Linux usermod, user password management and password random generation tool mkpasswd

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One, Usermod command 1. Usermod changing a user's properties

Usermod-u 111 User1 Change the UID of user User1 to 111

Usermod-g grp2 user2 Change user2 Group to User2

usermod-d/home/test User3 Change User3 's home directory to/home/test/

Usermod-s/sbin/nologin user2 Change user2 login Shell is not able to log in

2. ID User1

View information such as user Uid,gid, expansion group, etc.

A user can belong to more than one group, with an extension group:

Usermod-g Grp2 user1 Add User1 expansion group to GRP2

[[Email Protected]_46_188_centos ~]# usermod-g grp1,fxq user2[[email protected]_46_188_centos ~]# ID user2uid=1015 ( User2) gid=1017 (user2) groups=1017 (user2), + (FXQ), 1016 (GRP1) [[Email Protected]_46_188_centos ~]#

Second, the user password management 1. change user password:

passwd Root Change root password

passwd fxq change fxq user password

View password file Real storage file/etc/shadow

[[EMAIL PROTECTED]_46_188_CENTOS ~]# CAT /ETC/SHADOWROOT:$1$QOTJNBBE$O3XVX5L0KNPVMXMIVSFNF .:: 0:99999:7:::bin:*:16659:0:99999:7:::d aemon:*:16659:0:99999:7:::adm:*:16659:0:99999:7:::lp:*:16659:0:99999:7 ::: Sync:*:16659:0:99999:7:::shutdown:*:16659:0:99999:7:::halt:*:16659:0:99999:7:::mail:*:16659:0:99999:7:::o Perator:*:16659:0:99999:7:::games:*:16659:0:99999:7:::ftp:*:16659:0:99999:7:::nobody:*:16659:0:99999:7::: avahi-autoipd:!! : 16912::::::systemd-bus-proxy:!! : 16912::::::systemd-network:!! : 16912,:::::d bus:!! : 16912,:::::p olkitd:!! : 16912::::::abrt:!! : 16912::::::libstoragemgmt:!! : 16912::::::tss:!! : 16912::::::ntp:!! : 16912,:::::p ostfix:!! : 16912::::::chrony:!! : 16912::::::sshd:!! : 16912::::::tcpdump:!! : 16912::::::apache:!! : 17296::::::mysql:!! : 17319::::::fxq:$1$ymvfhplx$ixmvlg4chjsxr6ffxtugs1:17322:0:99999:7:::nginx:!! : 17323::::::saslauth:!! : 17344::::::mailnull:!! : 17344::::::smmsp:!! : 17344::::::test:$1$lv1g6wil$gprgn2db1dftlihgc9fbw.:17365:0:99999:7:::zabbix:!! : 17373:0:99999:7::: fxq1:$1$b5o76dkm$sougjjiu7px5avbewrz/o/:17386:0:99999:7:::user2:!! : 17391:0:99999:7:::user3:!! : 17391:0:99999:7:::[[email protected]_46_188_centos ~]#

2. Lock user and Unlock user

At the password! * They are not allowed to log in.

Passwd-l user2 put the user password before adding!!

passwd-u user2 Unlock user password

Usermod-l User2 can also lock the user User2

Usermod-u user2 Unlocking User User2

3. A command in the script changes the password of the user user2:

passwd--stdin user2 change user password

[[Email Protected]_46_188_centos ~]# passwd--stdin user2changing password for user User2.123456passwd:all Authenticatio N Tokens updated successfully. [[Email Protected]_46_188_centos ~]#

• echo "qing123." | passwd--stdin User2

[Email Protected]_46_188_centos ~]# echo "qing123." | passwd--stdin user2changing password for user User2.passwd:all authentication tokens updated successfully. [[Email Protected]_46_188_centos ~]#

Echo-e "123\naaa" implements \ n line-break usage

• Echo-e "qing123.\nqing123." | PASWD User2

[Email protected]_46_188_centos ~]# echo-e "qing123.\nqing123." | passwd user2changing password for user user2. New Password:retype New Password:passwd:all authentication tokens updated successfully. [[Email Protected]_46_188_centos ~]#

4. Password Security settings:

• Greater than 10 bits

• Contains numbers, uppercase and lowercase letters, special symbols

• cannot be set with regularity

• Cannot contain information such as name, birthday, etc.

Iii. mkpasswd Order

MKPASSWD Generate Anytime Password tool: (Make passwd)

If you do not have the MKPASSWD command, install the expect package

Yum Install expect

Options:

-l length number of digits

-s special sign bit number

[Email protected]_46_188_centos ~]# mkpasswd [email protected][[email protected]_46_188_centos ~]# mkpasswd-l 12yme0qzt#3xfe[[email protected]_46_188_centos ~]# mkpasswd-l 12-s 3g\fn%ha2nw7*[[email protected]_46_188_centos ~]# Mkpasswd-l 12-s 08oakipqcnfw3[[email Protected]_46_188_centos ~]#

Mkpasswd-l 12-s 0 Length 12 bits without special symbols

This article is from the "Feng Xiaoqing blog" blog, make sure to keep this source http://fengyunshan911.blog.51cto.com/995251/1956572

Linux usermod, user password management and password random generation tool mkpasswd