RHEV Manager Requirements

Requirements of RHEV
This post outlines the hardware and software requirements for installing the Red Hat Enterprise Virtualization platform. The requirements outlined herein are based on the minimum requirements for successful installation and configuration of a Red Hat Enterprise Virtualization environment. Production RHEV installations may have additional requirements depend on infrastructure.

Hardware requirements
To setup a Red Hat Enterprise Virtualization environment it is necessary to have, at least:

• One machine to act as the management server(RHEV-M).

• One machine to act as virtualization hosts(RHEV-H).

• One machine to use as client for accessing the Administration Portal.

• Storage infrastructure provided by NFS, iSCSI, SAN, or local storage.

Management Server Requirements (RHEV-M
The minimum hardware requirements outlined here are based on a typical small to medium sized installation.
===============================================================================
 Minimum                                                                Recommended
===============================================================================
A dual core CPU.                                                     A quad core CPU

4 GB of available system RAM.                                16 GB of system RAM.

25 GB of locally free disk space.                               50 GB of locally free disk space

1 NIC with bandwidth of at least 1 Gbps.                  1 NIC with bandwidth of at least 1 Gbps
===============================================================================

Virtualization Host Requirements (RHEV-Hypervisor).

A- CPU:  The Intel64 or AMD64 CPU extensions, and the AMD-V or Intel VT hardware virtualization extensions.

B- RAM: Virtualization hosts must have at least 10 GB of RAM and additional 1 GB for each virtual machine.

Software Requirements
Directory Services
Currently the two supported providers of directory services for use with the Red Hat Enterprise Virtualization Manager are Identity, Policy, and Audit (IPA) and Microsoft Active Directory. You will be able to learn IPA configuration soon on my blog as i am preparing for this.

Client Requirements.
To access the Administration Portal, you need a client with a supported web browser. The Administration Portal supports the following clients and browsers:

Clients.
 A-Windows XP,
 B-Windows 7 (x86, AMD64 and Intel 64), and
 C-Windows 2008/R2 (x86, AMD64 and Intel 64).

Browser.
 Internet Explorer 7 and higher on Windows, with the .NET Framework 4 installed. Firefox 10 or higher With SPICE plugin.

To check CPU Parameters use following commands:
#grep --color -E 'vmx|svm' /proc/cpuinfo 
you should see vmx flag for Intel or svm flag for AMD processor.

#grep --color -E 'nx' /proc/cpuinfo
you should see nx (No execute) flag is required for Hyper visor Installation.

Check detail of above options here
grep                =command to match pattern
--color             =display matched pattern highlighted
vmx|svm         =cpu flags required for virtualization vmx for Intel and svm for AMD processor
/proc/cpuinfo =file that contains the system information
nx                   =no execution a flag that prevent buffer overflow attack, must be present for hypervisor.

Installing RHEV Manager

Installation
Hello my dear friends in my previous post i have discussed a lot of about virtualization specially about Redhat virtualization, now its time to go for in deep, that is how to install RHEV-M. The Red Hat Enterprise Virtualization Manager and all of its dependencies are available via Red Hat Network ensure that you have all required packages and then follow simple steps to install RHEV-M.

Use yum to ensure that the most up to date versions of all installed packages are in use.
# yum upgrade

Update all existing packages and reboot necessary.
#yum update -y
#reboot 

Use yum to initiate installation of the rhevm package and all dependencies.
# yum -y install rhevm rhevm-reports

Configuration
Once package installation is complete the Red Hat Enterprise Virtualization Manager must be configured. The rhevm-setup command is used to perform this task. Use following steps to configure RHEV-M.

1. Start Setup Script
To begin configuring the system run rhevm-setup as the root user.
# rhevm-setup
Stop ovirt-engine service: yes
Override current httpd configuration:yes

2. Set Port for HTTP
The script prompts for entry of the port to use for HTTP communication. If you want to change it change value press Enter.

HTTP Port [80] :

3-Set Port for HTTPS
The script prompts for entry of the port to use for HTTPS communication.
HTTPS Port [443] :

4-Set Fully Qualified Domain Name (FQDN)
The script prompts for entry of the system's fully qualified domain name Host fully qualified domain name, note that this name should be fully resolvable
[rhevm.pod1.example.com] :

5-Set Administrator Password
The script creates an authentication domain internal to the Red Hat Enterprise Virtualization Manager for the default administrative account
Password for Administrator (admin@internal):example


6- Set Organization Name
The script prompts for entry of the Organization Name appears in the Subject field of the certificate
Organization Name for the Certificate :Red Hat Training

7- Configure Default Storage Type
The script prompts for selection of the default storage type that is used for the Default data center:NFS

8- DB Type: local

9- Set Database Password
Database password (required for secure authentication with the locally created database) :example

10- Configure NFS ISO Domain An ISO storage domain is used to store copies of removable media for use when provisioning and using virtual machines
Should the installer configure NFS share on this server to be used as an ISO Domain?
['yes'| 'no'] [yes] :

11- Local ISO domain path:/exports/rhevisos

12- Configure Firewall
Configure iptables:no

Press Enter to apply the configuration  otherwise type no to reconfigure.

Once the configuration values are applied. A number of services need to be started

13- Execute the rhevm-dwh-setup and rhevm-reports-setup command and select following options:
#rhevm-dwh-setup
Stop ovirt-engine service :yes
#Rhevm-reports-setup
Choose a password for admin users: redhat

12- Bind to the example.com domain authenticate as user rhevadmin with a password of  redhat by using following command. (however you can use local user also).

#rhevm-manage-domains -action=add -domain=example.com -user=rhevadmin -provider=IPA -interactive
Enter password:redhat
 #service ovirt-engine restart
Result: The Red Hat Enterprise Virtualization Manager has been installed and configured successfully. You
are now able to connect to the Administration Portal for the first time.

To access RHEV Manager open your browser and please go to the following URL: http://rhevm.pod1.example.com

1-Accept self-signed certificate

2-Click on web admin portal

3-Enter username(admin), password(redhat) & internal domain.

                                                                            See screenshot  here

 

4-Click on configure link.

5-Click on system permissions.

6-Click add and search rhevadmin

7-Select rhevadmin user choose Superuser from Role to Assign click ok and close

8-Logout from admin and try to login with rhevadmin user with example.com.

