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ON eee (ola eal dl Aire
OS Lab Presentation
Hossein Joukar 9031006 - Ehsan Edalat 9031066
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ا ا
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ا ادك
> It is necessary for regular users to run a command as if
they were root.
deh Uhl وروت رها
>» This command changes the UID and GID of the existing
6۲
>» The syntax for the su command is this:
su option username arguments
su -c 'Is /home/bob' - bob
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Pr een ante
> To return to the regular users’ identity
Lams
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a OLAS ادك
> It gives to the certain users only a few superuser
permissions.
> The list of authorized users is kept in /etc/sudoers
> Sudo will prompt for a password and then check the
/etc/sudoers.
> Sample:
< 500 66و10 1
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GO OG GOOO
> SU is a command that root user with his own password
can perform all commands but SUDO is a command
that regular user with his own password can perform
especial commands that mention in /usr/sbin/visudo.
> Users can add or remove from /usr/sbin/visudo in
format that mention below:
Ok emo (ne mee a)
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(Groups
> /etc/group
> The custom is to use GIDs of 500 or more for regular
users and less for administrations or special program.
> Groupname:password:gid:users
root:x:0:root
bin:x:1:root,bin,daemon
> Special group
تا تا ها
te iene ۱
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Phe Password Pile
> /etc/passwd
> It is the database file for all users on the system.
۱ a a
> * in password means disable.
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حل« سوحه ”) سدلككحا)
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> /etc/shadow
> It is considered to use the encrypted passwords found
in /etc/passwd.
> Only x or * appears in the passwprd field of
/etc/passwd..
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حل« سوحه ”) سدلككحا)
> Advantages of shadow over the traditional mode
» Shadow passwords improve system security by moving
encrypted password hashes from the world-readable
/etc/passwd file to /etc/shadow, which is readable only by
۱
» Shadow passwords store information about password
aging.
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CNN Des aNd 5
> The user’s login name
> The encrypted password
> The number of days since jan 1970
> The number of days before the the password can
be changed
> The number of days before the password is to
expire that the user is warned it will expire.
> The number of days after the password expires
the account is disabled.
> The number of days since jan 1 1970 that
account has been disabled.
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4 Viexercd Directory 5
> When each user is created, a home directory is
created for him (/nome/<username>).
> The set of files that initially are used to populated this
home directory are kept in /etc/skel.
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۱۱ مر Meal 1
> The User Accounts configuration tool allows you to
view, modify, add, and sae local users. To run the
the User Accounts مع
> By default, the tool only allows you to change certain
settings regarding yo count. This is because only
the root user is allowed to configure users and groups.
To unlock the configuration یا و۱ 05
1۱ رز are
corner of the window, and provide the correct
password when prompted.
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Osicry 00 eae cae Be
AL Settings
Jaromir Hradilek
Standard
English
Login Options
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فم
Create new account
Account Ty Standard
Fullname | Eva Kopalova
Username | ekopatova
Cancel
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فم
De you want to keep Eva Kepalova's files?
Itis possible to keep the home directory, mail spool and temporary files around
when deleting @ user account.
| Keep Files Cancel,
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you to view,
ind groups in the
application, either
Groups from
-config-users at a
lave superuser
عونا ع1 <-
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Osicry the Oser (ON ene ci ae
> Fedora reserves user and group IDs below 1000 for
system users and groups. By default, the User
Manager does not display the system users. To view all
users and groups, select Edit > Preferences to open
the Preferences dialog box, and clear the Hide system
users and groups check box.
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Apply fitter
Home Directory
مهدجه
قناماة م اء لع وم
Refresh
Full Name Login Shell
Jaromir Hradilek /bin/bash
Ibirvbash
Fle Edit Help
B® ©
Add User AddGroup Propert
Users | Graups
User Name User ID ¥ | Primary Group
1000
1001
jnradiek عافد
ekopalove ekopalova
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فم
Conti Password: [>= ۱
Logi Sha دا سم
1 Create home drectory
Home Directory: |snome/ekopatova
© Create a private group for the
Specify user 1D manually
1 Specity group 1D manually
۳
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CON NNO Ua Dic
> To specify a user ID for the user, select Specify user ID
manually. If the option is not selected, the next
available user ID above 1000 is assigned to the new
user. Because Fedora reserves user IDs below 1000 for
system users, it is not advisable to manually assign
۱۱۳ روت
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CONN NNR OD UPA (eae od
Group Name: | publishers
“) Specify group ID manually:
Cancel
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Properties
عه
Full Name دجم
Password: 0 "۱
Confirm Password, |***** ۱
6 9 ست:
Login Shell: {fbinibash -[
Cancet_||
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Group Data ۱ Group Users
Select the users to join this group:
cancel || 0K
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Oser ۱۹۱2۹ ac ri ea OA ARN ed
> useradd [option] user name
تس هه
< اعلرعدن
م
ع5 ها iCele
كا 2
> groupadd [option] group_name
تال سس هه
> groupdel
< منامعو ة عنعاءم
۲ ۵
انا 0
8 کیره
Pern ل ل uy
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4
> useradd [option] user name
>» Options:
"أمعمصممم' ع- ء
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> -d home_directory
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disabled. If 0 is specified, the account is disabled immediately
after the password expires. If -1 is specified, the account is not
معاطهدال ع5 ucm re eee Ken ice
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4
> Options:
> -g group_name
> Group name or group number for the user's default group.
> -G group _list
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>» Options:
> -p password
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۱۹ 7
> groupadd [option] group_name
> Options:
۲ او و
> Group ID for the group, which must be unique and greater than
ووو
> -p, --password password
۱ h ceo homeo
> -o, --non-unique
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> To configure password expiration for a user from a shell
prompt, run the following command as root:
> chage [options] username
> Options:
> -d days
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account is not locked after the password expires.
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الهس <
> Sends a message to the terminals of all user
connected to the system.
> talk
> Allows two-way communication between any two
eles
> write
> Send a message to a user
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لك 2
«- لمصطء
> Change file access permission
> chown
» Change file owner or group
> chroot
>» Run command with special root directory
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Thanks for your attention