Linux system Administrator Technology (Admin)-------Fifth day

Operation on the real machine, restoring the environment

[[Email protected] Desktop]# rht-vmctl Reset Classroom

[[Email protected] Desktop]# rht-vmctl Reset Server

[[Email protected] Desktop]# rht-vmctl Reset Desktop

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Configure the following static address parameters for the virtual machine server

– Host Name: server0.example.com

– IP Address: 172.25.0.11

– Subnet Mask: 255.255.255.0

– Default gateway: 172.25.0.254

–dns Server: 172.25.254.254

# Cat/etc/sysconfig/network-scripts/ifcfg-eth0

# cat/etc/resolv.conf

Test DNS resolution

[email protected] ~]# nslookup server0.example.com?

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? Cron Scheduled Tasks

System Services: Crond

Log file:/var/log/crond

? Using the crontab command

– Edit: Crontab-e [-u user Name]

– View: crontab-l [u user name]

– Clear: Crontab-r [-u user Name]

1. View service Status

[Email protected] ~]# systemctl status Crond

2. Writing a planning task?

? ?* ? ?* ? ?* ? ?* ? ?*

The day of the month?

[[Email protected] ~] #useradd Hanjie

[[Email protected] ~] #ls/Home

[[Email protected] ~] #su-hanjie?

[email protected] ~]#$ Touch a.txt

[[Email protected] ~] #crontab-e-U Hanjie

*/1 * * * */usr/bin/date?>>/home/hanjie/abc.txt

[[Email protected] ~] #watch-N 1 cat/home/natasha/abc.txt

[Email protected] ~]# Useradd Natasha

[email protected] ~]# which ifconfig?? #查询命令所对应的程序在那里

[email protected] ~]# which date

[Email protected] ~]# crontab-e-u Natasha

[Email protected] ~]# crontab-l-u Natasha

*/1 * * * */usr/bin/date?>>/home/natasha/abc.txt

[Email protected] ~]# Watch-n 1 cat/home/natasha/abc.txt

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Categories of basic permissions

? Access Mode (permissions)

– read: Allow viewing of content-read?? r

– Write: Allow content to be modified-write?? W

– Executable: Allow to run and switch-execute? x

? For text files:

? ? ? ? ? ? R:cat Head Tail Less

? ? ? ? ? ? W:? vim

? ? ? ? ? ? x:? run

? Permissions applicable object (attribution)

– Owner: The user who owns this file/directory-user?? U

– Owning group: The group that owns this file/directory-group??? G

– Other users:-other for users other than the owner, the owning group? o

Permission bit hard connection number belongs to main group size last modified time File/directory name

[Email protected] ~]# ls-l/etc/passwd

[Email protected] ~]# ls-ld/etc/

[Email protected] ~]# Ls-ld/root

[Email protected] ~]# ls-ld/home/student

[[email protected] ~]# ls-ld/tmp----is a special basic privilege

? Start with "-": File

? Start with "L": Shortcut

? Start with "D": Directory

? Using the chmod command

–chmod [-R] Attribution relationship +-= permission category document ...

? ? ? ? [-R] Recursion gives permission

[Email protected] ~]# mkdir/nsd010

[Email protected] ~]# LS-LD/NSD01

[Email protected] ~]# chmod u-x/nsd01

[Email protected] ~]# LS-LD/NSD01

[Email protected] ~]# chmod g+w/nsd01

[Email protected] ~]# LS-LD/NSD01

[Email protected] ~]# chmod o=rwx/nsd01

[Email protected] ~]# LS-LD/NSD01

[Email protected] ~]# chmod u=rwx,g=rx,o=r/nsd01

[Email protected] ~]# LS-LD/NSD01

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? How to tell if a user has permissions

??? 1. Determine the user's identity???? Owner > Owning group > Other people? Match and stop??

??? 2. See Permissions Division for corresponding permission bits

? ?

