sharesec

In Samba, sharesec refers to the mechanism (typically implemented as a TDB file, often named sharesec.tdb) that stores share-level security information. This data defines the access control lists (ACLs) for Samba shares—separate from the underlying filesystem permissions—mimicking the behavior of Windows share permissions.

Overview

• Purpose: sharesec holds the security descriptors for Samba shares. It determines which users or groups have access to a particular share and what level of access (read, write, full control) they have.

• Storage Mechanism: The share security information is stored in a Trivial Database (TDB) file, typically named sharesec.tdb, which is maintained by Samba. This file is automatically managed by Samba and is used to enforce share-level permissions when clients connect.

• Integration with Windows: By implementing share-level ACLs similar to Windows, Samba can provide a more familiar security model for Windows clients, ensuring consistent behavior across a mixed-OS environment.

Key Functions

• Access Control: Controls which users and groups can access a share and with what permissions. These settings complement filesystem-level permissions.

• Windows-Like Security Model: Allows Samba to emulate Windows share permissions, facilitating integration in networks where Windows and Unix systems coexist.

• Administrative Management: Administrators can indirectly manage share security through Samba configuration (using tools like smb.conf and various Samba utilities) rather than editing the sharesec.tdb file directly.

Usage and Management

• Automatic Handling: Samba automatically updates sharesec.tdb when changes are made to share permissions via configuration or administrative tools (e.g., using net rpc share commands).

• Administrative Tools: While direct editing of sharesec.tdb is uncommon, you can query or modify share security settings using Samba commands. For example:

  net rpc share info <sharename> -U <admin_user>

  This command displays detailed share information, including security settings stored in sharesec.tdb.

Best Practices

• Backup: Regularly include sharesec.tdb in your Samba backups to ensure that share security settings can be restored in case of corruption or accidental loss.

• Security: Set strict file permissions on sharesec.tdb so that only the Samba process and trusted administrators can access it.

• Monitoring: Keep an eye on changes to share permissions and audit logs to detect unauthorized modifications.

Conclusion

The sharesec mechanism, typically implemented as sharesec.tdb in Samba, is crucial for managing share-level ACLs. By emulating Windows share permissions, it enables consistent and secure access control across mixed operating system environments. Proper backup, security, and monitoring of sharesec.tdb are essential to maintain the integrity of your Samba share security settings.