Hack The Sec-Leading Resource Of Linux Tutorial: Linux

How To Implement Access Control List (ACL) For CentOS/RHEL 7

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<span style="color: red; font-size: large;"><u><i>Implement Access Control List (ACL) For <a href="http://www.hackthesec.co.in/search/label/centos7" target="_blank">CentOS 7</a>/<a href="http://www.hackthesec.co.in/search/label/Rhel7" target="_blank">RHEL7</a></i></u></span></h1>
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<span style="color: #0b5394; font-size: large;">What is Access Control List (ACL)?</span></h2>
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Files and directories or folders have permission sets for the owner of the file along with the group associated with that file and all other users of that system. But these permission sets have some limitations. For example, different permissions cannot be configured for different users. Thus, Access Control Lists (ACLs) were implemented.</div>
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ACLs can be configured as follows<br /></div>
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<li style="box-sizing: border-box; list-style: disc;">Per user</li>
<li style="box-sizing: border-box; list-style: disc;">Per group</li>
<li style="box-sizing: border-box; list-style: disc;">For users not in the user group for the file</li>
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ACL  provides an additional flexible permission mechanism for file system on a Linux system. It enhance the traditional <a href="http://www.hackthesec.co.in/search/label/Unix" target="_blank">UNIX </a>file permissions for files & folder. With ACL, you can give permissions for any user or any group with fine-grained access rights.</div>
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ACLs can be configured per user, per group or via the effective rights mask. These permissions then can be apply to an individual user or a group, and also you can use the same as rwx (Read, Write, Execute) found in regular file / folder permissions.</div>
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ACLs requires kernel support and your kernel musk support <a href="http://www.hackthesec.co.in/search/label/ACL_Permission" target="_blank">ACL </a>in order to implement ACL on your Linux distribution. Along with support in the kernel, the acl package is also required to implement ACLs. Acl package contains the utilities used to add, modify, remove, and retrieve ACL information from a file / folder.</div>
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<span style="color: #0b5394; font-size: large;">Why CentOS Linux?</span></h2>
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CentOS Linux is a community-supported distribution derived from sources freely provided to the public by Red Hat for Red Hat Enterprise Linux (<a href="http://www.hackthesec.co.in/search/label/RHEL" target="_blank">RHEL</a>). As such, CentOS Linux aims to be functionally compatible with <a href="http://www.hackthesec.co.in/search/label/Rhel7" target="_blank">RHEL</a>. The <a href="http://www.hackthesec.co.in/search/label/Centos" target="_blank">CentOS </a>Project mainly changes packages to remove upstream vendor branding and artwork. CentOS Linux is no-cost and free to redistribute. Each CentOS version is maintained for up to 10 years (by means of security updates — the duration of the support interval by Red Hat has varied over time with respect to Sources released). A new CentOS version is released approximately every 2 years and each CentOS version is periodically updated (roughly every 6 months) to support newer hardware. This results in a secure, low-maintenance, reliable, predictable and reproducible Linux environment.</div>
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You can download CentOS from <a href="https://wiki.centos.org/Download" style="-webkit-tap-highlight-color: transparent; background: 0px 0px; box-sizing: border-box; color: #ff5a00; text-decoration: none; transition: background 0.2s ease-out, color 0.2s ease-out;">here</a>. You can directly download the ISO file format disk image from <a href="http://buildlogs.centos.org/rolling/7/isos/x86_64/CentOS-7-x86_64-DVD.iso" style="-webkit-tap-highlight-color: transparent; background: 0px 0px; box-sizing: border-box; color: #ff5a00; text-decoration: none; transition: background 0.2s ease-out, color 0.2s ease-out;">here</a>.</div>
