rsync and Scp command in Linux

How to use Scp command in Linux Operating System.

With the scp (secure copy) command you can easily copy from and to a remote computer or between remote computers.

root@manish.bhadnari#] scp <Source> <destibation>



How to use rsynce command in Linux Operating System.

rsync is a program that behaves in much the same way that scp does, but has many more options and uses the rsync remote-update protocol to greatly speed up file transfers when the destination file already exists.

The rsync remote-update protocol allows rsync to transfer just the differences between two sets of files across the network link, using an efficient checksum-search algorithm described in the technical report that accompanies this package.



@ How to Install rsync command in Linux.

#yum install rsync


@Comman rsync command options

    --delete : delete files that don't exist on sender (system)
    -v : Verbose (try -vv for more detailed information)
    -e "ssh options" : specify the ssh as remote shell
    -a : archive mode
    -r : recurse into directories
    -z : compress file data


For more details for rsync read mention link:

http://linux.about.com/library/cmd/blcmdl1_rsync.htm

How to configure rssh on RHEL 5.5

Linux Configure rssh Chroot Jail To Lock Users To Their Home Directories Only

If you want to chroot users, then use rssh support chrooting option. It is used to set the directory where the root of the chroot jail will be located. This is a security feature.

A chroot on Linux or Unix OS is an operation that changes the root directory. It affects only the current process and its children. If your default home directory is /home/manish normal user can access files in /etc, /sbin or /bin directory. This allows an attacker to install programs / backdoor via your web server in /tmp. chroot allows to restrict file system access and locks down user to their own directory.

First download the rssh rpm (rssh-2.3.3-1.fc16.x86_64.rpm)

Configuring rssh chroot

chroot directory : /users

root@mansh.bhandari#] wget -c

Another url is wget http://dag.wieers.com/rpm/packages/rssh/rssh-2.3.2-1.2.el5.rf.x86_64.rpm

ftp://ftp.univie.ac.at/systems/linux/fedora/releases/16/Everything/x86_64/os/Packages/rssh-2.3.3-1.fc16.x86_64.rpm

root@mansh.bhandari#] rpm -ivh rssh-2.3.3-1.fc16.x86_64.rpm

root@mansh.bhandari#] mkdir /users

root@mansh.bhandari#] mkdir -p /users/{dev,etc,lib,usr,bin}

root@mansh.bhandari#] mkdir -p /users/usr/bin

root@mansh.bhandari#] mkdir -p /users/usr/libexec/openssh/

root@mansh.bhandari#] mkdir -p /users/libexec/openssh

Create /users/dev/null:

root@mansh.bhandari#] mknod -m 666 /users/dev/null c 1 3

Copy required /etc/ configuration files, as described above to your jail directory /users/etc:

root@mansh.bhandari#] cd /users/etc

root@mansh.bhandari#] cp /etc/ld.so.cache .

root@mansh.bhandari#] cp /etc/ld.so.conf .

root@mansh.bhandari#] cp /etc/nsswitch.conf .

root@mansh.bhandari#] cp /etc/passwd .

root@mansh.bhandari#] cp /etc/group .

root@mansh.bhandari#] cp /etc/hosts .

root@mansh.bhandari#] cp /etc/resolve.conf .

Open /usres/group and /users/passwd file and remove root and all other accounts.

Copy required binary files, as described above to your jail directory /users/bin and other locations:

root@mansh.bhandari#] cd /users/usr/bin

root@mansh.bhandari#] cp /usr/bin/scp .

root@mansh.bhandari#] cp /usr/bin/rssh .

root@mansh.bhandari#] cp /usr/bin/sftp .

root@mansh.bhandari#] cd /users/usr/libexec/openssh/

root@mansh.bhandari#] cp /usr/libexec/openssh/sftp-server .

or

root@manish.bhandari#] cp /usr/lib/openssh/sftp-server . (not found)

root@manish.bhandari#] cd /users/usr/libexec/

root@manish.bhandari#] cp /usr/libexec/rssh_chroot_helper .

