Configuring Encryption
By default, Redpanda data is sent unencrypted. A security best practice is to enable encryption with TLS or mTLS.
-
Transport Layer Security (TLS), previously SSL, provides encryption for client-server communication. A server certificate prevents third parties from accessing data transferred between the client and server.
-
mTLS, or 2-way TLS, is a protocol that authenticates both the server and the client. In addition to the server certificate required in TLS, mTLS also requires the client to give a certificate. This involves more overhead to implement, but it can be useful for environments that require additional security and only have a small number of verified clients.
For each Redpanda broker, specify the key file (broker.key
), the certificate file (broker.crt
), and the truststore file (ca.crt
). Each broker has its own broker.key
and broker.crt
, but all brokers can have the same ca.crt
.
For Kubernetes-specific information, see:
Prerequisites
TLS certificates are necessary for encryption. You can use your own certificates, either self-signed or issued by a trusted certificate authority (CA).
Create certificate signing requests
This step creates the certificate signing request for the CA to extend trust over the broker’s certificates.
1. Create broker configuration file (broker.cnf)
A subject alternative name (SAN) indicates all domain names and IP addresses secured by the certificate. Depending on the address the client uses to connect to Redpanda, you might need to create a CNF file for each broker to modify the alt_names
section with organizational details. For production usage, edit alt_names
with DNS resolutions and/or the IP addresses.
broker.cnf
[ CA_default ]
database = index.txt
serial = serial.txt
policy = signing_policy
[ signing_policy ]
organizationName = supplied
commonName = optional
[ req ]
prompt = no
distinguished_name = distinguished_name
req_extensions = extensions
[ distinguished_name ]
organizationName = Redpanda
[ extensions ]
keyUsage = critical,digitalSignature,keyEncipherment
extendedKeyUsage = serverAuth,clientAuth
subjectAltName = @alt_names
[ alt_names ]
DNS.1 = localhost
DNS.2 = redpanda
DNS.3 = console
DNS.4 = connect
IP.1 = 127.0.0.1
You could configure alternative names with a single version of broker.key
/broker.crt
, as long as you update the certificate for all brokers in the cluster any time you edit an entry. For example:
[ alt_names ]
DNS.1 = broker1.example.com
DNS.2 = broker2.example.com
DNS.3 = broker3.example.com
2. Generate broker private key (broker.key)
Generate a 2048-bit RSA private key for brokers:
openssl genrsa -out broker.key 2048
where:
Output |
Description |
|
The public key certificate of the CA. |
3. Sign certificates
Sign the certificate with the CA signature:
touch index.txt
echo '01' > serial.txt
openssl ca -config broker.cnf -keyfile broker.key -cert ca.crt -extensions extensions -in broker.csr -out broker.crt -outdir . -batch
If generated by a corporate CA, these certificate signing requests must be signed with the following extensions:
keyUsage = critical,digitalSignature,keyEncipherment
extendedKeyUsage = serverAuth,clientAuth
Create a local CA for self-signed certificates
This step is required if you want to generate multiple certificates all signed by the same root; for example, you want to use mTLS but issue different certificates to multiple Redpanda brokers and clients. To generate a self-signed certificate in a single command:
|
1. Create CA configuration file (ca.cnf)
Edit the distinguished_name
section with your own organization details. For default_md
, sha256
is the minimum message digest level. The subjectAltName
must be accurate for the broker’s certificate.