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Redhat Virtualization

Virtualization

Hello guy's finally i have decided to come with highly demanded technology in nowdays, that is virtualization. So here we are going to start a new series for Redhat Virtualization. I hope this will help you to understand virtualization technology and keep in touch for more upcoming posts.

Introduction: 

Virtualization is a technology that allows a physical system to be partitioned into multiple virtual systems which may each run its own Operating System simultaneously. These virtualization machines are isolated (independent)  from each other. Some major advantages of virtualization are:

1- Reduce management cost.

2- Lower operating costs.

3- Reduced power consumption.

4- Greater overall reliability.

5- Require less physical space.

6- Allow live migration and much more.

Virtualization Types

1-Full virtualization

Allow unmodified Operating systems and software's to be run on virutal machine exactly like as it were running on real hardware.

2- Hardware Assisted Virtualization
The development of Intel-VTx and AMD-V allow H/W assisted virtualization possible where CPU helps to Hypervisor to more efficience virtualization.

3- Parra-virtualization
Same kernel can be used for both physical and virtual machines that allow better performance.

There are so many organizations involved in this technology and each-one have its own features and limitations but in this post i will just going to discuss about REDHAT Virtualization technology.

Red Hat Enterprise Virtualization platform consists of one or more hosts and at least one manager. The virtual machines are hosted on the hosts. To understand this technology you should be familiar with some components of virtualization.

1-Red Hat Enterprise Virtualization Manager (RHEV-M)

The Red Hat Enterprise Virtualization Manager acts as a centralized management system that allows system administrators to view and manage virtual machines and images. It's a tool that runs on RHEL6 O.S.

The manager provides a graphical user interface to administer the whole virtual environment infrastructure. The RHEV-M can be manage through Administration Portal, User Portal, and an Application Programming  Interface (API).

1- The Administration Portal is used to perform setup, configuration, and management of the Red
Hat Enterprise Virtualization environment.

2- The User Portal is used to start, stop, reboot, and connect to virtual machines but you can not perform all tasks like as admin portal.

3- The REST API provides and interface for automation of tasks.

Red Hat Enterprise Virtualization Hypervisor (RHEV-H).
RHEV-Hypervisor is a fully featured virtualization platform for quick, easy deployment and management of  virtualized guests.

Red Hat Enterprise Linux Host(s).
The Red Hat Enterprise Virtualization Manager also supports the use of systems running RHEL6 AMD64/Intel64  versions as virtualization hosts (Means KVM as a Hypervisor).

=============================================
Red Hat Enterprise Virtualization Platform Overview
=============================================

Image source: www.redhat.com

1- This section used to provide authentication for users that may be LDAP/IPA or Active directory service.

2- PostgreSQL: This section define the database storage for entire virtual platform where all the will be stored.

3- VDSM is a service that is used to manage RHEV-Hypervisor and RHEL6 hosts by RHEV-manager.

4- This section describe protocols (SPICE or VNC) that can be used to take the console (means display) of RHEV-H.

5- This is a central point of administration for Linux virtual platform and managed by a tool called RHEV-M.

6- This is a point where administrator can administer RHEV-M through web interface, user can access virtual  machine through web interface, or this can be achieved via REST API (script based xml language) interface.

What is Difference between Workgroup and Domain

WORKGROUP AND DOMAIN

Hello my dear friends as we all know very well about network through which we can share and access information from one location to another location. A computer network can be divided logically in to two networking models:

• Work-group
• Domain

Workgroup is a peer-to-peer network while domain is a server-based network. The important differences between the two models are listed below:

WORKGROUP	DOMAIN
1. It is a peer-to-peer networking model.	1. It is a server-based networking model.
2. There is no client and no server. All the computers are equal in status.	2. There is a centralized dedicated server computer called Domain Controller (DC) which controls all other computers called Clients.
3. This model is recommended for small networks (up to 10 PCs).	3. This model is recommended for large networks.
4. There is no centralized administration and each computer is administrated separately.	4. There is centralized administration and each PC can be administrated and managed from the server.
5. There is only distributed processing.	5. Both centralized and distributed processing of resources happens.
6. In this model, low-grade OS like 2000/XP professional, win 98 etc. can be used.	6. In this model, high-grade OS like Win /2003/ server on the server end.
7.Workgroup can be given a name like sales, HR, accounts etc.	7.Domain can also given a name like xyz.com, abc.com etc.
8. User accounts are created in each PC and are called ‘Local Users’.	8. User accounts are created only in the server (DC) and are called ‘Domain Users’.

By default, the name of 'Workgroup' is Workgroup. however you can change it 

1-To change Workgroup Name:

2-right-click on My Computer. 


3-properties >  

4-Computer name > 

5-Change >

6-Workgroup > 

7-Type the name > O.K.

8-Restart the PC.

In a Workgroup network, name of Workgroup in every PC will the same. For example, if in your network, there are 10 computers and the name of Workgroup is Sales. So every computer will have Workgroup name as ‘Sales’. Click on ‘My Network Places’ > Entire Network > Microsoft Windows Network > you can see the name ‘sales’ > Click on the sales > you can see names of computers present in the Workgroup Sales. Click on a computer name to view its shared folders.

To create a Domain network, you have to first create a Domain Controller (DC) and then client computers are made member of the domain.
Read my active directory blogs for more information about Domain.

please share and like this, if it is useful for you.

Active Directory Group Types

Group are collection of users with some common attributes for easy management. Before creating groups in Active Directory i will recommend you to understand basic concept about group types and strategy. Today i am going to describe group types in active directory and hope this will help you to clear your concept.

Group Types:

1- Distribution

These groups are basically used by email application such as exchange server.
Distribution group does not have SID (Security Identification id).
They can not be used for security purpose.

2- Security
These types of group have a unique SID (Security Identification id).
They are used for security purpose.

Group Scope

Group Scopes are divided on the base of

Replication :     Where it can be replicate.
Membership :   What type object it can add.
Availability :      Where it can be used.

There are following group scopes are available.

A= Local Group
Members:    Users ,computers, local groups, global groups, and universal group from any domain in the forest.

Replication:  Membership can not replicate with other system.

Availability:  Only computer wide scope, local group can not be member of any other group.

B= Domain local:
Members:     Users, computers, global gropus, and universal group

Replication:  Membership are replicated in every domain controller in the domain.

Availability:  Available for only same domain.


C= Global group:

Membership: Limited membership only users, computers, and other global group can member of Global group.

