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Chapter 36. Authenticating a RHEL client to the network by using the 802.1X standard with a certificate stored on the file system

Port-based Network Access Control (NAC), based on the IEEE 802.1X standard, protects a network from unauthorized clients. If the network uses Extensible Authentication Protocol Transport Layer Security (EAP-TLS), you require a certificate to authenticate the client.

You can use the nmcli utility to configure an Ethernet connection with 802.1X network authentication on the command line.

Prerequisites

  • The network supports 802.1X network authentication.
  • The Ethernet connection profile exists in NetworkManager and has a valid IP configuration.

  • The following files required for TLS authentication exist on the client:

    • The client key stored is in the /etc/pki/tls/private/client.key file, and the file is owned and only readable by the root user.
    • The client certificate is stored in the /etc/pki/tls/certs/client.crt file.
    • The Certificate Authority (CA) certificate is stored in the /etc/pki/tls/certs/ca.crt file.
  • The wpa_supplicant package is installed.

Procedure

  1. Set the Extensible Authentication Protocol (EAP) to tls and the paths to the client certificate and key file: 

    # nmcli connection modify enp1s0 802-1x.eap tls 802-1x.client-cert /etc/pki/tls/certs/client.crt 802-1x.private-key /etc/pki/tls/private/client.key

    Note that you must set the 802-1x.eap, 802-1x.client-cert, and 802-1x.private-key parameters in a single command.

  2. Set the path to the CA certificate: 

    # nmcli connection modify enp1s0 802-1x.ca-cert /etc/pki/tls/certs/ca.crt

  3. Set the identity of the user used in the certificate: 

    # nmcli connection modify enp1s0 802-1x.identity user@example.com

  4. Optional: Store the password in the configuration: 

    # nmcli connection modify enp1s0 802-1x.private-key-password password
    Important

    By default, NetworkManager stores the password in clear text in the connection profile on the disk, but the file is readable only by the root user. However, clear text passwords in a configuration file can be a security risk.

    To increase the security, set the 802-1x.password-flags parameter to agent-owned. With this setting, on servers with the GNOME desktop environment or the nm-applet running, NetworkManager retrieves the password from these services, after you unlock the keyring. In other cases, NetworkManager prompts for the password.

  5. Activate the connection profile: 

    # nmcli connection up enp1s0

Verification

  • Access resources on the network that require network authentication.

You can use the declarative Nmstate API to configure an Ethernet connection with 802.1X network authentication. Nmstate ensures that the result matches the configuration file or rolls back the changes.

Note

The nmstate library only supports the TLS Extensible Authentication Protocol (EAP) method.

Prerequisites

  • The network supports 802.1X network authentication.
  • The managed node uses NetworkManager.

  • The following files required for TLS authentication exist on the client:

    • The client key stored is in the /etc/pki/tls/private/client.key file, and the file is owned and only readable by the root user.
    • The client certificate is stored in the /etc/pki/tls/certs/client.crt file.
    • The Certificate Authority (CA) certificate is stored in the /etc/pki/tls/certs/ca.crt file.

Procedure

  1. Create a YAML file, for example ~/create-ethernet-profile.yml, with the following content: 

    ---
interfaces:
- name: enp1s0
  type: ethernet
  state: up
  ipv4:
    enabled: true
    address:
    - ip: 192.0.2.1
      prefix-length: 24
    dhcp: false
  ipv6:
    enabled: true
    address:
    - ip: 2001:db8:1::1
      prefix-length: 64
    autoconf: false
    dhcp: false
  802.1x:
    ca-cert: /etc/pki/tls/certs/ca.crt
    client-cert: /etc/pki/tls/certs/client.crt
    eap-methods:
      - tls
    identity: client.example.org
    private-key: /etc/pki/tls/private/client.key
    private-key-password: password
routes:
  config:
  - destination: 0.0.0.0/0
    next-hop-address: 192.0.2.254
    next-hop-interface: enp1s0
  - destination: ::/0
    next-hop-address: 2001:db8:1::fffe
    next-hop-interface: enp1s0
dns-resolver:
  config:
    search:
    - example.com
    server:
    - 192.0.2.200
    - 2001:db8:1::ffbb

    These settings define an Ethernet connection profile for the enp1s0 device with the following settings:

    • A static IPv4 address - 192.0.2.1 with a /24 subnet mask
    • A static IPv6 address - 2001:db8:1::1 with a /64 subnet mask
    • An IPv4 default gateway - 192.0.2.254
    • An IPv6 default gateway - 2001:db8:1::fffe
    • An IPv4 DNS server - 192.0.2.200
    • An IPv6 DNS server - 2001:db8:1::ffbb
    • A DNS search domain - example.com
    • 802.1X network authentication using the TLS EAP protocol

  2. Apply the settings to the system: 

    # nmstatectl apply ~/create-ethernet-profile.yml

Verification

  • Access resources on the network that require network authentication.

By using the network RHEL system role, you can automate setting up Network Access Control (NAC) on remote hosts. You can define authentication details for clients in a playbook to ensure only authorized clients can access the network.

You can use an Ansible playbook to copy a private key, a certificate, and the CA certificate to the client, and then use the network RHEL system role to configure a connection profile with 802.1X network authentication.

Prerequisites

  • You have prepared the control node and the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions for these nodes.
  • The network supports 802.1X network authentication.
  • The managed nodes use NetworkManager.

