Windows & Linux Administration...: 2011

what is the different between thick and thin disk in vmware Or, thick-provisioned and thin-provisioned disks

what is the different between thick and thin disk in vmware Or, thick-provisioned and thin-provisioned disks

thick-provisioned disks are created with the entire size of the disk pre-allocated on physical storage at the time the disk is created. This pre-allocation means that creating a 50GB virtual disk actually consumes 50GB of physical disk space on your drives.

thin-provisioned disks are created with the amount of physical disk storage used by a virtual disk is equal to the amount of actual data on that disk. If you create a 100GB disk but only use 20GB of that disk, the actual disk consumption on your physical drives will be 20GB.

Note: Versions of ESX prior to 4.0 were only capable of creating thick-provisioned disks.

network throughput test in windows and linux

Install iperf on Ubuntu

root# apt-cache search iperf

iperf - Internet Protocol bandwidth measuring tool

root#apt-get install iperf

Install iperf on RHEL & Fedora

root#yum search iperf

iperf.i686 : Measurement tool for TCP/UDP bandwidth performance

iperf3.i686 : Measurement tool for TCP/UDP bandwidth performance

yum install iperf3.i686

Install iperf for Windows

download iperf.exe and copy into C:\Documents and Settings\abc. abc is the logged-in user location.

iperf can be installed on two machines. You'll run one as a server, and one as a client. On the server side, run below. -s:Act as a Server, -c:Act as a client, -p:specify a port

Open Command prompt and run below commands.

On server side run below and press enter
iperf.exe -s
-------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
-------------------------------------

On the client side, run:

iperf.exe -c [server_ip]
iperf.exe -c 192.168.xx.xx
--------------------------------------------------
Client connecting to 192.168.xx.xx, TCP port 5001
TCP window size: 65.0 KByte (default)
--------------------------------------------------
[  3] local 192.168.10.30 port 53345 connected with 192.168.xx.xx port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  37.9 MBytes  31.8 Mbits/sec

what is ssl

SSL (Secure Sockets Layer) is the standard security technology for establishing an encrypted link between a web server and a browser. This link ensures that all data passed between the web server and browsers remain private and integral. SSL is an industry standard.

What is the different between windows .msi and .msp file

An application that has been installed using the Microsoft Windows Installer can be upgraded by reinstalling an updated installation package (.msi file), or by applying a Windows Installer patch (an .msp file) to the application.

what is Hyper-Threading

Hyper-Threading technology is a technique which enables a single CPU to act like multiple CPU’s.

how to upgrade unbuntu kernel

Follow below steps to upgrade Ubuntu Kernel

#uname -a #Check current Kernel version

#aptitude search linux-image #Check which is the latest version

#aptitute install update

#aptitute install linux-iamge_*** -y

#reboot #reboot the system to take effect the new change

How to Move or Change Windows Paging File or Virtual Memory location on windows.

How to Move or Change Windows Paging File or Virtual Memory location on windows.
To enhance performance, it is good practice to put the paging file on a different partition and on a different physical hard disk drive. That way, Windows can handle multiple I/O requests more quickly. When the paging file is on the boot partition, Windows must perform disk reading and writing requests on both the system folder and the paging file. When the paging file is moved to a different partition, there is less competition between reading and writing requests.
Follow the steps to move or change paging file on Windows XP and Windows Server 2003
1. Log on to the computer as Administrator.
2. Open system properties, Press Windows + Pause/Break key to open system properties.
3. Click the Advanced tab, and then under Performance, click Settings.
4. Click the Advanced tab, and then under Virtual memory, click Change.
5. In the Drive [Volume Label] list, click a drive other than the one on which Windows is installed (Windows is usually installed on the drive C). Under Total paging file size for all drives, note the value that is displayed next to Recommended.
6. Click Custom size, and then type the recommended value in the Initial size (MB) box.
7. Type the maximum size that you want to allow for paging in the Maximum size (MB) box, and then click Set.
8. In the Drive [Volume Label] box, click the drive on which Windows is installed (usually the drive C), and then use one of the following steps:
Note: If you do not want a paging file on the drive, click No paging file, and then click Set. A message similar to the following message appears:
If the pagefile on volume C: has an initial size of less than 126 megabytes, then the system may not be able to create a debugging information file if a STOP error occurs.
Continue anyway?
Click Yes.
Note: If you want to keep the minimum size of the paging file on the drive, click Custom size, and then type a value that is equal to or greater than the amount of RAM in the computer in the Initial size (MB) box. Type that same value in the Maximum size (MB) box, and then click Set.
9. The following message appears:
The changes you have made require you to restart your computer before they can take effect.
Click OK, click OK, click OK, and then click Yes when you are prompted to restart the computer.

Follow the steps to change or move paging file on Windows 7, Vista and Windows Server 2008.
1. Log on to the computer as Administrator.
2. Open system properties, Press Windows + Pause/Break key to open system properties.
3. Click the Advanced system settings tab, and then under Performance, click Settings.
4. Click the Advanced tab, and then under Virtual memory, click Change.
5. In the Drive [Volume Label] list, click a drive other than the one on which Windows is installed (Windows is usually installed on the drive C). Under Total paging file size for all drives, note the value that is displayed next to Recommended.
6. Click Custom size, and then type the recommended value in the Initial size (MB) box.
7. Type the maximum size that you want to allow for paging in the Maximum size (MB) box, and then click Set.
8. In the Drive [Volume Label] box, click the drive on which Windows is installed (usually the drive C), and then use one of the following steps:
Note: If you do not want a paging file on the drive, click No paging file, and then click Set. A message similar to the following message appears:
If the pagefile on volume C: has an initial size of less than 126 megabytes, then the system may not be able to create a debugging information file if a STOP error occurs.
Continue anyway?
Click Yes.
Note: If you want to keep the minimum size of the paging file on the drive, click Custom size, and then type a value that is equal to or greater than the amount of RAM in the computer in the Initial size (MB) box. Type that same value in the Maximum size (MB) box, and then click Set.
9. The following message appears:
The changes you have made require you to restart your computer before they can take effect.
Click OK, click OK, click OK, and then click Yes when you are prompted to restart the computer.