Replication: All domain controllers in the domain.

Availability: Any domain in the forest, and trusting domain.

D= Universal group:
Membership: Users, computers, global groups, universal groups.

Replication:   Replicated via Global catalog.

Availability:   Available in everywhere in the forest.

Please share and like this if this is useful for you and your friends.

System error 5 has Occurred

Most of the users faces a problem with running many commands that shows system error 5 has occurred even running command with administrator user.

Reason:
There are two types of administrator in windows.
1- Built-in that is created by system automatically (has Full Authority).
2- Mad-in that is created by you during installation or later (has authority less than built-in).

So error occurred because you are trying to run command with mad-in administrator but some commands run  only with built-in administrator. In most of the windows operating system built-in administrator is
disabled by default. So you may need to enable this administrator  then you can run any command from cmd prompt.

How to enable built in administrator.
1-Click on Start button type cmd in search box
2-Right click on cmd select run-as administrator and you will access cmd prompt  with full admin rights.

 Now you can enable built-in administrator  by typing following command.
 net user administrator /active:yes
 yes means enable.
 no means disable.

 Note:You can also run any other command directly on cmd without error.

Note: Please share and like this post if this is useful for you.

New Changes in CCNA Exam

Hello guy's as we all know that CISCO has recently changed their CCNA code as well as syllabus also. Old code (that was 640-802) is now replaced by new code (that is 200-120).

Here are some list of topics that are included in new CCNA exam code and you should we aware about these if you belongs to IT sector and interested in CISCO technology. I hope this will help you and you will like this post.

1- NTP Network Time Protocol.

2- RSTP Rapid Spanning Tree Protocol.

3- PVSTP Per-VLAN Spanning Tree Protocol.

4- IPV6 Routing in Detail.

5- OSPF with Multi Area.

6- FHRP First Hop Redundancy Protocol .

7- HSRP Hot Standby Router Protocol.

8- VRRP Virtual Router Redundancy Protocol .

9- GLBP Gateway Load Balancing Protocol .

10- SNMP Simple Network Management Protocol.

11- Syslog A service that is used to store the logs of Router.

12- NetFlow An application for collecting IP traffic information.

13- GRE Tunnel A tunneling protocol that can encapsulate many protocols inside IP tunnels.

How to remove any virus without antivirus

There are some some Folder Viruses that can not be deleted directly even sometimes through Antiviruses so you can delete by a software called Unlocker. So download this software from given link and install it.  

http://www.filehippo.com/download_unlocker/
Ofter installing Right click on Folder that you want to delete (e.g $Recycle.Bin) and select unlocker then you will see a windowas shown in figure.

like below figure and select delete from drop down then ok, it should be delete now.

How to block facebook id if someone using my photo

Hello guys if someone other are using your photo's or pics that belongs to you or yours family member. You can block these photos by reporting to Facebook Authority, to do this you just need to follow these simple steps as given by me.

1-Open your browser and paste this url to open facebook violation reporting page.
https://www.facebook.com/help/contact/274459462613911
                                                   You will see next page look-like this.

2- Select your action that you need for example someone is using my photos.
                                                             see following screen shot

3-You should be redirected in next page where you need to select option according to you.

                                                   see following screen shot as given below.

4- Click fill out this form to submit your claim to Facebook Authority. You should be redirected in next page where you need to select content types that you want to block for example select photo.

5- Now you need to select following options according to your choice as given below in screen shot.

6- Finally click on send.

If you are authorized user to claim about blocking your photo using by someone other. Facebook Authority let you know by email and will take action that are required. Like and share if this is helpful for you.

Block any SIM card

How to block SIM card of mobile phone:

Hello guys today we are going to share a simple trick for block your enemy sim card, Blocking a sim card is too simple.What you have to do is just enter the below code in the desired phone.

**04*3814*7529*68243#

When you will enter above code it will ask you to enter the PUK code.To solve this issue just call customer care and get your PUK code. Entering of invalid PUK will cause permanent blocking of your SIM!

Note: This is only for Learning purpose, otherwise you will be self responsible.

Send anonymous sms anywhere

Hello guys I am here to share some sites which allow anonymous SMS but I would like to advise you not to use it for bothering any strangers (that is illegal). Use it to prank your friends and to send normal SMS.

Here are those some sites:-

http://seasms.com

This allows to send SMS to whole world anonymously. It allows 160 characters in sms.

http://spicesms.com/sendsms.php

It allows to send SMS only in india and it gives 130 characters.

http://www.bollywoodmotion.com/free-long-sms-india.html

It allows 500 characters in SMS and the service is very quick.

http://smsti.in/send-free-sms

It allows 160characters and this service is very fast.

http://Foosms.com

It is the very fast sms service but you can send only one SMS on a number within 24 hrs.

Note:-Do not send abusive messages to anyone. you can easily be traced with your IP address

Introducing Cisco IOS

Cisco Router IOS
The Cisco IOS is a proprietary kernel that provides routing, switching, internetworking, and telecommunications features. The first IOS was written by William Yeager in 1986,

Cisco router IOS software is responsible for:
1- Carrying network protocols and functions
2- Connecting high-speed traffic between devices
3- Adding security to control access and stop unauthorized network use
4- Supplying network reliability for connecting to network resources

Connecting to a Cisco Router
You can access the Cisco IOS through the console port of a router, from a modem into the auxiliary (or Aux) port, or even through Telnet. You can connect to a Cisco router to configure it, verify its configuration, and check statistics. Most often, the first method you would connect to router is the console port. The console port is usually an RJ-45 (8-pin ) connection located at the back of the router.

Booting Process of Router
1-When you first start a Cisco router, it will run a power-on self-test (POST).
2-If it passes, it will then look for and load the Cisco IOS from flash memory.
3-If an IOS file is present then it would expands it into RAM.
4-After that, the IOS loads and looks for a valid configuration the startup-config that’s stored in (NVRAM).

Router Configuration Modes
One key to navigating the CLI is to always be aware of which router configuration mode you are currently in (see Table 1.1). You can tell which configuration mode you are in by watching the CLI prompt.

