Access Control List

 

Access control list:

What is ACL?

• It provides an additional, more flexible permission mechanism for file systems. It is designed to assist with UNIX file permissions. ACL allows you to give permissions for any user or group to any disc resource.

Use of ACL:

• Think of the scenario in which particular user is not the member of the group created by you but still you want to give some read or wite access how can you do it without making user the member of the group here comes in picture ACL, ACL helps us to do this trick.

•basically ACLs are used to make the flexible permission mechanism in Linux. from Linux man pages ACLS are used to define more fine grained discretionary access rights for files and

directories.

•commands to assign and remove ACL permissions are: setfacl and getfacl

List of the commands for setting up ACL:

1. to add permission for user:

setfacl -m u:user:rwx  /path of file

2. To add permission for the group:

setfacl -m g:group:rw   /path of file

3. To allow all files or directories to inherit ACL entries from the directory it is within: 

setfacl -Rm "entry" /path to directory

4. To remove the specific entry:

 setfacl -x u:user /path to file

5. To remove all entries 

setfacl -b /path to file

Note:

• As you assign the ACL permissions to file/directory it adds + sign at the end of the permission

• Setting w permission with ACL does not allow to remove the file

getfacl file1: gives the owner and group info of the file, also gives the permission info of the file.

setfacl -m u:spathan:rw  /tmp/file1: gives spathan user the rw permission to file1 file.

setfacl -m g:admins:rw /tmp/file1: gives the members of the admins group the rw permission to file1

setfacl -x u:spathan /tmp/file1: removes the specific permissions given to spathan user on file1

setfacl -b /tmp/file1: removes all the permissions given to any specific user or group on file1.