create your own run commands in windows

Creating Your Own Run Commands
If you are like me, you will use a few programs very frequently. One way to make them start faster is to give them their own Run command:
   1. Press Windows Key + R to open the Run dialog box.
   2. Type %windir% on run dialog box and press enter key to open the Windows directory.
   3. Press Alt+F -->Click New --> Click on Shortcut.
   4.Click on Browse and choose the program you want to use on Run dialog box and click on OK.
   5.Click on Next -->give a name to the program and Click on Finish.
   6. Open Run dialog box and type the name you gave on step 5 and press enter. This will open
   the program from  Run dialog box.
   No need to go to program files to start a program or double click on any shortcut.

how to mount linux/fedora/Ubuntu folder from different Linux system without installing samba or nfs

Follow the steps to mount linux/fedora/Ubuntu folder from different Linux system without installing samba or nfs .
sshfs and fuse-sshfs allow to mount folder of networked systems using ssh port(22).
Step 1: Install sshfs into Ubuntu
root#apt-get install sshfs
Install sshfs into RHEL or Fedora
root#yum install fuse-sshfs
Step 2: Create a folder to mount
root#mkdir -p /opt/ssh-folder
Step 3: Run below command to mount and press enter.
root# sshfs -o nonempty,noatime -p 22 username@192.168.xxx.xx:"/home/test-folder" /opt/ssh-folder/
Step 4: It will prompt to enter password, type passsword and press enter
username@192.168.xxx.xx's password:******
Step 5: Run mount to check the 192.168.xxx.xx:"/home/test-folder is mounted or not.
root#mount

What is memory ballooning

Memory ballooning allows you to have your guest dynamically change it’s memory usage by evicting unused memory during runtime. This is a useful feature because it reduces the impact your guest can have on memory usage of your host by giving up unused memory back to the host.

change and update date & time, time zone in ubuntu

tzselect: It is a command to change time zone in ubuntu. Just run the command, select continent or ocean, and
country . Type tzselect and press enter...
#tzselect
Run below command to syncronize time with ntp server
#ntpdate ntp.ubuntu.com

What is cloud computing

Cloud computing is a general term for anything that involves delivering hosted services over the Internet. These services are broadly divided into some categories: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS) and Hardware as a Service (HaaS). The name cloud computing was inspired by the cloud symbol that's often used to represent the Internet in flowcharts and diagrams.

A cloud service has distinct characteristics that differentiate it from traditional hosting. It is sold on demand, typically by the minute or the hour; it is elastic -- a user can have as much or as little of a service as they want at any given time; and the service is fully managed by the provider (the consumer needs nothing but a personal computer and Internet access). Significant innovations in virtualization and distributed computing, as well as improved access to high-speed Internet and a weak economy, have accelerated interest in cloud computing.

A cloud can be private or public. A public cloud sells services to anyone on the Internet. (Currently, Amazon Web Services is the largest public cloud provider.) A private cloud is a proprietary network or a data center that supplies hosted services to a limited number of people. When a service provider uses public cloud resources to create their private cloud, the result is called a virtual private cloud. Private or public, the goal of cloud computing is to provide easy, scalable access to computing resources and IT services.
Hardware as a Service (HaaS) is a service provision model for hardware that is defined differently in managed services and grid computing contexts. In managed services, HaaS is similar to licensing. In grid computing, HaaS is a pay as you use model.
Infrastructure-as-a-Service(IaaS) like Amazon Web Services provides virtual server instanceAPI) to start, stop, access and configure their virtual servers and storage. In the enterprise, cloud computing allows a company to pay for only as much capacity as is needed, and bring more online as soon as required
Platform-as-a-service(PaaS) in the cloud is defined as a set of software and product development tools hosted on the provider's infrastructure. Developers create applications on the provider's platform over the Internet. PaaS providers may use APIs, website portals or gateway software installed on the customer's computer. Force.com, (an outgrowth of Salesforce.com) and GoogleApps are examples of PaaS.
software-as-a-service(SaaS) in this cloud model, the vendor supplies the hardware infrastructure, the software product and interacts with the user through a front-end portal. Services can be anything from Web-based email to inventory control and database processing. Because the service provider hosts both the application and the data, the end user is free to use the service from anywhere.

What is Hypervisor

A hypervisor, also called a virtual machine manager, is a program that allows multiple operating systems to share a single hardware host. Each operating system appears to have the host's processor, memory, and other resources all to itself. However, the hypervisor is actually controlling the host processor and resources, allocating what is needed to each operating system in turn and making sure that the guest operating systems (called virtual mahines) cannot disrupt each other.
Type 1 hypervisor runs directly on the hardware.
Type 2 hypervisor runs on another operating system, such as Linux.

Major Hypervisors
• Xen
• KVM
• VMware ESX
• Microsoft Hyper-V
• PowerVM
• Logical Domains / Oracle VM

p2v(Physical to Virtual) of Windows System using VMware vConverter

Below are the processes to convert P2V using VMware vCenter Converter Standalone 4.0.1

I. Download VMware vCenter converter Standalone client and install in your physical sysem.

II. Convert Windows Physical system to Virtual (P2V).

Download VMware vCenter converter and install on physical system and install it on your physical system

Download VMware vCenter Converter Standalone client from below link. http://www.vmware.com/products/converter/

Note:We need to register to download vCenter converter. Just register with your mail id, it is free to download.

Convert Windows Physical system to Virtual (P2V).

1. Open VMware vCenter Converter and Click on Convert Machine

2. Select Source type is “Powered-on machine” and “This local machine” then click on Next

3. Select Destination type “VMware Infrastructure virtual machine” and give ESX server details at “VMware Infrastructure server details” and clink next

4. Give Virtual Machine name and click Next

5. Under View/Edit Option select drive to convert and check the box of drive which you want to convert and un-check the box if you do not want to convert them. Click on Next to continue.

6. Click Finish to start conversion process.

8.You can see the status in progress marked in red

8.And the completed

9.Exit VMWare vCenter Converter once the conversion process is completed. Go to you ESX sever and start the converted VM.