Router Configuration Modes
Mode             Definition                                                                             Example
-------------------------------------------------------------------------------------------------------------------------
User                 EXEC mode Limited to basic monitoring commands            Router>
-------------------------------------------------------------------------------------------------------------------------
Privileged       EXEC mode Provides access to all other router commandsRouter#
-------------------------------------------------------------------------------------------------------------------------
Global mode   Commands that affect the entire system                             Router(config)#
-------------------------------------------------------------------------------------------------------------------------
Specific mode Commands that affect interfaces, routing processes,         Router(config-subif)#
or lines only
-------------------------------------------------------------------------------------------------------------------------         
Once you understand the different modes, you will need to be able to move from one mode to another within the CLI.

Command Meaning
Changes from user EXEC to privileged EXEC mode
Router>enable

Changes to user EXEC from privileged EXEC mode
Router#disable

Changes to global configuration mode from privileged mode
Router#config term

Exits from any configuration mode to privileged
mode (Ctrl+Z is also commonly used)
Router(config)#exit

Enters interface configuration mode from global configuration mode
Router(config)#interface <int>
example: Router(config)#interface fa0/0

Enters subinterface configuration mode from global configuration mode
Router(config)# interface <subint>
example: Router(config)#interface fa0/0.1

Enters line configuration mode from global configuration mode
Router(config)#line <line>
example: Router(config)#line console 0

Enters router configuration mode from global configuration mode
Router(config)# router eigrp 1 

Setting a hostname on a router:
Router#config t
Router(config)#hostname dixit
dixit(config)#

Configure NTP Server in Linux

According to the Red Hat Exam Prep Guide, you need to be able to synchronize clients with a higher stratum server. The term stratum is used to define different levels, from 1 to 15, of time servers that are available to sync with. A stratum 1 time server is the most accurate. For load balancing and redundancy, you would probably want to configure a primary NTP server and a secondary NTP server to sync with a stratum 1 time server. Now let’s look more closely at both the server and client side of NTP.

Configure NTP server
Step 1. Verify that the package has been installed:
# rpm -qa | grep ntp

To configure the primary NTP server, let’s look at part of the config file that comes with the system:
#vim /etc/ntp.conf
...
server 0.rhel.pool.ntp.org
server 1.rhel.pool.ntp.org
server 2.rhel.pool.ntp.org
...
#server 127.127.1.0
#fudge 127.127.1.0 stratum 10
The first three lines shown here are the Internet (public) NTP servers that you sync with for the correct time. The fourth server option, which is usually based on the BIOS click if used.

Step 2. Start the NTP service:
# service ntpd start

Client configuration:
With the server configured, you can turn your attention over to one of the client systems. For this example, use the Client01 system to sync with the server1 (192.168.1.100) primary NTP server.

Define server1 as the primary time server and make sure the driftfile line is uncommented:
#vim /etc/ntp.conf
...
Server 192.168.1.100
driftfile /var/lib/ntp/drift

Step 1. Use iptables to create the required firewall rules:
# iptables -I INPUT  -p udp -m udp --dport 123 -j ACCEPT
# iptables -I INPUT  -p tcp -m tcp --dport 123 -j ACCEPT

Step 2. Save the firewall rules you just created:
# service iptables save

Step 3. Then restart the iptables service:
# service iptables restart
#service ntpd restart

Step 4. Specify the upstream server that you want to sync against:
# ntpdate 0.rhel.pool.ntp.org

Step 5. Start the service again:
# service ntpd start

Step 6. Verify that the time is accurate with the date command:
# date

The next troubleshooting command is ntpq, which enables you to query for other NTP servers. Here, the only concern is the -p option, which polls for other NTP servers:
# ntpq -p

Process Management in Linux

Every time a program or command is run, a process is created for it. These processes are all unique and identified by the process identification (PID).

Here are some of the process management commands you can use:
ps Displays information about running processes

kill Terminates a process 

pgrep Finds a process based on its PID

pidof Displays all processes related to a service or command

top Monitors system resources (similar to Task Manager in Windows)

renice Adjusts the priority of a particular process

1-To view processes with more detailed information, you can use the following command:
# ps u
Or you could also use following command for more detail.
# ps aux

2-What happens if any process running on your system becomes out of control? you can use the kill command to terminate the process, even if it isn’t responding.
Syntax: kill PID

To find the PID(s) belonging to the SSH service, use the following:
# pidof sshd
4286
To achieve the same information you can also use the pgrep command:
# pgrep sshd
4286
Where 4286 is pid of sshd service
To kill the process forcefully the SSH service, you can use the following:
# kill 4286

top This command gives you an overview of processes on the system, including memory usage, CPU utilization, and more. Look the output as shown in figure (top 1.0).
#top                            
                                                                              top 1.0

You can use the renice command to change priority on the CPU.
Syntax: renice <priority> [options]
Options:
-p PID Changes process priority for a particular PID
-u user Changes process priority for a particular user(s)

The priority values range from –20 (very high priority) to 20 (very low priority).
For example following command will change the priority as -2 for pid 3874.
# renice -2 3874

Using the free Command The free command allows you to display the amount of free and used memory on the system. To do so, type the following at a shell prompt:
#free
 
Using the System Monitor Tool
The Resources tab of the System Monitor tool allows you to view the current CPU usage on the system.
To start the System Monitor tool, either select Applications > System Tools >? System Monitor from the panel, or type gnome-system-monitor at a shell prompt. Then click the Resources tab to view the system's CPU usage and Memory usage, (look figure System Monitor 1.0 ).

System Monitor 1.0

Job scheduling Using Crontab

Ther are two utilities that you can use to schedule a job in Linux 1- AT, 2- CRONTAB.
A-at
At utility is used to schedule a one-time task at a specific time. Before configuring at make sure that service is running and set start to boot by using following commands.
#service atd start
#chkconfig atd on

If you have any problem regarding service management click here to know more.
To schedule a one-time job for a specific time with the At utility, do the following:
Step 1. On the command line, type the command at TIME, where TIME is the time when the command is to be executed.

The TIME argument can be defined in any of the following formats:
HH:MM specifies the exact hour and minute; For example, 04:00 specifies 4:00 a.m.
midnight specifies 12:00 a.m.
noon specifies 12:00 p.m.
MONTHDAYYEAR format; For example, august 15 2013 specifies the 15th day of august in the year 2013.

Step 2. In the displayed at> prompt, define the job commands:
Type the command the job should execute and press Enter, repeat the step to provide multiple commands.
Once done, press Ctrl+D on an empty line to save task.

