# Access Control Lists

In Qpid, Access Control Lists (ACLs) specify which actions can be performed by each authenticated user. To enable, an Access Control Provider needs to be configured on the Broker. The Access Control Provider of type "AclFile" uses local file to specify the ACL rules. By convention, this file should have a .acl extension.

A Group Provider can be configured with ACL to define the user groups which can be used in ACL to determine the ACL rules applicable to the entire group. The configuration details for the Group Providers are described in . On creation of ACL Provider with group rules, the Group Provider should be added first. Otherwise, if the individual ACL rules are not defined for the logged principal the following invocation of management operations could be denied due to absence of the required groups.

Only one Access Control Provider can be used by the Broker. If several Access Control Providers are configured on Broker level only one of them will be used (the latest one).

The ACL Providers can be configured using REST Management interfaces and Web Management Console.

The following ACL Provider managing operations are available from Web Management Console:

- A new ACL Provider can be added by clicking onto "Add Access Control Provider" on the Broker tab.

- An ACL Provider details can be viewed on the Access Control Provider tab. The tab is shown after clicking onto ACL Provider name in the Broker object tree or after clicking onto ACL Provider row in ACL Providers grid on the Broker tab.

- An existing ACL Provider can be deleted by clicking onto buttons "Delete Access Control Provider" on the Broker tab or Access Control Provider tab.

## Writing .acl files

The ACL file consists of a series of rules associating behaviour for a user or group. Use of groups can serve to make the ACL file more concise. See Configuring Group Providers for more information on defining groups.

Each ACL rule grants or denies a particular action on an object to a user/group. The rule may be augmented with one or more properties, restricting the rule's applicability.

          ACL ALLOW alice CREATE QUEUE              # Grants alice permission to create all queues.
          ACL DENY bob CREATE QUEUE name="myqueue"  # Denies bob permission to create a queue called "myqueue"

The ACL is considered in strict line order with the first matching rule taking precedence over all those that follow. In the following example, if the user bob tries to create an exchange "myexch", the operation will be allowed by the first rule. The second rule will never be considered.

          ACL ALLOW bob ALL EXCHANGE
          ACL DENY bob CREATE EXCHANGE name="myexch"  # Dead rule

If the desire is to allow bob to create all exchanges except "myexch", order of the rules must be reversed:

          ACL DENY bob CREATE EXCHANGE name="myexch"
          ACL ALLOW bob ALL EXCHANGE

All ACL files end with an implict rule denying all operations to all users. It is as if each file ends with

    ACL DENY ALL ALL

If instead you wish to allow all operations other than those controlled by earlier rules, add

    ACL ALLOW ALL ALL

to the bottom of the ACL file.

When writing a new ACL, a good approach is to begin with an .acl file containing only

    ACL DENY-LOG ALL ALL

which will cause the Broker to deny all operations with details of the denial logged to the Qpid log file. Build up the ACL rule by rule, gradually working through the use-cases of your system. Once the ACL is complete, consider switching the DENY-LOG actions to DENY to improve performamce and reduce log noise.

ACL rules are very powerful: it is possible to write very granular rules specifying many broker objects and their properties. Most projects probably won't need this degree of flexibility. A reasonable approach is to choose to apply permissions at a certain level of abstraction (e.g. QUEUE) and apply them consistently across the whole system.

Some rules can be restricted to the virtual host if property virtualhost_name is specified.

Restrict rules to specific virtual hosts

          ACL ALLOW bob CREATE QUEUE virtualhost_name="test"
          ACL ALLOW bob ALL EXCHANGE virtualhost_name="prod"

In the example above the first rule allows user "bob" to create queues on virtual host "test" only. The second rule allows user "bob" any action with exchanges on virtual host "prod".

## Syntax

ACL rules follow this syntax:

         ACL {permission} {<group-name>|<user-name>|ALL} {action|ALL} [object|ALL] [property="<property-value>"]

Comments may be introduced with the hash (#) character and are ignored. Long lines can be broken with the slash (\) character.

