Kafka enforces security at four major levels: Authentication, Authorization, Encryption, and Auditing.

---

🔹 1. Authentication (Who are you?)

Kafka verifies the identity of clients (producers/consumers) and brokers using:

• SSL/TLS

  • Mutual TLS for client ↔ broker auth.

  • Certificates signed by CA.

• SASL (Simple Authentication and Security Layer)

  • SASL/PLAIN → username/password.

  • SASL/SCRAM → salted challenge-response (secure password storage).

  • SASL/GSSAPI (Kerberos) → enterprise-grade auth.

  • SASL/OAUTHBEARER → token-based (e.g., JWT, Keycloak, OAuth2.0).

👉 This ensures only legitimate clients and brokers can connect.

---

🔹 2. Authorization (What can you do?)

Kafka uses ACLs (Access Control Lists) stored in ZooKeeper or Kafka itself (depending on version).

• You can control which user can produce/consume from which topics, create topics, or access cluster resources.

• Example:

  kafka-acls.sh --add --allow-principal User:alice --operation Read --topic orders
  

• Supports fine-grained permissions on: Topics, Consumer Groups, and Clusters.

---

🔹 3. Encryption (Protect data in transit)

• Kafka supports SSL/TLS encryption for:

  • Client ↔ Broker communication.

  • Broker ↔ Broker replication traffic.

• Prevents man-in-the-middle (MITM) attacks and data snooping.

👉 Note: Kafka does not natively encrypt data at rest, but you can use disk encryption (LUKS, EBS encryption, etc.) or integrate with enterprise security tools.

---

🔹 4. Auditing & Monitoring

• Kafka logs security events (auth successes/failures, ACL denials).

• Integration with monitoring/logging tools (e.g., ELK, Splunk, Prometheus) for auditing.

• Helps detect unauthorized access attempts and meet compliance (GDPR, HIPAA, PCI DSS).

---

🔹 5. Multi-tenancy Security Features

• Quota enforcement → per-client request limits to prevent resource hogging.

• Isolation via SASL users & ACLs → separate apps/teams securely in a shared Kafka cluster.

---

🔹 In Short

Kafka enforces security via:

1. Authentication → SSL/TLS, SASL (SCRAM, Kerberos, OAuth).

2. Authorization → ACLs to restrict actions.

3. Encryption → SSL/TLS for in-transit data.

4. Auditing & Monitoring → logs + monitoring tools.

5. Quotas → protect cluster resources.

👉 Together, these ensure confidentiality, integrity, and controlled access in Kafka.