Exercise: Following example this will create a kamal directory on root's Desktop at 12:03 p.m.
Step 1.#at 1203
a1>mkdir /root/Desktop/kamal
at>ctl+d (to save)

To view the list of pending jobs, use the atq command.
Step 2. #atq
You can restrict the access to the at commands using the /etc/at.allow and /etc/at.deny files.
If the file at.allow exists, only users listed in the file are allowed to use at and the at.deny file is ignored.

B-Crontab.
In any operating system, it is possible to create jobs that you want to reoccur. This process, known as job
scheduling, is usually done based on user-defined jobs. For Red Hat, this process is handled by the cron service, which can be used to schedule tasks (also called jobs).

To start working with cron, you first need to look at the two config files that control access to the cron service. These two files are:
1-The /etc/cron.allow file:
 If it exists, only these users are allowed.
 If it doesn’t exist, all users except cron.deny are permitted.
2-The /etc/cron.deny file:
 If it exists and is empty, all users are allowed

You can use the crontab command to create, edit, and delete jobs.
Syntax: crontab [-u user] [option]
Options:
-e Edits the user’s crontab
-l Lists the user’s crontab
-r Deletes the user’s crontab

/etc/crontab file represent scheduled jobs and have the following format:
minute hour day month day of week username command

The following define the time when the job is to be run:
minute any integer from 0 to 59

hour  any value from 0 to 23

day  any value from 1 to 31 (must be a valid day if a month is specified)

month  any value from 1 to 12 (you can also use as jan, feb)

day of week  any value from 0 to 7, (0 or 7 Sunday) (or sun, mon)

username specifies the user under which the jobs are run

command command to be executed

Exercise1:
Step 1. Verify that the cron service is currently running:
# service crond status

Step 2. Also verify that the service is set to start when the system boots:
# chkconfig --list crond

Step 3. #vim /sample_script
#!/bin/bash
# Send a msg to all users on the console
wall “Hello World”

Save the file and set the following permissions:
# chmod 775 /sample_script

Step 4. Set up user1’s crontab:
# crontab -u user1 -e

Step 5. Add the following line:
* * * * * /sample_script
*/2 * * * * /sample_script
 Save the file and quit the editor.

Because we are using * in every field ofter 60 seconds you will see the message ”Hello World” on
your screen. In second line */2 means this will execute ofter every 2 minute.

List the current cron jobs of user01:
# crontab -u user

To remove a user’s crontab jobs, use the following command:
# crontab -u user1 -r1 -l

Configure ACL in RHEL6

ACL is extended set of permissions on files and directories that give advanced security when needed. For example you can set different permission for different user on a single file or directory. Two commands control ACLs: getfacl and setfacl. When you use the ls -l or ll command, a plus sign (+) on the side of the permission indicates ACL permission.

Step 1.  Before you can even use ACLs, however, you need to make sure that the file system has been mounted with the ACL parameter:
# mount | grep acl

If nothing is returned, it means that all currently mounted file systems do not have ACLs set up to be used. To mount the file system with the ACL option use the following command:
# mount –t ext4 -o acl,remount /dev/sda5 /data

Step 2. To verify, you can use the previous command:
# mount | grep acl
/dev/sda5 on /data type ext4 (rw,acl)

Step 3. Add the following line in your /etc/fstab file:
/dev/sda5 /data ext4 defaults,acl 1 2
Save and close the file.

Step 4. To make the changes take effect, you need to remount the file system:
# mount -o remount /data

Step 6. You can now verify that your file system has the ACL option:
# mount | grep -i acl
/dev/sda5 on /data type ext3 (rw,acl)

Exercise: To understand ACL let's look an example.
Step 1. Create a sample file (file1) on which you can test an ACL in the /data/backup directory:
#mkdir /data/backup
# cd /data/backup
#touch file1
Check default permission by using following command.
# getfacl /data/backup

Step 2. Set the test file so that user1 also has access to this file:
# setfacl -m u:user1:rwx /data/backup/file1
Where -m means modify, u means ACL for user, rwx means i want to set read, write and execute permission on user1 for file /data/backup/file1

Step 3. Now check the ACL permissions:
# getfacl /data/backup/file1

# file: file1
# owner: root
# group: root
user::rw-
user:user1:rwx
group::r--
mask::rwx
other::r--
Now login as user1 and try to modify file1 it should be modify.

Step 4. Use the setfacl command again to remove the ACL for user01:
# setfacl -x u:user1 /data/backup/file1
Notice -x is used to remove ACL.

Step 5. Verify that the ACL has been removed:
# getfacl file1
# file: file1
# owner: root
# group: root
user::rwgroup::
r--
mask:r--
other:r--

Step 6. If you have multiple ACLs set up on a single file, you can remove them all with the -b option
# setfacl -b filename

Components of Router

Router components:
To configure and troubleshoot a Cisco internetwork, you need to know the major components of Cisco routers and understand what each one does.

1-Bootstrap Stored in the ROM, It will boot the router and then load the IOS.

2-POST (power-on self-test) Stored in the ROM, the POST is used to check the basic  functionality of the router hardware and determines which interfaces are present.

3-ROM monitor Stored in the ROM, the ROM monitor is used for manufacturing, testing, and troubleshooting.

4-Mini-IOS Called the RXBOOT or bootloader by Cisco, the mini-IOS is a small IOS in ROM that can be used to bring up an interface and load a Cisco IOS into flash memory. The mini-IOS can also perform a few other maintenance operations. Mini-IOS is not present on every router.

5-RAM (random access memory) Used to hold ARP cache, routing tables, software and data structures that allow  the router to function. Running-config is stored in RAM, and most routers loads the IOS from flash into RAM upon boot.

6-ROM (read-only memory) Used to start and maintain the router. Holds the POST and the bootstrap program as well as the mini-IOS.

7-Flash memory Stores the Cisco IOS by default. It is EEPROM (electronically erasable programmable read-only memory) created by Intel.

8-NVRAM (nonvolatile RAM) Used to hold the permanent configuration of router. The configuration register is stored in NVRAM.

9-Configuration register It's a 16 digit hexadecimal configuration file that is used to control how the router boots up. Default value is set to 0x2102, which tells the router to load the IOS from flash memory as well as to load the configuration from NVRAM.

10- IOS Internet-networking Operating System. The kernel of Cisco Router IOS, developed by William Eager.

Now you know the different kinds of router components, you can move to learn Booting process of Router.

