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Transport Layer Security (TLS) is a form of public key cryptography. By default, Pulsar clients communicate with Pulsar services in plain text. This means that all data is sent in the clear. You can use TLS to encrypt this traffic to protect the traffic from the snooping of a man-in-the-middle attacker.
This section introduces how to configure TLS encryption in Pulsar. For how to configure mTLS authentication in Pulsar, refer to mTLS authentication. Alternatively, you can use another Athenz authentication on top of TLS transport encryption.
:::note
Enabling TLS encryption may impact the performance due to encryption overhead.
:::
TLS certificates include the following three types. Each certificate (key pair) contains both a public key that encrypts messages and a private key that decrypts messages.
For both server and client certificates, the private key with a certificate request is generated first, and the public key (the certificate) is generated after the trust cert signs the certificate request. When mTLS authentication is enabled, the server uses the trust cert to verify that the client has a key pair that the certificate authority signs. The Common Name (CN) of a client certificate is used as the client's role token, while the Subject Alternative Name (SAN) of a server certificate is used for Hostname verification.
:::note
The validity of these certificates is 365 days. It's highly recommended to use sha256
or sha512
as the signature algorithm, while sha1
is not supported.
:::
You can use either one of the following certificate formats to configure TLS encryption:
Hostname verification is a TLS security feature whereby a client can refuse to connect to a server if the Subject Alternative Name (SAN) does not match the hostname that the hostname is connecting to.
By default, Pulsar clients disable hostname verification, as it requires that each broker has a DNS record and a unique cert.
One scenario where you may want to enable hostname verification is where you have multiple proxy nodes behind a VIP, and the VIP has a DNS record, for example, pulsar.mycompany.com
. In this case, you can generate a TLS cert with pulsar.mycompany.com
as the SAN, and then enable hostname verification on the client.
To enable hostname verification in Pulsar, ensure that SAN exactly matches the fully qualified domain name (FQDN) of the server. The client compares the SAN with the DNS domain name to ensure that it is connecting to the desired server. See Configure clients for more details.
Moreover, as the administrator has full control of the CA, a bad actor is unlikely to be able to pull off a man-in-the-middle attack. allowInsecureConnection
allows the client to connect to servers whose cert has not been signed by an approved CA. The client disables allowInsecureConnection
by default, and you should always disable allowInsecureConnection
in production environments. As long as you disable allowInsecureConnection
, a man-in-the-middle attack requires that the attacker has access to the CA.
By default, Pulsar uses netty-tcnative. It includes two implementations, OpenSSL
(default) and JDK
. When OpenSSL
is unavailable, JDK
is used.
Creating TLS certificates involves creating a certificate authority, a server certificate, and a client certificate.
You can use a certificate authority (CA) to sign both server and client certificates. This ensures that each party trusts the others. Store CA in a very secure location (ideally completely disconnected from networks, air-gapped, and fully encrypted).
Use the following command to create a CA.
openssl genrsa -out ca.key.pem 2048 openssl req -x509 -new -nodes -key ca.key.pem -subj "/CN=CARoot" -days 365 -out ca.cert.pem
:::note
The default openssl
on macOS doesn't work for the commands above. You need to upgrade openssl
via Homebrew:
brew install openssl export PATH="/usr/local/Cellar/openssl@3/3.0.1/bin:$PATH"
Use the actual path from the output of the brew install
command. Note that version number 3.0.1
might change.
:::
Once you have created a CA, you can create certificate requests and sign them with the CA.
Generate the server's private key.
openssl genrsa -out broker.key.pem 2048
The broker expects the key to be in PKCS 8 format. Enter the following command to convert it.
openssl pkcs8 -topk8 -inform PEM -outform PEM -in broker.key.pem -out broker.key-pk8.pem -nocrypt
Create a broker.conf
file with the following content:
[ req ] default_bits = 2048 prompt = no default_md = sha256 distinguished_name = dn [ v3_ext ] authorityKeyIdentifier=keyid,issuer:always basicConstraints=CA:FALSE keyUsage=critical, digitalSignature, keyEncipherment extendedKeyUsage=serverAuth subjectAltName=@alt_names [ dn ] CN = broker [ alt_names ] DNS.1 = pulsar DNS.2 = pulsar.default IP.1 = 127.0.0.1 IP.2 = 192.168.1.2
:::tip
To configure hostname verification, you need to enter the hostname of the broker in alt_names
as the Subject Alternative Name (SAN). To ensure that multiple machines can reuse the same certificate, you can also use a wildcard to match a group of broker hostnames, for example, *.broker.usw.example.com
.
