Red Hat Enterprise Linux 3: System Administration Guide
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# Chapter 8. Access Control Lists

Files and directories have permission sets for the owner of the file, the group associated with the file, and all other users for the system. However, these permission sets have limitations. For example, different permissions can not be configured for different users. Thus, Access Control Lists (ACLs) were implemented.

The Red Hat Enterprise Linux 3 kernel provides ACL support for the ext3 file system and NFS-exported file systems. ACLs are also recognized on ext3 file systems accessed via Samba.

Along with support in the kernel, the `acl` package is required to implement ACLs. It contains the utilities used to add, modify, remove, and retrieve ACL information.

The `cp` and `mv` commands copy or move any ACLs associated with files and directories.

# 8.1. Mounting File Systems

Before using ACLs for a file or directory, the partition for the file or directory must be mounted with ACL support. If it is a local ext3 file system, it can mounted with the following command:

    mount -t ext3 -o acl <device-name> <partition>

For example:

    mount -t ext3 -o acl /dev/hdb3 /work

Alternatively, if the partition is listed in the `/etc/fstab` file, the entry for the partition can include the `acl` option:

    LABEL=/work      /work       ext3    acl        1 2

If an ext3 file system is accessed via Samba and ACLs have been enabled for it, the ACLs are recognized because Samba has been compiled with the `--with-acl-support` option. No special flags are required when accessing or mounting a Samba share.

## 8.1.1. NFS

By default, if the file system being exported by an NFS server supports ACLs and the NFS client can read ACLs, ACLs are utilized by the client system.

To disable ACLs on NFS shares when configuring the server, include the `no_acl` option in the `/etc/exports` file. To disable ACLs on an NFS share when mounting it on a client, mount it with the `no_acl` option via the command line or the `/etc/fstab` file.

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