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new 03ddb27210b MINOR: Add section on listener configuration (including
kraft) to security docs (#12682)
03ddb27210b is described below
commit 03ddb27210bd155bcaa7b33a33aeac926add1519
Author: Jason Gustafson <ja...@confluent.io>
AuthorDate: Mon Sep 26 19:33:32 2022 -0700
MINOR: Add section on listener configuration (including kraft) to security
docs (#12682)
This patch adds a section in security.html about listener configuration.
This includes the basics of how to define the security mapping of each listener
as well as the configurations to control inter-cluster traffic.
Reviewers: José Armando García Sancio <jsan...@users.noreply.github.com>,
Luke Chen <show...@gmail.com>
---
docs/security.html | 167 +++++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 149 insertions(+), 18 deletions(-)
diff --git a/docs/security.html b/docs/security.html
index d9b26f5d15e..f401c1c11a8 100644
--- a/docs/security.html
+++ b/docs/security.html
@@ -36,7 +36,136 @@
The guides below explain how to configure and use the security features in
both clients and brokers.
- <h3 class="anchor-heading"><a id="security_ssl" class="anchor-link"></a><a
href="#security_ssl">7.2 Encryption and Authentication using SSL</a></h3>
+ <h3 class="anchor-heading"><a id="listener_configuration"
class="anchor-link"></a><a href="#listener_configuration">7.2 Listener
Configuration</a></h3>
+
+ <p>In order to secure a Kafka cluster, it is necessary to secure the
channels that are used to
+ communicate with the servers. Each server must define the set of
listeners that are used to
+ receive requests from clients as well as other servers. Each listener
may be configured
+ to authenticate clients using various mechanisms and to ensure traffic
between the
+ server and the client is encrypted. This section provides a primer for
the configuration
+ of listeners.</p>
+
+ <p>Kafka servers support listening for connections on multiple ports. This
is configured through
+ the <code>listeners</code> property in the server configuration, which
accepts a comma-separated
+ list of the listeners to enable. At least one listener must be defined
on each server. The format
+ of each listener defined in <code>listeners</code> is given below:</p>
+
+ <pre class="line-numbers"><code
class="language-text">{LISTENER_NAME}://{hostname}:{port}</code></pre>
+
+ <p>The <code>LISTENER_NAME</code> is usually a descriptive name which
defines the purpose of
+ the listener. For example, many configurations use a separate listener
for client traffic,
+ so they might refer to the corresponding listener as <code>CLIENT</code>
in the configuration:</p
+
+ <pre class="line-numbers"><code
class="language-text">listeners=CLIENT://localhost:9092</code></pre>
+
+ <p>The security protocol of each listener is defined in a separate
configuration:
+ <code>listener.security.protocol.map</code>. The value is a
comma-separated list
+ of each listener mapped to its security protocol. For example, the
follow value
+ configuration specifies that the <code>CLIENT</code> listener will use
SSL while the
+ <code>BROKER</code> listener will use plaintext.</p>
+
+ <pre class="line-numbers"><code
class="language-text">listener.security.protocol.map=CLIENT:SSL,BROKER:PLAINTEXT</code></pre>
+
+ <p>Possible options for the security protocol are given below:</p>
+ <ol>
+ <li>PLAINTEXT</li>
+ <li>SSL</li>
+ <li>SASL_PLAINTEXT</li>
+ <li>SASL_SSL</li>
+ </ol>
+
+ <p>The plaintext protocol provides no security and does not require any
additional configuration.
+ In the following sections, this document covers how to configure the
remaining protocols.</p>
+
+ <p>If each required listener uses a separate security protocol, it is also
possible to use the
+ security protocol name as the listener name in <code>listeners</code>.
Using the example above,
+ we could skip the definition of the <code>CLIENT</code> and
<code>BROKER</code> listeners
+ using the following definition:</p>
+
+ <pre class="line-numbers"><code
class="language-text">listeners=SSL://localhost:9092,PLAINTEXT://localhost:9093</code></pre>
+
+ <p>However, we recommend users to provide explicit names for the listeners
since it
+ makes the intended usage of each listener clearer.</p>
+
+ <p>Among the listeners in this list, it is possible to declare the
listener to be used for
+ inter-broker communication by setting the
<code>inter.broker.listener.name</code> configuration
+ to the name of the listener. The primary purpose of the inter-broker
listener is
+ partition replication. If not defined, then the inter-broker listener is
determined
+ by the security protocol defined by
<code>security.inter.broker.protocol</code>, which
+ defaults to <code>PLAINTEXT</code>.</p>
+
+ <p>For legacy clusters which rely on Zookeeper to store cluster metadata,
it is possible to
+ declare a separate listener to be used for metadata propagation from the
active controller
+ to the brokers. This is defined by
<code>control.plane.listener.name</code>. The active controller
+ will use this listener when it needs to push metadata updates to the
brokers in the cluster.