:::
Generate the certificate request.
openssl req -new -config broker.conf -key broker.key.pem -out broker.csr.pem -sha256
Sign the certificate with the CA.
openssl x509 -req -in broker.csr.pem -CA ca.cert.pem -CAkey ca.key.pem -CAcreateserial -out broker.cert.pem -days 365 -extensions v3_ext -extfile broker.conf -sha256
At this point, you have a cert, broker.cert.pem
, and a key, broker.key-pk8.pem
, which you can use along with ca.cert.pem
to configure TLS encryption for your brokers and proxies.
Generate the client's private key.
openssl genrsa -out client.key.pem 2048
The client expects the key to be in PKCS 8 format. Enter the following command to convert it.
openssl pkcs8 -topk8 -inform PEM -outform PEM -in client.key.pem -out client.key-pk8.pem -nocrypt
Generate the certificate request. Note that the value of CN
is used as the client's role token.
openssl req -new -subj "/CN=client" -key client.key.pem -out client.csr.pem -sha256
Sign the certificate with the CA.
openssl x509 -req -in client.csr.pem -CA ca.cert.pem -CAkey ca.key.pem -CAcreateserial -out client.cert.pem -days 365 -sha256
At this point, you have a cert client.cert.pem
and a key client.key-pk8.pem
, which you can use along with ca.cert.pem
to configure TLS encryption for your clients.
To configure a Pulsar broker to use TLS encryption, you need to add these values to broker.conf
in the conf
directory of your Pulsar installation. Substitute the appropriate certificate paths where necessary.
# configure TLS ports brokerServicePortTls=6651 webServicePortTls=8081 # configure CA certificate tlsTrustCertsFilePath=/path/to/ca.cert.pem # configure server certificate tlsCertificateFilePath=/path/to/broker.cert.pem # configure server's priviate key tlsKeyFilePath=/path/to/broker.key-pk8.pem # enable mTLS tlsRequireTrustedClientCertOnConnect=true # configure mTLS for the internal client brokerClientTlsEnabled=true brokerClientTrustCertsFilePath=/path/to/ca.cert.pem brokerClientCertificateFilePath=/path/to/client.cert.pem brokerClientKeyFilePath=/path/to/client.key-pk8.pem
To configure the broker (and proxy) to require specific TLS protocol versions and ciphers for TLS negotiation, you can use the TLS protocol versions and ciphers to stop clients from requesting downgraded TLS protocol versions or ciphers that may have weaknesses.
By default, Pulsar uses OpenSSL when it is available, otherwise, Pulsar defaults back to the JDK implementation. OpenSSL currently supports TLSv1.1
, TLSv1.2
and TLSv1.3
. You can acquire a list of supported ciphers from the OpenSSL ciphers command, i.e. openssl ciphers -tls1_3
.
Both the TLS protocol versions and cipher properties can take multiple values, separated by commas. The possible values for protocol versions and ciphers depend on the TLS provider that you are using.
tlsProtocols=TLSv1.3,TLSv1.2 tlsCiphers=TLS_DH_RSA_WITH_AES_256_GCM_SHA384,TLS_DH_RSA_WITH_AES_256_CBC_SHA
tlsProtocols=TLSv1.3,TLSv1.2
: List out the TLS protocols that you are going to accept from clients. By default, it is not set.tlsCiphers=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
: A cipher suite is a named combination of authentication, encryption, MAC and key exchange algorithm used to negotiate the security settings for a network connection using TLS network protocol. By default, it is null. See OpenSSL Ciphers and JDK Ciphers for more details.For JDK 11, you can obtain a list of supported values from the documentation:
Configuring mTLS on proxies includes two directions of connections, from clients to proxies, and from proxies to brokers.
