doc: Document TLS security setup for noVNC proxy
The nova noVNC proxy server has gained the ability to use the VeNCrypt authentication scheme to secure network communications with the compute node VNC servers. This documents how to configure the QEMU/KVM compute nodes and the noVNC proxy server nodes. Change-Id: If3cea87568efff0874cd8851cabc6770812c545b Blueprint: websocket-proxy-to-host-security Co-Authored-By: Stephen Finucane <sfinucan@redhat.com>
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Daniel Berrange
Stephen Finucane
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@ -9,7 +9,7 @@ command line. Best practice is to select only one of them to run.
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.. _about-nova-consoleauth:
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About nova-consoleauth
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~~~~~~~~~~~~~~~~~~~~~~
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----------------------
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The client proxies leverage a shared service to manage token authentication
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called ``nova-consoleauth``. This service must be running for either proxy to
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@ -21,7 +21,7 @@ which is a XenAPI-specific service that most recent VNC proxy architectures do
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not use.
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SPICE console
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~~~~~~~~~~~~~
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-------------
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OpenStack Compute supports VNC consoles to guests. The VNC protocol is fairly
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limited, lacking support for multiple monitors, bi-directional audio, reliable
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@ -57,7 +57,7 @@ Replace ``IP_ADDRESS`` with the management interface IP address of the
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controller or the VIP.
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VNC console proxy
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~~~~~~~~~~~~~~~~~
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-----------------
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The VNC proxy is an OpenStack component that enables compute service users to
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access their instances through VNC clients.
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@ -72,8 +72,7 @@ The VNC console connection works as follows:
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#. A user connects to the API and gets an ``access_url`` such as,
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``http://ip:port/?token=xyz``.
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#. The user pastes the URL in a browser or uses it as a client
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parameter.
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#. The user pastes the URL in a browser or uses it as a client parameter.
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#. The browser or client connects to the proxy.
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@ -104,8 +103,137 @@ client can talk to VNC servers. In general, the VNC proxy:
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:alt: noVNC process
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:width: 95%
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VNC proxy security
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~~~~~~~~~~~~~~~~~~
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Deploy the public-facing interface of the VNC proxy with HTTPS to prevent
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attacks from malicious parties on the network between the tenant user and proxy
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server. When using HTTPS, the TLS encryption only applies to data between the
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tenant user and proxy server. The data between the proxy server and Compute
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node instance will still be unencrypted. To provide protection for the latter,
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it is necessary to enable the VeNCrypt authentication scheme for VNC in both
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the Compute nodes and noVNC proxy server hosts.
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QEMU/KVM Compute node configuration
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+++++++++++++++++++++++++++++++++++
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Ensure each Compute node running QEMU/KVM with libvirt has a set of
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certificates issued to it. The following is a list of the required
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certificates:
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- :file:`/etc/pki/libvirt-vnc/server-cert.pem`
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An x509 certificate to be presented **by the VNC server**. The ``CommonName``
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should match the **primary hostname of the compute node**. Use of
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``subjectAltName`` is also permitted if there is a need to use multiple
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hostnames or IP addresses to access the same Compute node.
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- :file:`/etc/pki/libvirt-vnc/server-key.pem`
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The private key used to generate the ``server-cert.pem`` file.
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- :file:`/etc/pki/libvirt-vnc/ca-cert.pem`
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The authority certificate used to sign ``server-cert.pem`` and sign the VNC
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proxy server certificates.
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The certificates must have v3 basic constraints [3]_ present to indicate the
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permitted key use and purpose data.
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We recommend using a dedicated certificate authority solely for the VNC
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service. This authority may be a child of the master certificate authority used
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for the OpenStack deployment. This is because libvirt does not currently have
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a mechanism to restrict what certificates can be presented by the proxy server.
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For further details on certificate creation, consult the QEMU manual page
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documentation on VNC server certificate setup [2]_.
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Configure libvirt to enable the VeNCrypt authentication scheme for the VNC
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server. In :file:`/etc/libvirt/qemu.conf`, uncomment the following settings:
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- ``vnc_tls=1``
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This instructs libvirt to enable the VeNCrypt authentication scheme when
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launching QEMU, passing it the certificates shown above.
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- ``vnc_tls_x509_verify=1``
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This instructs QEMU to require that all VNC clients present a valid x509
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certificate. Assuming a dedicated certificate authority is used for the VNC
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service, this ensures that only approved VNC proxy servers can connect to the
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Compute nodes.
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After editing :file:`qemu.conf`, the ``libvirtd`` service must be restarted:
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.. code:: shell
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$ systemctl restart libvirtd.service
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Changes will not apply to any existing running guests on the Compute node, so
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this configuration should be done before launching any instances.
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noVNC proxy server configuration
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++++++++++++++++++++++++++++++++
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The noVNC proxy server initially only supports the ``none`` authentication
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scheme, which does no checking. Therefore, it is necessary to enable the
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``vencrypt`` authentication scheme by editing the :file:`nova.conf` file to
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set.
