April 17, 2016 user name file,

2.6 User Name File

Types of Linux users: Super user, Normal user, virtual user
User name is for people to see, the system only identifies the UID and GID
Virtual User:
Distinguished from real ordinary users, the biggest feature of this type of user is that the system is installed by default and most of the users cannot log on to the system by default.
Puppet:
Security Optimizations: You can delete a user to a virtual user after you install the system. When we create users ourselves, we can create virtual users in order to meet the needs of the service!
Virtual users typically take
Sbin/nologin
Uid
User Roles

0
Super User

1-499
Virtual user
To serve the needs of the role like Mysql,apache
500-65535
Normal User
General Account UID
Configuration file/etc/passwd/etc/shadow/etc/group/etc/gshadow

Types of Linux users: Super user, Normal user, virtual user
User name is for people to see, the system only identifies the UID and GID
Virtual User:
Distinguished from real ordinary users, the biggest feature of this type of user is that the system is installed by default and most of the users cannot log on to the system by default.
Puppet:
Security Optimizations: You can delete a user to a virtual user after you install the system. When we create users ourselves, we can create virtual users in order to meet the needs of the service!

Uid
User Roles

0
Super User

1-499
Virtual user
To serve the needs of the role like Mysql,apache
500-65535
Normal User
General Account UID

Root:x:0:0:root:/root:/bin/bash

1. Username 2. Password 3.uid 4. Group ID 5. Description property Related 6. Home directory 7.shell

2.7 Password file

In the hash value column, $id $salt$encrypted
The digital IDs between the two "$" symbols represent different cryptographic algorithms, and the algorithms used vary from one system to another. The string after the second "$" symbol is the salt value, which needs to be used when encrypting. The string after the 3rd "$" is the ciphertext after encryption (part)

3, the digital ID and the encryption algorithm used to correspond to the relationship:
1:MD5, (22-bit)
2a:blowfish, encryption methods that are used only in a subset of the Linux branches
5:SHA-256 (43-bit)
6:SHA-512 (86-bit)

Root: $6$safheku:21344:0:99999:7:::

1. User Name 2. password File 3. Indicates the date of the password modification and how much time has passed since 1970 4. How many days to change the password 0 does not mean that you do not set 5. How many days to change the password 6. How many days will you be prompted 7. Password lock file after expiration 8. Account life cycle 9. No meaning to keep

2.8 Creating and deleting user groups

Groupadd APS create groups.

Tail/etc/gshadow See password

Groupdel Delete a group if there are users in the group cannot delete

Group-g The AP creation is the user group sequence number directly starting from 512

April 17, 2016 user name file,