Linux User Management

Linux User Management

User: UID,/etc/passwd

User group: GID,/etc/group

Shadow Password:

User password:/etc/shadow

User group Password:/etc/gshadow

User Category:

Admin: 0

Normal Users: 1-66535

System users: 1-499

General Users: 500-6000

User Group Category:

Private group: When you create a user, if you have a group that you specify, the system automatically creates a group with the same name as the user

Basic Group

Additional groups

Encryption method:

Symmetric encryption: Encrypt and decrypt using the same password

Public Key cryptography: each password appears in pairs, one for the private key (secret key) and one for the public key

One-way encryption/hash encryption: Extracting data signatures, often used for data integrity checks

1. Avalanche effect

2, fixed-length output

Md5:message digest,128 fixed-length output

Sha1:secure Hash algorithm,160 bit fixed length output

To create a user:

Useradd username

To create a user group:

Groupadd GroupName

This article is from the "Forget the Past" blog, please be sure to keep this source http://xujingbo.blog.51cto.com/4633099/1825891

Linux User Management