Revision 4fbe765c SECURITY

b/SECURITY
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Host issues
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-----------
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For a host on which the Ganeti software has been installed but which has
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not been joined in a cluster, there are no changes to the system.
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For a host on which the Ganeti software has been installed, but not joined to a
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cluster, there are no changes to the system.
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For a host that has been joined to the cluster, there are very important
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changes:
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  - the host will have its ssh host key replaced with the one of the
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  - The host will have its SSH host key replaced with the one of the
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    cluster (which is the one the initial node had at the cluster
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    creation)
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  - root will have added to its authorized_keys file a public key which
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    grants access to all other nodes in the cluster, and furthermore it
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    will also get the private part of this key, which will allow it to
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    login to the other nodes in the cluster (its previous private key
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    will be backed up)
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  - the Ganeti node daemon will accept RPC requests from any host which
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    has the cluster shared secret, and the operations it will do as a
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  - A new public key will be added to root's authorized_keys file, granting
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    root access to all nodes of the cluster. The private part of the key
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    is also distributed to all nodes. Old files are renamed.
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  - Communication between nodes is encrypted using SSL/TLS. A common
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    key and certificate combo is shared between all nodes of the cluster.
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    At this time, no CA is used.
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  - The Ganeti node daemon will accept RPC requests from any host within the
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    cluster with the correct certificate, and the operations it will do as a
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    result of these requests are:
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      - running commands under the /etc/ganeti/hooks directory
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      - creating DRBD disks between it and the IP it has been told
......
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other nodes in the cluster, and the security of the cluster is
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determined by the weakest node.
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Note that only the ssh key will allow other machines to run random
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Note that only the SSH key will allow other machines to run random
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commands on this node; the RPC method will run only:
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  - well defined commands to create, remove, activate logical volumes,
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    drbd devices, start/stop instances, etc;
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  - run ssh commands on other nodes in the cluster, again well-defined
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  - run SSH commands on other nodes in the cluster, again well-defined
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  - scripts under the /etc/ganeti/hooks directory
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It is therefore important to make sure that the contents of the
......
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As told above, there are multiple ways of communication between cluster
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nodes:
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  - ssh-based, for high-volume traffic (image dumps) or for low-level
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    command (restart the Ganeti node daemon)
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  - python-twisted based, for the usual operation
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  - DRBD traffic, for real-time disk replication traffic
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  - SSH-based, for high-volume traffic like image dumps or for low-level
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    command, e.g. restarting the Ganeti node daemon
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  - RPC communication between master and nodes
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  - DRBD real-time disk replication traffic
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The ssh traffic is protected (after the initial login to a new node) by
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the cluster-wide shared ssh key.
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The SSH traffic is protected (after the initial login to a new node) by
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the cluster-wide shared SSH key.
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The python-twisted traffic is secured by SSL and two pre-conditions: the
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client will refuse to connect to servers which don't have the
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cluster-wide shared SSL certificate, and server will not allow clients
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which don't have the cluster-wide shared secret.
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RPC communication between the master and nodes is protected using SSL/TLS
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encryption. Both the client and the server must have the cluster-widely
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shared SSL/TLS certificate and verify it when establishing the connection
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by comparing fingerprints. We decided not to use a CA to simplify the
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key handling.
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The DRBD traffic is not protected by anything. DRBD does not support
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The DRBD traffic is not protected by encryption. DRBD does not support
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traffic encryption. It's therefore recommended to implement host-level
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firewalling or to use a separate range of IP addresses for the DRBD
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traffic (this is supported in Ganeti) which is not routed outside the
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cluster.
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cluster. DRBD connections are protected from connecting to random other
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machines by using a shared secret exchanged via RPC requests when
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starting the device.
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Remote API
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----------
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Starting with Ganeti 2.0, Remote API traffic is encrypted using SSL/TLS by
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default. It supports Basic authentication as per RFC2617.
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Paths for certificate, private key and CA files required for SSL/TLS will
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be set at source configure time. Symlinks or command line parameters may
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be used to use different files.

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