+ The benefit of using a control plane listener is that it uses a separate
processing thread,
+ which makes it less likely for application traffic to impede timely
propagation of metadata changes
+ (such as partition leader and ISR updates). Note that the default value
is null, which
+ means that the controller will use the same listener defined by
<code>inter.broker.listener</code></p>
+
+ <p>In a KRaft cluster, a broker is any server which has the
<code>broker</code> role enabled
+ in <code>process.roles</code> and a controller is any server which has
the <code>controller</code>
+ role enabled. Listener configuration depends on the role. The listener
defined by
+ <code>inter.broker.listener.name</code> is used exclusively for requests
between brokers.
+ Controllers, on the other hand, must use separate listener which is
defined by the
+ <code>controller.listener.names</code> configuration. This cannot be set
to the same
+ value as the inter-broker listener.</p>
+
+ <p>Controllers receive requests both from other controllers and from
brokers. For
+ this reason, even if a server does not have the <code>controller</code>
role enabled
+ (i.e. it is just a broker), it must still define the controller listener
along with
+ any security properties that are needed to configure it. For example, we
might
+ use the following configuration on a standalone broker:</p>
+
+ <pre class="line-numbers"><code class="language-text">process.roles=broker
+listeners=BROKER://localhost:9092
+inter.broker.listener.name=BROKER
+controller.quorum.voters=0@localhost:9093
+controller.listener.names=CONTROLLER
+listener.security.protocol.map=BROKER:SASL_SSL,CONTROLLER:SASL_SSL</code></pre>
+
+ <p>The controller listener is still configured in this example to use the
<code>SASL_SSL</code>
+ security protocol, but it is not included in <code>listeners</code>
since the broker
+ does not expose the controller listener itself. The port that will be
used in this case
+ comes from the <code>controller.quorum.voters</code> configuration,
which defines
+ the complete list of controllers.</p>
+
+ <p>For KRaft servers which have both the broker and controller role
enabled, the configuration
+ is similar. The only difference is that the controller listener must be
included in
+ <code>listeners</code>:</p>
+
+ <pre class="line-numbers"><code
class="language-text">process.roles=broker,controller
+listeners=BROKER://localhost:9092,CONTROLLER://localhost:9093
+inter.broker.listener.name=BROKER
+controller.quorum.voters=0@localhost:9093
+controller.listener.names=CONTROLLER
+listener.security.protocol.map=BROKER:SASL_SSL,CONTROLLER:SASL_SSL</code></pre>
+
+ <p>It is a requirement for the port defined in
<code>controller.quorum.voters</code> to
+ exactly match one of the exposed controller listeners. For example, here
the
+ <code>CONTROLLER</code> listener is bound to port 9093. The connection
string
+ defined by <code>controller.quorum.voters</code> must then also use port
9093,
+ as it does here.</p>
+
+ <p>The controller will accept requests on all listeners defined by
<code>controller.listener.names</code>.
+ Typically there would be just one controller listener, but it is
possible to have more.
+ For example, this provides a way to change the active listener from one
port or security
+ protocol to another through a roll of the cluster (one roll to expose
the new listener,
+ and one roll to remove the old listener). When multiple controller
listeners are defined,
+ the first one in the list will be used for outbound requests.</p>
+
+ <p>It is conventional in Kafka to use a separate listener for clients.
This allows the
+ inter-cluster listeners to be isolated at the network level. In the case
of the controller
+ listener in KRaft, the listener should be isolated since clients do not
work with it
+ anyway. Clients are expected to connect to any other listener configured
on a broker.
