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11. Users, groups, and permissions (1)

2022-07-01 18:55:00 【51CTO】

1、Linux Security model

3A（authentication、authorization、accouting aduition）： authentication 、 to grant authorization 、 Audit

user

Linux Each user in is through User ID（UID） To represent only

Administrators root: uid by 0

Ordinary users ：1-60000 Automatically assigned

System users ：1-499（centos6） 1-999（centos7） It is used for the daemon to obtain resources and allocate permissions

The logged in user ：500+（centos6） 1000+（centos7） Interactive login for ordinary users

User group

Linux You can add one or more users to a user group , User groups also have GID （group id）

Administrators group root：0

The normal group ：

System group ：1-499（centos6） 1-999（centos7） It is used for the daemon to obtain resources and allocate permissions

The normal group ：500+（centos6） 1000+（centos7） For users

The relationship between users and groups

The primary group of users ： Users must belong to one and only one main group , By default, when creating a user, a group with the same name as the user name will be automatically created , As the primary group of users , Because there is only one user in this group , Also a private group ;

Additional group ： A user can belong to more than one additional group ;

11、 user 、 Groups and permissions （1）_linux

Security context

Linux Security context context： Running program , Process , Run as the process initiator , The permission of a process to read resources depends on the identity of the process operator ;

2、 User and group profiles

User profile

/etc/passwd ( User information , primary unix System user passwords are stored here ） /etc/shadow（ Store user password related information ）

/etc/passwd File format

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/etc/shadow File format

11、 user 、 Groups and permissions （1）_linux_04

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encryption algorithm ： It is generally used sha512, Algorithm of changing password ：authconfig --passalgo=sha256 --update

Random password generation ：

11、 user 、 Groups and permissions （1）_ Users and groups _06

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group File format

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The name of the group Group password group id The current group has been added to the list of users

gshadow File format

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The name of the group Group password Group administrator list List of users with the current group as an additional group ： Multiple users are separated by commas ;