User and rights management

Users:

Concept:

User: is a resource use isolation mechanism that identifies each user, and the user is the user

ID: a special ID that identifies an individual in a computer, providing a unique usage ID for each user, and this unique usage ID is the user's id

Authentication: the process of determining through a scheme that a user associates it with a user identity in the system through some identification technology.

Password: it is a means of authentication. User name corresponds to one user.

Authorization: the ability to operate resources, the level of use of resources

Audit: supervise the use of authority

Group: user group: a container for users to facilitate permission assignment

User category:

Ordinary users: divided into system users and login users

The user ID (UID) library address is located in the system: / etc/passwd

The group ID address is located at: / etc/group

Password library address: / etc/shadow

Group password Library: / etc/gshadow

Rights Management:

Rights management: permissions restrict users' operations on files

Rwxrwxrwx: three digits from the left: defines the permissions of users, defines the permissions of user groups, and defines the permissions of other users.

Permissions: r:read, read w:write, write x:excute, execute

File: r: data of the file can be obtained w: data of the file can be modified x: this file can be run as a process

Table of contents:

R: you can use the ls command to get a list of all the files under it

W: you can modify the list of files in this directory: that is, create or delete files

X: you can cd to this directory, and you can use ls-l to get detailed attribute information for all files

Permission combination mechanism: it can be expressed in octal: rDNA 4 wt 2 x x 1 plus conversion

Example: rw-rw-r-664 rwxrwxr-x 775

Rights management commands:

There are three types of users: U-owner g-group o-other a-all

Chmod command:

Format: three:

(1) chmod directly operates the ownership limit rwx of a class of users

Example: # chmod g=rw fstab belongs to the group with read and write

# chmod uprirwx GRW fstab o = the owner has read and write execution, the group has read and write, and the others do not have any permissions

# chmod ug=r fstab owners and groups have read permissions

# chmod uprirwxdir _ RWX _

# chmod go= fstab belongs to groups and others do not have any permissions

"A permission used for direct operation of a class, rperior wpje x. To express the use of upright recording, galling, recording, writing, etc.

Example: # chmod Umurx fstab owner removes the execution permission

# chmod otakr fstab other plus read permissions

# chmod ug+x fstab owners and groups all add execution permissions

# chmod g-wx fstab belongs to the group without write and execute permissions

# chmod + x fstab all have execute permission

# chmod + w fstab Note: global writes are only valid for owners

The simultaneous operation of multiple types of permissions can be separated by commas:

Example: # chmod utilise Grunw fstab

(2) Octal representation:

Example: # chmod 660fstab

(3)

Example: # chmod-reference=/var/log/mes fstab

Fstab and mes permissions are the same

Option:-R: recursive modification (file permissions in the directory are also modified, use with caution)

Dependency management commands: chown, chgrp

Chown command:

Option:-R recursive modification

Example: # chown-R doker skel/ skel directory internal file ownership is changed to doker group:

Example: # chownn-R archlinux:mygrp skel/ (colons can also be replaced by dots)

Refer to one and change the other:

Example: # chown-R-reference=/tmp/moosefs/ / tmp/skel/

Chgrp: can only be used to reorganize

Note: the user has write permission to the directory and no write permission to the file in the directory. You can delete this file.