Publish/Subscribe policy examples
The policy you use depends on how you're connecting to AWS IoT Core. You can
connect to AWS IoT Core by using an MQTT client, HTTP, or WebSocket. When you
connect with an MQTT client, you're authenticating with an X.509 certificate.
When you connect over HTTP or the WebSocket protocol, you're authenticating with
Signature Version 4 and Amazon Cognito.
Using wildcard characters in MQTT and AWS IoT Core policies
MQTT and AWS IoT Core policies have different wildcard characters and you
should choose them after careful consideration. In MQTT, the wildcard
characters + and # are used in MQTT topic
filters to subscribe to multiple topic names. AWS IoT Core policies
use * and ? as wildcard characters and follow the
conventions of IAM policies. In a policy document, the *
represents any combination of characters and a question mark ?
represents any single character. In policy documents, the MQTT wildcard
characters, + and # are treated as those
characters with no special meaning. To describe multiple topic names and
topic filters in the resource attribute of a policy, use the
* and ? wildcard characters in place of the
MQTT wildcard characters.
When choosing wildcard characters to use in a policy document, consider
that the * character is not confined to a single topic level as
the + character is in an MQTT topic filter. To help constrain a
wildcard specification to a single MQTT topic filter level, consider using
multiple ? characters. For more information about using
wildcard characters in a policy resource and more examples of what they
match, see Using wildcards in resource ARNs.
The table below shows the different wildcard characters used in MQTT and AWS IoT Core
policies for MQTT clients.
| Wildcard character |
Is MQTT wildcard character |
Example in MQTT |
Is AWS IoT Core policy wildcard character |
Example in AWS IoT Core policies for MQTT clients |
# |
Yes |
some/# |
No |
N/A |
+ |
Yes |
some/+/topic |
No |
N/A |
* |
No |
N/A |
Yes |
topicfilter/some/*/topic
|
? |
No |
N/A |
Yes |
topic/some/?????/topic
topicfilter/some/sensor???/topic
|
Policies to publish, subscribe and
receive messages to/from specific topics
The following shows examples for registered and unregistered devices to
publish, subscribe and receive messages to/from the topic named
"some_specific_topic". The examples also highlight that Publish
and Receive use "topic" as the resource, and
Subscribe uses "topicfilter" as the resource.
- Registered devices
-
For devices registered in AWS IoT Core's Registry, the following
policy allows devices to connect with clientId that matches the
name of a thing in AWS IoT Core's Registry. It also provides
Publish, Subscribe and
Receive permissions for the topic named
"some_specific_topic".
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/${iot:Connection.Thing.ThingName}"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Publish"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/some_specific_topic"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Subscribe"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topicfilter/some_specific_topic"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Receive"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/some_specific_topic"
]
}
]
}
- Unregistered devices
-
For devices not registered in AWS IoT Core's Registry, the following policy
allows devices to connect using either clientId1, clientId2 or
clientId3. It also provides Publish,
Subscribe and Receive permissions
for the topic named "some_specific_topic".
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/clientId1",
"arn:aws:iot:us-east-1:123456789012:client/clientId2",
"arn:aws:iot:us-east-1:123456789012:client/clientId3"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Publish"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/some_specific_topic"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Subscribe"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topicfilter/some_specific_topic"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Receive"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/some_specific_topic"
]
}
]
}
Policies to publish,
subscribe and receive messages to/from topics with a specific
prefix
The following shows examples for registered and unregistered devices to
publish, subscribe and receive messages to/from topics prefixed with
"topic_prefix".
Note the use of the wildcard character * in this example. Although the
wildcard character * is useful to provide permissions for multiple topic
names in a single statement, it can lead to unintended consequences by
providing more privileges to devices than required. So we recommend that
you only use the wildcard character * after careful
consideration.
- Registered devices
-
For devices registered in AWS IoT Core's Registry, the following
policy allows devices to connect with clientId that matches the
name of a thing in AWS IoT Core's Registry. It also provides
Publish, Subscribe and
Receive permissions for topics prefixed with
"topic_prefix".
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/${iot:Connection.Thing.ThingName}"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Publish",
"iot:Receive"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/topic_prefix*"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Subscribe"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topicfilter/topic_prefix*"
]
}
]
}
- Unregistered devices
-
For devices not registered in AWS IoT Core's Registry, the following
policy allows devices to connect using either clientId1,
clientId2 or clientId3. It also provides Publish,
Subscribe and Receive permissions
for topics prefixed with "topic_prefix".