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<span style="color: #134f5c; font-size: large;"><span style="font-family: Oswald, Lato, Arial, sans-serif;"><span style="line-height: 35px;"><u>Prerequisites</u></span></span></span><span style="font-family: Lato, Arial, sans-serif; font-size: 16px; line-height: 1.8em;">Before beginning, you must know whether your Linux OS kernel supports ACL or not.</span></h2>
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First, switch to root user. This is not required if your current local user have sudo privileges. This is only for this tutorial. Do not practise this for regular system administration.</div>
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Type your root user password for continue.</div>
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To know whether your kernel supports ACL or not, type the following command in a terminal.</div>
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<span style="line-height: 28.8px;">After issuing the above command, you will see something like this which indicates that your kernel has the support for ACL.</span></div>
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<span style="line-height: 28.8px;">Now, let’s check whether we have the ACL package installed on our system or not. To check such case, issue the below command in a terminal.</span></div>
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<span style="line-height: 28.8px;">You you will see something like below image.</span></div>
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<span style="line-height: 28.8px;">If you don’t have ACL package installed on your system, then issue the below command to install ACL package onto your system.</span></div>
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<span style="color: #0b5394; font-size: large;">Let’s Start</span></h2>
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<span style="box-sizing: border-box; font-weight: 700;">Mounting File Systems</span></div>
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Before using any ACLs for a file or directory, the partition for the file or directory must be mounted with ACL support.</div>
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A local file system can be mounted with the following command syntax shown as below.</div>
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Here, <span style="box-sizing: border-box; font-weight: 700;">/dev/sdb</span> is a disk device block and <span style="box-sizing: border-box; font-weight: 700;">acltest</span> is the folder where it will be mounted for access.</div>
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After that, you need to edit the file <span style="box-sizing: border-box; font-weight: 700;">/etc/fstab</span> for the <span style="box-sizing: border-box; font-weight: 700;">/dev/sdb</span> partition and you need to include the acl as follows. This will mount <span style="box-sizing: border-box; font-weight: 700;">/dev/sdb</span> automatically whenever you are rebooting your system.</div>
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Open the file by using the following command.</div>
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and then type the following on the /etc/fstab file.</div>
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Save & exit from the file /etc/fstab. So, whenever you will reboot, your partition will be mounted automatically with acl support.</div>
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After editing the file we need to remount the partition again. To do so,</div>
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<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); color: #333333; line-height: 19.2px; margin: 0px 0px 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="line-height: 15.6px;"><span style="font-size: large;"><span style="color: white;">[root@hackthesec]#</span><span style="color: lime;"> mount -o remount,acl /dev/sdb</span></span></span></pre>
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You can issue the below command to confirm whether your previous remount command worked or not.</div>
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<h1 class="entry-title" itemprop="headline" style="-webkit-text-stroke-width: 0px; background-color: white; box-sizing: border-box; color: black; font-family: Oswald, Lato, Arial, sans-serif; font-style: normal; font-variant: normal; font-weight: 400; letter-spacing: normal; line-height: 50px; margin: 0px 0px 5px; orphans: auto; padding: 0px; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 1; word-spacing: 0px;">