The r permission of the directory: Ability to view this directory content ls

The W permission of the directory: ability to perform rm/mv/cp/mkdir/touch/... Actions to change directory contents

? directory x permissions: Ability to switch to this directory on CD

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Create a new/nsddir/directory with the root user, create a new Readme.txt file in this directory, and further complete the following operations

1) Enable user Zhangsan to create subdirectories in this directory? Switch users? Su-zhangsan

? ? chmod o+w?/nsddir/

[Email protected] ~]# Mkdir/nsddir

[Email protected] ~]# Touch/nsddir/readme.txt

[Email protected] ~]# Useradd Zhangsan

[Email protected] ~]# Su-zhangsan

[[Email protected] ~]$ exit

[Email protected] ~]# chmod o+w/nsddir/

[Email protected] ~]# Su-zhangsan

[Email protected] ~]$ MKDIR/NSDDIR/ABC

[Email protected] ~]$ ls/nsddir/

2) make the user Zhangsan not be able to create subdirectories under this directory

? ? chmod o-w?/nsddir/

3) Enable user Zhangsan to modify Readme.txt file

? ? chmod o+w?/nsddir/readme.txt

4) Adjust permissions on this directory so that all users cannot access this directory

?? chmod u-x,g-x,o-x?/nsddir/

5) Set permissions for this directory and all documents under it rwxr-x---

?? chmod-r? u=rwx,g=rx,o=---?/nsddir/

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Set document Attribution

? Using the Chown command

–chown [-R] belongs to main document ...

–chown [-R]: belongs to group document ...

–chown [-R] Owner: a group of documents ...

[Email protected] ~]# MKDIR/NSD05

[Email protected] ~]# LS-LD/NSD05

[Email protected] ~]# Groupadd tedu

[Email protected] ~]# chown dc:tedu/nsd05

[Email protected] ~]# LS-LD/NSD05

[Email protected] ~]# chown student/nsd05

[Email protected] ~]# LS-LD/NSD05

[Email protected] ~]# chown:root/nsd05/

[Email protected] ~]# ls-ld/nsd05/

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? Special permissions (Additional permissions)

Set UID

? Attached to the X-position of the owner

– The owner's permission identifier becomes S

– For executable files, Set UID allows the user to have the file

Master identity and Partial permissions (pass-through owner identity)

Set GID

? Attached to the X-position of the genus Group

– the permission identifier of the group becomes S

– for executables, similar to set UID (pass as group identity)

– For directories, set GID allows new documents to be automatically set in the directory

The same group as the parent directory

??

[Email protected] ~]# Mkdir/tarena

[Email protected] ~]# Ls-ld/tarena

[Email protected] ~]# Chown:tedu/tarena

[Email protected] ~]# Ls-ld/tarena

[Email protected] ~]# MKDIR/TARENA/NSD01

[Email protected] ~]# LS-LD/TARENA/NSD01

[Email protected] ~]# chmod g+s?/tarena/

[Email protected] ~]# ls-ld?/tarena/

[Email protected] ~]# mkdir? /tarena/nsd02

[Email protected] ~]# ls-ld?/tarena/nsd02

[email protected] ~]# touch?/tarena/nsd02/abc.txt

[Email protected] ~]# ls-l?/tarena/nsd02/abc.txt

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Sticky Bit

? Attached to another person's X-position

– The other person's permission ID will change to T

– A directory for open W permissions that can prevent users from abusing W writes

Permissions (Prohibit manipulating others ' documents)

