You might think of it this way: a light meter reads the scene before you take the photo; the histogram analyzes the photo you’ve just taken. You can choose to have the histogram appear on the camera’s LCD along with the playback display of your photo (see your Nikon D-SLR manual for the exact procedure).

That’s what the histogram is. But why is it an important, fundamental tool of digital photography? Simply because your understanding of the histogram will tell you if it’s necessary to adjust your exposure, and it will indicate how to make that adjustment.

The first thing to realize, though, is that it’s not always necessary to use the histogram. In fact, selective use is best. Few if any photographers look at the histogram for each and every photo they take. In the majority of instances, your camera’s meter will accurately and precisely set the correct exposure for the scene.

But you should check the histogram when a scene’s lighting is especially tricky; when there are areas of deep shadow and bright light in the same scene; and when you’re going to take a series of images in the same setting and want to be sure your exposure is right on target.

A glance at the histogram will tell you if parts of your photo are over- or underexposed. Overexposure means lack of detail in the highlights; underexposure, loss of detail in the shadows. The histogram will instantly reveal the situation: a heavy concentration at the left side of the graph means the image is underexposed and you’ve lost detail in the shadow areas; a heavy concentration at the right means your highlights may be blown out. The remedy? You can increase your shutter speed, close down aperture or lower your ISO to correct overexposure; the opposite settings will serve to correct an underexposure.

Here’s something you might want to use in connection with the histogram: the highlight overexposure warning. Set this option (again, see your manual for the specific activation method) and areas of overexposure will blink in the playback image. When you see these flashes of light—most people call them “blinkies”—you’ll know exactly which areas of the image are overexposed.

Several Nikon D-SLRs feature secondary, color histograms. Choose to display them and you’ll see three small graphs that show the intensity of the RGB (red, green and blue) color values in the scene. If you need to adjust these values, the camera’s white balance control is the way to do it.

Some Nikon D-SLRs also allow you to magnify specific areas of the photo on playback so you can check exposure and detail rendering in very specific parts of the image. In effect, you’re directing the histogram’s area of analysis.

The accompanying images provide examples of what we’ve been talking about, but the best way to see exactly how the histogram can help you take control of your photography is experimentation and experience. Just go out and take pictures in a number of situations and become familiar with what the histogram can tell you about the results.

Source: nikon.com

Configure Telnet for root logins

Simply edit the file /etc/default/login and comment out the following line as follows:

# If CONSOLE is set, root can only login on that device.
# Comment this line out to allow remote login by root.
#
# CONSOLE=/dev/console

Configure FTP for root logins

First remove the ‘root’ line from /etc/ftpusers.Also, don’t forget to edit the file /etc/ftpaccess and comment out the ‘deny-uid’ and ‘deny-gid’ lines. If the file doesn’t exist, there is no need to create it.

NOTE: If you are using Solaris 9 or Solaris 10, the ftp* files are located in /etc/ftpd

After searching on the web, i found that Minicom can do the job, running on linux Console. Now i can console to Router or Switch and capture all my activity to a file.

Get application:

$sudo apt-get install minicom

To create application launcher on Ubuntu desktop:

Right click on desktop > Create Launcer…

Fill “Command” field with: gnome-terminal -t “Router Console” -e “sudo minicom -s”

note: option -s to allow configuration every time minicom start on console, you can remove this option only if you already configure minicom to work with use-to-serial adapter, usually mount at /dev/ttyUSB0. To make sure where is usb-to-serial is mounted, submit following command after you plug usb-to-serial to your usb port

$dmesg

Open Application > Accessories > Terminal and type:

gconftool  – -recursive-unset /apps/panel

(Caution: There should be no spaces between the two dashes before shutdown.)

Then enter the next command:

rm -rf ~/.gconf/apps/panel

And enter one more command:

pkill gnome-panel
NOTE: This method will work in Gutsy Gibbon (7.10) and above.

• Qt 4.5.1 (or higher)
• Python 2.5 (or higher)
• Sip 4.5 (or higher)
• PyQt 4.5 (or higher)

Step to install:

1. Download GNS3 and extract
2. Download Dynamips and change to executable
3. Get all GNS3 dependencies

• [root@fedora ades]# yum install qt4
• [root@fedora ades]# yum install python
• [root@fedora ades]# yum install sip
• [root@fedora ades]# yum install PyQt
• [root@fedora ades]# yum install wireshark [optional]

Double click to extracted gns3 file in GNS3-* folder. When you first start up GNS3, it need to be configure, point to executable dinamips file and add cisco IOS.

Since my laptop is already installed with eclipse, that was the screenshot that came up.

Install ADT from eclipse with plugin point to ADT, http://dl-ssl.google.com/android/eclipse/

Select by checking ‘Developer Tools’ and click ‘Finish’ to start download and install.

Eclipse and Android Development Tools is installed, now you need to download SDK to start develop android application. From eclipse menu, click on Window – > Android SDK and AVD Manager.

Click on the arrow in right coloumn where sites, packages and archives in listed. Select SDK Platform Android and Google API that you need. Google API is SDK Platform Android that customize by google (google phone).

My selection in SDK and Google API v2.1 and v1.6, as the latest SDK and most available current android phone version.

Now that all requirement are meet, let’s start creating our android emulator phone (Android Virtual Device, AVD). Still on Android SDK and AVD Manager window open, select on ‘Virtual Devices’ and click ‘New’

Name: name emulator device as you like

Target: select Android 1.6 – API Level 4 (or any SDK ou wish)

Size: size of SD card on the emulator

click ‘Create AVD’ to create the emulator, click ‘OK’ on popup window that confirm of succesfull AVD creation.