# configure TLS ports servicePortTls=6651 webServicePortTls=8081 # configure certificates for clients to connect proxy tlsCertificateFilePath=/path/to/broker.cert.pem tlsKeyFilePath=/path/to/broker.key-pk8.pem tlsTrustCertsFilePath=/path/to/ca.cert.pem # enable mTLS tlsRequireTrustedClientCertOnConnect=true # configure TLS for proxy to connect brokers tlsEnabledWithBroker=true brokerClientTrustCertsFilePath=/path/to/ca.cert.pem brokerClientCertificateFilePath=/path/to/client.cert.pem brokerClientKeyFilePath=/path/to/client.key-pk8.pem
To enable TLS encryption, you need to configure the clients to use https://
with port 8443 for the web service URL, and pulsar+ssl://
with port 6651 for the broker service URL.
As the server certificate that you generated above does not belong to any of the default trust chains, you also need to either specify the path of the trust cert (recommended) or enable the clients to allow untrusted server certs.
The following examples show how to configure TLS encryption for Java/Python/C++/Node.js/C#/WebSocket clients.
<Tabs groupId="lang-choice" defaultValue="Java" values={[{"label":"Java","value":"Java"},{"label":"Python","value":"Python"},{"label":"C++","value":"C++"},{"label":"Node.js","value":"Node.js"},{"label":"C#","value":"C#"},{"label":"WebSocket API","value":"WebSocket API"}]}> <TabItem value="Java"> ```java import org.apache.pulsar.client.api.PulsarClient; PulsarClient client = PulsarClient.builder() .serviceUrl("pulsar+ssl://broker.example.com:6651/") .tlsKeyFilePath("/path/to/client.key-pk8.pem") .tlsCertificateFilePath("/path/to/client.cert.pem") .tlsTrustCertsFilePath("/path/to/ca.cert.pem") .enableTlsHostnameVerification(false) // false by default, in any case .allowTlsInsecureConnection(false) // false by default, in any case .build(); ``` </TabItem> <TabItem value="Python"> ```python from pulsar import Client client = Client("pulsar+ssl://broker.example.com:6651/", tls_hostname_verification=False, tls_trust_certs_file_path="/path/to/ca.cert.pem", tls_allow_insecure_connection=False) // defaults to false from v2.2.0 onwards ``` </TabItem> <TabItem value="C++"> ```cpp #include <pulsar/Client.h> ClientConfiguration config = ClientConfiguration(); config.setUseTls(true); // shouldn't be needed soon config.setTlsTrustCertsFilePath(caPath); config.setTlsAllowInsecureConnection(false); config.setAuth(pulsar::AuthTls::create(clientPublicKeyPath, clientPrivateKeyPath)); config.setValidateHostName(false); ``` </TabItem> <TabItem value="Node.js"> ```javascript const Pulsar = require('pulsar-client'); (async () => { const client = new Pulsar.Client({ serviceUrl: 'pulsar+ssl://broker.example.com:6651/', tlsTrustCertsFilePath: '/path/to/ca.cert.pem', useTls: true, tlsValidateHostname: false, tlsAllowInsecureConnection: false, }); })(); ``` </TabItem> <TabItem value="C#"> ```csharp var certificate = new X509Certificate2("ca.cert.pem"); var client = PulsarClient.Builder() .TrustedCertificateAuthority(certificate) //If the CA is not trusted on the host, you can add it explicitly. .VerifyCertificateAuthority(true) //Default is 'true' .VerifyCertificateName(false) //Default is 'false' .Build(); ``` :::note `VerifyCertificateName` refers to the configuration of hostname verification in the C# client. ::: </TabItem> <TabItem value="WebSocket API"> ```python import websockets import asyncio import base64 import json import ssl import pathlib ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT) client_cert_pem = pathlib.Path(__file__).with_name("client.cert.pem") client_key_pem = pathlib.Path(__file__).with_name("client.key.pem") ca_cert_pem = pathlib.Path(__file__).with_name("ca.cert.pem") ssl_context.load_cert_chain(certfile=client_cert_pem, keyfile=client_key_pem) ssl_context.load_verify_locations(ca_cert_pem) # websocket producer uri wss, not ws uri = "wss://localhost:8080/ws/v2/producer/persistent/public/default/testtopic" client_pem = pathlib.Path(__file__).with_name("pulsar_client.pem") ssl_context.load_verify_locations(client_pem) # websocket producer uri wss, not ws uri = "wss://localhost:8080/ws/v2/producer/persistent/public/default/testtopic" # encode message s = "Hello World" firstEncoded = s.encode("UTF-8") binaryEncoded = base64.b64encode(firstEncoded) payloadString = binaryEncoded.decode('UTF-8') async def producer_handler(websocket): await websocket.send(json.dumps({ 'payload' : payloadString, 'properties': { 'key1' : 'value1', 'key2' : 'value2' }, 'context' : 5 })) async def test(): async with websockets.connect(uri) as websocket: await producer_handler(websocket) message = await websocket.recv() print(f"< {message}") asyncio.run(test()) ``` :::note In addition to the required configurations in the `conf/client.conf` file, you need to configure more parameters in the `conf/broker.conf` file to enable TLS encryption on WebSocket service. For more details, see [security settings for WebSocket](client-libraries-websocket.md#security-settings). ::: </TabItem> </Tabs>
Command-line tools like pulsar-admin
, pulsar-perf
, and pulsar-client
use the conf/client.conf
config file in a Pulsar installation.