  • The following files required for the TLS authentication exist on the control node:

    • The client key is stored in the /srv/data/client.key file.
    • The client certificate is stored in the /srv/data/client.crt file.
    • The Certificate Authority (CA) certificate is stored in the /srv/data/ca.crt file.

Procedure

  1. 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>

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

      pwd: <password>
    3. Save the changes, and close the editor. Ansible encrypts the data in the vault.

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

    ---
- name: Configure an Ethernet connection with 802.1X authentication
  hosts: managed-node-01.example.com
  vars_files:
    - ~/vault.yml
  tasks:
    - name: Copy client key for 802.1X authentication
      ansible.builtin.copy:
        src: "/srv/data/client.key"
        dest: "/etc/pki/tls/private/client.key"
        mode: 0600

    - name: Copy client certificate for 802.1X authentication
      ansible.builtin.copy:
        src: "/srv/data/client.crt"
        dest: "/etc/pki/tls/certs/client.crt"

    - name: Copy CA certificate for 802.1X authentication
      ansible.builtin.copy:
        src: "/srv/data/ca.crt"
        dest: "/etc/pki/ca-trust/source/anchors/ca.crt"

    - name: Ethernet connection profile with static IP address settings and 802.1X
      ansible.builtin.include_role:
        name: redhat.rhel_system_roles.network
      vars:
        network_connections:
          - name: enp1s0
            type: ethernet
            autoconnect: yes
            ip:
              address:
                - 192.0.2.1/24
                - 2001:db8:1::1/64
              gateway4: 192.0.2.254
              gateway6: 2001:db8:1::fffe
              dns:
                - 192.0.2.200
                - 2001:db8:1::ffbb
              dns_search:
                - example.com
            ieee802_1x:
              identity: <user_name>
              eap: tls
              private_key: "/etc/pki/tls/private/client.key"
              private_key_password: "{{ pwd }}"
              client_cert: "/etc/pki/tls/certs/client.crt"
              ca_cert: "/etc/pki/ca-trust/source/anchors/ca.crt"
              domain_suffix_match: example.com
            state: up

    The settings specified in the example playbook include the following:

    ieee802_1x
    This variable contains the 802.1X-related settings.
    eap: tls
    Configures the profile to use the certificate-based TLS authentication method for the Extensible Authentication Protocol (EAP).

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

  3. Validate the playbook syntax: 

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

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

  4. Run the playbook: 

    $ ansible-playbook --ask-vault-pass ~/playbook.yml

Verification

  • Access resources on the network that require network authentication.

By using the network RHEL system role, you can automate setting up Network Access Control (NAC) on remote hosts. You can define authentication details for clients in a playbook to ensure only authorized clients can access the network.

You can use an Ansible playbook to copy a private key, a certificate, and the CA certificate to the client, and then use the network RHEL system role to configure a connection profile with 802.1X network authentication.

Prerequisites

  • You have prepared the control node and the managed nodes.
  • The account you use to connect to the managed nodes has sudo permissions for these nodes.
  • The network supports 802.1X network authentication.
  • You installed the wpa_supplicant package on the managed node.
  • DHCP is available in the network of the managed node.

  • The following files required for TLS authentication exist on the control node:

    • The client key is stored in the /srv/data/client.key file.
    • The client certificate is stored in the /srv/data/client.crt file.
    • The CA certificate is stored in the /srv/data/ca.crt file.

Procedure

  1. 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>

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

      pwd: <password>
    3. Save the changes, and close the editor. Ansible encrypts the data in the vault.

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

    ---
- name: Configure a wifi connection with 802.1X authentication
  hosts: managed-node-01.example.com
  tasks:
    - name: Copy client key for 802.1X authentication
      ansible.builtin.copy:
        src: "/srv/data/client.key"
        dest: "/etc/pki/tls/private/client.key"
        mode: 0400

    - name: Copy client certificate for 802.1X authentication
      ansible.builtin.copy:
        src: "/srv/data/client.crt"
        dest: "/etc/pki/tls/certs/client.crt"

    - name: Copy CA certificate for 802.1X authentication
      ansible.builtin.copy:
        src: "/srv/data/ca.crt"
        dest: "/etc/pki/ca-trust/source/anchors/ca.crt"

    - name: Wifi connection profile with dynamic IP address settings and 802.1X
      ansible.builtin.import_role:
        name: redhat.rhel_system_roles.network
      vars:
        network_connections:
          - name: Wifi connection profile with dynamic IP address settings and 802.1X
            interface_name: wlp1s0
            state: up
            type: wireless
            autoconnect: yes
            ip:
              dhcp4: true
              auto6: true
            wireless:
              ssid: "Example-wifi"
              key_mgmt: "wpa-eap"
            ieee802_1x:
              identity: <user_name>
              eap: tls
              private_key: "/etc/pki/tls/client.key"
              private_key_password: "{{ pwd }}"
              private_key_password_flags: none
              client_cert: "/etc/pki/tls/client.pem"
              ca_cert: "/etc/pki/tls/cacert.pem"
              domain_suffix_match: "example.com"

    The settings specified in the example playbook include the following:

    ieee802_1x
    This variable contains the 802.1X-related settings.
    eap: tls
    Configures the profile to use the certificate-based TLS authentication method for the Extensible Authentication Protocol (EAP).

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

  3. Validate the playbook syntax: 

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

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

  4. Run the playbook: 

    $ ansible-playbook --ask-vault-pass ~/playbook.yml
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