Domain client configuration

[root@localhost named]      rpm -qa ypbind
[root@localhost named]      rpm -ivh ypbind
[root@localhost named]      rpm -ivh portmap
[root@localhost named]      rpm -ivh ypserver
[root@localhost named]      authconfig-tai
domain name or sever name & server IP
[root@localhost named]      getent passwd username ( to check)
[root@localhost named]      vim /etc/auto.master
/disc /etc/auto.disc
/home /etc/auto.home
save & exit
[root@localhost named]      vim /etc/auto.home
* -fstype=nfs domainIP:/home/$
save & exit
* means any user can to log in
if we provide username to * then only that user will gets access to log in


[root@localhost named]      service autofs restart

Automount & create more than one user at a single command

Drive Automount

root@localhost named]    vim /etc/auto.master
/misc /etc/auto.misc
copy the above line & edit like as the following --
/mountpoint to misc /etc/auto.mom
such as /momin /etc/auto.mom

root@localhost named]    vim /etc/auto.mom
* -fstype=nfs serverIP:/data (source) /test (mount point)
root@localhost named]    service autofs restart
root@localhost named]    cd /test
root@localhost named]    ls ( to see)
-----------------------------------------------------------
create more than one user at  a single command

root@localhost named]    vim myusers1
type here ----
"for u in u1 u2 u3 u4"
useradd $u
echo 123| passwd --stdir $u
passwd $u ( when he will first log in then he input a password that is his password)
save & exit
[root@localhost named]    sh myusers1 (run this command)

Create link between two files and Interface up and shutdown process

[root@localhost named]    vim /etc/sysconfig/network-scripts/ifcfg-eth0
if not shows IP till you assign IP address on lAN setup the you input IP here manually
[root@localhost named]    ifup eth0
[root@localhost named]    ifdown eth0 ( now you gets IP )
[root@localhost named]    top ( to see recent process )
[root@localhost named]    vim /etc/inittab
we can select run level by default here.

To create link between two files. 

[root@localhost named]    ln filename filename ( hard link)
[root@localhost named]    ln -il filename ( to see inode )
[root@localhost named]    ln -s filename filename ( to soft link)
[root@localhost named]    tail /etc/group ( to query a group)
[root@localhost named]    passwd -d username ( change password)
[root@localhost named]    fdisk -l ( to see windows disk both)
[root@localhost named]    shutdown -h 10 ( to shutdown pc after 10 minutes )

Run level & SElinux

[root@localhost named]    chkconfig -- list vsftpd
[root@localhost named]    service servicename status
[root@localhost named]    chkconfig --level 5 vsftpd off
[root@localhost named]    chkconfig vsftpd off
[root@localhost named]     chkconfig --level 35 vsftpd on
[root@localhost named]    chkconfig --list 

=========SElinux===========

[root@localhost named]    getenforce
[root@localhost named]    setenforce 1
[root@localhost named]    setenforce 0
[root@localhost named]    vim /etc/selinux/config

We can use this file to entry this function.

OS default=client of time server=Recover a file of linux operating system

How to set default operating system in linux

[root@localhost named]    vim /etc/grub.conf
just type here "1" for windows "0" for linux
Time server client configuration
[root@localhost named]    vim /etc/ntp.conf
just type here server IP or server name
[root@localhost named]    vim /etc/ntp/step_tickers
just type here server IP
[root@localhost named]    service ntpd restart
[root@localhost named]    system-config-data
here go to networktime tab -add -server IP-ok 

Recover a file of linux os

at first insert a CD into CD ROM the reboot the PC press "a" during booting type here "linux rescue"-

Enter

Then you should to take step as your requirement *

IP forwarding & prevent ot reply of ping----

[root@localhost named]    vim /etc/sysctl.conf

Just enable IP forwarding here by "1" /against "0" 1 for enable 0 for disable.

[root@localhost named]    sysctl -p

Ping reply prevent-------- 

[root@localhost named]    cat /proc/sys/net/icmp_echo_ignore_all (to see the status)
[root@localhost named]    echo 1 > /proc/sys/net/icmp_echo_ignore_all ( to prevent )
[root@localhost named]    echo 0 > /proc/sys/net/icmp_echo_ignore_all (to enable)
[root@localhost named]    vim /etc/sysctl.conf

Just enable this line --net.ipv4.icmp_echo_ignore_all=1

Init function & default virtual mode

[root@localhost named]    init 0 : Shutdown (goes thru the /etc/rc0.d/* scripts then halts)

[root@localhost named]    init 1 : Single user mode or emergency mode means no network no multitasking is present in this mode only root has access in this runlevel

[root@localhost named]    init 2 : No network but multitasking support is present .

[root@localhost named]    init 3 : Network is present multitasking is present but with out GUI .

[root@localhost named]    init 4 : It is similar to runlevel 3; It is reserved for other purposes in research.

[root@localhost named]    init 5 : Network is present multitasking and GUI is present with sound etc.

[root@localhost named]    init 6 : This runlevel is defined to system restart.
by default virtual mode-------
[root@localhost named]    vim /etc/inittab

replace here "3" to "5" NB: 3 for virtual 5 for multiple

[root@localhost named]    startx ( for going to graphical)

user & group policy

Remember these------

Refault permission for directory & file

directory =777-022=755
file=666-022=644
x+suid=s or -+suid=S value=4
x+sgid=s or -+sgid=S value=2
x+stickybit=t or -+stickybit=T value=1
read=4 write=2 execute=1 total value=7


[root@localhost named]    umask 027 username
[root@localhost named]#    chmod o+rwx u+rwx g+rwx
[root@localhost named]    chown username dir/filename
[root@localhost named]    chown .groupname dir/filename
[root@localhost named]    chgrp groupname dir/filename
[root@localhost named]    chown username.groupname dir/filename

[root@localhost named]    usermod groupname,groupname,groupname username (to add a user to more additional/secondary group both)

[root@localhost named]    usermod -a -G groupname,groupname,groupname username ( to add a user that is already exist in a secondary group, to more additional/secondary group)

[root@localhost named]    groupmod -g 700 (ID) groupname ( to change group ID)

[root@localhost named]    gpasswd -M username,username,username groupname (to add one more users to a specific group both)

[root@localhost named]    finger username (to see a user information)
[root@localhost named]    usermod -s /sbin/nologin username (to detect a users shell)
[root@localhost named]    usermod -s /bin/bash username ( to add a users shell)
[root@localhost named]    usermod -l username (to lock a user)
[root@localhost named]    usermod -u username ( to unlock a user)
[root@localhost named]    usermod -G 0 username (to remove a user from his existing group)
[root@localhost named]    chage -l username (to see users change information)
[root@localhost named]    chage -e 2012-08-01 username ( to expire a user)
[root@localhost named]    chage -1 username ( to change to the previous mode)
[root@localhost named]    usermod -l newname oldname ( to change login name)
[root@localhost named]    mv /home/username (old path) /home/username ( new path) ( to change directory of a user)

[root@localhost named]    usermod -c userfullname oldname (to change users full name)

Remote installations

At first need to copy Linux OS & copy to the following path 

/var/ftp/pub 

Then need to configure FTP server to this PC

Then you can to try from another PC

Insert a Linux into CD rom & start booting 

During this time you will get a option to input server IP & path by pressing "a"

Just follow the steps there

 
Then you will see that remote installation has started, Now you can to eject the CD

config IP address & change computer name for installation

Open Network and sharing

center then click “

Managenetwork connections”

 

Disable the network cards that

you don’t u

se to avoid error indomain installation. In thisscence, we use the wireless

adapter so we’ll disable the wired adapter