          # A comment
          ACL ALLOW admin CREATE ALL # Also a comment
          ACL DENY guest \
          ALL ALL   # A broken line

List of ACL permission

`ALLOW` | Allow the action
`ALLOW-LOG` | Allow the action and log the action in the log
`DENY` | Deny the action
`DENY-LOG` | Deny the action and log the action in the log

List of ACL actions

Action | Description | Supported object types | Supported properties
--- | --- | --- | ---
`CONSUME` | Applied when subscriptions are created | QUEUE | name, autodelete, temporary, durable, exclusive, alternate, owner, virtualhost_name
`PUBLISH` | Applied on a per message basis on publish message transfers | EXCHANGE | name, routingkey, immediate, virtualhost_name
`CREATE` | Applied when an object is created, such as bindings, queues, exchanges | EXCHANGE, QUEUE, USER, GROUP | see properties on the corresponding object type
`ACCESS` | Applied when an object is read or accessed | VIRTUALHOST, MANAGEMENT | name (for VIRTUALHOST only)
`BIND` | Applied when queues are bound to exchanges | EXCHANGE | name, routingKey, queuename, virtualhost_name, temporary, durable
`UNBIND` | Applied when queues are unbound from exchanges | EXCHANGE | name, routingKey, queuename, virtualhost_name, temporary, durable
`DELETE` | Applied when objects are deleted | EXCHANGE, QUEUE, USER, GROUP | see properties on the corresponding object type
`PURGE` | Applied when purge the contents of a queue | QUEUE |
`UPDATE` | Applied when an object is updated | EXCHANGE, QUEUE, USER, GROUP | see EXCHANGE and QUEUE properties
`CONFIGURE` | Applied when an object is configured via REST management interfaces. | BROKER |
`ACCESS_LOGS` | Allows/denies to the specific user an operation to download broker log file(s) over REST interfaces | BROKER |

List of ACL objects

Object type | Description | Supported actions | Supported properties
--- | --- | --- | ---
`VIRTUALHOST` | A virtualhost | ALL, ACCESS | name
`MANAGEMENT` | Management - for web and JMX | ALL, ACCESS |
`QUEUE` | A queue | ALL, CREATE, DELETE, PURGE, CONSUME, UPDATE | name, autodelete, temporary, durable, exclusive, alternate, owner, virtualhost_name
`EXCHANGE` | An exchange | ALL, ACCESS, CREATE, DELETE, BIND, UNBIND, PUBLISH, UPDATE | name, autodelete, temporary, durable, type, virtualhost_name, queuename(only for BIND and UNBIND), routingkey(only for BIND and UNBIND, PUBLISH)
`USER` | A user | ALL, CREATE, DELETE, UPDATE | name
`GROUP` | A group | ALL, CREATE, DELETE, UPDATE | name
`METHOD` | Management or agent or broker method | ALL, ACCESS, UPDATE | name, component, virtualhost_name
`BROKER` | The broker | ALL, CONFIGURE, ACCESS_LOGS |

List of ACL properties

`name` | String. Object name, such as a queue name, exchange name or JMX method name.
`durable` | Boolean. Indicates the object is durable
`routingkey` | String. Specifies routing key
`autodelete` | Boolean. Indicates whether or not the object gets deleted when the connection is closed
`exclusive` | Boolean. Indicates the presence of an exclusive flag
`temporary` | Boolean. Indicates the presence of an temporary flag
`type` | String. Type of object, such as topic, fanout, or xml
`alternate` | String. Name of the alternate exchange
`queuename` | String. Name of the queue (used only when the object is something other than queue
`component` | String. JMX component name
`from_network` | Comma-separated strings representing IPv4 address ranges. Intended for use in ACCESS VIRTUALHOST rules to apply firewall-like restrictions. The rule matches if any of the address ranges match the IPv4 address of the messaging client. The address ranges are specified using either Classless Inter-Domain Routing notation (e.g. 192.168.1.0/24; see RFC 4632) or wildcards (e.g. 192.169.1.*).
`from_hostname` | Comma-separated strings representing hostnames, specified using Perl-style regular expressions, e.g. .*\.example\.company\.com Intended for use in ACCESS VIRTUALHOST rules to apply firewall-like restrictions. The rule matches if any of the patterns match the hostname of the messaging client. To look up the client's hostname, Qpid uses Java's DNS support, which internally caches its results. You can modify the time-to-live of cached results using the *.ttl properties described on the Java Networking Properties page. For example, you can either set system property sun.net.inetaddr.ttl from the command line (e.g. export QPID_OPTS="-Dsun.net.inetaddr.ttl=0") or networkaddress.cache.ttl in $JAVA_HOME/lib/security/java.security. The latter is preferred because it is JVM vendor-independent.
`virtualhost_name` | String. A name of virtual host to which the rule is applied.
`immediate` | Boolean. A property can be used to restrict PUBLISH action to publishing only messages with given immediate flag.

