- 24 Oct, 2025
- 0 Comments
- 3 Mins Read
PostgreSQL User Authentication
Introduction
When it comes to database security, user authentication and access control form the first line of defense.
PostgreSQL, being one of the most secure open-source databases, provides robust mechanisms to manage users, roles, and permissions — ensuring only authorized users can access or modify data.
Common Authentication Methods in PostgreSQL
1 . Password Authentication (md5 or scram-sha-256)
This is the most widely used authentication method.
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Users must provide a username and password when connecting.
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PostgreSQL verifies this against credentials stored in the system catalog.
There are two main password-based options:
md5:
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Uses MD5 hashing for password storage and transmission.
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Now considered less secure due to hash vulnerabilities.
scram-sha-256:
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Introduced in PostgreSQL 10+.
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More secure because it uses SHA-256 hashing and salt-based protection.
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Recommended for all production environments.
Example configuration:
2 .Trust Authentication
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The simplest (but least secure) method.
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Allows users to connect without a password.
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PostgreSQL simply “trusts” the incoming connection.
✅ Use case:
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Suitable only for local testing, development, or air-gapped environments.
Not recommended for production.
Example:
3 . Peer Authentication
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Works for local Unix/Linux connections.
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PostgreSQL checks whether the operating system username matches the database username.
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No password is needed — access is controlled by the OS.
✅ Use case:
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Useful for local system automation or admin scripts running under specific OS accounts.
Example:
4 . Ident Authentication
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Similar to peer authentication, but used for remote connections.
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PostgreSQL queries an external Ident server to verify the username of the connecting host.
✅ Use case:
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Secure internal networks where Ident servers are configured to validate user identity.
Example:
5 . LDAP (Lightweight Directory Access Protocol)
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Enables authentication through a centralized LDAP directory (e.g., Active Directory or OpenLDAP).
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PostgreSQL delegates authentication to the LDAP server.
✅ Use case:
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Enterprise environments with many users.
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Simplifies user management — no need to create each PostgreSQL user manually.
Example configuration:
Tip:
You can integrate LDAP with SSL/TLS for encrypted authentication.
6 . GSSAPI (Generic Security Services API)
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Supports Kerberos-based single sign-on (SSO) authentication.
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Clients authenticate to PostgreSQL using a Kerberos ticket, not a password.
✅ Use case:
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Secure, enterprise-grade environments where users are already managed via Kerberos.
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Common in organizations using centralized authentication (like Active Directory).
Example configuration:
How it works:
1 . The client obtains a Kerberos ticket from the Key Distribution Center (KDC).
2 . The client presents this ticket to PostgreSQL.
3 . PostgreSQL verifies it using the KDC — no password exchange happens.
7 . SSPI (Security Support Provider Interface)
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Windows-specific authentication mechanism.
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Essentially the Windows version of GSSAPI, allowing integrated Windows authentication.
✅ Use case:
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PostgreSQL running on Windows Server environments.
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Allows users to connect using their Windows credentials without entering passwords.
Example:
Benefits:
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Seamless authentication for Windows domain users.
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Eliminates password management overhead.
Conclusion:
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