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/clientId1",
"arn:aws:iot:us-east-1:123456789012:client/clientId2",
"arn:aws:iot:us-east-1:123456789012:client/clientId3"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Publish",
"iot:Receive"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/topic_prefix*"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Subscribe"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topicfilter/topic_prefix*"
]
}
]
}
Policies to publish,
subscribe and receive messages to/from topics specific to each
device
The following shows examples for registered and unregistered devices to
publish, subscribe and receive messages to/from topics that are specific to
the given device.
- Registered devices
-
For devices registered in AWS IoT Core 's Registry, the following
policy allows devices to connect with clientId that matches the
name of a thing in AWS IoT Core's Registry. It provides permission
to publish to the thing-specific topic
(sensor/device/${iot:Connection.Thing.ThingName})
and also subscribe to and receive from the thing-specific topic
(command/device/${iot:Connection.Thing.ThingName}).
If the thing name in Registry is "thing1", then the device will
be allowed to publish to the topic "sensor/device/thing1", and
also subscribe to and receive from the topic
"command/device/thing1".
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/${iot:Connection.Thing.ThingName}"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Publish"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/sensor/device/${iot:Connection.Thing.ThingName}"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Subscribe"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topicfilter/command/device/${iot:Connection.Thing.ThingName}"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Receive"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/command/device/${iot:Connection.Thing.ThingName}"
]
}
]
}
- Unregistered devices
-
For devices not registered in AWS IoT Core's Registry, the
following policy allows devices to connect using either
clientId1, clientId2 or clientId3. It provides permission to
publish to the client-specific topic
(sensor/device/${iot:ClientId}), and also
subscribe to and receive from the client-specific topic
(command/device/${iot:ClientId}). If the device
connects with clientId as clientId1, then it will be permitted
to publish to the topic "sensor/device/clientId1", and subscribe
to and receive from the topic
device/clientId1/command.
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/clientId1",
"arn:aws:iot:us-east-1:123456789012:client/clientId2",
"arn:aws:iot:us-east-1:123456789012:client/clientId3"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Publish"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/sensor/device/${iot:Connection.Thing.ThingName}"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Subscribe"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topicfilter/command/device/${iot:Connection.Thing.ThingName}"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Receive"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/command/device/${iot:Connection.Thing.ThingName}"
]
}
]
}
Policies to publish, subscribe and
receive messages to/from topics with thing attribute in topic
name
The following shows an example for registered devices to publish,
subscribe and receive messages to/from topics whose names include thing
attributes.
Thing attributes only exist for devices registered in AWS IoT Core's
Registry. There is no corresponding example for unregistered
devices.
- Registered devices
-
For devices registered in AWS IoT Core's Registry, the following
policy allows devices to connect with clientId that matches the
name of a thing in AWS IoT Core's Registry. It provides permission
to publish to the topic
(sensor/${iot:Connection.Thing.Attributes[version]}),
and subscribe to and receive from the topic
(command/${iot:Connection.Thing.Attributes[location]})
where the topic name includes thing attributes. If the thing
name in Registry has version=v1 and
location=Seattle, the device will be allowed to
publish to the topic "sensor/v1", and subscribe to and receive
from the topic "command/Seattle".
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/${iot:Connection.Thing.ThingName}"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Publish"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/sensor/${iot:Connection.Thing.Attributes[version]}"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Subscribe"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topicfilter/command/${iot:Connection.Thing.Attributes[location]}"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Receive"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/command/${iot:Connection.Thing.Attributes[location]}"
]
}
]
}
- Unregistered devices
-
Because thing attributes only exist for devices registered in
AWS IoT Core's Registry, there is no corresponding example for
unregistered things.
Policies to deny publishing messages
to subtopics of a topic name
The following shows examples for registered and unregistered devices to
publish messages to all topics except certain subtopics.
- Registered devices
-
For devices registered in AWS IoT Core's Registry, the following
policy allows devices to connect with clientId that matches the
name of a thing in AWS IoT Core's Registry. It provides permission
to publish to all topics prefixed with "department/" but not to
the "department/admins" subtopic.
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/${iot:Connection.Thing.ThingName}"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Publish"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/department/*"
]
},
{
"Effect": "Deny",
"Action": [
"iot:Publish"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/department/admins"
]
}
]
}
- Unregistered devices
-
For devices not registered in AWS IoT Core's Registry, the following
policy allows devices to connect using either clientId1,
clientId2 or clientId3. It provides permission to publish to all
topics prefixed with "department/" but not to the
"department/admins" subtopic.