List of ACL JMX Components

`UserManagement` | User maintainance; create/delete/view users, change passwords etc
`ConfigurationManagement` | Dynammically reload configuration from disk.
`LoggingManagement` | Dynammically control Qpid logging level
`ServerInformation` | Read-only information regarding the Qpid: version number etc
`VirtualHost.Queue` | Queue maintainance; copy/move/purge/view etc
`VirtualHost.Exchange` | Exchange maintenance; bind/unbind queues to exchanges
`VirtualHost.VirtualHost` | Virtual host maintainace; create/delete exchanges, queues etc

## Worked Examples

Here are some example ACLs illustrating common use cases. In addition, note that the Java broker provides a complete example ACL file, located at etc/broker_example.acl.

### Worked example 1 - Management rights

Suppose you wish to permission two users: a user 'operator' must be able to perform all Management operations, and a user 'readonly' must be enable to perform only read-only functions. Neither 'operator' nor 'readonly' should be allowed to connect clients for messaging.

    # Deny (loggged) operator/readonly permission to connect messaging clients.
    ACL DENY-LOG operator ACCESS VIRTUALHOST
    ACL DENY-LOG readonly ACCESS VIRTUALHOST
    # Give operator permission to perfom all other actions
    ACL ALLOW operator ALL ALL
    # Give readonly permission to execute only read-only actions
    ACL ALLOW readonly ACCESS ALL
    ...
    ... rules for other users
    ...
    # Explicitly deny all (log) to eveyone
    ACL DENY-LOG ALL ALL

### Worked example 2 - User maintainer group

Suppose you wish to restrict User Management operations to users belonging to a group 'usermaint'. No other user is allowed to perform user maintainence This example illustrates the permissioning of an individual component.

    # Give usermaint access to management and permission to execute all JMX Methods on the
    # UserManagement MBean and perform all actions for USER objects
    ACL ALLOW usermaint ACCESS MANAGEMENT
    ACL ALLOW usermaint ALL METHOD component="UserManagement"
    ACL ALLOW usermaint ALL USER
    ACL DENY ALL ALL METHOD component="UserManagement"
    ACL DENY ALL ALL USER
    ...
    ... rules for other users
    ...
    ACL DENY-LOG ALL ALL

### Worked example 3 - Request/Response messaging

Suppose you wish to permission a system using a request/response paradigm. Two users: 'client' publishes requests; 'server' consumes the requests and generates a response. This example illustrates the permissioning of AMQP exchanges and queues.

    # Allow client and server to connect to the virtual host.
    ACL ALLOW client ACCESS VIRTUALHOST
    ACL ALLOW server ACCESS VIRTUALHOST

    # Client side
    # Allow the 'client' user to publish requests to the request queue. As is the norm for the request/response paradigm, the client
    # is required to create a temporary queue on which the server will respond.  Consequently, there are rules to allow the creation
    # of the temporary queues and consumption of messages from it.
    ACL ALLOW client CREATE QUEUE temporary="true"
    ACL ALLOW client CONSUME QUEUE temporary="true"
    ACL ALLOW client DELETE QUEUE temporary="true"
    ACL ALLOW client BIND EXCHANGE name="amq.direct" temporary="true"
    ACL ALLOW client UNBIND EXCHANGE name="amq.direct" temporary="true"
    ACL ALLOW client PUBLISH EXCHANGE name="amq.direct" routingKey="example.RequestQueue"

    # Server side
    # Allow the 'server' user to consume from the request queue and publish a response to the temporary response queue created by
    # client.  We also allow the server to create the request queue.
    ACL ALLOW server CREATE QUEUE name="example.RequestQueue"
    ACL ALLOW server CONSUME QUEUE name="example.RequestQueue"
    ACL ALLOW server BIND EXCHANGE
    ACL ALLOW server PUBLISH EXCHANGE name="amq.direct" routingKey="TempQueue*"

    ACL DENY-LOG all all

### Worked example 4 - firewall-like access control

This example illustrates how to set up an ACL that restricts the IP addresses and hostnames of messaging clients that can access a virtual host.