How to check start, restart or shutdown time of Windows Operating System

How to check start, restart or shutdown time of Windows Operating System. I found 2 ways to check start,restart or shutdown time of windows operating system.
1. Open command prompt and type below command and press enter. It will show up time of Windows OS.
C:\Documents and Settings\abc> systeminfo
2.We can check in Event Viewer.Open event viewer and go to System Events. Find
System Event ID:1074
The process C:\Windows\system32\shutdown.exe (WIN-6FP1VCCPJ0T) has initiated the restart of computer WIN-6FP1VCCPJ0T on behalf of user PR\Administrator for the following reason: No title for this reason could be found
Reason Code: 0x800000ff
Shutdown Type: restart
Comment:
System Event ID:109
The kernel power manager has initiated a shutdown transition.
Also check many services are stopped at a particular time.
System Event ID :6005 (This event id means the System went down at that time)
System Event ID :6006 (This event id means the System started at that time)

netcat to transfer files between linux and windows

netcat in windows On Source PC(Windows) download and copy nc.exe netcat works as a Server and Client model.
Below steps show how to copy data from a Windows system into Linux(Ubuntu) system.Currently I am using Ubuntu Server.Varify
Windows System IP :192.168.xxx.xx and   Linxu(Ubuntu) system IP: 192.168.yyy.yy
     Copy files from Windows To Linux
Setp1:Download netcat into Windows System and copy nc.exe into the directory where your file is exist.
Ex: C:\test\nc.exe
Step 2:Install netcat on ubuntu
#apt-get install netcat
Step 3: Now netcat is available on both Windows and Linxu(Ubuntu)
Open command prompt and go to the directory where your file is located and run below command.This will act as a Server.
C:\test> type backup.iso | nc.exe -l -p 3333
Note: "type" is a command in windows.
Step 4: Receive backup.iso on the client machineLinux(Ubuntu) with the following.This will act as a Client
# nc 192.168.xxx.xx 3333 > backup.iso
Issue a ^C on the source system and your done one u see file size in destination directory. Be sure to check the file to be sure it is the same size as the original.
   Copy files from Linxu to Windows
On Linxu system run below command. Now this will act as a Server
#cat backup.iso | nc -l -p 3333
On Windows Run below command. Now this will act as a Client.
C:\test> nc.exe 192.168.yyy.yy 3333 > backup.iso
Issue a ^C on the source system and your done one u see file size in destination directory. Be sure to check the file to be sure it is the same size as the original.

Linux filesystem

/ : This(/) is the root folder, all other folders come under root.. it is like C: drive in a Windows OS

/boot : Linux kernel and boot loader configuration files

/usr : This folder and its sub-folders contains user installed programs and utilities and libraries.It is like
Program files in windows.
/etc : Configuration files of all installed softwares or applications
/var : This folder contains files that change alot (“Variable files”). Mail, print web spool files
/tmp : Temp directory
/home : This folder contains the home folders of all the normal (non – root ) users on the system
/dev : Device files corresponding to various peripherals of your comp. (hard disk, printer, mouse, modem)
/mnt : Devices mounted onto OS to increase storage space
/lost+found : Orphan files are moved here
/root : Root's home directory
/proc : Process information pseudo filesystem.
/bin : various console utilities and apps
/sbin : system administration utilities
/lib : Shared Library files for your operating system.

netstat : check open ports and connections to system

Using netstat command we can see all the used and listening ports on your computer. NETSTAT command will work in Windows and as well as in Linux Operating System.
Linux
Will Show all connected Ports
netstat -an | grep -i "connected"

Will Show all listening Ports
netstat -an | grep -i "listening"

Will Show all established connections
netstat -an | grep -i "established"

Windows
Will Show all connected Connected Ports
netstat -an |find /i "connected"

Will Show all listening Ports
netstat -an |find /i "listening"

Will Show all established connections
netstat -an |find /i "established"

Note: -i & /i is used to ignore case-sensitive.

restore grub in vyatta router

grub> linux /boot/vmlinuz root=/dev/sda1
grub> initrd /boot/initrd.img
grub> boot
Agter reboot run below command to re-install grub
grub-install /dev/sda
reboot ##Reboot again to so that the Server will boot normally

How to manually extend the evaluation period for Windows Server 2008

When the initial 60 or 180 days evaluation period nears its end, you can run the Slmgr.vbs script to reset the evaluation period. To do this, follow these steps:

1. Login As a Administrator. Click Start, and then click Command Prompt.
2. Type slmgr.vbs -dli, and then press ENTER to check the current status of your evaluation period.
3. To reset the evaluation period, type slmgr.vbs –rearm, and then press ENTER.
4. Restart the computer.
5. Open Computer Properties. Right Click on Computer ==> Click Properties ==>At Windows Activation
Screen ==> Click on Activate ==> Click on Activate online ==> Click Next to finish actiavation.

This resets the evaluation period to 60 or 180 as per your last evaluation period.

how to get entire system information in ubuntu

facter : It is a tool to collect and display facts about the current system. The library behind Facter is easy to expand, making Facter an easy way to collect information about a system from within the shell or within Ruby.