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/clientId1",
"arn:aws:iot:us-east-1:123456789012:client/clientId2",
"arn:aws:iot:us-east-1:123456789012:client/clientId3"
]
},
{
"Effect": "Allow",
"Action": [
"iot:Publish"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/department/*"
]
},
{
"Effect": "Deny",
"Action": [
"iot:Publish"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:topic/department/admins"
]
}
]
}
Policies to deny receiving messages
from subtopics of a topic name
The following shows examples for registered and unregistered devices to
subscribe to and receive messages from topics with specific prefixes except
certain subtopics.
- Registered devices
-
For devices registered in AWS IoT Core's Registry, the following
policy allows devices to connect with clientId that matches the
name of a thing in AWS IoT Core's Registry. The policy allows
devices to subscribe to any topic prefixed with "topic_prefix".
By using NotResource in the statement for
iot:Receive, we allow the device to receive
messages from all topics that the device has subscribed to,
except the topics prefixed with "topic_prefix/restricted". For
example, with this policy, devices can subscribe to
"topic_prefix/topic1" and even "topic_prefix/restricted",
however, they will only receive messages from the topic
"topic_prefix/topic1" and no messages from the topic
"topic_prefix/restricted".
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/${iot:Connection.Thing.ThingName}"
]
},
{
"Effect": "Allow",
"Action": "iot:Subscribe",
"Resource": "arn:aws:iot:us-east-1:123456789012:topicfilter/topic_prefix/*"
},
{
"Effect": "Allow",
"Action": "iot:Receive",
"NotResource": "arn:aws:iot:us-east-1:123456789012:topic/topic_prefix/restricted/*"
}
]
}
- Unregistered devices
-
For devices not registered in AWS IoT Core's Registry, the following
policy allows devices to connect using either clientId1,
clientId2 or clientId3. The policy allows devices to subscribe
to any topic prefixed with "topic_prefix". By using NotResource
in the statement for iot:Receive, we allow the device to receive
messages from all topics that the device has subscribed to,
except topics prefixed with "topic_prefix/restricted". For
example, with this policy, devices can subscribe to
"topic_prefix/topic1" and even "topic_prefix/restricted",
however, they will only receive messages from the topic
"topic_prefix/topic1" and no messages from the topic
"topic_prefix/restricted".
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/clientId1",
"arn:aws:iot:us-east-1:123456789012:client/clientId2",
"arn:aws:iot:us-east-1:123456789012:client/clientId3"
]
},
{
"Effect": "Allow",
"Action": "iot:Subscribe",
"Resource": "arn:aws:iot:us-east-1:123456789012:topicfilter/topic_prefix/*"
},
{
"Effect": "Allow",
"Action": "iot:Receive",
"NotResource": "arn:aws:iot:us-east-1:123456789012:topic/topic_prefix/restricted/*"
}
]
}
Policies to subscribe to topics
using MQTT wildcard characters
MQTT wildcard characters + and # are treated as literal strings, but they
are not treated as wildcards when used in AWS IoT Core policies. In MQTT, + and
# are treated as wildcards only when subscribing to a topic filter but as a
literal string in all other contexts. We recommend that you only use these
MQTT wildcards as part of AWS IoT Core policies after careful
consideration.
The following shows examples for registered and unregistered things using
MQTT wildcards in AWS IoT Core policies. These wildcards are treated as literal
strings.
- Registered devices
-
For devices registered in AWS IoT Core's Registry, the following
policy allows devices to connect with clientId that matches the
name of a thing in AWS IoT Core's Registry. The policy allows devices to
subscribe to the topics "department/+/employees" and
"location/#". Note that since + and # are treated as literal
strings in AWS IoT Core policies, devices can subscribe to the
topic "department/+/employees" but not to the topic
"department/engineering/employees". Similarly, devices can
subscribe to the topic "location/#" but not to the topic
"location/Seattle". However, once the device subscribes to the
topic "department/+/employees", the policy will allow them to
receive messages from the topic
"department/engineering/employees". Similarly, once the device
subscribes to the topic "location/#", they will receive messages
from the topic "location/Seattle" as well.
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/${iot:Connection.Thing.ThingName}"
]
},
{
"Effect": "Allow",
"Action": "iot:Subscribe",
"Resource": "arn:aws:iot:us-east-1:123456789012:topicfilter/department/+/employees"
},
{
"Effect": "Allow",
"Action": "iot:Subscribe",
"Resource": "arn:aws:iot:us-east-1:123456789012:topicfilter/location/#"
},
{
"Effect": "Allow",
"Action": "iot:Receive",
"Resource": "arn:aws:iot:us-east-1:123456789012:topic/*"
}
]
}
- Unregistered devices
-
For devices not registered in AWS IoT Core's Registry, the
following policy allows devices to connect using either
clientId1, clientId2 or clientId3. The policy allows devices to
subscribe to the topics of "department/+/employees" and
"location/#". Note that since + and # are treated as literal
strings in AWS IoT Core policies, devices can subscribe to the
topic "department/+/employees" but not to the topic
"department/engineering/employees". Similarly, devices can
subscribe to the topic "location/#" but not "location/Seattle".
