What is ACL? –
File and directories have permission sets for
the owner of the file the group associated with the file and all other user for
the system. How ever these permission sets have limitation. For example
different permission can not be configured for different user Thus access
control list (ACL) was implemented. ACLs are supported in all the major Linux
file systems — ext2, ext3, XFS, ReiserFS, and JFS (begin ritual debate over
which filesystem is best). ACLs on Linux are still bleeding-edge, though, with
the major distributions just beginning to include them.
Applying
ACL –
STEP
1 –
Before using ACL for a file or directory. The partition for the file or
directory must be mounted with ACL support. If a local ext3 file system. It can
mount with the following command.
#mount -t
ext3 -o acl
/dev/hda7 /mnt
|
For mount it permanently –
/dev/hda7
|
/mnt
|
Ext3,acl
|
Defaults
|
0 0
|
STEP 2 –
Now set the ACL permission on the users or
groups.
#mkdir ajay
(at 1st I created a
directory for understanding ACL)
#getfacl ajay/
The above command is used to check the detail of
permissions.
Applying ACL on users –
#setfacl -m
u:ram:r-x ajay/
ram = user name
r-x = type of permission for ram user.
ajay = is directory
Now ajay directory is
permitted for read and execute.
Applying ACL for groups –
#setfacl -m
g:raja:rwx ajay/
raja = group name
rwx = type of permission for raja group
ajay = is directory.
ACL TYPES
There are two types of ACL
1.
Access ACL – Access
ACL Is the access control list for specific file or directory.
2. Default ACL
– Can only be associated with a
directory if files with in the directory dose not have an access ACL. It uses
the rules of the default ACL for the directory default ACL are option.
ACL
can be configuration:-
~
Per user.
~
Per group.
~
via the effective rights mask.
~
For users not in the user group for the file.