+ Any requests that are bound for the controller will be forwarded as
described
+ <a href="#kraft_principal_forwarding">below</a></p>
+
+ <p>In the following <a href="#security_ssl">section</a>, this document
covers how to enable SSL
+ on a listener for encryption as well as authentication. The subsequent
<a href="#security_sasl">section</a> will then
+ cover additional authentication mechanisms using SASL.</p>
+
+ <h3 class="anchor-heading"><a id="security_ssl" class="anchor-link"></a><a
href="#security_ssl">7.3 Encryption and Authentication using SSL</a></h3>
Apache Kafka allows clients to use SSL for encryption of traffic as well
as authentication. By default, SSL is disabled but can be turned on if needed.
The following paragraphs explain in detail how to set up your own PKI
infrastructure, use it to create certificates and configure Kafka to use these.
@@ -314,10 +443,8 @@ keyUsage = digitalSignature,
keyEncipherment</code></pre>
</li>
</ol>
</li>
+
<li><h4 class="anchor-heading"><a id="security_configbroker"
class="anchor-link"></a><a href="#security_configbroker">Configuring Kafka
Brokers</a></h4>
- Kafka Brokers support listening for connections on multiple ports.
- We need to configure the following property in server.properties,
which must have one or more comma-separated values:
- <pre><code class="language-text">listeners</code></pre>
If SSL is not enabled for inter-broker communication (see below
for how to enable it), both PLAINTEXT and SSL ports will be necessary.
<pre class="line-numbers"><code
class="language-text">listeners=PLAINTEXT://host.name:port,SSL://host.name:port</code></pre>
@@ -397,7 +524,7 @@ ssl.key.password=test1234</code></pre>
> kafka-console-consumer.sh --bootstrap-server localhost:9093 --topic test
--consumer.config client-ssl.properties</code></pre>
</li>
</ol>
- <h3 class="anchor-heading"><a id="security_sasl"
class="anchor-link"></a><a href="#security_sasl">7.3 Authentication using
SASL</a></h3>
+ <h3 class="anchor-heading"><a id="security_sasl"
class="anchor-link"></a><a href="#security_sasl">7.4 Authentication using
SASL</a></h3>
<ol>
<li><h4 class="anchor-heading"><a id="security_sasl_jaasconfig"
class="anchor-link"></a><a href="#security_sasl_jaasconfig">JAAS
configuration</a></h4>
@@ -1135,8 +1262,12 @@ sasl.mechanism.inter.broker.protocol=GSSAPI (or one of
the other enabled mechani
</li>
</ol>
- <h3 class="anchor-heading"><a id="security_authz"
class="anchor-link"></a><a href="#security_authz">7.4 Authorization and
ACLs</a></h3>
- Kafka ships with a pluggable Authorizer and an out-of-box authorizer
implementation that uses zookeeper to store all the acls. The Authorizer is
configured by setting <tt>authorizer.class.name</tt> in server.properties. To
enable the out of the box implementation use:
+ <h3 class="anchor-heading"><a id="security_authz"
class="anchor-link"></a><a href="#security_authz">7.5 Authorization and
ACLs</a></h3>
+ Kafka ships with a pluggable authorization framework, which is configured
with the <tt>authorizer.class.name</tt> property in the server confgiuration.
+ Configured implementations must extend
<code>org.apache.kafka.server.authorizer.Authorizer</code>.
+ Kafka provides default implementations which store ACLs in the cluster
metadata (either Zookeeper or the KRaft metadata log).
+
+ For Zookeeper-based clusters, the provided implementation is configured as
follows:
<pre class="line-numbers"><code
class="language-text">authorizer.class.name=kafka.security.authorizer.AclAuthorizer</code></pre>
Kafka acls are defined in the general format of "Principal P is
[Allowed/Denied] Operation O From Host H on any Resource R matching
ResourcePattern RP". You can read more about the acl structure in <a
href="https://cwiki.apache.org/confluence/display/KAFKA/KIP-11+-+Authorization+Interface";>KIP-11</a>
and resource patterns in <a
href="https://cwiki.apache.org/confluence/display/KAFKA/KIP-290%3A+Support+for+Prefixed+ACLs";>KIP-290</a>.
In order to add, remove or list acls you can use th [...]
