System & Network Administration (MCSA & RHCSA) Lecture 1-2 By Waseem Ahmad Topic :LINUX BOOT

Login Process DHCP SERVER INTRO: IT ASSIGN IP ADDRESS TO NEWLY CONNECTED NODE IN THE NETWORK. ------------------------------------------------------- DHCP SCOPE: DHCP ALSO CONFIGURE SOME OTHERS IP WITH ITSELF THAT CALLLED THE SCOPE OF THE DHCP . DHCP SCOPE OPTION :Men whtas type of scope parameter is configure with DHCP SERVER. Like DNS SERVER IP ADRESS, YPUR GATEWAY IP ADDRESS. -------------------------------------------------------- DHCP DISCOVERY: A message of the broadcast type send by the host that need Ip Address .the DCHP assign the ip address for short time 3 hour in Lan and 8 Hour in wireless network but you can modify the time . ------------------------------------------------------Reservation: IP address to server like a web server or other type of server is not assigned by the DHCP SERVER its should be separated otherwise DNS have to updated daily .

After Running that it set rest of variable and set them in Profile .d After Completing the work of Profile .d the next script is run in the user Home Dir. .bash_profile Then it also set the .bashrc ->you can Change your cmd Look and feel from Here.

Now Login as Root Make new user Command: SU - For Switching the user as Root Useradd waseem Ls /home/ Userdel –r waseem ///////// -r mean recursive deletion if we used the all data regarding user including its home dir and mailbox also deleted. Until you not gives the password and run user add command this user remain in active . 2- Check user home directory create or not .

User Important If we want to to show complete name of the user on login useradd –c “waseem ” ahmad By default the user directory create in home we can change the location of directory. Mkdir/home/admin Useradd –c “fawad” -d /home/admin/fawad fawad To modify the user used usermod command Like e.g usermod –c “asim khan ” asim

User Important How to Expire the user passwd Lock user account Passwd –l user9 // it will lock user9 Passwd –u user9 // it will unlock user9 We Enforce User to change its passwd after some time period / Chage –M 90 user1 Chage –W 3 user1 How to Expire the user passwd Chage -E 2016-4-20 user1 //expire user passwd on this date

Location of user files /etc/ passwd /etc/shadow /etc/group /etc/gshadow

Help and shutdown in Linux MAN AND INFO www.centos.org www.fedorforums.org www.linuxforum.org Reboot , init 6, init 0, Shutdown -r +5 //after 5 minute it shutdown Shutdown –c //to cancel Shutdown -h 22:00 “system will not available after 10 pm ”//show warning to all user