To use mTLS encryption with Pulsar CLI tools, you need to add the following parameters to the conf/client.conf
file.
webServiceUrl=https://localhost:8081/ brokerServiceUrl=pulsar+ssl://localhost:6651/ authPlugin=org.apache.pulsar.client.impl.auth.AuthenticationTls authParams=tlsCertFile:/path/to/client.cert.pem,tlsKeyFile:/path/to/client.key-pk8.pem
By default, Pulsar uses Conscrypt for both broker service and Web service.
You can use Java's keytool
utility to generate the key and certificate for each machine in the cluster.
DAYS=365 CLIENT_COMMON_PARAMS="-storetype JKS -storepass clientpw -keypass clientpw -noprompt" BROKER_COMMON_PARAMS="-storetype JKS -storepass brokerpw -keypass brokerpw -noprompt" # create keystore keytool -genkeypair -keystore broker.keystore.jks ${BROKER_COMMON_PARAMS} -keyalg RSA -keysize 2048 -alias broker -validity $DAYS \ -dname 'CN=broker,OU=Unknown,O=Unknown,L=Unknown,ST=Unknown,C=Unknown' keytool -genkeypair -keystore client.keystore.jks ${CLIENT_COMMON_PARAMS} -keyalg RSA -keysize 2048 -alias client -validity $DAYS \ -dname 'CN=client,OU=Unknown,O=Unknown,L=Unknown,ST=Unknown,C=Unknown' # export certificate keytool -exportcert -keystore broker.keystore.jks ${BROKER_COMMON_PARAMS} -file broker.cer -alias broker keytool -exportcert -keystore client.keystore.jks ${CLIENT_COMMON_PARAMS} -file client.cer -alias client # generate truststore keytool -importcert -keystore client.truststore.jks ${CLIENT_COMMON_PARAMS} -file broker.cer -alias truststore keytool -importcert -keystore broker.truststore.jks ${BROKER_COMMON_PARAMS} -file client.cer -alias truststore
:::note
To configure hostname verification, you need to append -ext SAN=IP:127.0.0.1,IP:192.168.20.2,DNS:broker.example.com
to the value of BROKER_COMMON_PARAMS
as the Subject Alternative Name (SAN).
:::
Configure the following parameters in the conf/broker.conf
file and restrict access to the store files via filesystem permissions.
brokerServicePortTls=6651 webServicePortTls=8081 # Trusted client certificates are required to connect TLS # Reject the Connection if the Client Certificate is not trusted. # In effect, this requires that all connecting clients perform TLS client # authentication. tlsRequireTrustedClientCertOnConnect=true tlsEnabledWithKeyStore=true # key store tlsKeyStoreType=JKS tlsKeyStore=/var/private/tls/broker.keystore.jks tlsKeyStorePassword=brokerpw # trust store tlsTrustStoreType=JKS tlsTrustStore=/var/private/tls/broker.truststore.jks tlsTrustStorePassword=brokerpw # internal client/admin-client config brokerClientTlsEnabled=true brokerClientTlsEnabledWithKeyStore=true brokerClientTlsTrustStoreType=JKS brokerClientTlsTrustStore=/var/private/tls/client.truststore.jks brokerClientTlsTrustStorePassword=clientpw brokerClientTlsKeyStoreType=JKS brokerClientTlsKeyStore=/var/private/tls/client.keystore.jks brokerClientTlsKeyStorePassword=clientpw
To disable non-TLS ports, you need to set the values of brokerServicePort
and webServicePort
to empty.