#apt-get install facter

#facter and press enter to get the system details

Below is the output of facter

# facter

architecture => i386

facterversion => 1.5.4

hardwareisa => unknown

hardwaremodel => i686

hostname => my-desktop

id => root

interfaces => eth0

ipaddress => 192.168.xxx.xxx

ipaddress_eth0 => 192.168.xxx.xxx

kernel => Linux

kernelrelease => 2.6.31-22-generic-pae

kernelversion => 2.6.31

lsbdistcodename => karmic

lsbdistdescription => Ubuntu 9.10

lsbdistid => Ubuntu

lsbdistrelease => 9.10

lsbmajdistrelease => 9

macaddress => 00:16:ec:da:bc:21

macaddress_eth0 => 00:16:ec:da:bc:21

manufacturer => HP Pavilion 061

memoryfree => 1.28 GB

memorysize => 1.90 GB

netmask => 255.255.255.0

netmask_eth0 => 255.255.255.0

network_eth0 => 192.xxx.xxx.0

operatingsystem => Ubuntu

operatingsystemrelease => 9.10

physicalprocessorcount => 1

processor0 => Intel(R) Pentium(R) D CPU 2.80GHz

processor1 => Intel(R) Pentium(R) D CPU 2.80GHz

processorcount => 2

productname => RC562AA-ACJ a1514in

ps => ps -ef

rubysitedir => /usr/local/lib/site_ruby/1.8

rubyversion => 1.8.7

serialnumber => INI6370L08 AP640

sshdsakey => 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

sshrsakey => AAAAB3NzaC1yc2EAAAABIwAAAQEAy6l8d9gOYGQ9CHQoQBmoJ74NDnSZBreIXD/nsAwj93i7pCv9LJ1ifybP7am7kJq3qaHhoU3sB8oaTUUfeXMXGfoHrwRvcIdYFdDKQ7KvjpZU7jWSsKECk0aibaVzqni5sixquLXcjte18T7DU1ki/K/sQPvSQII2Y9EWOAzdzoov4ezj30uer6sR6BkXSR5LK3LW+qoRPKT+xIQMBseJ9TZ8Tz7hpiz1AmcmPNhLj61aK0/1bbRBKzfr8bd8kkI3vkHvfE5Sqzu4VplSCNxa9QNG9jNFCdN/cGCYlL7GdWPNdBP3jzFXeLNgH+bTA82FrBqFaQo5bUOBSSCKFZyuaQ==

swapfree => 5.58 GB

swapsize => 5.58 GB

timezone => IST

type => Desktop

uniqueid => 007f0101

uptime => 4 days

uptime_days => 4

uptime_hours => 109

uptime_seconds => 395539

virtual => physical

sc (service control) command to start/stop any service in windows

SC (service control) command, allows u a lot more options than just start & stop a service
DESCRIPTION:SC is a command line program used for communicating with the NT Service Controller and services.
USAGE: sc [command] [service name] ...
Ex: sc query dhcpserver
sc start dhcpserver
Note:We should know the Service name of any windows service.
Further help on commands can be obtained by typing: "sc [command]"
Commands:
query-----------Queries the status for a service, or enumerates the status for types of services.
queryex---------Queries the extended status for a service, or enumerates the status for types of service.
start-----------Starts a service.
pause-----------Sends a PAUSE control request to a service.
interrogate-----Sends an INTERROGATE control request to a service.
continue--------Sends a CONTINUE control request to a service.
stop------------Sends a STOP request to a service.
config----------Changes the configuration of a service (persistant).
description-----Changes the description of a service.
failure---------Changes the actions taken by a service upon failure.
qc--------------Queries the configuration information for a service.
qdescription----Queries the description for a service.
qfailure--------Queries the actions taken by a service upon failure.
delete----------Deletes a service (from the registry).
create----------Creates a service. (adds it to the registry).
control---------Sends a control to a service.
sdshow----------Displays a service's security descriptor.
sdset-----------Sets a service's security descriptor.
GetDisplayName--Gets the DisplayName for a service.
GetKeyName------Gets the ServiceKeyName for a service.
EnumDepend------Enumerates Service Dependencies.

useradd in ubuntu

The useradd command will let you add a new user easily from the command line:
#useradd username
Ex : useradd user1
This command adds the user, but without any extra options your user won’t have a password or a home directory. You can use the -d option to set the home directory for the user. The -m option will force useradd to create the home directory.
We will try creating a user account with those options, and then use the passwd command to set the password for the account. You can alternatively set a password using -p on the useradd command, but I prefer to set the password using passwd.
#useradd -d /home/user1 -m user1
#passwd user1
Important locations for users
   * /etc/passwd - User account information.
   * /etc/shadow - Secure user account information such as password.
   * /etc/group - Group account information.
   * /etc/default/useradd - Default values for account creation.
   * /etc/skel/ - Directory containing default files.
   * /etc/login.defs - Shadow password suite configuration.

mount windows shared folder from ubuntu

Two methods, depending on share host cifs or smbfs
smbfs is the "original" method.However, smbfs is not compatible with security signatures, which are enabled by default and
not recommended to disable on Windows Server 2003 and later. If a share is served by Windows Server 2003 or later, you should use cifs.
The "smbfs" package provides the tools needed to mount "smbfs" and "cifs" filesytems. You may have smbfs installed on your machine. If not, run

#sudo apt-get install smbfs
Mount Windows Shared folder with windows authentication
#mkdir -p /opt/win-share
#mount -t cifs //192.168.155.xxx/tools/ /opt/win-share/ --verbose -o username=administrator #this will prompt for administrator password
#mount -t cifs //192.168.155.xxx/tools/ /opt/win-share/ --verbose -o username=administrator,password=****
Mount Windows Shared folder without authentication
#touch win-share-pass
#vi win-share-pass #open win-share-pass and add below lines on it
username=administrator #we can specify a user name to access the shared folder
password=********
Save the file

mount -t cifs //192.168.155.117/tools/ /opt/win-share/ --verbose -o credentials=/home/user/win-share-pass

Useful commands for Windows

Type below commands and press Enter in the command prompt in Window

net view : Display information about the domains, computers, or resources that are shared by the specified computer, including the offline client caching settings.
net share : Create, delete, manage, and display shared resources.
net file : View and control resources that are shared on the network. The Server service must be running for you to use this command.

net config : View the maximum number of users who can access a shared resource and the maximum open files per session.

how to mount ISO on Ununtu

Mount iso in Ubuntu
mount -o loop -t iso9660 /path/to/iso/file.iso /media/cdrom
umount /media/cdrom or umount -f /media/cdrom

commands to check whether vmware tools installed or not in ubuntu guest & the version

# ps -ef | grep vmware-guestd
root 10213 1 0 15:33 ? 00:00:00 /usr/lib/vmware-tools/sbin32/vmw are-guestd --background /var/run/vmware-guestd.pid
root 10446 10429 0 15:44 pts/0 00:00:00 grep vmware-guestd