<div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); color: #333333; line-height: 19.2px; margin: 0px 0px 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="line-height: 15.6px;"><span style="font-size: large;"><span style="color: white;">[root@hackthesec]#</span><span style="color: lime;"> mount</span></span></span></pre>
</div>
</h1>
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<div>
<span style="font-family: Lato, Arial, sans-serif; font-size: 16px; line-height: 28.8px;"> Now Create a user . and SET password</span></div>
</h1>
<h1 class="entry-title" itemprop="headline" style="background-color: white; box-sizing: border-box; font-family: Oswald, Lato, Arial, sans-serif; font-weight: 400; line-height: 50px; margin: 0px 0px 5px; padding: 0px;">
<div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); line-height: 19.2px; margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="line-height: 15.6px;"><span style="font-size: large;"><span style="color: white;">[root@hackthesec]#</span><span style="color: lime;"> useradd hackthesec1
</span><span style="color: white;">[root@hackthesec]#</span><span style="color: lime;"> passwd hackthesec1</span></span></span></pre>
</div>
</h1>
<h1 class="entry-title" itemprop="headline" style="background-color: white; box-sizing: border-box; font-family: Oswald, Lato, Arial, sans-serif; font-weight: 400; line-height: 50px; margin: 0px 0px 5px; padding: 0px;">
</h1>
<h1 class="entry-title" itemprop="headline" style="background-color: white; box-sizing: border-box; font-family: Oswald, Lato, Arial, sans-serif; font-weight: 400; line-height: 50px; margin: 0px 0px 5px; padding: 0px;">
<div>
</div>
<div>
<div style="box-sizing: border-box; font-family: Lato, Arial, sans-serif; font-size: 16px; line-height: 1.8em; margin-bottom: 0.9em; margin-top: 0.9em;">
To test acl, we will need at least two users and I will use root and hackthesec1. However you can use different users and it’s up to you.</div>
<div style="box-sizing: border-box; font-family: Lato, Arial, sans-serif; font-size: 16px; line-height: 1.8em; margin-bottom: 0.9em; margin-top: 0.9em;">
First we create a file <span style="box-sizing: border-box; font-weight: 700;">demoacltest.txt</span> in folder <span style="box-sizing: border-box; font-weight: 700;">/acltest </span>folder path location.</div>
</div>
<div>
<div style="box-sizing: border-box; font-family: Lato, Arial, sans-serif; font-size: 16px; line-height: 1.8em; margin-bottom: 0.9em; margin-top: 0.9em;">
We will add acl for user hackthesec1 which will allow hackthesec 1user to write /acltest/demoacltest.txt file.</div>
<div style="box-sizing: border-box; font-family: Lato, Arial, sans-serif; font-size: 16px; line-height: 1.8em; margin-bottom: 0.9em; margin-top: 0.9em;">
</div>
<h1 class="entry-title" itemprop="headline" style="-webkit-text-stroke-width: 0px; background-color: white; box-sizing: border-box; color: black; font-family: Oswald, Lato, Arial, sans-serif; font-style: normal; font-variant: normal; font-weight: 400; letter-spacing: normal; line-height: 50px; margin: 0px 0px 5px; orphans: auto; padding: 0px; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 1; word-spacing: 0px;">
</h1>
</div>
</h1>
<h1 class="entry-title" itemprop="headline" style="-webkit-text-stroke-width: 0px; background-color: white; box-sizing: border-box; font-family: Oswald, Lato, Arial, sans-serif; font-style: normal; font-variant: normal; font-weight: 400; letter-spacing: normal; line-height: 50px; margin: 0px 0px 5px; orphans: auto; padding: 0px; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 1; word-spacing: 0px;">
<div>
<pre style="background-attachment: scroll; background-clip: initial; background-color: #3c3c3c; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 4px; border: 1px solid rgb(229, 229, 229); line-height: 19.2px; margin: 0px 0px 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="line-height: 15.6px;"><span style="font-size: large;"><span style="color: white;">[root@hackthesec]#</span><span style="color: lime;"> setfacl -R -m u:</span></span><span style="color: white;"><span style="font-size: large;">hackthesec1:rwx /acttest/demoacltest.txt
</span><span style="font-size: medium;">
and for default permission just use this command bellow