:::note
The default value of tlsRequireTrustedClientCertOnConnect
is false
, which represents one-way TLS. When it's set to true
(mutual TLS is enabled), brokers/proxies require trusted client certificates; otherwise, brokers/proxies reject connection requests from clients.
:::
Configuring mTLS on proxies includes two directions of connections, from clients to proxies, and from proxies to brokers.
servicePortTls=6651 webServicePortTls=8081 tlsRequireTrustedClientCertOnConnect=true # keystore tlsKeyStoreType=JKS tlsKeyStore=/var/private/tls/proxy.keystore.jks tlsKeyStorePassword=brokerpw # truststore tlsTrustStoreType=JKS tlsTrustStore=/var/private/tls/proxy.truststore.jks tlsTrustStorePassword=brokerpw # internal client/admin-client config tlsEnabledWithKeyStore=true brokerClientTlsEnabled=true brokerClientTlsEnabledWithKeyStore=true brokerClientTlsTrustStoreType=JKS brokerClientTlsTrustStore=/var/private/tls/client.truststore.jks brokerClientTlsTrustStorePassword=clientpw brokerClientTlsKeyStoreType=JKS brokerClientTlsKeyStore=/var/private/tls/client.keystore.jks brokerClientTlsKeyStorePassword=clientpw
Similar to Configure mTLS encryption with PEM, you need to provide the TrustStore information for a minimal configuration.
The following is an example.
<Tabs groupId="lang-choice" defaultValue="Java client" values={[{"label":"Java client","value":"Java client"},{"label":"Java admin client","value":"Java admin client"}]}> <TabItem value="Java client"> ```java import org.apache.pulsar.client.api.PulsarClient; PulsarClient client = PulsarClient.builder() .serviceUrl("pulsar+ssl://broker.example.com:6651/") .useKeyStoreTls(true) .tlsTrustStoreType("JKS") .tlsTrustStorePath("/var/private/tls/client.truststore.jks") .tlsTrustStorePassword("clientpw") .tlsKeyStoreType("JKS") .tlsKeyStorePath("/var/private/tls/client.keystore.jks") .tlsKeyStorePassword("clientpw") .enableTlsHostnameVerification(false) // false by default, in any case .allowTlsInsecureConnection(false) // false by default, in any case .build(); ``` :::note If you set `useKeyStoreTls` to `true`, be sure to configure `tlsTrustStorePath`. ::: </TabItem> <TabItem value="Java admin client"> ```java PulsarAdmin amdin = PulsarAdmin.builder().serviceHttpUrl("https://broker.example.com:8443") .tlsTrustStoreType("JKS") .tlsTrustStorePath("/var/private/tls/client.truststore.jks") .tlsTrustStorePassword("clientpw") .tlsKeyStoreType("JKS") .tlsKeyStorePath("/var/private/tls/client.keystore.jks") .tlsKeyStorePassword("clientpw") .enableTlsHostnameVerification(false) // false by default, in any case .allowTlsInsecureConnection(false) // false by default, in any case .build(); ``` </TabItem> </Tabs>
For Command-line tools like pulsar-admin
, pulsar-perf
, and pulsar-client
, use the conf/client.conf
config file in a Pulsar installation.
authPlugin=org.apache.pulsar.client.impl.auth.AuthenticationKeyStoreTls authParams={"keyStoreType":"JKS","keyStorePath":"/var/private/tls/client.keystore.jks","keyStorePassword":"clientpw"}
You can enable TLS debug logging at the JVM level by starting the brokers and/or clients with javax.net.debug
system property. For example:
-Djavax.net.debug=all
For more details, see Oracle documentation.