OR

# ps -ef | grep vmware-tools
root 10213 1 0 15:33 ? 00:00:00 /usr/lib/vmware-tools/sbin32/vmware-guestd --background /var/run/vmware-guestd.pid
root 10559 10429 0 15:52 pts/0 00:00:00 grep vmware-tools
# vmware-config-tools.pl -h
Use of uninitialized value $gSystem{"system"} in concatenation (.) or string at /usr/bin/vmware-config-tools.pl line 2421.
VMware Tools 4.0.0 build-171294 for configurator
Usage: /usr/bin/vmware-config-tools.pl [[-][-]d[efault]] [[-][-]c[ompile]]
[[-][-]p[rebuilt]] [[-][-]t[ry-modules]] [[-][-]p[reserve]]
[[-][-]o[verwrite][[-][-]m[odules-only]] [[-][-]k[ernel-version] version]
. default: Automatically answer questions with the proposed answer.
. compile: Force the compilation of kernel modules.
. prebuilt: Force the use of pre-built kernel modules.
. try-modules: Try to load all the compatible modules . preserve: Always
preserve user-modified configuration files.
. overwrite: Always overwrite user-modified configuration files.from the VMware
Tools package.
. modules-only: Only build/install kernel modules, skip all other configuration
steps.
. kernel-version: Build/install modules for the given kernel version instead of
the running one, implies modules-only, skip-stop-start and compile.
Command line arguments: The acceptable characters are:
   the letters A, B, C, ...,
   the letters a, b, c, ...,
   the numbers 0, 1, 2, ...,
   and the special characters '_' and '-' and '='.

# grep buildNr /usr/bin/vmware-config-tools.pl
  my $buildNr;
  $buildNr = '4.0.0 build-171294';
  return remove_whitespaces($buildNr);

Add Swap Partition in Linux/Ubuntu

  Create a 512MB swap file
  #dd if=/dev/zero of=/mnt/new.swap bs=1M count=512
  Change Permission to new.swap
  #chmod 600 /mnt/new.swap
  Formatting that file to create a swapping device:
  #mkswap /mnt/512Mb.swap
  Adding the swap to the running system:
  #swapon /mnt/512Mb.swap
  To check swap info
  #cat /proc/meminfo.
Making the change permanent, open fstab
# vi /etc/fstab
Add below line at the end of the file and save.
/mnt/new.swap none swap sw 0 0

Change Computer or Host Name in Windows Using Command

Below is the command to rename Computer Name or Hostname in Windows.Changing Computer name will require a reboot. Follow below commands to change computer name and reboot system.

wmic computersystem where name="OLDNAME" call rename name="NEWNAME"
shutdown -r ---Reboot System
hostname ----Display Computer Name or Hostname in Windwos and Linux as well.

check running status & kill services in Windows from command line

tasklist --- To see the list of running services & PID (Process ID) on Windows from command line.

taskkill --- To kill any running services on Windows from command line

Go to Start > Run, then type CMD and press Enter.
In the Command Prompt window type any of the above commands(taskkill,tasklist) and press enter key

Ex: taskkill /PID 1412 /PID 139 /T /F ---- To kill running service

above command will kill process id 1412 and 139 forcefully

/T -Tree kill

/F -forcefully

Fastest way of transferring files between 2 server's over network in Linux

Fastest way of transferring files between 2 server's over network in Linux

-- SCP : It showed 20MB/sec
-- FTP : Requires ftp installed id/password : 40MB/sec
-- NetCAT : Might work if netcat is installed. : 60MB/sec
   source : tar -cvzf /dir/ |netcat -l 7777
   client : netcat source_ip:7777 |tar -xvzf path

-- Using Python / WGet : 80MB/sec

Server:
# cd $folder_have the file
# Start python webserver with this command.
python -m SimpleHTTPServer
Client :
wget -c http://Server IP:8000/$file
-c will recover from a file break if something broke half way.

Convert Windows Physical System to Virtual Using disk2vhd

Disk2vhd is a tool that creates VHD (Virtual Hard Disk - Microsoft's Virtual Machine disk format) versions of physical disks for use in Microsoft Virtual PC or Microsoft Hyper-V virtual machines (VMs) or Latest KVM Hypervisor.

Steps to Convert Windows 2003 Physical System to VHD format
============================================
1.Download disk2vhd tool from below link into windows server 2003
http://technet.microsoft.com/en-us/sysinternals/ee656415.aspx
2.Extaract Disk2vhd.zip file
3.Run or double click disk2chd.exe, it will pupup a windows with all drives selected.On it select the drive you would like to convert into VHD format. De-select other drives and only keep selected C drive.
For now we need to convert only C Drive, so select only C Drive.Please find enclosed image.
4.At VHD File Name:
Browse a target location where we want to store or save VHD. Make sure we have sufficient space on it.Means we should have free space on target drive as C drive' data size.
5.Click on Create to start conversion process.
6.Once the conversion process completed, click Close to close the tool.

Domain,Tree,Forest & Domain Controller

Domain: Domain is a logical grouping present in the network, in which one or more systems can access one or more shared resources and there is a centralized database.
All the systems are depend upon the Server carrying the Database.
Once we created Domain, it logically creates Domain,Tree and Forest
Tree: Tree is a set of one or more Domains with contiguous names or Collection of multiple Domains.
Root Domain: The first Domain created is the "Root Domain" of the first tree.The first domain that you create in your Active Directoryforest is automatically designated as the forest root domain
Child Domain: Other Domains in the same domain tree is called Child Domain.
Parent Domain: A Domain immediately above another domain in the same domain tree is it Parent Domain

Forest: Forest is a collection of multiple Trees.

Domain Controller: The system which maintain Active Directory Service(ADS) is called Domain
Controller.
ADDS: In Windows Server 2008 the Active Directory Service(ADS) is called Active Directory Domain
Service(ADDS).

smtp mail test in windows with Telnet

Testing with Telnet: Sent a mail using command line
You can also use TELNET to test your SMTP service. SMTP uses port number 25,so in order to use telnet to open an SMTP session with the command
telnet abc.test.com 25 or telnet 192.168.10.17 (EX:IP of smtp server space and port number)
If the connection is successful, we should see a banner and a command line interface.We then need to follow RFC 821 for the accepted SMTP commands, which are quite simple(as the name says...)
220 abc.test.com Microsoft ESMTP MAIL Service, Version: 5.0.2195.5329 ready at Mon,25
Nov 2002 02:51:06 +0200
helo abc.test.com or helo 192.168.10.17 (EX:ip address of smpt or name)
250 abc.test.com Hello [192.168.0.100]
mail from:admin@gmail.com or mail form zyz (Ex:can specify mail id or name)
250 2.1.0 admin@gmail.com....Sender OK
rcpt to:testmailid@gmail.com (mail id to whom you want to send)
250 2.1.5 testmailid@gmail.com
data
354 Start mail input; end with .(Means once you done with matter then press enter and .(dot) to finish)
subject: this is a test
Hi John
I'm trying to test this connection from Telnet.
Let me know if you get this message.
. (this dot will end of your mail matter)

=========================
options to send mail
=========================
telnet [-a][-e escape char][-f log file][-l user][-t term][host [port]]
-a      Attempt automatic logon. Same as -l option except uses
         the currently logged on user's name.
-e      Escape character to enter telnet client prompt.
-f      File name for client side logging
-l      Specifies the user name to log in with on the remote system.
         Requires that the remote system support the TELNET ENVIRON option.
-t      Specifies terminal type.
         Supported term types are vt100, vt52, ansi and vtnt only.
host    Specifies the hostname or IP address of the remote computer
         to connect to.
port    Specifies a port number or service name.

