startup

Libreswan

To confirm that a connection is successfully loaded:

ipsec status | grep <connectionname>

To confirm that a connection is successfully started:

ipsec trafficstatus | grep <connectionname>

To verify that a certificate has been imported (requires that the connection has loaded successfully). Note that if the same certificate is used for multiple connections, it may show up in the output for this command, even though there was an error on the connection being checked:

ipsec whack --listcerts

If a connection did not successfully load, it is recommended to run the following command to manually try to add the connection. This will give more specific information indicating why the connection failed to establish:

ipsec auto --add <connectionname>

Any errors that may have occurred during the process of loading and starting the connection are in the logs, which can be found in /var/log/pluto.log in RHEL 8, or by issuing the command journalctl -u ipsec in RHEL 7. Since these logs can be verbose and contain old entries, it is generally recommended to try to manually add the connection to obtain log messages from the standard output instead.

Firewall

The firewall must be configured to allow traffic on 500 and 4500/UDP ports for the IKE, ESP, and AH protocols. In the future, the firewall system role may be used for this configuration, however in the meantime these settings will need to be manually configured.

RHEL 8 and 9

The following commands configure the firewall for RHEL 8 and 9 systems, and other systems which use firewalld:

firewall-cmd --add-service="ipsec"
firewall-cmd --runtime-to-permanent

Use Cases

• Host-to-Host (openstack): Specific nodes connecting to each other. Use IPsec for IP failover between these nodes (so all other nodes don't need to be aware of anything happening). Keys are FreeIPA certificates, and pre-shared keys
• Host-to-Host (data centers): Two systems in different data centers communicate encrypted with each other using FreeIPA certificates, and pre-shared keys
• Host-to-Host (one host): One system communicating with an existing system (e.g., cisco) in an other organization that uses pre-shared keys
• Network-to-Network (two routers): One organization router connecting to a second one bringing together two distinct networks. Keys are FreeIPA certificates, and pre-shared keys.
• VPN Remote Access Server / Roadwarrior: One organization router accepting connections from multiple clients. Clients connect to a single router using FreeIPA certificates.
• MESH: node independent configurations. When adding/removing a node, you don't need to reconfigure all other nodes. They all attempt to setup individual host-to-host connections. A PKI is used to authenticate nodes (FreeIPA, potentially in the future DNSSEC)

Note that for a couple of these use cases, you cannot use host-scoped settings (e.g. global settings specified in all.hosts).

Examples

Host-to-host (multiple VPN tunnels with one externally managed host)

This playbook sets up the tunnel bastion_east-to-bastion_west using pre-shared key authentication with keys auto-generated by the system role. Additionally, the local ends of two more tunnels are set up: bastion_east-to-bastion_north and bastion_west-to-bastion_north. In this case, one of the hosts, bastion_north, is external to the inventory e.g. in a remote datacenter, and only the local ends of the tunnels can be set up. The hostname field contains all the information necessary to ensure that the local ends of the tunnel are set up correctly.

all:
  hosts:
    bastion_east:
      ansible_host: bastion1.example.com
    bastion_west:
      ansible_host: bastion2.example.com
  vars:
    vpn_connections:
      - hosts:
          bastion_east:
          bastion_west:
          bastion_north: # not in the hosts list
            hostname: 192.168.122.103

Host-to-host (multiple VPN tunnels with multiple NICS)

In this case, the hosts have multiple vpn tunnels associated with multiple NICs e.g. some OpenStack and OpenShift use cases.

all:
  hosts:
    bastion_east: {...}
    bastion_west: {...}
    bastion_north: {...}
  vars:
    vpn_connections:
      - name: control_plane_vpn
        hosts:
          bastion_east:
            hostname: 192.168.122.101 # IP for control plane
          bastion_west:
            hostname: 192.168.122.102
          bastion_north:
            hostname: 192.168.122.103
      - name: data_plane_vpn
        hosts:
          bastion_east:
            hostname: 10.0.0.1 # IP for data plane
          bastion_west:
            hostname: 10.0.0.2
          bastion_north:
            hostname: 10.0.0.3

Host-to-host (multiple VPN tunnels using certificates)

This playbook sets up host-to-host tunnels between each pair of hosts in the list of hosts using certificates for authentication.

  hosts:
    bastion1.example.com: {...}
    bastion2.example.com: {...}
    bastion3.example.com: {...}
  vars:
    vpn_connections:
      - name: vpn-tunnel-x
        auth_method: cert
        auto: start
        hosts:
          bastion1.example.com:
            cert_name: bastion1cert
          bastion2.example.com:
            cert_name: bastion2cert
          bastion3.example.com:
            cert_name: bastion3cert

To be added in a future release

The following global variables will be added. Additionally, pubkey will be added as a valid option under vpn_auth_method to perform public key authentication without certificates (enforces SHA-2).

Two dictionaries (ike and ipsec) will be added to the vpn_connections dictionary:

The following variables will be added under the hosts dictionary:

shared_key

shared_key_src indicates the path to a file on the controller host containing a PSK to be copied to the ipsec.secrets file on the managed node.

shared_key_content contains the actual PSK in a vault secret or base64 encoded string. This will also be copied to the ipsec.secrets file on the managed node.

Notes: It is not recommended to populate either of these two fields, since the role will automatically generate a secure pre-shared key if none is provided by the user. If the user does wish to provide their own pre-shared key, the recommendation is to vault encrypt the value. See https://docs.ansible.com/ansible/latest/user_guide/vault.html. Also, since it is still unclear how the role will allow users to specific pre-shared keys for each pair of hosts in a tunnel, it is reiterated that users should rely on the role's abilty to generate secure pre-shared keys automatically.

public_key

public_key_src specifies a path to a file on the controller host containing the public key used by this host for public key authentication without certificates. Otherwise, the user can directly specify the public key for this host by populating public_key_content. public_key_content can also accept a CKAID or nickname for a public key in the NSS database.

Note that public_key_src and public_key_content may also be specified as host-scoped Ansible variables. The variable names in this case will be vpn_public_key_src and vpn_public_key_content..

If neither public_key_src nor public_key_content is populated, the role will generate key pairs for each host.

Algorithms

Libreswan

Minimum acceptable algorithms are AES, MODP2048 and SHA2.

License

MIT.