[Email protected] ~]# Mkdir/public

[Email protected] ~]# chmod u=rwx,g=rwx,o=rwx/public

[Email protected] ~]# Ls-ld/public

[Email protected] ~]# chmod o+t/public

[Email protected] ~]# Ls-ld/public

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The role of ACL policies

? Limitations of document Attribution

– No one belongs to three roles: owner, group, other person

– Unable to achieve finer control

? ACL Access Policy

– Ability to set independent permissions on individual users, individual groups

– Most mounted EXT3/4, XFS file systems are supported by default

[Email protected] ~]# mkdir/test

[Email protected] ~]# ls-ld/test

[Email protected] ~]# chmod o=---/test

[Email protected] ~]# ls-ld/test

[Email protected] ~]# Su-zhangsan

[Email protected] ~]$ cd/test/

-BASH:CD:/test/: Permission denied

[[Email protected] ~]$ exit

Logout

[Email protected] ~]# setfacl-m u:zhangsan:rx/test/

[Email protected] ~]# getfacl/test/

[Email protected] ~]# Su-zhangsan

[Email protected] ~]$ cd/test/

[Email protected] test]$ pwd

[[Email protected] test]$ exit

? Using the Getfacl, Setfacl command

–getfacl documentation ...

–setfacl?-M u: User name: Permission category Document ...

–setfacl?-M G: Group name: Permissions Category Document ...

–setfacl?-X u: User name?? Document...? ? ? ? #删除指定的ACL策略??

–setfacl?-B documentation ...? ? ? ? ? ? ? ? ? ? ? ? ? ? #清空ACL策略?????

[Email protected] ~]# getfacl/test/

[Email protected] ~]# setfacl-m u:dc:rwx/test/

[Email protected] ~]# setfacl-m u:natasha:rx/test/

[Email protected] ~]# getfacl/test/

[Email protected] ~]# setfacl-x u:dc/test/? #删除指定的ACL

[Email protected] ~]# getfacl/test/

[Email protected] ~]# setfacl-b/test/?? #清空所有的ACL

[Email protected] ~]# getfacl/test/

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[Email protected] ~]# MKDIR/NSD20

[Email protected] ~]# chmod U=RWX,G=RWX,O=RWX/NSD20

[Email protected] ~]# LS-LD/NSD20

Drwxrwxrwx. 2 root root 6 October 15:49/nsd20

[Email protected] ~]# setfacl-m U:natasha:---/nsd20

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Using LDAP authentication

"????" Traditional username password: locally created for local login?/etc/passwd

???? network users: Created on the LDAP server, you can log on to each machine in the domain

? LDAP server: Classroom

? ? Client: Specify the server-side LDAP location

? ??

? 1. Installing the Client Software

? ? ? Package

? ? ? ? ? SSSD: Communication software with the server

? ? ? ? ? AUTHCONFIG-GTK: Graphics Configuration SSSD Tool

[Email protected] ~]# rpm-q sssd????? #验证软件包安装成功

[Email protected] ~]# rpm-q AUTHCONFIG-GTK

? 2. Run the Graphics Configuration SSSD tool: AUTHCONFIG-GTK

[Email protected] ~]# AUTHCONFIG-GTK

? User account Database: LDAP

? LDAP Search Base dn:dc=example,dc=com

? LDAP server: classroom.example.com

Check: Connect with TLS encryption

? ? ? ? Specify Certificate encryption:

?????? http://172.25.254.254/pub/example-ca.crt

?? Authentication method: LDAP password

3. Start the SSSD service and set it to boot from

[Email protected] ~]# systemctl restart SSSD

[Email protected] ~]# Systemctl enable SSSD

4. Verification

[[email protected] ~]# grep ' Ldapuser0 '/etc/passwd

[[email protected] ~]# ID LDAPUSER0

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Home directory Roaming

? Network File system

– The specified folder is shared to the client by the NFS server

– The client will mount this shared directory to a local directory to access this share

Resources are as convenient as accessing a local directory

– Similar to EXT4, XFS and other types, except that resources are online

? View NFS Resources

[Email protected] ~]# showmount-e 172.25.254.254

? Mount to mount NFS shared content on the server to a local directory

[Email protected] ~]# mkdir/home/guests

# Mount 172.25.254.254:/home/guests/??/home/guests

[Email protected] ~]# ls/home/guests

[Email protected] ~]# Su-ldapuser0

Linux system Administrator Technology (Admin)-------Fifth day