</span><span style="font-size: large;">[root@hackthesec]# setfacl -R -m d:u:hackthesec1:rwx /acltest/demoacltest.txt</span></span></span></pre>
</div>
</h1>
<h1 class="entry-title" itemprop="headline" style="background-color: white; box-sizing: border-box; font-family: Oswald, Lato, Arial, sans-serif; font-weight: 400; line-height: 50px; margin: 0px 0px 5px; padding: 0px;">
<div>
<div style="box-sizing: border-box; font-family: Lato, Arial, sans-serif; font-size: 16px; line-height: 1.8em; margin-bottom: 0.9em; margin-top: 0.9em;">
Now if you want to see the file permission just run the bellow command</div>
<pre style="background-attachment: scroll; background-clip: initial; background-color: #3c3c3c; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 4px; border: 1px solid rgb(229, 229, 229); line-height: 19.2px; margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="line-height: 15.6px;"><span style="font-size: large;"><span style="color: white;">[root@hackthesec]#</span><span style="color: lime;"> getfacl</span></span><span style="color: white;"><span style="font-size: large;"> /acttest/demoacltest.txt
</span><span style="font-size: medium;">

Result: - 
#file: acltest/demoacltest.txt
#owner: root
#group: root
#flags: -s-
user::rwx
user::hackthesec1:rwx
group::rwx
mask::rwx
other::---
default:user::rwx
default:user:hackthesec1:rwx
default:group::--x
default:mask::rwx
default:other::--x</span></span></span></pre>
</div>
</h1>
<h2 style="background-color: white; box-sizing: border-box; font-family: Oswald, Lato, Arial, sans-serif; font-weight: 400; line-height: 35px; margin: 0px 0px 1.3em; padding: 0px;">
<span style="color: #0b5394; font-size: large;"><u>Removing any acls</u></span></h2>
<h1 class="entry-title" itemprop="headline" style="background-color: white; box-sizing: border-box; font-family: Oswald, Lato, Arial, sans-serif; font-weight: 400; line-height: 50px; margin: 0px 0px 5px; padding: 0px;">
<div style="box-sizing: border-box; font-family: Lato, Arial, sans-serif; font-size: 16px; line-height: 1.8em; margin-bottom: 0.9em; margin-top: 0.9em;">
To remove all of the currently defined ACLs from a file or folder, issue the below command.</div>
<div style="box-sizing: border-box; font-family: Lato, Arial, sans-serif; font-size: 16px; line-height: 1.8em; margin-bottom: 0.9em; margin-top: 0.9em;">
</div>
</h1>
<h1 class="entry-title" itemprop="headline" style="-webkit-text-stroke-width: 0px; background-color: white; box-sizing: border-box; color: black; font-family: Oswald, Lato, Arial, sans-serif; font-style: normal; font-variant: normal; font-weight: 400; letter-spacing: normal; line-height: 50px; margin: 0px 0px 5px; orphans: auto; padding: 0px; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 1; word-spacing: 0px;">
</h1>
<br />
<h1 class="entry-title" itemprop="headline" style="-webkit-text-stroke-width: 0px; background-color: white; box-sizing: border-box; font-family: Oswald, Lato, Arial, sans-serif; font-style: normal; font-variant: normal; font-weight: 400; letter-spacing: normal; line-height: 50px; margin: 0px 0px 5px; orphans: auto; padding: 0px; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 1; word-spacing: 0px;">
<div>
<pre style="background-attachment: scroll; background-clip: initial; background-color: #3c3c3c; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 4px; border: 1px solid rgb(229, 229, 229); line-height: 19.2px; margin: 0px 0px 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="line-height: 15.6px;"><span style="font-size: large;"><span style="color: white;">[root@hackthesec]#</span><span style="color: lime;"> setfacl -b </span><span style="color: white;">/acltest/demoacltest.txt</span></span></span></pre>
</div>
</h1>
<h1 class="entry-title" itemprop="headline" style="background-color: white; box-sizing: border-box; font-family: Oswald, Lato, Arial, sans-serif; font-weight: 400; line-height: 50px; margin: 0px 0px 5px; padding: 0px;">
<div style="box-sizing: border-box; font-family: Lato, Arial, sans-serif; font-size: 16px; line-height: 1.8em; margin-bottom: 0.9em; margin-top: 0.9em;">
Here, demoacltest.txt is a file name.</div>
<div style="box-sizing: border-box; font-family: Lato, Arial, sans-serif; font-size: 16px; line-height: 1.8em; margin-bottom: 0.9em; margin-top: 0.9em;">
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</h1>
</div>

How To Implement Access Control List (ACL) For CentOS/RHEL 7

Implement Access Control List (ACL) For CentOS 7/RHEL7 What is Access Control List (ACL)? Files and directories or folders have permission sets for the owner of the file along with the group associat…

