How to configure permission management on Linux
In the Linux operating system, permission management is a very important component. By configuring permissions correctly, we can protect our files and systems from unauthorized access and ensure that users can only access the resources for which they are authorized. This article will introduce how to configure permission management on Linux to protect the security of files and systems.
Before configuring permission management, we need to first understand the concepts of users and user groups in Linux. A user is a specific individual in the system, while a user group is a group of related users. Each user belongs to a primary user group and can also belong to multiple additional user groups.
In order to manage users and user groups, we can use the following command:
useradd
: Create a userpasswd
: Set the user's passwordgroupadd
: Create a user groupusermod
: Modify the user's attributesuserdel
: Delete a usergroupmod
: Modify the attributes of the user groupgroupdel
: Delete a user groupuseradd -G groupname username
: Add a user to a user groupFor example, the following code demonstrates how to create a new userjohn
And set the password:
$ sudo useradd john $ sudo passwd john
In Linux, each file and directory has three different permissions: read, write and implement. These permissions can be set for the file's owner, group, and other users. Each permission is represented by a letter:
r
: Read permissionw
: Write permissionx
: Executable permissionsWe can use thels -l
command to view the permissions of files and directories:
$ ls -l -rw-rw-r-- 1 john john 0 Aug 1 15:30 myfile.txt drwxrwxr-x 2 john john 4096 Aug 1 15:30 mydir
In the above example, the permissions of themyfile.txt
file are-rw-rw-r--
, which means that the file owner and group have read and write permissions, and other users Can only be read.mydir
The permissions of the directory aredrwxrwxr-x
, which means that the directory owner and the group to which it belongs have read, write and execute permissions, and other users only have read and execute permissions.
We can use the following commands to set the permissions of files and directories:
chmod
: Change the permissions of files and directorieschown
: Change the owner of files and directorieschgrp
: Change the group to which files and directories belongFor example, the following code demonstrates How to setmyfile.txt
file permissions so that only the owner can write to:
$ chmod 600 myfile.txt
besides the basics In addition to file and directory permissions, Linux also provides some other permission settings. The more important ones are SUID, SGID and Sticky Bit.
passwd
command to enable normal users to change their own passwords./usr/bin/mail
so that ordinary users can send emails to a certain user.We can use the following command to set SUID, SGID and Sticky Bit permissions:
chmod u s
: Set SUID permissionschmod g s
: Set SGID permissionschmod t
: Set Sticky Bit permissionsFor example, the following code demonstrates how to/usr/bin/mail
The command is set to have SGID permissions:
$ sudo chmod g+s /usr/bin/mail
By correctly configuring permission management, we can effectively protect the security of our files and systems. By properly assigning users and user groups, setting correct file and directory permissions, and using SUID, SGID, and Sticky Bit permissions, we can limit user access to sensitive files and system resources and prevent unauthorized modification and deletion.
Summary
In this article, we introduced how to configure permission management on Linux. We learned the management of users and user groups, the setting of file and directory permissions, and the use of SUID, SGID and Sticky Bit permissions. By configuring permissions correctly, we can protect our files and systems from unauthorized access. I hope this article will help you configure permission management on Linux.
The above is the detailed content of How to configure permission management on Linux. For more information, please follow other related articles on the PHP Chinese website!