<pre class="line-numbers"><code
class="language-text">allow.everyone.if.no.acl.found=true</code></pre>
@@ -1934,7 +2065,7 @@ bin/kafka-acls.sh --bootstrap-server localhost:9092
--command-config /tmp/adminc
</tbody>
</table>
- <h3 class="anchor-heading"><a id="security_rolling_upgrade"
class="anchor-link"></a><a href="#security_rolling_upgrade">7.5 Incorporating
Security Features in a Running Cluster</a></h3>
+ <h3 class="anchor-heading"><a id="security_rolling_upgrade"
class="anchor-link"></a><a href="#security_rolling_upgrade">7.6 Incorporating
Security Features in a Running Cluster</a></h3>
You can secure a running cluster via one or more of the supported
protocols discussed previously. This is done in phases:
<p></p>
<ul>
@@ -1944,7 +2075,7 @@ bin/kafka-acls.sh --bootstrap-server localhost:9092
--command-config /tmp/adminc
<li>A final incremental bounce to close the PLAINTEXT port.</li>
</ul>
<p></p>
- The specific steps for configuring SSL and SASL are described in sections
<a href="#security_ssl">7.2</a> and <a href="#security_sasl">7.3</a>.
+ The specific steps for configuring SSL and SASL are described in sections
<a href="#security_ssl">7.3</a> and <a href="#security_sasl">7.4</a>.
Follow these steps to enable security for your desired protocol(s).
<p></p>
The security implementation lets you configure different protocols for
both broker-client and broker-broker communication.
@@ -1992,10 +2123,10 @@ security.inter.broker.protocol=SSL</code></pre>
<pre class="line-numbers"><code
class="language-text">listeners=SSL://broker1:9092,SASL_SSL://broker1:9093
security.inter.broker.protocol=SSL</code></pre>
- ZooKeeper can be secured independently of the Kafka cluster. The steps for
doing this are covered in section <a href="#zk_authz_migration">7.6.2</a>.
+ ZooKeeper can be secured independently of the Kafka cluster. The steps for
doing this are covered in section <a href="#zk_authz_migration">7.7.2</a>.
- <h3 class="anchor-heading"><a id="zk_authz" class="anchor-link"></a><a
href="#zk_authz">7.6 ZooKeeper Authentication</a></h3>
+ <h3 class="anchor-heading"><a id="zk_authz" class="anchor-link"></a><a
href="#zk_authz">7.7 ZooKeeper Authentication</a></h3>
ZooKeeper supports mutual TLS (mTLS) authentication beginning with the
3.5.x versions.
Kafka supports authenticating to ZooKeeper with SASL and mTLS -- either
individually or both together --
beginning with version 2.5. See
@@ -2027,8 +2158,8 @@ security.inter.broker.protocol=SSL</code></pre>
Use the <tt>-zk-tls-config-file <file></tt> option (note the
single-dash rather than double-dash)
to set TLS configs for the <tt>zookeeper-shell.sh</tt> CLI tool.
</p>
- <h4 class="anchor-heading"><a id="zk_authz_new" class="anchor-link"></a><a
href="#zk_authz_new">7.6.1 New clusters</a></h4>
- <h5 class="anchor-heading"><a id="zk_authz_new_sasl"
class="anchor-link"></a><a href="#zk_authz_new_sasl">7.6.1.1 ZooKeeper SASL
Authentication</a></h5>
+ <h4 class="anchor-heading"><a id="zk_authz_new" class="anchor-link"></a><a
href="#zk_authz_new">7.7.1 New clusters</a></h4>
+ <h5 class="anchor-heading"><a id="zk_authz_new_sasl"
class="anchor-link"></a><a href="#zk_authz_new_sasl">7.7.1.1 ZooKeeper SASL
Authentication</a></h5>
To enable ZooKeeper SASL authentication on brokers, there are two
necessary steps:
<ol>
<li> Create a JAAS login file and set the appropriate system property
to point to it as described above</li>
@@ -2037,7 +2168,7 @@ security.inter.broker.protocol=SSL</code></pre>
The metadata stored in ZooKeeper for the Kafka cluster is world-readable,
but can only be modified by the brokers. The rationale behind this decision is
that the data stored in ZooKeeper is not sensitive, but inappropriate
manipulation of that data can cause cluster disruption. We also recommend
limiting the access to ZooKeeper via network segmentation (only brokers and
some admin tools need access to ZooKeeper).