22 Feb 2016

How to Configure ACL in Linux FileSystem

<div dir="ltr" style="text-align: left;" trbidi="on">
<h2 class="title single-title title20" style="background-color: white; border: 0px; font-family: 'Roboto Slab'; font-size: 28px; line-height: 38px; margin: 0px 0px 5px; opacity: 1; outline: 0px; padding: 0px; transition: opacity 0.24s ease-in-out; vertical-align: baseline; visibility: visible;">
<span style="color: #990000;"><u><i>Configure ACL in Linux FileSystem</i></u></span></h2>
<div>
<div style="background-color: white; border: 0px; font-size: 16px; line-height: 28px; margin-bottom: 20px; outline: 0px; padding: 0px; vertical-align: baseline;">
<span style="font-family: "georgia" , "times new roman" , serif;"><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-size: inherit; font-weight: 700; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">Ext3</span> and <span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-size: inherit; font-weight: 700; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">Ext4</span> filesystem includes support of ACLs on files and directories. ACL provides more control permissions on file than standard three access categories (owner, group and other ). Using ACL you can provide permission to specific user or group to file.<br /></span></div>
<div style="background-color: white; border: 0px; font-size: 16px; line-height: 28px; margin-bottom: 20px; outline: 0px; padding: 0px; vertical-align: baseline;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8PIUgbEhY7YRkoZkY_ycfUsaC1iFBDlfTI2RPseUTTGJFwqo_RxDQOGRx-81DG42DgZeHzXtC9PcieWNIbyVz53baCPbuyUP0WPC7WZ7rrW5NlG23aHC8o474ZV_Qau4j-mRYNWvZyhBg/s1600/acls_map_ext_www.hackthesec.co.in.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="108" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8PIUgbEhY7YRkoZkY_ycfUsaC1iFBDlfTI2RPseUTTGJFwqo_RxDQOGRx-81DG42DgZeHzXtC9PcieWNIbyVz53baCPbuyUP0WPC7WZ7rrW5NlG23aHC8o474ZV_Qau4j-mRYNWvZyhBg/s320/acls_map_ext_www.hackthesec.co.in.png" width="320" /></a><span style="font-family: "georgia" , "times new roman" , serif;">Before working on <b>ACL </b>make sure that <b>ACL </b>is enabled on <b>mounted </b>file system. You can enable it during mounting filesystem with ACL option.</span></div>
<div style="background-color: white; border: 0px; font-size: 16px; line-height: 28px; margin-bottom: 20px; outline: 0px; padding: 0px; vertical-align: baseline;">
<span style="font-family: "georgia" , "times new roman" , serif;">Use following command Check if ACL is enabled on filesystem or not.</span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); line-height: 1.3em; margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="font-family: "courier new" , "courier" , monospace; font-size: large;"><span style="color: white;"># </span><span style="color: lime;">mount</span><span style="color: white;">

