setcifsacl

setcifsacl is a command-line utility used to modify and manage Windows NT-style Access Control Lists (ACLs) on files and directories mounted via CIFS (Common Internet File System). This tool is particularly useful in environments where Linux systems access Windows or Samba shares and need to enforce fine-grained permission control consistent with Windows ACL semantics.

Purpose

• Modify CIFS ACLs: setcifsacl enables administrators to add, change, or remove ACL entries on files and directories residing on CIFS mounts.

• Granular Permission Management: It provides a way to enforce detailed permission settings (e.g., read, write, execute) similar to those available in Windows environments.

• Ensure Consistency: By using setcifsacl, you can maintain consistent permission policies on network shares across heterogeneous environments.

Basic Syntax

setcifsacl [options] <file_or_directory> <acl-specification>

• <file_or_directory>: The path to the target file or directory on the CIFS mount.

• <acl-specification>: A string (or file) describing the ACL entries to be applied. This typically follows the Windows NT ACL format (e.g., user:DOMAIN\username:RW).

Common Options

• -h, --help: Display usage and help information.

• -v, --verbose: Enable verbose output to provide more details about the operation.

• -R, --recursive: Apply the ACL changes recursively to all files and subdirectories under a specified directory.

Example Usage

1. Setting a New ACL on a File

   To set an ACL that grants user DOMAIN\alice read and write permissions on a file:

   setcifsacl /mnt/cifs/share/document.txt "user:DOMAIN\alice:RW"

2. Recursively Updating ACLs on a Directory

   To apply an ACL change to a directory and all its subdirectories—granting group DOMAIN\staff read and execute permissions:

   setcifsacl -R /mnt/cifs/share/folder "group:DOMAIN\staff:RX"

Best Practices

• Backup Existing ACLs: Before making changes, use a tool like getcifsacl (if available) to retrieve and save the current ACL configuration.

• Test on Sample Data: Try the ACL change on a test file or directory first to confirm the effect before applying it broadly.

• Verify Mount Options: Ensure that the CIFS share is mounted with the appropriate options (e.g., cifsacl) so that ACL modifications are supported and effective.

Conclusion

setcifsacl is an essential utility for administrators managing CIFS-mounted shares in mixed-platform environments. It provides a straightforward mechanism to set and modify Windows NT-style ACLs on files and directories, ensuring that access permissions are enforced consistently and securely across networked resources.