Linux Learning Notes-A detailed description of users and permissions

Detailed user and authority  

Users, Groups, permissions

Security context (secure contexts);

Permissions:

R W X

File:

R: Readable, you can use similar commands such as cat to view the contents of the file;

W: writable, can edit or delete this file;

X: Executable, exacutable, can be at the command prompt as a command to submit to the kernel to run;

Directory:

R: You can perform LS on this directory to list all internal files;

W: Files can be created in this directory;

X: You can switch to this directory using a CD, or you can use Ls-l to view the details of the internal files;

Rwx

r--: Read-only

R-x: Read and Execute

---: No permissions

0---: No permissions

1 001--x: Execution

2 010-w-: Write

3 011-wx: Write and Execute

4r--: Read-only

5 101r-x: Read and Execute

6rw-: Read and Write

7 111rwx: Read and write execution

User: UID,/etc/passwd

Group: Gid,/etc/group

Shadow Password:

Users:/etc/shadow

Group:/etc/gshadow

User Category:

admin: (UID) 0

Normal User: (UID) 1-65535

System User: (UID) 1-499

General User: (UID) 500-60000

User groups:

Administrators group:

Normal Group:

System Group:

General Group:

User Group Category:

Private group: When a user is created, a group that has the same name as the user is automatically created if the group to which it belongs is not specified

Basic group: Default group for users

Additional groups, additional groups: groups other than the default group

Process

Parsing: Name resolution,

/etc/passwd

Account: Login Name

Password: password

Uid:

GID: Basic Group ID

Comment: Notes

Home dir: Home directory

Shell: User's default shell

/etc/shadow

Account: Login Name

Encrypted Password: encrypted password

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 applied to data integrity checks

Characteristics: 1, avalanche effect

2, fixed-length output

Md5:message Digest, 128-bit fixed-length output

Sha1:secure Hash algorithm,160 bit fixed length output

Useradd USERNAME:

Groupadd GRPNAME:

User management:

Useradd,userdel,usermod,passwd,chsh,chfn,finger,id,chage

Group Management:

groupadd,groupdel,groupmod,gpasswd

Rights Management:

Chown,chgrp,chmod,umask

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Linux Learning Notes-A detailed description of users and permissions