Solaris and Linux Runlevel

Default Linux Run Level: Total 7 Run Level

RunLevel 0: Halt System - To shutdown the system
RunLevel 1: Single user mode
RunLevel 2: Basic multi user mode without NFS
RunLevel 3: Full multi user mode (text based)
RunLevel 4: unused
RunLevel 5: Multi user mode with Graphical User Interface
RunLevel 6: Reboot System

Default Solaris Run Level: Total 8 Run Level

RunLevel S: Single user state (useful for recovery)

RunLevel 0: Access Sun Firmware (ok> prompt)

RunLevel 1: System administrator mode

RunLevel 2: Multi-user w/o NFS

RunLevel 3: Multi-user with NFS

RunLevel 4: Unused

RunLevel 5: Completely shutdown the host (like performing a power-off)

RunLevel 6: Reboot but depend upon initdefault entry in /etc/inittab

Update system

Configure Services in CentOs5/RHEL5

1) List All services



2)  List Running services at Runlevel 3



3) Start service



4)      Stop service



5)   Start service on different RunLevel



6)  Restart services



7)  Add services



8 ) Remove Services

CentOS5/RHEL5 User Administration

1) Add User



2)      Delete user



3)      Modify user



4) Add Group





5) Delete group



6) Modify group



7) Add User to Group

Use useradd command to add new users to existing group (or create a new group and then add user). If group does not exist, create it. Syntax:

Syntax:

useradd -G {group-name1},{group-name2} username (for secondary group)

useradd -g {group-name} username (for primary group)

Automated Installation of DenyHost on RedHat/Fedora

#Script

#!/bin/bash

# This script installs Deny Host on RedHat(RHEL) or Fedora.

################################################################################

# This script comes with no warranty or guarantee. Please review the script

# before you run it to ensure that it will not cause adverse effects on your

# system.

#

# If you have any questions or comments, please e-mail: sanjaydalal4u@gmail.com

################################################################################

sudo echo

if [ -f /etc/init.d/denyhosts ]; then

echo Removing existing init scripts

sudo /etc/init.d/denyhosts stop

sudo rm -rf /etc/init.d/denyhosts

sudo chkconfig --remove denyhosts

echo '*********************'

echo

fi

if [ -d /usr/share/denyhosts/ ]; then

echo Removing existing installation

sudo rm -rf /usr/share/denyhosts

echo '*********************'

echo

fi

echo Installing 'python' and dependencies.

sudo yum -y install python

echo '*********************'

echo

cd /root

echo Downloading DenyHost

wget http://downloads.sourceforge.net/project/denyhosts/denyhosts/2.6/DenyHosts-2.6.tar.gz?use_mirror=biznetnetworks

echo '*********************'

echo

echo Unpacking DenyHost

#!/bin/bash

# This script installs Deny Host on RedHat(RHEL) or Fedora.

################################################################################

# This script comes with no warranty or guarantee. Please review the script

# before you run it to ensure that it will not cause adverse effects on your

# system.

# If you have any questions or comments, please e-mail: sanjaydalal4u@gmail.com

################################################################################

sudo echo

if [ -f /etc/init.d/denyhosts ]; then

echo Removing existing init scripts

sudo /etc/init.d/denyhosts stop

sudo rm -rf /etc/init.d/denyhosts

sudo chkconfig --remove denyhosts

echo '*********************'

echo

fi

if [ -d /usr/share/denyhosts/ ]; then

echo Removing existing installation

sudo rm -rf /usr/share/denyhosts

echo '*********************'

echo

fi

echo Installing 'python' and dependencies.

sudo yum -y install python

echo '*********************'

echo

cd /root

echo Downloading DenyHost

wget http://downloads.sourceforge.net/project/denyhosts/denyhosts/2.6/DenyHosts-2.6.tar.gz?use_mirror=biznetnetworks

echo '*********************'

echo

echo Unpacking DenyHost

tar -xzf DenyHosts-2.6.tar.gz

cd /root/DenyHosts-2.6

echo '*********************'

echo

echo Installing DenyHost

sudo python setup.py install

echo '*********************'

echo

cd /usr/share/denyhosts

echo Configuring DenyHost

sudo cp denyhosts.cfg-dist denyhosts.cfg

sudo sed -i.bak 's/^\s*\(SECURE_LOG\s*=.*\)$/#\1/' denyhosts.cfg

sudo sed -i.bak 's/^\s*#\s*SECURE_LOG\s*=\s*\/var\/log\/secure/SECURE_LOG = \/var\/log\/secure/' denyhosts.cfg

sudo sed -i.bak 's/^\s*\(LOCK_FILE\s*=.*\)$/#\1/' denyhosts.cfg

sudo sed -i.bak 's/^\s*#\s*LOCK_FILE\s*=\s*\/var\/run\/denyhosts.pid/LOCK_FILE = \/var\/run\/denyhosts.pid/' denyhosts.cfg

sudo sed -i.bak 's/^\s*\(BLOCK_SERVICE\s*=.*\)$/#\1/' denyhosts.cfg

sudo sed -i.bak 's/^\s*#\s*BLOCK_SERVICE\s*=\s*ALL/BLOCK_SERVICE  = ALL/' denyhosts.cfg

echo '*********************'

echo

echo Configuring executable

sudo cp daemon-control-dist daemon-control

sudo sed -i.bak 's/^\(\s*DENYHOSTS_BIN\s*=\s\).*$/\1"\/usr\/bin\/denyhosts.py"/' daemon-control

sudo sed -i.bak 's/^\(\s*DENYHOSTS_LOCK\s*=\s\).*$/\1"\/var\/run\/denyhosts.pid"/' daemon-control

sudo sed -i.bak 's/^\(\s*DENYHOSTS_CFG\s*=\s\).*$/\1"\/usr\/share\/denyhosts\/denyhosts.cfg"/' daemon-control

sudo chown root daemon-control

sudo chmod 700 daemon-control

echo '*********************'

echo

echo Adding ddclient to rc scripts

cd /etc/init.d

sudo ln -s /usr/share/denyhosts/daemon-control denyhosts

sudo chkconfig --add denyhosts

sudo chkconfig --level 35 denyhosts on

echo '*********************'

echo