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).

The exception to the above is when you define a hostname variable under any given host, containing an FQDN, in which case the role will assume this is a managed host and won't attempt to make any changes to it (more details in hosts)

Requirements

The Ansible controller requires the python ipaddress package on EL7 systems, or other systems that use python 2.7. On python 3.x systems, the VPN role uses the python3 built-in ipaddress module.

Collection requirements

The role requires the firewall role and the selinux role from the fedora.linux_system_roles collection, if vpn_manage_firewall and vpn_manage_selinux are set to true, respectively. (Please see also the variables in the Firewall and Selinux section.) The role requires additional collections to manage rpm-ostree systems.

If using the vpn role from the fedora.linux_system_roles collection or from the Fedora RPM package, the requirements are already satisfied.

Otherwise, please run the following command line to install the collections.

ansible-galaxy collection install -r meta/collection-requirements.yml

Top-level 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

The value specified in this variable will determine the value of the authby field for the Libreswan tunnels opened. Acceptable values:

• psk for pre-shared key (PSK) authentication
• cert for authentication using certificates

vpn_ensure_openssl

The role uses openssl to generate PSKs. It requires this to be installed on the controller node. The default value is true. If you have pre-generated your PSKs, or you are not using PSKs, then set vpn_ensure_openssl: false. You can also define the PSKs using the shared_key_content variable in a host in any given tunnel.

vpn_connections

vpn_connections is a list of connections. Each connection is either:

• A list of hosts specified by hosts. In this host-to-host use case, the role creates tunnels between each pair of hosts. At least one tunnel must be defined in this list. If a single tunnel is required, you only need to specify the remote side.

• A mesh configuration consisting of one or more subnets and profiles. In this mesh use case, the role deploys an opportunistic mesh configuration using the policy/cidr pairs that you define in the policies.

Connection-specific variables

In addition to the global variables, you may provide a number of other variables that will be applied to the configuration for each tunnel. NOTE All time fields (for example ikelifetime and others) accept the time as a number + unit e.g. 13h for 13 hours, 10s for 10 seconds.

For the default values, and possible values, of ike, esp, type, et. al., please consult the libreswan documentation. You will usually not need to set these.

name

By default, the role generates a descriptive name for each tunnel it creates from the perspective of each system. For example, when creating a tunnel between bastion1 and bastion2, the descriptive name of this connection on bastion1 is bastion1-to-bastion2 but on bastion2 the connection is named bastion2-to-bastion1. You may add a prefix to these auto-generated names by specifying a value in the name field.

auth_method

Optionally, you can define an authentication method to use at the connection level. If auth_method is not defined, the role uses the global variable vpn_auth_method. The value of auth_method, or vpn_auth_method, determines the value of the authby field for the Libreswan tunnel opened for this connection. Acceptable values:

• psk for pre-shared key (PSK) authentication
• cert for authentication using certificates

auto

What operation, if any, should be done automatically at IPsec startup. Currently accepted values are add, ondemand, start, and ignore. The default value is null, which means no automatic startup operation.

opportunistic

By default, the VPN System Role creates a host-to-host tunnel between each pair of nodes specified within a vpn_connection. You can instead configure an opportunistic mesh VPN by setting opportunistic to true, which will include all hosts in the Ansible inventory in the opportunistic mesh configuration.

Note: When configuring an opportunistic mesh VPN using a control node that shares the same CIDR as one or more of mesh CIDRs used for encryption, add a clear policy entry for the control node CIDR in order to prevent an SSH connection loss during the play. See example.

leftupdown

It is best to keep it simple - no arguments with spaces, shell metacharacters, or other characters which require quoting or escaping - it will be difficult to pass them through the various layers of yaml, ansible, jinja, and shell. Example:

  leftupdown: ipsec_updown --route yes

will result in the config file

leftupdown="ipsec_updown --route yes"

If you need to pass an argument which requires quoting, use single quotes:

  leftupdown: ipsec_updown --route 'a quoted route value'

will result in the config file

leftupdown="ipsec_updown --route 'a quoted route value'"

If you need a custom script, the role does not current have the ability to copy or create a script on the managed host. You'll have to figure out some way to place the script on the host. Then you can point to the script using the full path, like /usr/local/bin/myscript.