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.. code::
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[vnc]
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auth_schemes=vencrypt,none
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The :oslo.config:option:`vnc.auth_schemes` values should be listed in order
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of preference. If enabling VeNCrypt on an existing deployment which already has
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instances running, the noVNC proxy server must initially be allowed to use
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``vencrypt`` and ``none``. Once it is confirmed that all Compute nodes have
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VeNCrypt enabled for VNC, it is possible to remove the ``none`` option from the
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list of the :oslo.config:option:`vnc.auth_schemes` values.
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At that point, the noVNC proxy will refuse to connect to any Compute node that
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does not offer VeNCrypt.
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As well as enabling the authentication scheme, it is necessary to provide
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certificates to the noVNC proxy.
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- :file:`/etc/pki/nova-novncproxy/client-cert.pem`
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An x509 certificate to be presented **to the VNC server**. While libvirt/QEMU
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will not currently do any validation of the ``CommonName`` field, future
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versions will allow for setting up access controls based on the
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``CommonName``. The ``CommonName`` field should match the **primary hostname
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of the controller node**. If using a HA deployment, the ``Organization``
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field can also be configured to a value that is common across all console
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proxy instances in the deployment. This avoids the need to modify each
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compute node's whitelist every time a console proxy instance is added or
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removed.
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- :file:`/etc/pki/nova-novncproxy/client-key.pem`
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The private key used to generate the ``client-cert.pem`` file.
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- :file:`/etc/pki/nova-novncproxy/ca-cert.pem`
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The certificate authority cert used to sign ``client-cert.pem`` and sign the
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compute node VNC server certificates.
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The certificates must have v3 basic constraints [3]_ present to indicate the
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permitted key use and purpose data.
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Once the certificates have been created, the noVNC console proxy service must
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be told where to find them. This requires editing :file:`nova.conf` to set.
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.. code::
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[vnc]
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vencrypt_client_key=/etc/pki/nova-novncproxy/client-key.pem
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vencrypt_client_cert=/etc/pki/nova-novncproxy/client-cert.pem
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vencrypt_ca_certs=/etc/pki/nova-novncproxy/ca-cert.pem
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VNC configuration options
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-------------------------
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~~~~~~~~~~~~~~~~~~~~~~~~~
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To customize the VNC console, use the following configuration options in your
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``nova.conf`` file:
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@ -177,7 +305,7 @@ To customize the VNC console, use the following configuration options in your
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same network as the proxies.
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Typical deployment
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------------------
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~~~~~~~~~~~~~~~~~~
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A typical deployment has the following components:
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@ -197,7 +325,7 @@ A typical deployment has the following components:
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options, as follows.
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nova-novncproxy (noVNC)
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-----------------------
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~~~~~~~~~~~~~~~~~~~~~~~
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You must install the noVNC package, which contains the ``nova-novncproxy``
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service. As root, run the following command:
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@ -242,7 +370,7 @@ configuration options to your ``nova.conf`` file:
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connecting to instance ``vncservers``.
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Frequently asked questions about VNC access to virtual machines
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---------------------------------------------------------------
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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- **Q: What is the difference between ``nova-xvpvncproxy`` and
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``nova-novncproxy``?**
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@ -325,7 +453,7 @@ Frequently asked questions about VNC access to virtual machines
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set explicitly where the ``nova-novncproxy`` service is running.
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Serial Console
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~~~~~~~~~~~~~~
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--------------
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The *serial console* feature [1]_ in nova is an alternative for graphical
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consoles like *VNC*, *SPICE*, *RDP*. The example below uses these nodes:
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@ -366,6 +494,8 @@ Keep these things in mind:
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proxying the console interaction.
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References
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~~~~~~~~~~
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----------
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.. [1] https://specs.openstack.org/openstack/nova-specs/specs/juno/implemented/serial-ports.html
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.. [1] https://specs.openstack.org/openstack/nova-specs/specs/juno/implemented/serial-ports.html
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.. [2] https://qemu.weilnetz.de/doc/qemu-doc.html#vnc_005fsec_005fcertificate_005fverify
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.. [3] https://tools.ietf.org/html/rfc3280#section-4.2.1.10
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@ -9,6 +9,10 @@ features:
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- ``vencrypt_client_key``
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- ``vencrypt_client_cert``
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- ``vencrypt_ca_certs``
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For more information, refer to `the documentation`__.
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__ https://docs.openstack.org/nova/latest/admin/remote-console-access.html
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- |
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The *nova-novncproxy* server can now be configured to do a security
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negotiation with the compute node VNC server. If the VeNCrypt auth scheme
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@ -31,3 +35,7 @@ features:
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Once all compute nodes have VeNCrypt enabled, the ``auth_schemes``
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parameter can be set to just ``['vencrypt']``.
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For more information, refer to `the documentation`__.
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__ https://docs.openstack.org/nova/latest/admin/remote-console-access.html
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