/dev/mapper/VolGroup00-LogVol00 on / type ext3 (</span><span style="color: lime;">rw,noatime,<span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-weight: 700; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">acl</span></span><span style="color: white;">)</span></span><span style="color: white; font-size: 0.9em;">
</span></pre>
<div style="background-color: white; border: 0px; font-size: 16px; line-height: 28px; margin-bottom: 20px; outline: 0px; padding: 0px; vertical-align: baseline;">
<span style="font-family: "georgia" , "times new roman" , serif;">Enable ACL by remounting file system using following command.</span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); line-height: 1.3em; margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: lime; font-family: "courier new" , "courier" , monospace; font-size: large;"># mount -o remount,acl  /
</span></pre>
<div style="background-color: white; border: 0px; font-size: 16px; line-height: 28px; margin-bottom: 20px; outline: 0px; padding: 0px; vertical-align: baseline;">
<span style="font-family: "georgia" , "times new roman" , serif;">To enable ACL default on system bootup update following entry in <span style="color: #990000;">/etc/fstab</span> file.</span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); line-height: 1.3em; margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="font-family: "courier new" , "courier" , monospace; font-size: large;"><span style="color: white;">/dev/VolGroup00/LogVol00    /    ext3  defaults,</span><span style="color: lime;"><orange>acl</orange>  </span><span style="color: white;">1 1
</span></span></pre>
<h4 class="heading1" style="background-color: white; border: 0px; font-family: 'Roboto Slab'; font-size: 24px; font-weight: bolder; line-height: 34px; margin: 45px 0px 12px; opacity: 1; outline: 0px; padding: 0px; transition: opacity 0.24s ease-in-out; vertical-align: baseline; visibility: visible;">
<span style="color: #0b5394;">Configure ACL on File</span></h4>
<div style="background-color: white; border: 0px; font-size: 16px; line-height: 28px; margin-bottom: 20px; outline: 0px; padding: 0px; vertical-align: baseline;">
<span style="font-family: "georgia" , "times new roman" , serif;">If we want that user Bob to have all permissions on a file. Use following command.</span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); line-height: 1.3em; margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="font-family: "courier new" , "courier" , monospace; font-size: large;"><span style="color: white;"># setfacl -m u:Bob:rwx </span><span style="color: lime;">hackthesec.txt</span><span style="color: white;">
</span></span></pre>
<div style="background-color: white; border: 0px; font-size: 16px; line-height: 28px; margin-bottom: 20px; outline: 0px; padding: 0px; vertical-align: baseline;">
<span style="font-family: "georgia" , "times new roman" , serif;">Details of parameters:</span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); line-height: 1.3em; margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="font-family: "courier new" , "courier" , monospace; font-size: large;"><span style="color: lime;">setfacel</span><span style="color: white;">:  is a command itself
 -m : is used to modify ACL.
  u : it denotes to assign permission to a user
bob : a system user
</span><span style="color: lime;">rwx : file permissions.
</span><span style="color: white;">hackthesec.txt: file on which bob will get access.</span></span><span style="color: white; font-size: 0.9em;">
</span></pre>
<h4 class="heading1" style="background-color: white; border: 0px; font-family: 'Roboto Slab'; font-size: 24px; font-weight: bolder; line-height: 34px; margin: 45px 0px 12px; opacity: 1; outline: 0px; padding: 0px; transition: opacity 0.24s ease-in-out; vertical-align: baseline; visibility: visible;">
<span style="color: #0b5394;">Check ACL on File</span></h4>
<div style="background-color: white; border: 0px; font-size: 16px; line-height: 28px; margin-bottom: 20px; outline: 0px; padding: 0px; vertical-align: baseline;">
<span style="font-family: "georgia" , "times new roman" , serif;">Use following command to check ACL configured on a file.</span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); line-height: 1.3em; margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="font-family: "courier new" , "courier" , monospace; font-size: large;"><span style="color: white;"># </span><span style="color: lime;">getfacl</span><span style="color: white;"> hackthesec.txt
</span></span></pre>
<div style="background-color: white; border: 0px; font-size: 16px; line-height: 28px; margin-bottom: 20px; outline: 0px; padding: 0px; vertical-align: baseline;">
<span style="font-family: "georgia" , "times new roman" , serif;">Output:</span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); line-height: 1.3em; margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="font-family: "courier new" , "courier" , monospace; font-size: large;"><span style="color: white;"># file: hackthesec.txt
# owner: root
# group: root
user::rw-
</span><span style="color: lime;"><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-weight: 700; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline;">user:Bob:rwx</span>
</span><span style="color: white;">group::r--
mask::rwx
other::r--</span></span><span style="color: white; font-size: 0.9em;">
</span></pre>
<h4 class="heading1" style="background-color: white; border: 0px; font-family: 'Roboto Slab'; font-size: 24px; font-weight: bolder; line-height: 34px; margin: 45px 0px 12px; opacity: 1; outline: 0px; padding: 0px; transition: opacity 0.24s ease-in-out; vertical-align: baseline; visibility: visible;">
<span style="color: #0b5394;">Remove ACL from File</span></h4>
<div style="background-color: white; border: 0px; font-size: 16px; line-height: 28px; margin-bottom: 20px; outline: 0px; padding: 0px; vertical-align: baseline;">
<span style="font-family: "georgia" , "times new roman" , serif;">If we don’t need the ACL in file, we can simply remove using following command.</span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); line-height: 1.3em; margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="font-family: "courier new" , "courier" , monospace; font-size: large;"><span style="color: white;"># </span><span style="color: lime;">setfacl -x u:Bob</span><span style="color: white;"> hackthesec.txt

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</div>
</div>

How to Configure ACL in Linux FileSystem

Configure ACL in Linux FileSystem Ext3 and Ext4 filesystem includes support of ACLs on files and directories. ACL provides more control permissions on file than standard three access categories (owne…

09 Feb 2016

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