    ################
    # Hostname rules
    ################

    # Allow messaging clients from company1.com and company1.co.uk to connect
    ACL ALLOW all ACCESS VIRTUALHOST from_hostname=".*\.company1\.com,.*\.company1\.co\.uk"

    # Deny messaging clients from hosts within the dev subdomain
    ACL DENY-LOG all ACCESS VIRTUALHOST from_hostname=".*\.dev\.company1\.com"

    ##################
    # IP address rules
    ##################

    # Deny access to all users in the IP ranges 192.168.1.0-192.168.1.255 and 192.168.2.0-192.168.2.255,
    # using the notation specified in RFC 4632, "Classless Inter-domain Routing (CIDR)"
    ACL DENY-LOG messaging-users ACCESS VIRTUALHOST \
      from_network="192.168.1.0/24,192.168.2.0/24"

    # Deny access to all users in the IP ranges 192.169.1.0-192.169.1.255 and 192.169.2.0-192.169.2.255,
    # using wildcard notation.
    ACL DENY-LOG messaging-users ACCESS VIRTUALHOST \
      from_network="192.169.1.*,192.169.2.*"

    ACL DENY-LOG all all

### Worked example 5 - REST management ACL example

This example illustrates how to set up an ACL that restricts usage of REST management interfaces.

    # allow to the users from webadmins group to change broker model
    # this rule allows adding/removing/editing of Broker level objects:
    # Broker, Virtual Host, Group Provider, Authentication Provider, Port, Access Control Provider etc
    ACL ALLOW-LOG webadmins CONFIGURE BROKER

    # allow to the users from webadmins group to perform
    # create/update/delete on Virtual Host children
    ACL ALLOW-LOG webadmins CREATE QUEUE
    ACL ALLOW-LOG webadmins UPDATE QUEUE
    ACL ALLOW-LOG webadmins DELETE QUEUE
    ACL ALLOW-LOG webadmins PURGE  QUEUE
    ACL ALLOW-LOG webadmins CREATE EXCHANGE
    ACL ALLOW-LOG webadmins DELETE EXCHANGE
    ACL ALLOW-LOG webadmins BIND   EXCHANGE
    ACL ALLOW-LOG webadmins UNBIND EXCHANGE

    # allow to the users from webadmins group to create/update/delete groups on Group Providers
    ACL ALLOW-LOG webadmins CREATE GROUP
    ACL ALLOW-LOG webadmins DELETE GROUP
    ACL ALLOW-LOG webadmins UPDATE GROUP

    # allow to the users from webadmins group to create/update/delete users for Authentication Providers
    ACL ALLOW-LOG webadmins CREATE USER
    ACL ALLOW-LOG webadmins DELETE USER
    ACL ALLOW-LOG webadmins UPDATE USER

    # allow to the users from webadmins group to move, copy, delete messagaes, and clear the queue
    # using REST management interfaces
    ACL ALLOW-LOG webadmins UPDATE METHOD

    # at the moment only the following UPDATE METHOD rules are supported by web management console
    #ACL ALLOW-LOG webadmins UPDATE METHOD component="VirtualHost.Queue" name="moveMessages"
    #ACL ALLOW-LOG webadmins UPDATE METHOD component="VirtualHost.Queue" name="copyMessages"
    #ACL ALLOW-LOG webadmins UPDATE METHOD component="VirtualHost.Queue" name="deleteMessages"
    #ACL ALLOW-LOG webadmins UPDATE METHOD component="VirtualHost.Queue" name="clearQueue"

    ACL DENY-LOG all all