Access Control by ACL2013/06/05

	Configure ACL(Access Control Lists).
[1]	Set ACL For example, set ACL to the file "/home/test.txt".

root@dlp:~#

aptitude -y install acl

# set r(read) for "wheezy" user to /home/test.txt

root@dlp:~#

setfacl -m u:wheezy:r /home/test.txt

# after setting ACL, "+" is added on attribute

root@dlp:~#

ll /home/test.txt

-rwxr-----+ 1 root root 5 Jun  6 11:59 /home/test.txt

# confirm settings

root@dlp:~#

getfacl /home/test.txt

getfacl: Removing leading '/' from absolute path names
# file: home/test.txt
# owner: root
# group: root
user::rwx
user:wheezy:r--
group::---
mask::r--
other::---

# try to access with "wheezy"

wheezy@dlp:~$

cat /home/test.txt

ACL test file

# it can read normally

# try to access with another user

fedora@dlp:~$

cat /home/test.txt

cat: /home/test.txt: Permission denied

# it can not read normally

[2]	Set ACL to a directory recursively.

# set r(read) for "wheezy" to "/home/testdir" recursively

root@dlp:~#

setfacl -R -m u:wheezy:r /home/testdir

root@dlp:~#

ll -laR /home/testdir

/home/testdir:
total 12
drwxr-----+ 2 root root 4096 Jun  6 14:23 .
drwxr-xr-x  6 root root 4096 Jun  6 14:23 ..
-rwxr-----+ 1 root root    9 Jun  6 14:23 testfile

root@dlp:~#

getfacl -R /home/testdir

getfacl: Removing leading '/' from absolute path names
# file: home/testdir
# owner: root
# group: root
user::rwx
user:wheezy:r--
group::---
mask::r--
other::---

# file: home/testdir/testfile
# owner: root
# group: root
user::rwx
user:wheezy:r--
group::---
mask::r--
other::---

[3]	Set ACL by group

# set rw(read/write) for "security" group to "/home/test.txt"

root@dlp:~#

setfacl -m g:security:rw /home/test.txt

root@dlp:~#

getfacl /home/test.txt

getfacl: Removing leading '/' from absolute path names
# file: home/test.txt
# owner: root
# group: root
user::rwx
group::---
group:security:rw-
mask::rw-
other::---

# try to access with "wheezy" user who in "security" group

wheezy@dlp:~$

echo "test write" >> /home/test.txt

wheezy@dlp:~$

cat /home/test.txt

ACL test file
test write

# it can write normally

# try to access with a user who in not in "security" group

fedora@dlp:~$

echo "test write" >> /home/test.txt

-bash: /home/test.txt: Permission denied

# it cannot write normally

[4]	Remove ACL

# remove ACL from "/home/test.txt"

root@dlp:~#

setfacl -b /home/test.txt

# remove ACL only for "fedora" user on "/home/test.txt"

root@dlp:~#

setfacl -x u:fedora /home/test.txt

[5]	Set default ACL to a directory. If files/directories are created under the directory set default ACL, default access attribute is inherited. But be careful, if you change attribute with "chmod", then ACL would be invalid.

root@dlp:~#

setfacl -m u:wheezy:r-x /home/testdir

# set default ACL "r-x(read/execute)" for "wheezy" to "/home/testdir" directory

root@dlp:~#

setfacl -d -m u:wheezy:r-x /home/testdir

root@dlp:~#

getfacl /home/testdir

getfacl: Removing leading '/' from absolute path names
# file: home/testdir
# owner: root
# group: root
user::rwx
user:wheezy:r-x
group::---
mask::r-x
other::---
default:user::rwx
default:user:wheezy:r-x
default:group::---
default:mask::r-x
default:other::---

root@dlp:~#

echo "ACL default setting" > /home/testdir/test.txt

root@dlp:~#

ll /home/testdir/test.txt

-rw-r-----+ 1 root root 20 Jan 31 22:32 /home/testdir/test.txt

# try to access with "wheezy"

wheezy@dlp:~$

cat /home/testdir/test.txt

ACL default setting

# it can read normally

[6]	Remove default ACL

root@dlp:~#

setfacl -k /home/testdir

root@dlp:~#

getfacl /home/testdir

getfacl: Removing leading '/' from absolute path names
# file: home/testdir
# owner: root
# group: root
user::rwx
user:wheezy:r-x
group::---
mask::r-x
other::---

[7]	Set ACL from a configration file

# create a configuration file for ACL

# if there is ACL you'd like to set on other system, there is a way to export with "getfacl" command

root@dlp:~#

vi acl.txt

# file: /home/testdir
# owner: root
# group: root
user::rwx
user:wheezy:r-x
group::---
mask::r-x
other::---

# file: /home/test.txt
# owner: root
# group: root
user::rwx
user:wheezy:r--
group::---
mask::r--
other::---

root@dlp:~#

setfacl --restore=acl.txt

root@dlp:~#

ll /home

total 16
drwx------. 2 wheezy   wheezy   4096 Jan 31 12:14 wheezy
drwx------  2 fedora fedora 4096 Jan 31 12:14 fedora
drwxr-x---+ 2 root   root   4096 Jan 31 22:32 testdir
-rwxr-----+ 1 root   root     25 Jan 31 21:56 test.txt

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