OR
root@manish.bhandari#] cp /usr/lib/rssh/rssh_chroot_helper (not found)

root@manish.bhandari#] cd /users/bin/

root@manish.bhandari#] cp /bin/sh .
OR
root@manish.bhandari#] cp /bin/bash .

Copy all shared library files

The library files that any of these binary files need can be found by using the ldd / strace command. For example, running ldd against /usr/bin/sftp provides the following output:

ldd /usr/bin/sftp

Output:

linux-gate.so.1 =>  (0×00456000)

libresolv.so.2 => /lib/libresolv.so.2 (0x0050e000)

libcrypto.so.6 => /lib/libcrypto.so.6 (0x0013e000)

libutil.so.1 => /lib/libutil.so.1 (0x008ba000)

libz.so.1 => /usr/lib/libz.so.1 (0×00110000)

libnsl.so.1 => /lib/libnsl.so.1 (0x0080e000)

libcrypt.so.1 => /lib/libcrypt.so.1 (0x00a8c000)

libgssapi_krb5.so.2 => /usr/lib/libgssapi_krb5.so.2 (0×00656000)

libkrb5.so.3 => /usr/lib/libkrb5.so.3 (0×00271000)

libk5crypto.so.3 => /usr/lib/libk5crypto.so.3 (0×00304000)

libcom_err.so.2 => /lib/libcom_err.so.2 (0×00777000)

libdl.so.2 => /lib/libdl.so.2 (0×00123000)

libnss3.so => /usr/lib/libnss3.so (0×00569000)

libc.so.6 => /lib/libc.so.6 (0x00b6c000)

libkrb5support.so.0 => /usr/lib/libkrb5support.so.0 (0×00127000)

libkeyutils.so.1 => /lib/libkeyutils.so.1 (0×00130000)

/lib/ld-linux.so.2 (0×00525000)

libplc4.so => /usr/lib/libplc4.so (0x008c9000)

libplds4.so => /usr/lib/libplds4.so (0×00133000)

libnspr4.so => /usr/lib/libnspr4.so (0x00d04000)

libpthread.so.0 => /lib/libpthread.so.0 (0x0032a000)

libselinux.so.1 => /lib/libselinux.so.1 (0×00341000)

libsepol.so.1 => /lib/libsepol.so.1 (0×00964000)

You need to copy all those libraries to /lib and other appropriate location. However, I recommend using this automated script called l2chroot:

root@manish.bhandari#] cd /sbin

root@manish.bhandari#] wget -O l2chroot http://www.cyberciti.biz/files/lighttpd/l2chroot.txt

root@manish.bhandari#] chmod +x l2chroot

Open l2chroot and set BASE variable to point to chroot directory (jail) location:

BASE=”/users”

Now copy all shared library files

root@manish.bhandari#] l2chroot /usr/bin/scp

root@manish.bhandari#] l2chroot /usr/bin/rssh

root@manish.bhandari#] l2chroot /usr/bin/sftp

root@manish.bhandari#] l2chroot /usr/libexec/openssh/sftp-server
OR
root@manish.bhandari#] l2chroot /usr/lib/openssh/sftp-server (not found)

root@manish.bhandari#] l2chroot /usr/libexec/rssh_chroot_helper
OR
root@manish.bhandari#] l2chroot /usr/lib/rssh/rssh_chroot_helper

root@manish.bhandari#] l2chroot /bin/sh
OR
root@manish.bhandari#]l2chroot /bin/bash

Modify syslogd configuration

root@mansh.bhandari#] vi /etc/sysconfig/syslog

Find line that read as follows:
SYSLOGD_OPTIONS=”-m 0″
Append -a /users/dev/log
SYSLOGD_OPTIONS=”-m 0 -a /users/dev/log”
Save and close the file. Restart syslog:

root@manish.bhandari#] /etc/init.d/syslog restart

Set chroot path

Open configuration file /etc/rssh.conf:


root@manish.bhandari#] vi /etc/rssh.conf


Set chrootpath to /users


chrootpath=/users


user=manish:022:00010:”/users”
Save and close the file. If sshd is not running start it:


root@manish.bhandari#] /etc/init.d/sshd restart

Set chroot path:

root@manish.bhandari3] vim /etc/rssh.conf

chrootpath=/users

Subsystem sftp internal-sftp

root@manish.bhandari#] /etc/init.d/sshd restart

Add user to jail

root@manish.bhandari#] useradd -m -d /users/manish -s /usr/bin/rssh manish

root@manish.bhandari#] passwd manish

Now vivek can login using sftp or copy files using scp:

root@manish.bhandari#] sftp manish@192.168.100.xx

manish@192.168.100.x password

sftp>

sftp> ls

sftp > pwd

Remote working directory : /users/manish

sftp > cd /tmp

Couldn't canonicalise: No such file or directory

User manish is allowed to login to server to trasfer files, but not allowed to browse entier file system.

http://pensacola-tech.com/pensacola/2010/05/05/configure-rssh/

                                                                                                                                 Manish Bhandari

Process Monitoring Scripts in Linux

#!/bin/bash
#set -x
#
#Variable secetion 
#=====================================================
#list process to monitor in the variable below;
PROGRAM1="firefox"
#Variabele check to see if $PROGRAM1
#is running
APPCHK=$(ps aux | grep -c $PROGRAM1 )
#$Company & Site variable are for populating the alert email
COMPANY="Hungama"
SITE="JMX"
# $SUPPORTSTAFF is the recipient of our alert email
SUPPORTSTAFF="manish.bhandari@fosteringlinux.com"
#=======================================================
# The ‘if’ statement below checks to see if the process is running
# with the ‘ps’ command.  If the value is returned as a ’0′ then
# an email will be sent and the process will be safely restarted.
#
echo "COUNT IS " $APPCHK

if [ $APPCHK -eq '1' ];then
echo mail -s "Manish PBX at $COMPANY $SITE may be down " $SUPPORTSTAFF >> notrunning.log
else
echo "$PROGRAM1 is running $APPCHK processes" >> manish-check.log
fi
echo $APPCHK
exit

How to create new partition on Linux

Here i create new partition on 4 setps:

Step #1 For create new partition used fdisk command;

Following command will list all detected hard disks:
root@manish.bhandari#] fdisk -l | grep '^Disk'

Output:

Disk /dev/sda: 251.0 GB, 251000193024 bytes
Disk /dev/sdb: 251.0 GB, 251000193024 bytes

To partition the disk - /dev/sdb, enter:
root@manish.bhandari#] fdisk /dev/sdb

The basic fdisk commands you need are:

• m - print help
• p - print the partition table
• n - create a new partition
• d - delete a partition
• q - quit without saving changes
• w - write the new partition table and exit

for avoid to reboot the system type this command;

root@manish.bhandari#] partprobe

Step #2 Format the new disk partition using mkfs.ext3 or mkfs.ext4 command;

root@manish.bhandari#] mkfs.ext4 /dev/sdb1

Step #3 Mount the new partition using command but first you create mount point /manish and mount command to mount /dev/sdb1;

root@manish.bhandari#] mkdir /manish

root@manish.bhandari#] mount /dev/sdb1 /manish

root@manish.bhandari#] df -h

Step #4 Update /etc/fstab file for parment mount;

root@manish.bhandari#] vim /etc/fstab

/dev/sdb1                           /manish                           ext4                defaults           1   2


Thanks & Regards
                                                                                                                     Manish Bhandari

How to mount iso image in Linux

Q How to mount iso image in linux

 Ans root@manish.bhandari#] mount -o loop example.iso /mnt

        root@manish.bhandari#] ls /mnt

Now mount the iso permanently

root@manish.bhandari#] vim /etc/fstab

/iso/rhel-server-5.5-x86_64-dvd.iso /mnt        iso9660   loop          0 0



                                             That' s all

                                                                                                                    Thanks & Regards
                                                                                                                         Manish Bhandari

Virtulization in Linux

                                 KVM Installation and configuration

What is the difference between KVM and Xen?

Xen is an external hypervisor; it assumes control of the machine and divides resources among guests. On the other hand, KVM is part of Linux and uses the regular Linux scheduler and memory management. This means that KVM is much smaller and simpler to use; it is also more featureful; for example KVM can swap guests to disk in order to free RAM.

