Explaining SASL in Kafka for AWS MSK

The aim of this page📝 is to explain the concept of SASL authentication in Apache Kafka based on the particular example of connecting to AWS MSK as I am trying to configure the app to successfully send data into a client’s AWS MSK with highly elaborate security measures.

Pavol Kutaj
2 min readJan 31, 2024
SASL hAIku: 19th century \ realism with bodyguards \ chasing dreams
  • SASL (Simple Authentication and Security Layer) is a framework for adding authentication and security services to network protocols.
  • SASL provides a flexible way to authenticate clients and servers and negotiate a secure communication channel.
  • SASL is used in Apache Kafka to authenticate clients (producers and consumers) and brokers.
  • It supports various authentication mechanisms like PLAIN, SCRAM-SHA-256, SCRAM-SHA-512, and GSSAPI (Kerberos).
  • SASL ensures that only authorized clients can access the Kafka cluster and protects the data.
  • SASL authentication ensures that only authorized clients can access the Kafka cluster.
  • The choice of SASL mechanism depends on the security requirements and the authentication infrastructure in use.
  • The broker’s configuration determines which SASL mechanisms are enabled.
  • If the requested SASL mechanism is not supported by the broker, an error like “Invalid SASL Mechanism” may occur.
  • Troubleshooting steps include verifying the SASL mechanism, checking the credentials, updating the broker configuration, and verifying network connectivity.
  • SASL authentication can be combined with Kafka’s built-in authorization mechanisms, such as ACLs (Access Control Lists), for fine-grained access control.

Credentials are often hashed

  • Hashing credentials, like passwords, adds an extra layer of security by making it difficult to retrieve the original plaintext value from the hash.
  • Hashing is a one-way function, and a good hashing algorithm, like SHA-256, has a low probability of producing the same hash value for different inputs.
  • Salting, adding a random value to the password before hashing, further enhances security by preventing the use of precomputed tables (rainbow tables) for password cracking.
  • While hashing is beneficial, it should be combined with other security measures like strong hashing algorithms, proper key management, and secure network protocols.
  • SASL authentication can integrate with existing authentication platforms like LDAP or AD, allowing Kafka to leverage the authentication services provided by these platforms.

SASL is decoupled from application protocol and offers integration with other security platforms like LDAP

  • Integrating with LDAP or AD provides benefits such as centralized user management, single sign-on (SSO), and seamless integration with other applications.
  • SASL authentication with LDAP or AD requires proper configuration and setup, which may vary depending on the Kafka version and the authentication mechanism being used.




Pavol Kutaj

Today I Learnt | Infrastructure Support Engineer at snowplow.io with a passion for cloud infrastructure/terraform/python/docs. More at https://pavol.kutaj.com