Virtualization

Virtualization:Industry moving from concept of buying to leasing
    Software as a Service ( SaaS)
    Platform as a Service (PaaS)
    Hardware as a Service ( HaaS)

Virtualization is the creation of a virtual (rather than actual) version of something, such as an operating system, a server, a storage device or network resources.
Allows to create multiple virtual machines on a single physical server
Allows to run multiple operating System environment in a single Physical server.
Better utilization of Hardware resources - CPU, Memory
Reduces the need for huge no of Physical servers

There are several different forms of virtualization that need to be understood as a basis for making the right technology choice.
* Network virtualization is a method of combining the available resources in a network by splitting up the available bandwidth into channels, each of which is independent from the others, and each of which can be assigned (or reassigned) to a particular server or device in real time. The idea is that virtualization disguises the true complexity of the network by separating it into manageable parts, much like your partitioned hard drive makes it easier to manage your files.
   * Storage virtualization is the pooling of physical storage from multiple network storage devices into what appears to be a single storage device that is managed from a central console. Storage virtualization is commonly used in storage area networks (SANs).
   * Server virtualization is the masking of server resources (including the number and identity of individual physical servers, processors, and operating systems) from server users. The intention is to spare the user from having to understand and manage complicated details of server resources while increasing resource sharing and utilization and maintaining the capacity to expand later.
   * Server Hardware Virtualization. Also known as a hypervisor, Server Hardware Virtualization runs a very lightweight core operating system. The hypervisor can host independent virtual machines (VMs). This form of virtualization requires hardware that has embedded virtualization awareness capabilities. Since the hypervisor is very lightweight, there is little overhead in the system, which allows for more scalability in the virtual machines.
   * Server Software Virtualization: An operating system, such as Windows Server® 2003 or Windows Server 2008, runs an application that is able to host virtual machines. Each virtual machine runs a completely separate operating system and application set.
   * Presentation Virtualization: Centralized systems host multiple user sessions, and all processing is done on those host systems. The user sessions are isolated from each other. Only the presentation information, such as keyboard and mouse inputs, and video updates are sent between the client and the host system. The client can be a full Windows-based workstation or a Windows-based terminal device.
   * Application Virtualization: An application is isolated from the underlying operating system by means of wrapper software that encapsulates it. This allows multiple applications that may have conflicting dynamic link libraries (DLLs) or other incompatibilities to run on the same machine without affecting each other.
   * Desktop Virtualization: This is similar to Server Software Virtualization, but it runs on client systems such as Windows Vista®. The client operating system runs a virtualization application that hosts virtual machines. This is often used when a specific person needs to run one or a limited number of legacy applications on a legacy operating system.
Virtualization products
Linux
Linux virtualization users have two free, open source hypervisors to choose from: Xen and KVM.
VMware
VMware workstation
VMware Fusion ( MAC os)
VMware server ( GSX Server)
VMware ESX Server 4.0/4.0i & Vsphere
Microsoft
Microsoft Virtual PC
Microsoft Virtual Server
Hyper-V (This feature available only on Microsoft Windows Server 2008 )
Citrix
XEN Server
Virtualization environment
Host Machine - Physical server/Machine where Virtualization software deployed
Virtualization software : Software that allows to create, manage virtual machines & Virtual environment
Guest operating system : Operating system installed into virtual machine
Virtual Machine or VM :A machine is made up of Software files, provides Virtual hardware created by Virtualization software.A Virtual Machine will have Virtual Devices like Processor, Disk, Ethernet, Motherboard, VGA, etc..

properties of user in linux

To check the user properties grep for a user name.
root# grep user-name | /etc/passwd
user-name:x:500:500: :/home/user-name:/bin/bash # this line contains 7 information of a user.

{user-name}:{x}:{500}:{500}:{ }:{/home/user-name}:{/bin/bash} # I have divided each part with a bracket.

1.{user-name}                    = User name
2.{x}                       =Encrypted password
3.{500}                               =UID
4.{500}                               =GID
5.{ }    =Comment
6.{/home/user-name}       =User's default or home directory
7.{/bin/bash}                      =Default Shell of Linux

Users in Linux

In Linux platform their are 2 types of user such as System User and Normal User
System User : The user which are created default by Operating System are called system users.The function of this user to access or manange system services which cannot be utilized by normal user. The system services are Ex:shutdown,restart and application service like mail services and apache services etc..
The system users can also be recognized with the help of an UID(Unique Identifier) which starts from 0(zero) and reserved up-to 499 by default.

Normal User: The user which are created manually by an administrator or by a system user to access system objects and resources are called normal users. Normal user can be recognized with the help of an UID(Unique Identifier) which starts from 500 and reserved up-to 60,000 by default.

Authentication Protocol in Windows

NTLM(New Technology Lan Manager)
It is used authenticating user credentials in a work-group model.In a work-group model SAM(Security Account Manager) database used to store and retrieve user credentials.

Kerberos
It is used to authenticating user credentials in a Domain environment. In a Domain environment NTDS.DIT database is used to store and retrieve user credentials.