However, once the device subscribes to the topic
"department/+/employees", the policy will allow them to receive
messages from the topic "department/engineering/employees".
Similarly, once the device subscribes to the topic "location/#",
they will receive messages from the topic "location/Seattle" as
well.
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": [
"arn:aws:iot:us-east-1:123456789012:client/clientId1",
"arn:aws:iot:us-east-1:123456789012:client/clientId2",
"arn:aws:iot:us-east-1:123456789012:client/clientId3"
]
},
{
"Effect": "Allow",
"Action": "iot:Subscribe",
"Resource": "arn:aws:iot:us-east-1:123456789012:topicfilter/department/+/employees"
},
{
"Effect": "Allow",
"Action": "iot:Subscribe",
"Resource": "arn:aws:iot:us-east-1:123456789012:topicfilter/location/#"
},
{
"Effect": "Allow",
"Action": "iot:Receive",
"Resource": "arn:aws:iot:us-east-1:123456789012:topic/*"
}
]
}
Policies for HTTP and WebSocket
clients
When you connect over HTTP or the WebSocket protocol, you're
authenticating with Signature Version 4 and Amazon Cognito. Amazon Cognito identities can be
authenticated or unauthenticated. Authenticated identities belong to users
who are authenticated by any supported identity provider. Unauthenticated
identities typically belong to guest users who do not authenticate with an
identity provider. Amazon Cognito provides a unique identifier and AWS credentials
to support unauthenticated identities. For more information, see Authorization with Amazon Cognito identities.
For the following operations, AWS IoT Core uses AWS IoT Core policies attached to Amazon Cognito
identities (through the AttachPolicy API) to scope down the
permissions attached to the Amazon Cognito Identity pool with authenticated identities.
-
iot:Connect
-
iot:Publish
-
iot:Subscribe
-
iot:Receive
-
iot:GetThingShadow
-
iot:UpdateThingShadow
-
iot:DeleteThingShadow
That
means an Amazon Cognito Identity needs permission from the IAM role policy attached to the
pool and the AWS IoT Core policy attached to the Amazon Cognito Identity through the AWS IoT Core
AttachPolicy API.
Authenticated and unauthenticated users are different identity types. If you don't attach an AWS IoT policy to the Amazon Cognito Identity,
an authenticated user fails authorization in AWS IoT and doesn't have access to AWS IoT resources and actions.
For other AWS IoT Core operations or for unauthenticated identities, AWS IoT Core
does not scope down the permissions attached to the Amazon Cognito identity pool
role. For both authenticated and unauthenticated identities, this is the
most permissive policy that we recommend you attach to the Amazon Cognito pool
role.
HTTP
To allow unauthenticated Amazon Cognito identities to publish messages over HTTP on
a topic specific to the Amazon Cognito Identity, attach the following IAM policy to the Amazon Cognito Identity
pool role:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Publish",
],
"Resource": ["arn:aws:iot:us-east-1:123456789012:topic/${cognito-identity.amazonaws.com:sub}"]
}
]
}
To allow authenticated users, attach the preceding policy to the Amazon Cognito Identity
pool role and to the Amazon Cognito Identity using the AWS IoT Core AttachPolicy API.
When authorizing Amazon Cognito identities, AWS IoT Core considers both policies and
grants the least privileges specified. An action is allowed only if both
policies allow the requested action. If either policy disallows an
action, that action is unauthorized.
MQTT
To allow unauthenticated Amazon Cognito identities to publish MQTT messages over
WebSocket on a topic specific to the Amazon Cognito Identity in your account, attach the
following IAM policy to the Amazon Cognito Identity pool role:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"iot:Publish"
],
"Resource": ["arn:aws:iot:us-east-1:123456789012:topic/${cognito-identity.amazonaws.com:sub}"]
},
{
"Effect": "Allow",
"Action": [
"iot:Connect"
],
"Resource": ["arn:aws:iot:us-east-1:123456789012:client/${cognito-identity.amazonaws.com:sub}"]
}
]
}
To allow authenticated users, attach the preceding policy to the Amazon Cognito Identity
pool role and to the Amazon Cognito Identity using the AWS IoT Core AttachPolicy API.
When authorizing Amazon Cognito identities, AWS IoT Core considers both and grants
the least privileges specified. An action is allowed only if both
policies allow the requested action. If either policy disallows an
action, that action is unauthorized.
