Messaging security

Messaging security

This section discusses security hardening approaches for the three most common message queuing solutions used in OpenStack: RabbitMQ, Qpid, and ZeroMQ.

Messaging transport security

AMQP based solutions (Qpid and RabbitMQ) support transport-level security using TLS. ZeroMQ messaging does not natively support TLS, but transport-level security is possible using labelled IPsec or CIPSO network labels.

We highly recommend enabling transport-level cryptography for your message queue. Using TLS for the messaging client connections provides protection of the communications from tampering and eavesdropping in-transit to the messaging server. Below is guidance on how TLS is typically configured for the two popular messaging servers Qpid and RabbitMQ. When configuring the trusted certificate authority (CA) bundle that your messaging server uses to verify client connections, it is recommended that this be limited to only the CA used for your nodes, preferably an internally managed CA. The bundle of trusted CAs will determine which client certificates will be authorized and pass the client-server verification step of the setting up the TLS connection. Note, when installing the certificate and key files, ensure that the file permissions are restricted, for example using chmod 0600, and the ownership is restricted to the messaging server daemon user to prevent unauthorized access by other processes and users on the messaging server.

RabbitMQ server SSL configuration

The following lines should be added to the system-wide RabbitMQ configuration file, typically /etc/rabbitmq/rabbitmq.config:

  {rabbit, [
     {tcp_listeners, [] },
     {ssl_listeners, [{"<IP address or hostname of management network interface>", 5671}] },
     {ssl_options, [{cacertfile,"/etc/ssl/cacert.pem"},

Note, the tcp_listeners option is set to [] to prevent it from listening on a non-SSL port. The ssl_listeners option should be restricted to only listen on the management network for the services.

For more information on RabbitMQ SSL configuration see:

Qpid server SSL configuration

The Apache Foundation has a messaging security guide for Qpid. See:

Queue authentication and access control

RabbitMQ and Qpid offer authentication and access control mechanisms for controlling access to queues. ZeroMQ offers no such mechanisms.

Simple Authentication and Security Layer (SASL) is a framework for authentication and data security in Internet protocols. Both RabbitMQ and Qpid offer SASL and other pluggable authentication mechanisms beyond simple user names and passwords that allow for increased authentication security. While RabbitMQ supports SASL, support in OpenStack does not currently allow for requesting a specific SASL authentication mechanism. RabbitMQ support in OpenStack allows for either user name and password authentication over an unencrypted connection or user name and password in conjunction with X.509 client certificates to establish the secure TLS connection.

We recommend configuring X.509 client certificates on all the OpenStack service nodes for client connections to the messaging queue and where possible (currently only Qpid) perform authentication with X.509 client certificates. When using user names and passwords, accounts should be created per-service and node for finer grained auditability of access to the queue.

Before deployment, consider the TLS libraries that the queuing servers use. Qpid uses Mozilla’s NSS library, whereas RabbitMQ uses Erlang’s TLS module which uses OpenSSL.

Authentication configuration example: RabbitMQ

On the RabbitMQ server, delete the default guest user:

# rabbitmqctl delete_user guest

On the RabbitMQ server, for each OpenStack service or node that communicates with the message queue set up user accounts and privileges:

# rabbitmqctl add_user compute01 RABBIT_PASS
# rabbitmqctl set_permissions compute01 ".*" ".*" ".*"

Replace RABBIT_PASS with a suitable password.

For additional configuration information see:

OpenStack service configuration: RabbitMQ

rpc_backend = nova.openstack.common.rpc.impl_kombu
rabbit_use_ssl = True
rabbit_host = RABBIT_HOST
rabbit_port = 5671
rabbit_user = compute01
rabbit_password = RABBIT_PASS
kombu_ssl_keyfile = /etc/ssl/node-key.pem
kombu_ssl_certfile = /etc/ssl/node-cert.pem
kombu_ssl_ca_certs = /etc/ssl/cacert.pem

Authentication configuration example: Qpid

For configuration information see:

OpenStack service configuration: Qpid

rpc_backend = nova.openstack.common.rpc.impl_qpid
qpid_protocol = ssl
qpid_hostname = <IP or hostname of management network interface of messaging server>
qpid_port = 5671
qpid_username = compute01
qpid_password = QPID_PASS

Optionally, if using SASL with Qpid specify the SASL mechanisms in use by adding:

qpid_sasl_mechanisms = <space separated list of SASL mechanisms to use for auth>

Message queue process isolation and policy

Each project provides a number of services which send and consume messages. Each binary which sends a message is expected to consume messages, if only replies, from the queue.

Message queue service processes should be isolated from each other and other processes on a machine.


Network namespaces are highly recommended for all services running on OpenStack Compute Hypervisors. This will help prevent against the bridging of network traffic between VM guests and the management network.

When using ZeroMQ messaging, each host must run at least one ZeroMQ message receiver to receive messages from the network and forward messages to local processes through IPC. It is possible and advisable to run an independent message receiver per project within an IPC namespace, along with other services within the same project.

Network policy

Queue servers should only accept connections from the management network. This applies to all implementations. This should be implemented through configuration of services and optionally enforced through global network policy.

When using ZeroMQ messaging, each project should run a separate ZeroMQ receiver process on a port dedicated to services belonging to that project. This is equivalent to the AMQP concept of control exchanges.

Mandatory access controls

Use both mandatory access controls (MACs) and discretionary access controls (DACs) to restrict the configuration for processes to only those processes. This restriction prevents these processes from being isolated from other processes that run on the same machine(s).

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