Click ‘Starts selected AVD’ to start the emulator. It that a while for AVD to start up, but if it’s already start developing/programming Android application and test on AVD is fast, don’t closed AVD window while still developing.

Play around with the AVD to familiarize Android phone. Have a nice coding

Eclipse Software Sites for Eclipse 3.5 Galileo:
1. Releases: http://download.eclipse.org/releases/galileo (should be automatically installed)
2. Maintenance builds: http://download.eclipse.org/eclipse/updates/3.5 (should be automatically installed)
3. EPP Packages http://download.eclipse.org/technology/epp/packages/galileo/

Now edit your /etc/hosts file and append the following to it’s contents:
80.239.156.215 mirrors.fedoraproject.org
213.129.242.84 mirrors.rpmfusion.org

If your computer behind proxy, try this:
[root@fedora ades]# http_proxy=172.16.42.200:3128
[root@fedora ades]# export http_proxy

or (if proxy need username and password)
[root@fedora ades]# http_proxy=http://[username]:[password]@172.16.42.200:3128
[root@fedora ades]# export http_proxy

You need to install the following software:

1. MySQL Server, store cacti data
2. NET-SNMP server – SNMP (Simple Network Management Protocol) is a protocol used for network management.
3. PHP with net-snmp module – Access SNMP data using PHP.
4. Apache, web server to display graphs created with PHP and RRDTOOL.

Install the software

First, login as root user and type the following command to install mysql, apache and php:

# yum install mysql-server mysql php-mysql php-pear php-common php-gd php-devel php php-mbstring php-cli php-snmp php-pear-Net-SMTP php-mysql httpd

Configure MySQL server

First, set root password:
# mysqladmin -u root password NEWPASSWORD

Create cacti MySQL database

Create a database called cacti, enter:
# mysql -u root -p -e 'create database cacti'

Create a user called cacti with a password called zYn95ph43zYtq, enter:
# mysql -u root -p

mysql> GRANT ALL ON cacti.* TO cacti@localhost IDENTIFIED BY 'zYn95ph43zYtq';
mysql> FLUSH privileges;
mysql> \q

Install snmpd

Type the following command to install net-snmpd
# yum install net-snmp-utils php-snmp net-snmp-libs
Configure snmpd, open /etc/snmp/snmpd.conf
# vi /etc/snmp/snmpd.conf

Append / modify it as follows (see snmpd.conf man page for details):

com2sec local     localhost           public
group MyRWGroup v1         local
group MyRWGroup v2c        local
group MyRWGroup usm        local
view all    included  .1                               80
access MyRWGroup ""      any       noauth    exact  all    all    none
syslocation Unknown (edit /etc/snmp/snmpd.conf)
syscontact Root  (configure /etc/snmp/snmp.local.conf)
pass .1.3.6.1.4.1.4413.4.1 /usr/bin/ucd5820stat

Save and close the file. Turn on snmpd service:
# /etc/init.d/snmpd start
# chkconfig snmpd on
Make sure you are getting information from snmpd:
# snmpwalk -v 1 -c public localhost

Install cacti

First, make sure EPEL repo is enabled.

# rpm -Uvh http://download.fedora.redhat.com/pub/epel/5/i386/epel-release-5-3.noarch.rpm

If you faild to install from terminal, download file from the link and execute with rpm command. Cek EPEL repo is already installed.

# yum repolist

Type the following command to install cacti:

# yum install cacti

Install cacti tables

Type the following command to find out cacti.sql path:
# rpm -ql cacti | grep cacti.sql
Sample output:

/usr/share/doc/cacti-0.8.7d/cacti.sql

Type the following command to install cacti tables (you need to type the cacti user password):
# mysql -u cacti -p cacti < /usr/share/doc/cacti-0.8.7d/cacti.sql

Configure cacti

Open /etc/cacti/db.php file, enter:
# vi /etc/cacti/db.php
Make changes as follows:

/* make sure these values refect your actual database/host/user/password */
$database_type = "mysql";
$database_default = "cacti";
$database_hostname = "localhost";
$database_username = "cacti";
$database_password = "zYn95ph43zYtq";
$database_port = "3306";

Save and close the file.

Configure httpd

Open /etc/httpd/conf.d/cacti.conf file, enter:
# vi /etc/httpd/conf.d/cacti.conf
You need to update allow from line. Either set to ALL or your LAN subnet to allow access to cacti:

#
# Cacti: An rrd based graphing tool
#
Alias /cacti    /usr/share/cacti

<Directory /usr/share/cacti/>
        Order Deny,Allow
        Deny from all
        Allow from 10.0.0.0/8
</Directory>

Another option is create /usr/share/cacti/.htaccess file and password protect the directory. Finally, restart httpd:
# service httpd restart

Setup cacti cronjob

Open /etc/cron.d/cacti file, enter:
# vi /etc/cron.d/cacti
Uncomment the line:

*/5 * * * *     cacti   /usr/bin/php /usr/share/cacti/poller.php > /dev/null 2>&1

Save and close the file.

Run cacti installer

Now cacti is ready to install. Fire a webbrowser and type the url:
http://your.example.com/cacti/
OR
http://your.server.ip.address/cacti/
Just follow on screen instructions. The default username and password for cacti is admin / admin. Upon first login, you will be force to change the default password.