The Router Boot Sequence
Every device that uses operating system performs a series of steps, called the boot sequence, to test the hardware and load the necessary software. The router boot sequence consists of the following steps:

Step 1. The router performs a POST. The POST tests the hardware to verify that all components of the device are operational and present. The POST is stored in and run from ROM (read-only memory).

Step 2. The bootstrap then looks for and loads the Cisco IOS software. The bootstrap program is responsible for finding where each IOS program is located and then loading the file. By default, the IOS software is loaded from flash memory in all Cisco routers. The default order of an IOS loading from a router is flash, TFTP server, then ROM.

Step 3. The IOS software looks for a valid configuration file stored in NVRAM. This file is called startup-config.

Step 4. If a startup-config file is in NVRAM, the router will copy this file and place it in RAM and call the file running-config.

Step 5. Finally you will get router user console prompt. Where you can perform all the tasks.

CCNA Dumps Part4

Hi guy's i know you are so much interested in CCNA Certification and i hope this will help you to prepare to became a CCNA certified.

1. On a VLSM network, which mask should you use on point-to-point WAN links in order to reduce the waste of IP addresses?
A. /27
B. /28
C. /29
D. /30
E. /31

2. To test the IP stack on your local host, which IP address would you ping?
A. 127.0.0.0
B. 1.0.0.127
C. 127.0.0.1
D. 127.0.0.255
E. 255.255.255.255

3. What is the only connection type that supports the use of the /30 mask?
A. Point-to-multipoint
B. Point-to-point
C. Multipoint-to-multipoint
D. Host to switch

4. To use VLSM, what capability must the routing protocols in use possess?
A. Support for multicast
B. Multi-protocol support
C. Transmission of subnet mask information
D. Support for unequal load balancing

5. What is another term for route aggregation?
A. VLSM
B. Load balancing
C. Subnetting
D. Summarization

6. Which of the following is a result of route aggregation?
A. Smaller routing tables
B. More complete routing tables
C. Increased memory usage
D. Increased CPU usage

7. The network address used to advertise a summary address is always which of the following?
A. The last network address in the block
B. The next to last network in the block
C. The second network in the block
D. The first network in the block

8. When a ping to the loopback address fails, what can you assume?
A. The IP address of the local host is incorrect.
B. The IP address of the remote host is incorrect.
C. The NIC is not functional.
D. The IP stack has failed to initialize.

9. When a ping to the local host IP address fails, what can you assume?
A. The IP address of the local host is incorrect.
B. The IP address of the remote host is incorrect.
C. The NIC is not functional.
D. The IP stack has failed to initialize.

10. When a ping to the local host IP address succeeds but a ping to the default gateway IP address fails, what can you rule out? (Choose all that apply.)
A. The IP address of the local host is incorrect.
B. The IP address of the gateway is incorrect.
C. The NIC is not functional.
D. The IP stack has failed to initialize.

11. If a remote host can be pinged, what problems can you rule out?
A. The IP address of the local host is incorrect.
B. The IP address of the gateway is incorrect.
C. The NIC is not functional.
D. The IP stack has failed to initialize.
E. All of the above.

12. What network service is the most likely problem if you can ping a computer by IP address but not by name?
A. DNS
B. DHCP
C. ARP
D. ICMP

13. When you issue the ping command, what protocol are you using?
A. DNS
B. DHCP
C. ARP
D. ICMP

14. Which of the following commands displays the networks traversed on a path to a network destination?
A. ping
B. traceroute
C. pingroute
D. pathroute

15. Which of the following commands uses ICMP echo requests and replies?
A. ping
B. traceroute
C. arp
D. tracert

16. What command is the Windows version of the Cisco command that displays the networks traversed on a path to a network destination?
A. ping
B. traceroute
C. arp
D. tracert

17. Which command displays IP-to-MAC-address mappings on a Windows PC?
A. ping
B. traceroute
C. arp -a
D. tracert

18. What command displays the ARP table on a Cisco router?
A. show ip arp
B. traceroute
C. arp -a
D. tracert

19. What switch must be added to the ipconfig command on a PC to verify DNS configuration?
A. /dns
B. -dns
C. /all
D. -all

20. Which of the following is the best summarization of the following networks: 192.168.128.0 through 192.168.159.0
A. 192.168.0.0/24
B. 192.168.128.0/16
C. 192.168.128.0/19
D. 192.168.128.0/20

21. Which mask should you use on point-to-point WAN links in order to reduce the waste of IP addresses?
A. /27
B. /28
C. /29
D. /30
E. /31

22. What is the subnetwork number of a host with an IP address of 172.16.66.0/21?
A. 172.16.36.0
B. 172.16.48.0
C. 172.16.64.0
D. 172.16.0.0

23. You have an interface on a router with the IP address of 192.168.192.10/29. Including the router interface, how many hosts can have IP addresses on the LAN attached to the router interface?
A. 6
B. 8
C. 30
D. 62
E. 126

24. You need to configure a server that is on the subnet 192.168.19.24/29. The router has the first available host address. Which of the following should you assign to the server?
A. 192.168.19.0 255.255.255.0
B. 192.168.19.33 255.255.255.240
C. 192.168.19.26 255.255.255.248
D. 192.168.19.31 255.255.255.248
E. 192.168.19.34 255.255.255.240

25. You have an interface on a router with the IP address of 192.168.192.10/29. What is the broadcast address the hosts will use on this LAN?
A. 192.168.192.15
B. 192.168.192.31
C. 192.168.192.63
D. 192.168.192.127
E. 192.168.192.255

26. You need to subnet a network that has 5 subnets, each with at least 16 hosts. Which classful subnet mask would you use?
A. 255.255.255.192
B. 255.255.255.224
C. 255.255.255.240
D. 255.255.255.248

27. You configure a router interface with the IP address 192.168.10.62 255.255.255.192 and receive the following error:Bad mask /26 for address 192.168.10.62, Why did you receive this error?
A. You typed this mask on a WAN link and that is not allowed.
B. This is not a valid host and subnet mask combination.
C. ip subnet-zero is not enabled on the router.
D. The router does not support IP.