ca.cnf
[ ca ]
default_ca = CA_default
[ CA_default ]
default_days = 365
default_md = sha256
unique_subject = no
[ req ]
prompt = no
distinguished_name = distinguished_name
x509_extensions = extensions
[ distinguished_name ]
organizationName = Redpanda
commonName = Redpanda CA
[ extensions ]
keyUsage = critical,digitalSignature,nonRepudiation,keyEncipherment,keyCertSign
basicConstraints = critical,CA:true,pathlen:1
subjectAltName = @alt_names
[ alt_names ]
DNS.1 = localhost
IP.1 = 127.0.0.1
2. Generate CA private key and public certificate
Create a CA key to self-sign certificates:
openssl genrsa -out ca.key 2048
chmod 400 ca.key
Create a public certificate for the CA:
openssl req -new -x509 -config ca.cnf -key ca.key -days 365 -batch -out ca.crt
where:
Inputs | Description |
---|---|
|
New request. |
|
Create an X.509 certificate, instead of a certificate signing request (CSR). |
|
Configuration file to use when generating certificates (created above). |
|
Private key of the CA (created above). |
|
Number of days signed certificates are valid. |
|
Batch mode, where certificates are certified automatically. |
Output | Description |
---|---|
|
The public key certificate of the CA. |
3. Sign certificates
Sign and generate an X.509 certificate for the Redpanda broker:
openssl x509 -req -signkey ca.key -days 365 -extfile broker.cnf -extensions extensions -in broker.csr -out broker.crt
where:
Inputs | Description |
---|---|
|
Input is a certificate request. Sign and output. |
|
Private key of the CA (created above). |
|
Number of days signed certificates are valid. |
|
Configuration file for CA. |
|
Section in |
|
Broker certificate signing request (CSR generated above). |
Output | Description |
---|---|
|
The signed public key certificate for the broker. |
Configure TLS
To configure TLS, in redpanda.yaml
, enter:
redpanda.yaml
redpanda:
rpc_server_tls: {}
kafka_api:
- address: 0.0.0.0
port: 9092
name: tls_listener
kafka_api_tls:
- name: tls_listener
key_file: broker.key
cert_file: broker.crt
truststore_file: ca.crt
enabled: true
require_client_auth: false
admin_api_tls: []
pandaproxy:
pandaproxy_api_tls: []
schema_registry:
schema_registry_api_tls: []
To set the RPC port to encrypt replication, add:
redpanda.yaml
redpanda:
rpc_server_tls:
enabled: true
require_client_auth: false
key_file: broker.key
cert_file: broker.crt
truststore_file: ca.crt
Schema Registry and HTTP Proxy connect to Redpanda over the Kafka API. If you configure a TLS listener for the Kafka API, you must add schema_registry_client::broker_tls
and pandaproxy_client::broker_tls
. All APIs, except the internal RPC port, support multiple listeners. See:
- Configure Schema Registry and HTTP Proxy to connect to Redpanda with SASL
- Configure Listeners
Configure mTLS
To enable mTLS, add require_client_auth
set to true
.
For example, for the Kafka API, in redpanda.yaml
, enter:
redpanda.yaml
redpanda:
kafka_api:
- address: 0.0.0.0
port: 9092
name: mtls_listener
kafka_api_tls:
- name: mtls_listener
key_file: mtls_broker.key
cert_file: mtls_broker.crt
truststore_file: mtls_ca.crt
enabled: true
require_client_auth: true
See also: Configure Listeners.
Configure mTLS for a Kafka API listener
To enable mTLS for a Kafka API listener, edit redpanda.yaml
:
redpanda.yaml
redpanda:
kafka_api:
- name: internal
address: 0.0.0.0
port: 9092
advertised_kafka_api:
- name: internal
address: <port-clients-connect-to>
port: 9092
kafka_api_tls:
- name: internal
enabled: true
require_client_auth: true
cert_file: <path-to-PEM-formatted-cert-file>
key_file: <path-to-PEM-formatted-key-file>
truststore_file: <path-to-PEM-formatted-CA-file>
|
See also: Configure Listeners.
Use rpk with TLS
If you’re using rpk
to interact with the Kafka API using mTLS identity (for example, to manage topics or messages), pass the --tls-key
, --tls-cert
, and --tls-truststore
flags to authenticate.
To interact with the Admin API (for example, to manage users), pass the --admin-api-tls-key
, --admin-api-tls-cert
, and --admin-api-tls-truststore
flags.
rpk topic create test-topic \
--tls-key <path-to-PEM-formatted-key-file> \
--tls-cert <path-to-PEM-formatted-cert-file> \
--tls-truststore <path-to-PEM-formatted-CA-file>
Remember to replace placeholders in brackets. |
Example output:
TOPIC STATUS
test-topic OK
To check the configuration of the topic, run:
rpk topic describe test-topic <tls-flags-from-above>
By default, rpk
connects to localhost:9092
for Kafka protocol commands. If you’re connecting to a remote broker or if you configured your local broker differently, use the --brokers <address:port>
flag.