By default, Libreswan runs ipsec_updown --route yes. You can disable that by using leftupdown: null.

policies

In this dictionary, you can set policy rules related to opportunistic encryption. If no policy rules are set, the default policy rule is private-or-clear. To override this default policy rule, see cidr. Note that the default policy does not add a 0.0.0.0/0 entry into a policy file. Instead, individual classless inter-domain routing (CIDR) values are added to policy files based on the CIDRs of the managed nodes. The default policy rule will be applied to CIDRs of all the hosts over which this role is run, unless you specify in this section a different policy rule for the CIDR of a particular managed node or group of managed nodes. If users wish to add a 0.0.0.0/0 entry to a particular policy file, they may add an item to this list where the policy value is the desired policy to be applied, and the CIDR value is 0.0.0.0/0.

policy

Valid values are private, private-or-clear, and clear.

cidr

In addition to any valid CIDR value, you may specify default in this field to apply the corresponding policy to all hosts that do not fit into one of the other specified policy groups, thereby overriding the default private-or-clear policy rule.

hosts

Each key in this dictionary is the unique name of a host. If a host is listed in hosts and not in the inventory file, the host will not be managed by the inventory. In such case, the hostname parameter is required because it is necessary for setting up the local ends of such a tunnel.

If the host key in the hosts list of your inventory is not the fully qualified domain name (FQDN) you want to use, you must use the hostname field under each host in this vpn_connections hosts dictionary to specify the actual FQDN or IP address you want the VPN role to use for setting up the tunnel. If you do not specify hostname, then the role will use ansible_host if defined, or the host key in your hosts list if neither ansible_host nor hostname is defined.

For each host key in this dictionary, the following host-specific parameters can be specified.

hostname

Can hold a host name or IP address. Specified only when overriding host names used by Ansible for SSH. Note that if a host name is specified, it must be fully qualified to ensure that DNS resolution works 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

Verifying 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 and Selinux

The firewall must be configured to allow traffic on 500/UDP, 4500/UDP, and 4500/TCP ports for the IKE, ESP, and AH protocols.

NOTE: The firewall configuration is prerequisite for managing selinux. If the firewall is not installed, managing selinux policy is skipped.

NOTE: vpn_manage_firewall and vpn_manage_selinux are limited to adding ports and policy, respectively. It cannot be used for removing them. If you want to remove ports and/or, you will need to use the firewall system role and/or the selinux role directly.

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. This also shows the optional parameters you can specify for the tunnel.

all:
  hosts:
    bastion_east:
      ansible_host: bastion1.example.com
    bastion_west:
      ansible_host: bastion2.example.com
  vars:
    vpn_connections:
      - ike: aes256-sha2;dh19
        esp: aes-sha2_512+sha2_256
        ikelifetime: 11h
        salifetime: 9h
        type: transport
        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 connections 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

Managed-host-to-unmanaged-host (e.g. remote is appliance)

This playbook sets up a host-to-host tunnel between the current host in the inventory, and a remote host not managed by Ansible (like an appliance) which requires proper identification. In this example this_host should be manually set with the same name as inventory_hostname. The shared key is the key shared between the hosts.

  vars:
    vpn_connections:
      - auth_method: psk
        auto: start
        shared_key_content: !vault |
          $ANSIBLE_VAULT;1.2;AES256;dev
          ....
        hosts:
          this_host:
            leftid: idoftheclient
          nfsserver:
            hostname: nfsserver.example.com
            rightid: idoftheserver

Opportunistic Mesh VPN configuration

This playbook sets up an opportunistic mesh VPN configuration on each host in the list of hosts, using certificates for authentication. In this example, the controller machine shares the same CIDR as both of the target machines (192.168.110.0/24) and has IP address 192.168.110.7. Therefore the controller machine will fall under a private policy which will automatically be created for the CIDR 192.168.110.0/24. To prevent an SSH connection loss during the play, a clear policy for the controller machine has been added to the list of policies. Note that there is also an item in the policies list where the cidr is equal to default. This is because this playbook is overriding the default policy rule to make it private instead of private-or-clear.

  hosts:
    bastion1.example.com:
      cert_name: bastion1cert
    bastion2.example.com:
      cert_name: bastion2cert
    bastion3.example.com:
      cert_name: bastion3cert
  vars:
    vpn_connections:
      - opportunistic: true
        auth_method: cert
        policies:
          - policy: private
            cidr: default
          - policy: private-or-clear
            cidr: 192.168.122.0/24
          - policy: private
            cidr: 192.168.110.0/24
          - policy: clear
            cidr: 192.168.110.7/32

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).

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.

Notes: It is recommended to not specify a pre-shared key, 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 ability 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 algorithms

Minimum acceptable algorithms are AES, MODP2048 and SHA2.

rpm-ostree

See README-ostree.md

License

MIT.