28. If an Ethernet port on a router were assigned an IP address of 172.16.112.1/25, what would be the valid subnet address of this interface?
A. 172.16.112.0
B. 172.16.0.0
C. 172.16.96.0
D. 172.16.255.0
E. 172.16.128.0

29. Using the illustration from the previous question, what would be the IP address of S0 if you were using the first subnet? The network ID is 192.168.10.0/28 and you need to use the last available IP address in the range. Again, the zero subnet should not be considered valid for this question.
A. 192.168.10.24
B. 192.168.10.62
C. 192.168.10.30
D. 192.168.10.127

30. Which configuration command must be in effect to allow the use of 8 subnets if the Class C subnet mask is 255.255.255.224?
A. Router(config)#ip classless
B. Router(config)#ip version 6
C. Router(config)#no ip classful
D. Router(config)#ip unnumbered
E. Router(config)#ip subnet-zero
F. Router(config)#ip all-nets

31. You have a network with a subnet of 172.16.17.0/22. Which is the valid host address?
A. 172.16.17.1 255.255.255.252
B. 172.16.0.1 255.255.240.0
C. 172.16.20.1 255.255.254.0
D. 172.16.16.1 255.255.255.240
E. 172.16.18.255 255.255.252.0
F. 172.16.0.1 255.255.255.0

32. Your router has the following IP address on Ethernet0: 172.16.2.1/23. Which of the following can be valid host IDs on the LAN interface attached to the router? (Choose two.)
A. 172.16.0.5
B. 172.16.1.100
C. 172.16.1.198
D. 172.16.2.255
E. 172.16.3.0
F. 172.16.3.255

33. To test the IP stack on your local host, which IP address would you ping?
A. 127.0.0.0
B. 1.0.0.127
C. 127.0.0.1
D. 127.0.0.255
E. 255.255.255.255

34. Which of the following connection methods available to connect to a router is considered out-of-band?
A. Serial port
B. VTY port
C. HTTP port
D. Aux port

35. Which two of the following commands are required when configuring SSH on your router?
A. enable secret password
B. exec-timeout 0 0
C. ip domain-name name
D. username name password password
E. ip ssh version 2

36. Which command will show you whether a DTE or a DCE cable is plugged into serial 0?
A. sh int s0
B. sh int serial 0
C. show controllers s 0
D. show serial 0 controllers

37. Which of the following is a correct combination of file type and default location in a Cisco router?
A. IOS/NVRAM
B. Startup configuration/flash memory
C. IOS/flash memory
D. Running configuration/NVRAM

38. You set the console password, but when you display the configuration, the password doesn’t show up; it looks like this:
[output cut]
Line console 0
Exec-timeout 1 44
Password 7 09FGH68QR
Login
[output cut]
What command would configure the password to be stored this way?
A. encrypt password
B. service password-encryption
C. service-password-encryption
D. exec-timeout 1 22

39. Which of the following commands will configure all the default VTY ports on a router?
A. Router#line vty 0 4
B. Router(config)#line vty 0 4
C. Router(config-if)#line console 0
D. Router(config)#line vty all

40. Which of the following commands sets the secret password to Kamal?
A. enable secret password Kamal
B. enable secret kamal
C. enable secret Kamal
D. enable password Kamal

41. If you wanted administrators to see a message when logging into the router, which command would you use?
A. message banner motd
B. banner message motd
C. banner motd
D. message motd

42. What command do you type to save the configuration stored in RAM to NVRAM?
A. Router(config)#copy current to starting
B. Router#copy starting to running
C. Router(config)#copy running-config startup-config
D. Router#copy run start

43. You try to telnet into SRouter from router Corp and receive this message:
Corp#telnet SRouter
Trying SRouter (10.0.0.1)…Open
Password required, but none set
[Connection to SRouter closed by foreign host]
Corp#
Which of the following sequences will address this problem correctly?
A. Corp(config)#line console 0
Corp (config-line)#password password
Corp (config-line)#login
B. SRemote(config)#line console 0
Corp (config-line)#enable secret password
Corp (config-line)#login
C. Corp(config)#line vty 0 4
Corp (config-line)#password password
Corp (config-line)#login
D. SRemote(config)#line vty 0 4
Corp (config-line)#password password
Corp (config-line)#login

44. Which command will delete the contents of NVRAM on a router?
A. delete NVRAM
B. delete startup-config
C. erase NVRAM
D. erase start

45. What is the problem with an interface if you type show interface serial 0 and receive the following message?
Serial0 is administratively down, line protocol is down
A. The keepalives are different times.
B. The administrator has the interface shut down.
C. The administrator is pinging from the interface.
D. No cable is attached.

46. Which of the following commands displays the configurable parameters and statistics of all interfaces on a router?
A. show running-config
B. show startup-config
C. show interfaces
D. show versions

47. If you delete the contents of NVRAM and reboot the router, what mode will you be in?
A. Privileged mode
B. Global mode
C. Setup mode
D. NVRAM loaded mode

48. You type the following command into the router and receive the following output:
Router#show serial 0/0
^
% Invalid input detected at '^' marker.
Why was this error message displayed?
A. You need to be in privileged mode.
B. You cannot have a space between serial and 0/0.
C. The router does not have a serial0/0 interface.
D. Part of the command is missing.

49. Which of the following commands will display the current IP addressing and the layer 1 and 2 status of an interface? (Choose two.)
A. show version
B. show interfaces
C. show controllers
D. show ip interface
E. show running-config

50. At which layer of the OSI model would you assume the problem is if you type show interface serial 1 and receive the following message?
Serial1 is down, line protocol is down
A. Physical layer
B. Data Link layer
C. Network layer
D. None; it is a router problem

OK Now it's time to check your answer and get score, if your score is below than 80% i will recommend to retake your test.

1. D. A point-to-point link uses only two hosts. A /30, or 255.255.255.252, mask provides two hosts per subnet.

2. C. To test the local stack on your host, ping the loopback interface of 127.0.0.1.

3. B. The only connection type that supports the use of the /30 mask is point-to-point.

4. C. To use VLSM, the routing protocols in use possess the capability to transmit subnet mask information.

5. D. Another term for route aggregation is summarization.

6. A. Route aggregation results in smaller routing tables.

7. D. The network address used to advertise a summary address is always the first network in the block.

8. D. When a ping to the loopback address fails, you can assume the IP stack has failed to initialize.

9. C. When a ping to the local host IP address fails, you can assume the NIC is not functional.

10. C, D. If a ping to the local host succeeds, you can rule out IP stack or NIC failure.

11. E. If you can ping a remote host, everything is working locally.

12. A. The most likely problem if you can ping a computer by IP address but not by name is a failure of DNS.

13. D. When you issue the ping command, you are using the ICMP protocol.

14. B. The traceroute command displays the networks traversed on a path to a network destination.

15. A. The ping command uses ICMP echo requests and replies.

16. D. tracert is the Windows version of the Cisco command that displays the networks traversed on a path to a network destination.