Configure Static IP for OpenSolaris

Configure Static IP for OpenSolaris
Follow step below:
   1. svcadm disable network/physical:nwam (Execute in terminal)
   2. svcadm enable network/physical:default (Execute in terminal)
   3. cp /etc/nsswitch.dns /etc/nsswitch.conf
   4. Put DNS in /etc/resolv.conf ( eg: nameserver 172.16.17.x, this should be your dns server ip)
   5. Put the default router(gateway) ip into /etc/defaultrouter (eg:172.16.17.11)
   6. #dladm show-phys or ifconfig -a (Check the Enternet Interface of your system.
   7. If your Ethernet interface name is e1000g0, create /etc/hostname.e1000g0, and add below two lines as
   eg: line 1: 172.16.17.x (the static IP you wuold like to assign)
        line 2: netmask 255.255.255.0 broadcast + up
   8. Restart Machine (Some time reoot is not required, for confirmation reboot and check if you are getting
    static ip)

Outher OpenSolaris commands
cat /etc/nwam/llp ( to check the ip )
#svcadm restart network/physical:nwam (Restart nwam:)
Add your new IP and hostname into /etc/hosts following the same format as already exists
#svcadm enable network/physical:default
#svcadm restart network/routing-setup (To add just the ip address of your default router to /etc/defaultrouter)
#dladm show-phys or ifconfig -a (Check the Enternet Interface of your system.
LINK         MEDIA               STATE      SPEED DUPLEX    DEVICE
yge0            Ethernet               unknown    0           unknown      yge0
e1000g0      Ethernet               up              1000      full              e1000g0
e1000g1      Ethernet               unknown    0            half         e1000g1
ath0             Wifi                     up              1000      full          ath0

change boot order for dual boot(Windows XP and Ubuntu)

If you installed Windows and Ubuntu as dual boot then by default windows will boot 1st. To change the boot order we need to change the boot order.

Change default operating system at boot

To change which operating system starts by default when the computer starts up, edit the grub configuration file.

1.Make a backup of the configuration file, and open it in a text editor:

cp /boot/grub/menu.lst /boot/grub/menu.lst backup-menu.lst ### this will to keep a backup of original file

vi /boot/grub/menu.lst ### open menu.lst file

2. Find “default 0” line in the menu.lst file

Ex: type /default and press enter to go to that line.

3. Replace with the following line:

default X

Note: You should replace X with a number, according to the order which your operating systems appear in the configuration file. You should start counting from 0. For example, if you wish the default operating system to be the first in the list, replace X with 0, if you wish the default operating system to be the second in the list, replace X with 1, and so on.

post configuration of mysql in ubuntu : allow database access to remote system

Configuration changes on MySQL to accept remote connections from a particular ipaddress

    If you are using Debian Linux file is located at /etc/mysql/my.cnf location
    If you are using Red Hat Linux/Fedora/Centos Linux file is located at /etc/my.cnf location
    If you are using FreeBSD you need to create a file /var/db/mysql/my.cnf

now edit my.cnf depending on your Linux
vi /etc/mysql/my.cnf

Make sure line skip-networking is commented
Add line, go to the line bind-address and repalce 127.0.0.1 to your sql server IP
bind-address=YOUR-SERVER-IP
exit my.cnf file after saving...
/etc/init.d/mysql restart

  open mysql prompt
mysql -u root -p mysql
GRANT ALL ON yourdatabasename.* TO username@'your-ipaddress' IDENTIFIED BY
'PASSWORD';

Note: your databasename is replace by your database name and your-ipaddress is replaced by ip address of remote machine from which you want to connect to MySql database

how to restore windows MBR : fix windows boot loder (MBR)

If a computer has dual boot with Windows and Linux, then the linux bootloder is used to boot the OS . So, if we loose linux OS or the linux partition deleted accidentally then the windows OS wouldn't boot and we will get grub screen. To resolve this issue we need to fix the windows MBR(Mater Boot Record).
Requirement for this process:1.Windwos OS cd/dvd
2.Administrator password of Windows OS
Follow below steps for Windows XP and Windows Server 2003
1.Boot the windows os using os CD/DVD .Insert the Windows os CD/DVD into CD/DVD drive and reboot the system with CD/DVD.
2.Once the os boot with CD/DVD, press R to go to Repair Mode.
3.Press 1 to change environment to CD/DVD.
4.Give Administrator password of windows os.
5.Type FIXMBR and press enter.
6.Press Yes to continue
7.Remove CD/DVD form drive and reboot the system.
Now your windows will boot as normal.

Follow below steps for Windows 7

1. Boot your computer to the Windows 7 DVD (or to a "Repair CD"). At this screen choose to install now.
2. Select your language and click next.
3. Click the button for "Use recovery tools" and Click Next
4. Click on "Command Prompt".
5.We need to know what drive letter has been assigned the DVD drive to access the folder.
  Type diskpart and press enter
  Type list vouume and press enter ---This command will show all drives on the system.Remember the drive letter of CD/DVD
  Type exit and press enter
6.Type G: to go to G drive. ( Assue G is the CD/DVD drive)
  CD root and press enter
  Type dir and press. Verify that bootcect.exe is there in boot directory.
8. To restore the "bootsector code"
   Type bootsect /nt60 SYS /mbr and press enter
9. Type exit and reboot the system.

installation of SugarCRM in ubuntu server

Below packages required to Installed SugarCRM. In 2 different Ubuntu Server.
Ex: Server-01: Apache and PHP & Server-02: Database Server (MySQL)

Install all the required packages using the following commands on Server-02

sudo apt-get install mysql-server

Install all the required packages using the following commands on Server-01

sudo apt-get install apache2

sudo apt-get install libapache2-mod-php5 libapache2-mod-perl2

sudo apt-get install php5 php5-cli php5-common php5-curl php5-dev php5-gd php5-imap php5-ldap unzip

sudo apt-get install php5-mhash php5-mysql php5-odbc curl libwww-perl imagemagick

Creating Database for SugarCRM

mysql -u root –p
Then type your MySQL password and run this command

mysql> create database sugarcrm;
mysql> exit

Follow the steps to allow access of MySql form remote server or system

Loging into mysql server. Now need to edit my.cnf depending on your Linux

vi /etc/mysql/my.cnf

Make sure line skip-networking is commented.

Go to the line bind-address and replace 127.0.0.1 to your mysql server IP, the new line should look like below..

bind-address=YOUR-SERVER-IP

exit my.cnf file after saving...