- <h5 class="anchor-heading"><a id="zk_authz_new_mtls"
class="anchor-link"></a><a href="#zk_authz_new_mtls">7.6.1.2 ZooKeeper Mutual
TLS Authentication</a></h5>
+ <h5 class="anchor-heading"><a id="zk_authz_new_mtls"
class="anchor-link"></a><a href="#zk_authz_new_mtls">7.7.1.2 ZooKeeper Mutual
TLS Authentication</a></h5>
ZooKeeper mTLS authentication can be enabled with or without SASL
authentication. As mentioned above,
when using mTLS alone, every broker and any CLI tools (such as the <a
href="#zk_authz_migration">ZooKeeper Security Migration Tool</a>)
must generally identify itself with the same Distinguished Name (DN)
because it is the DN that is ACL'ed, which means
@@ -2084,7 +2215,7 @@ zookeeper.set.acl=true</code></pre>
to a value different from the keystore password itself.
Be sure to set the key password to be the same as the keystore password.
- <h4 class="anchor-heading"><a id="zk_authz_migration"
class="anchor-link"></a><a href="#zk_authz_migration">7.6.2 Migrating
clusters</a></h4>
+ <h4 class="anchor-heading"><a id="zk_authz_migration"
class="anchor-link"></a><a href="#zk_authz_migration">7.7.2 Migrating
clusters</a></h4>
If you are running a version of Kafka that does not support security or
simply with security disabled, and you want to make the cluster secure, then
you need to execute the following steps to enable ZooKeeper authentication with
minimal disruption to your operations:
<ol>
<li>Enable SASL and/or mTLS authentication on ZooKeeper. If enabling
mTLS, you would now have both a non-TLS port and a TLS port, like this:
@@ -2114,17 +2245,17 @@ ssl.trustStore.password=zk-ts-passwd</code></pre>
<pre class="line-numbers"><code class="language-bash">>
bin/zookeeper-security-migration.sh --zookeeper.acl=secure
--zookeeper.connect=localhost:2181</code></pre>
<p>Run this to see the full list of parameters:</p>
<pre class="line-numbers"><code class="language-bash">>
bin/zookeeper-security-migration.sh --help</code></pre>
- <h4 class="anchor-heading"><a id="zk_authz_ensemble"
class="anchor-link"></a><a href="#zk_authz_ensemble">7.6.3 Migrating the
ZooKeeper ensemble</a></h4>
+ <h4 class="anchor-heading"><a id="zk_authz_ensemble"
class="anchor-link"></a><a href="#zk_authz_ensemble">7.7.3 Migrating the
ZooKeeper ensemble</a></h4>
It is also necessary to enable SASL and/or mTLS authentication on the
ZooKeeper ensemble. To do it, we need to perform a rolling restart of the
server and set a few properties. See above for mTLS information. Please refer
to the ZooKeeper documentation for more detail:
<ol>
<li><a
href="https://zookeeper.apache.org/doc/r3.5.7/zookeeperProgrammers.html#sc_ZooKeeperAccessControl";>Apache
ZooKeeper documentation</a></li>
<li><a
href="https://cwiki.apache.org/confluence/display/ZOOKEEPER/Zookeeper+and+SASL";>Apache
ZooKeeper wiki</a></li>
</ol>
- <h4 class="anchor-heading"><a id="zk_authz_quorum"
class="anchor-link"></a><a href="#zk_authz_quorum">7.6.4 ZooKeeper Quorum
Mutual TLS Authentication</a></h4>
+ <h4 class="anchor-heading"><a id="zk_authz_quorum"
class="anchor-link"></a><a href="#zk_authz_quorum">7.7.4 ZooKeeper Quorum
Mutual TLS Authentication</a></h4>
It is possible to enable mTLS authentication between the ZooKeeper servers
themselves.
Please refer to the <a
href="https://zookeeper.apache.org/doc/r3.5.7/zookeeperAdmin.html#Quorum+TLS";>ZooKeeper
documentation</a> for more detail.
- <h3 class="anchor-heading"><a id="zk_encryption"
class="anchor-link"></a><a href="#zk_encryption">7.7 ZooKeeper
Encryption</a></h3>
+ <h3 class="anchor-heading"><a id="zk_encryption"
class="anchor-link"></a><a href="#zk_encryption">7.8 ZooKeeper
Encryption</a></h3>
ZooKeeper connections that use mutual TLS are encrypted.
Beginning with ZooKeeper version 3.5.7 (the version shipped with Kafka
version 2.5) ZooKeeper supports a sever-side config
<tt>ssl.clientAuth</tt> (case-insensitively:
<tt>want</tt>/<tt>need</tt>/<tt>none</tt> are the valid options, the default is
<tt>need</tt>),