17. C. The arp -a command displays IP-to-MAC-address mappings on a Windows PC.
18. A. The command that displays the ARP table on a Cisco router is show ip arp.

19. C. The /all switch must be added to the ipconfig command on a PC to verify DNS configuration.
20. C. If you start at 192.168.128.0 and go through 192.168.159.0, you can see this is a block of 32 in the third octet. Since the network address is always the first one in the range, the summary address is 192.168.128.0. What mask provides a block of 32 in the third octet? The answer is 255.255.224.0, or /19

21. D. A point-to-point link uses only two hosts. A /30, or 255.255.255.252, mask provides two hosts per subnet.

22. C. A /21 is 255.255.248.0, which means we have a block size of 8 in the third octet, so we just count by 8 until we reach 66. The subnet in this question is 64.0. The next subnet is 72.0, so the broadcast address of the 64 subnet is 71.255.

23. A. A /29 (255.255.255.248), regardless of the class of address, has only 3 host bits. Six hosts is the maximum number of hosts on this LAN, including the router interface.

24. C. A /29 is 255.255.255.248, which is a block size of 8 in the fourth octet. The subnets are 0, 8, 16, 24, 32, 40, etc. 192.168.19.24 is the 24 subnet, and since 32 is the next subnet, the broadcast address for the 24 subnet is 31. 192.168.19.26 is the only correct answer.

25. A. A /29 (255.255.255.248) has a block size of 8 in the fourth octet. This means the subnets are 0, 8, 16, 24, etc. 10 is in the 8 subnet. The next subnet is 16, so 15 is the broadcast address.

26. B. You need 5 subnets, each with at least 16 hosts. The mask 255.255.255.240 provides 16 subnets with 14 hosts—this will not work. The mask 255.255.255.224 provides 8 subnets, each with 30 hosts. This is the best answer.

27. C. First, you cannot answer this question if you can’t subnet. The 192.168.10.62 with a mask of 255.255.255.192 is a block size of 64 in the fourth octet. The host 192.168.10.62 is in the zero subnet, and the error occurred because ip subnet-zero is not enabled on the router.

28. A. A /25 mask is 255.255.255.128. Used with a Class B network, the third and fourth octets are used for subnetting with a total of 9 subnet bits, 8 bits in the third octet and 1 bit in the fourth octet. Since there is only 1 bit in the fourth octet, the bit is either off or on—which is a value of 0 or 128. The host in the question is in the 0 subnet, which has a broadcast address of 127 since 112.128 is the next subnet.

29. C. A /28 is a 255.255.255.240 mask. The first subnet is 16 (remember that the question stated not to use subnet zero) and the next subnet is 32, so our broadcast address is 31. This makes our host range 17–30. 30 is the last valid host.

30. E. A Class C subnet mask of 255.255.255.224 is 3 bits on and 5 bits off (11100000) and provides 8 subnets, each with 30 hosts. However, if the command ip subnet-zero is not used, then only 6 subnets would be available for use.

31. E. A Class B network ID with a /22 mask is 255.255.252.0, with a block size of 4 in the third octet. The network address in the question is in subnet 172.16.16.0 with a broadcast address of 172.16.19.255. Only option E has the correct subnet mask listed, and 172.16.18.255 is a valid host.

32. D, E. The router’s IP address on the E0 interface is 172.16.2.1/23, which is 255.255.254.0. This makes the third octet a block size of 2. The router’s interface is in the 2.0 subnet, and the broadcast address is 3.255 because the next subnet is 4.0. The valid host range is 2.1 through 3.254. The router is using the first valid host address in the range.

33. C. To test the local stack on your host, ping the loopback interface of 127.0.0.1.

34. D. The auxiliary port can be configured with modem commands so that a modem can be connected to the router. It lets you dial up a remote router and attach to the auxiliary port if the router is down and you need to configure it out-of-band (means out of the network).

35. C, D. To configure SSH on your router, you need to set the username command, the ip domain-name, login local, and the transport input ssh under the VTY lines, and the crypto key command. However, SSH version 2 is not required, but suggested.

36. C. The show controllers serial 0 command will show you whether either a DTE or DCE cable is connected to the interface. If it is a DCE connection, you need to add clocking with the clock rate command.

37. C. The default locations of the files are IOS in flash memory, startup configuration in NVRAM, and running configuration in RAM.

38. B. The command service password-encryption, from global configuration mode, will encrypt the passwords.

39. B. From global configuration mode, use the line vty 0 4 command to set all five default VTY lines.

40. C. The enable secret password is case sensitive, so the second option is wrong. To set the enable secret password, use the enable secret password command from global configuration mode.

41. C. The typical banner is a message of the day (MOTD) and is set by using the global configuration mode command banner motd.

42. D. To copy the running-config to NVRAM so that it will be used if the router is restarted, use the copy running-config startup-config command in privileged mode (copy run start for short).

43. D. To allow a VTY (Telnet) session into your router, you must set the VTY password. Option C is wrong because it is setting the password on the wrong router. Notice that the answers you have to set the password before you set the login command. Remember, Cisco may have you set the password before the login command.

44. D. The erase startup-config command erases the contents of NVRAM and will put you in setup mode if the router is restarted.

45. B. If an interface is shut down, the show interface command will show the interface as administratively down. (It is possible that no cable is attached, but you can’t tell that from this message.)

46. C. With the show interfaces command, you can view the configurable parameters, get statistics for the interfaces on the router, verify if the interfaces are shut down, and see the IP address of each interface.

47. C. If you delete the startup-config and reload the router, the router will automatically enter setup mode. You can also type setup from privileged mode at any time.

48. D. You can view the interface statistics from user mode, but the command is show interface serial 0/0.

49. B, D. The commands show interfaces and show ip interface will show you the layer 1 and 2 status and the IP addresses of your router’s interfaces.

50. A. If you see that a serial interface and the protocol are both down, then you have a Physical layer problem. If you see serial1 is up, line protocol is down, then you are not receiving (Data Link) keepalives from the remote end.