User Admin
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- Words: 424
- Pages: 15
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User & Group Administration
Unix/Linux is multi user and multi tasking OS Redhat Linux uses User Private Group (UPG) Scheme :User always get created with primary group One Primary Group per User When a user is created in Linux :-home directory ( /home/username) mail account
(/var/spool/mail/username)
unique UID & GID
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2
Types of Users
TYPES TYPES OF OF USERS USERS
System System Users Users 00 499 499
Normal Normal Users Users 500 500 60,000 60,000
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3
User and Group Administration Database Files
/etc/passwd /etc/shadow /etc/group
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4
/etc/passwd - Database file of users
u1:x:500:500:prog:/home/u1:/bin/bash
User User
UID UID
Mask Mask Passwd Passwd
User User Comment Comment
GID GID
Shell Shell
Home Home Directory Directory
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5
/etc/shadow
This file contains the encrypted user passwords assigned by the password binary file Password s are encrypted through DES (Data Encryption Standard ) or MD5 (Message Digest Ver. 5) Algorithm
u1: hjkadfhs8974uyh5jrt/ :13536:0:99999:7:::
User UserName Name
Encrypted Encrypted Password Password
No. No.of ofdays days Since Since1970 1970
Max Maxno. no.of of days daysto tochange change password password
Min. Min.no. no.of of days daysto tochange change password password
Warning Warning 6 Days Days
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/etc/group
This file contains Group Name and GID of the groups
u1:x:500:sachin,tom
Group Group Name Name
GID GID
Mask Mask Members Members of of Passwd Passwd that that Group Group
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User Creation
Creating CreatingaaUser User [root@comp1 ~]#useradd [root@comp1 ~]#useradd <username> <username>
Options : -u
- UID
-g
- Primary group name/ GID
-o
- Override
-G
- Secondary group
-c
- Comment
-d
- Home directory
-s
- Shell 8
8
User Modification
Modifying Modifyingaa User User [root@comp1 ~]#usermod [root@comp1 ~]#usermod <username> <username>
Options : -l
- Change login name
-L
- Lock the account
-U
- Unlock the account
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User Deletion
Deleting DeletingaaUser User [root@comp1 ~]#userdel [root@comp1 ~]#userdel <username> <username>
Options : -r
- recursively
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10
Group Creation
Creating CreatingaaGroup Group [root@comp1 ~]#groupadd [root@comp1 ~]#groupadd
Options : -g
- GID
-o
- override
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11
Group Modification
Modifying ModifyingaaGroup Group [root@comp1 ~]#groupmod [root@comp1 ~]#groupmod
Options : -g
- GID
-o
- Override
-n
- To change the group name
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12
Group Deletion
Deleting DeletingaaGroup Group [root@comp1 ~]#groupdel [root@comp1 ~]#groupdel
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Changing user setting
Changing ChangingUser Usersetting setting [root@comp1 ~]#chage <username> [root@comp1 ~]#chage <username>
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Group setting
Group Groupsetting setting [root@comp1 ~]#gpasswd [root@comp1 ~]#gpasswd
Options : -a
- add a user
-d
- Delete a user from group
-M
- Creating multiple members
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1
User & Group Administration
Unix/Linux is multi user and multi tasking OS Redhat Linux uses User Private Group (UPG) Scheme :User always get created with primary group One Primary Group per User When a user is created in Linux :-home directory ( /home/username) mail account
(/var/spool/mail/username)
unique UID & GID
2
2
Types of Users
TYPES TYPES OF OF USERS USERS
System System Users Users 00 499 499
Normal Normal Users Users 500 500 60,000 60,000
3
3
User and Group Administration Database Files
/etc/passwd /etc/shadow /etc/group
4
4
/etc/passwd - Database file of users
u1:x:500:500:prog:/home/u1:/bin/bash
User User
UID UID
Mask Mask Passwd Passwd
User User Comment Comment
GID GID
Shell Shell
Home Home Directory Directory
5
5
/etc/shadow
This file contains the encrypted user passwords assigned by the password binary file Password s are encrypted through DES (Data Encryption Standard ) or MD5 (Message Digest Ver. 5) Algorithm
u1: hjkadfhs8974uyh5jrt/ :13536:0:99999:7:::
User UserName Name
Encrypted Encrypted Password Password
No. No.of ofdays days Since Since1970 1970
Max Maxno. no.of of days daysto tochange change password password
Min. Min.no. no.of of days daysto tochange change password password
Warning Warning 6 Days Days
6
/etc/group
This file contains Group Name and GID of the groups
u1:x:500:sachin,tom
Group Group Name Name
GID GID
Mask Mask Members Members of of Passwd Passwd that that Group Group
7
7
User Creation
Creating CreatingaaUser User [root@comp1 ~]#useradd [root@comp1 ~]#useradd
Options : -u
- UID
-g
- Primary group name/ GID
-o
- Override
-G
- Secondary group
-c
- Comment
-d
- Home directory
-s
- Shell 8
8
User Modification
Modifying Modifyingaa User User [root@comp1 ~]#usermod [root@comp1 ~]#usermod
Options : -l
- Change login name
-L
- Lock the account
-U
- Unlock the account
9
9
User Deletion
Deleting DeletingaaUser User [root@comp1 ~]#userdel [root@comp1 ~]#userdel
Options : -r
- recursively
10
10
Group Creation
Creating CreatingaaGroup Group [root@comp1 ~]#groupadd [root@comp1 ~]#groupadd
Options : -g
- GID
-o
- override
11
11
Group Modification
Modifying ModifyingaaGroup Group [root@comp1 ~]#groupmod [root@comp1 ~]#groupmod
Options : -g
- GID
-o
- Override
-n
- To change the group name
12
12
Group Deletion
Deleting DeletingaaGroup Group [root@comp1 ~]#groupdel [root@comp1 ~]#groupdel
13
13
Changing user setting
Changing ChangingUser Usersetting setting [root@comp1 ~]#chage <username> [root@comp1 ~]#chage <username>
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14
Group setting
Group Groupsetting setting [root@comp1 ~]#gpasswd [root@comp1 ~]#gpasswd
Options : -a
- add a user
-d
- Delete a user from group
-M
- Creating multiple members
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