/etc/init.d/mysql restart

open mysql prompt

mysql -u root -p mysql

GRANT ALL ON yourdatabasename.* TO username@'your-ipaddress' IDENTIFIED BY

'PASSWORD';

*yourdatabasename is replace by your database name,your-ipaddress is replaced by ip address of remote machine from which you want to connect to MySql database

Installed SugarCRM
Now you need to go to your webserver document root directory (default location is /var/www) or your choice…

cd /var/www

Download SugarCRM

http://dl.sugarforge.org/sugarcrm/1SugarCE6.1.0GA/SugarCE6.1.0/SugarCE-6.1.2.zip

Now unzip file for using this command

unzip SugarCE-6.1.2.zip

Changed the folder name

sudo mv SugarCE-6.1.2.zip sugarcrm

Changed the ownership of this folder

sudo chown –Rf www-data:www-data sugarcrm

Give Write permitions for apache on some of SugarCRM Files

cd /var/www/sugarcrm

sudo chmod 766 config.php
sudo chmod 766 custom
sudo chmod -R 766 data
sudo chmod -R 766 cache
sudo chmod -R 766 modules

Open php configuration file do below chane

vi /etc/php5/apache2/php.ini

Change
;memory_limit = 16M to memory_limit = 50M
Change
;upload_max_filesize = 2M to upload_max_filesize = 10M

Restart web server using the following command

sudo /etc/init.d/apache2 restart

Configure sugarCRM

Now open your webbrowser and enter the following address
http:// hostname or server-ip/sugarcrm/install.php
While configuring give mysql server ip and password as we have installed mysql database on different server.

Range of IP Address

There are 2 versions of IP i.e. IPV4 and IPV6
IPV4:IPV4 is called decimal doted notation, it is a 32bit address .
IPV6:IPV6 is called hexadecimal doted notation, it is a 128bit address..

IPV4 divided into classes.Please find below
Class A Range : 0.0.00 to 127.255.255.255        Reserved for LAN & WAN
Class B Range :128.0.0.0 to 192.255.255.255    Reserved for LAN & WAN
Class C Range:192.0.0.0 to 223.255.255.255     Reserved for LAN & WAN
Class D Range:224.0.0.0 to 239.255.255.255     Reserved for Multicasting
Class E Range: 240.0.0.0.0 to 255.255.255.255 Reserved for R&D(Research & Development)

IPV4 divided in Private and Public ip address.
Private IP address
Class A Range: 10.0.0.0 to 10.255.255.255
Class B Range:172.16.0.0 to 172.31.255.255
Class C Range:192.168.0.0 to 192.168.255.255
Above ip address are not valid for internet.These ip address are only valid for private organizations.All other ip address are public ip.

mount windows shared folder in Linux, Fedora & Ubuntu

#mkdir /mnt/win-shared-folder
#mount -o username=administrator,password=***** //192.168.239.17/shared-folder /mnt/win-shared-folder

create or add a new local user account in windows using command line

Create or add new local user account in windows using command line

net user /ADD /active:yes /expires:never /fullname:user-test /passwordchg:no

net user new-user 123!@# /ADD /active:yes /expires:never /fullname:wucc-test /passwordchg:no

linux file shareing server

Linux has 3 types of File Shareing Servers. P
1.FTP (File Transfer Protocol)
FTP usages port number 20 & 21
2.NFS(Network File Shareing)
NFS usages port number 204 and 111
3.Samba(It is a network service for file and print shareing)
Usages port number 137,138 & 139

Installation and configuration will be updated soon.....

ftp(File Transfer Protocol) server installation and configuration in linux

Before install and configuration of ftp server in linux.The ftp server called in linux is vsftpd(Very Secure FTP Daemon). Default ports for FTP are 20 and 21.
Port 20 is used for Data Channel or Data Communication(Upload or Download Data).
Port 21 is used for Control Channel or establish connection

Install vsftpd in linux: yum install vsftpd*
If we have download rpm of vsftpd then got the directory and ran below command
rpm -ivh vsftpd*
Once vsftpd is installed, it will create a default directory in /var/ftp/pub . By default vsftp allow only download.

To enable upload we need create a folder in /var/ftp/pub and allow download in vsftpd configuration file.
vsftpd.conf is a configuration of vsftpd located in /etc/vsftpd/.
1.Create download folder in /var/ftp/
mkdir -p /var/ftp/download
chmod 777 /var/ftp/downlad ###give full permission to download folder
2.Open vsftpd.conf and allow download
vi /etc/vsftpd/vsftpd.conf
Uncomment or remove "#" form line number 27th   ###This will enable uploading
Uncomment or remove "#" form line number 83rd ###This will provide message to user
Uncomment or remove "#" form line number 27th ###This will enable log file option. By default vsftpd doesn't creat any log file. Once we enable log then a log file will be created as vsftpd.log in /var/log/vsftpd.log
Need to restart vsftpd service to effect the chanes.
service vsftpd restart ### The settings temporary
chkconfig vsftpd on ### Settings saved permanently

Commands to connect ftp server and upload or download data.
ftp
ls                  ###List
get               ### Download data
mget            ### Download multiple
mget *       ###Download complete data
put              ### Upload Data
mput         ###Upload multiple files or folders
mput *    ###Upload complete data
!                 ### Exit form ftp session temporarily
exit            ### To back to ftp session
lcd /opt      ### Change Directory
bye           ### Quit ftp session
prompt     ### To enable or disable passive mode

map or disconnect a network drive in Windows

We can use the net use command to map or disconnect a network drive in Windows.

To map a network drive.

1.Click Start, and then click Run.

2.In the Open box, type cmd.

3.Type net use y: \\computer name or IP address\shared folder name, where y: is the drive letter you want to assign to the shared resource.

Ex: net use y:\\192.168.x.x\\abc

net use y:\\server-002\\abc

To disconnect a mapped drive:

1.Click Start, and then click Run.

2.In the Open box, type cmd.

3.Type net use y: /delete, where y: is the drive letter of the shared resource.

inittab file in ubuntu and linux

There is no /etc/inittab file in Ubuntu because Ubuntu has /etc/event.d/rc-default file
runlevel # to check current runlevel

The following runlevels are defined:
       N      System bootup (NONE).
       S      Single user mode (not to be switched to directly)
       0      halt
       1      single user mode
       2 to 5 multi user mode
       6      reboot