KVM only run on processors that supports x86 hvm (vt/svm instructions set) whereas Xen also allows running modified operating systems on non-hvm x86 processors using a technique called paravirtualization. KVM does not support paravirtualization for CPU but may support paravirtualization for device drivers to improve I/O performance.

System requirements:

Minimum system requirements:

• 6GB free disk space (6GB plus the required disk space recommended by the guest operating system per guest. For most operating systems more than 6GB of disk space is recommended. )
• 2GB of RAM. (2GB of RAM plus additional RAM virtualized guests.)

Xen para-virtualization requirements:
Para-virtualized guests require a Red Hat Enterprise Linux 5 installation tree available over the network using the NFS, FTP or HTTP protocols.

Xen full virtualization requirements:

Full virtualization with the Xen Hypervisor requires:
• an Intel processor with the Intel VT extensions,
• an AMD processor with the AMD-V extensions, or
• an Intel Itanium processor.

KVM requirements:

The KVM hypervisor requires:
• an Intel processor with the Intel VT and the Intel 64 extensions, or
• an AMD processor with the AMD-V and the AMD64 extensions.

Installation of XEN and KVM installation in RHELx 64 bit.

First create the yum server

root@manish.bhandari#] vim /etc/yum.repo/yum.repo
 [server]

 name=yum server

baseurl=file:///mnt/Server
gpgcheck=0

[VT]
name=VT
baseurl=file:///mnt/VT
gpgcheck=0
:wq!


Now check the virtualization flag

root@manish.bhandari#] egrep '(vmx|svm)' --color=always /proc/cpuinfo
or
root@manish.bhandari#] grep -E 'svm|vmx' /proc/cpuinfo

XEN virtualization required packages are:

XEN : The xen package contains the hypervisor and basic virtualization tools.

Kernel-xen : The kernel-xen package contains a modified Linux kernel which runs as a virtual machine guest on the hypervisor.
Python-virtinst : Provides the virt-install command for creating virtual machines.
libvirt : libvirt is an API library for interacting with hypervisors. libvirt uses the xm virtualization framework and the virsh command line tool to manage and control virtual machines.

libvirt-python : The libvirt-python package contains a module that permits applications written in the Python programming language to use the interface supplied by the libvirt API.
virt-manager : virt-manager, also known as Virtual Machine Manager, provides a graphical tool for administering virtual machines. It uses libvirt library as the management API.

root@manish.bhandari#] yum install xen kernel-xen virt-manager libvirt libvirt-python python-virtinst virt-manager

KVM virtualization required packages are:

KVM : The kvm package contains the KVM kernel module providing the KVM
hypervisor on the default Red Hat Enterprise Linux kernel.

root@manish.bhandari#] yum install virt-manager kvm* libvirt libvirt-python python-virtinst qemu*

Then start the libvirtd service :

root@manish.bhandari#] /etc/init.d/libvirtd start

To check if KVM has successfully been installed, run

root@manish.bhandari#] virsh -c qemu:///system list

It should display something like this:
Id Name
State
----------------------------------

To configure the bridge create a file br0

root@manish.bhandari#] vim /etc/sysconfig/network-scripts/ifcfg-br0

DEVICE=br0
TYPE=Bridge
BOOTPROTO=static
GATEWAY=192.168.4.1
IPADDR=192.168.4.12       (bash machine IP)
NETMASK=255.255.255.0
ONBOOT=yes
Modify /etc/sysconfig/network-scripts/ifcfg-eth0 as follow

root@manish.bhandri#] vim /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0
#BOOTPROTO=none
#DNS1=145.253.2.75
#GATEWAY=192.168.0.1
HWADDR=00:1e:90:f3:f0:02
#IPADDR=192.168.4.12
#NETMASK=255.255.255.0
ONBOOT=yes
TYPE=Ethernet
IPV6INIT=no
USERCTL=no
BRIDGE=br0

Then restart the system
root@manish.bhandari#] init 6

Now run the following command to start virtual machine.

root@manish.bhandari#] virt-manager

Then install virtual machine as your requirement :

                                                                                                                    Thanks &  Regards
                                                                                                                     Manish Bhandari