GixEsperiene: marzo 2010

lunedì 22 marzo 2010

Compact Flash cards Speeds

Flash memory devices are non-volatile and solid-state, and thus are more robust than disk drives. Cards consume around 5% of the power required by small disk drives and still have reasonable transfer rates of over 45 MB/s for the more expensive 'high speed' cards.[6]

Card speed is usually specified in "x" ratings, e.g. 8x, 20x, 133x. This is the same system used for CD-ROMs and gives the data rate as a multiple of the data rate of the first CD-ROMs (i.e. the data rate of an audio CD). The base rate is 150 kB/s, so for example, 20x = 20 * 150 kB/s = 3.0 MB/s.

The following table lists some common ratings and their respective maximum transfer rates.
Rating Speed (MB/s)
6x 0.9
32x 4.8
40x 6.0
66x 10.0
100x 15.0
133x 20.0
150x 22.5
200x 30.0 EXTREME3
266x 40.0 EXTREME4
280x 42.0
300x 45.0
333x 50.0
400x 60.0
433x 65.0
600x 90.0 UDMA
667x 100.0

mercoledì 17 marzo 2010

FireFox keeps asking for Proxy Authentication

1. close Firefox ***edit the java script file all.js

set the pref network.auth.force-generic-ntlm set to “true” in the following file:

c:\program files\mozilla firefox\greprefs\all.js
Restart Firefox

sabato 6 marzo 2010

UBUNTU 9.10 resolution problems solved.

The fastway.

cvt 1280 1024
# 1280x1024 59.89 Hz (CVT 1.31M4) hsync: 63.67 kHz; pclk: 109.00 MHz
Modeline "1280x1024_60.00" 109.00 1280 1368 1496 1712 1024 1027 1034 1063 -hsync +vsync

xrandr --newmode "1280x1024_60.00" 109.00 1280 1368 1496 1712 1024 1027 1034 1063 -hsync +vsync

xrandr --addmode VGA1 1280x1024_60.00

xrandr --output VGA1 --mode 1280x1024_60.00

Resetting an out-of-range resolution

If you set a resolution inappropriate for your monitor in the Screen Resolution GUI tool, you can reset it by running rm ~/.config/monitors.xml from a terminal.

Dynamically testing different resolutions

You can either use the Screen Resolution GUI tool to experiment with different resolutions, or the more powerful xrandr command-line tool:

  $ xrandr

shows you the names of different outputs available on your system (LVDS, VGA-0, etc.) and resolutions available on each:

Screen 0: minimum 320 x 200, current 1400 x 1050, maximum 1400 x 1400
VGA disconnected (normal left inverted right x axis y axis)
LVDS connected 1400x1050+0+0 (normal left inverted right x axis y axis) 286mm x 214mm
 1400x1050      60.0*+   50.0
[...]

You can direct xrandr to set a different resolution like this:

  $ xrandr --output LVDS --mode 1024x768

The refresh rate may also be changed, either at the same time or independently:

  $ xrandr --output LVDS --mode 1024x768 --rate 75

Note that changes you make using xrandr only last through the current session. xrandr has a lot more capabilities - see man xrandr for details.

Adding undetected resolutions

Due to buggy hardware or drivers, your monitor's correct resolutions may not always be detected. For example, the EDID data block queried from your monitor may be incorrect.

If the mode already exists, but just isn't associated for the particular output, you can add it like this:

  $ xrandr --addmode S-video 800x600

If the mode doesn't yet exist, you'll need to create it first by specifying a modeline:

  $ xrandr --newmode

You may create a modeline using the gtf or cvt utility. For example, if you want to add a mode with resolution 800x600, you can enter the following command: (The output is shown following.)

  $ cvt 800 600
# 800x600 59.86 Hz (CVT 0.48M3) hsync: 37.35 kHz; pclk: 38.25 MHz
Modeline "800x600_60.00"   38.25  800 832 912 1024  600 603 607 624 -hsync +vsync

Then copy the information after the word "Modeline" into the xrandr command:

  $ xrandr --newmode "800x600_60.00"   38.25  800 832 912 1024  600 603 607 624 -hsync +vsync

Setting xrandr changes persistently

There are several ways to make xrandr customizations permanent from session to session: a) .xprofile, b) kdm/gdm, c) xorg.conf. Each of these mechanisms will be discussed in turn.

Setting xrandr commands in .xprofile

A user's ~/.xprofile file is executed on Xorg startup if it exists and is executable. You can copy and paste xrandr command line strings into this file so they're executed when you log in. For example:

  $ xrandr --output VGA-0 --mode 800x600

There are two disadvantages to using .xprofile for xrandr settings. First, it occurs fairly late in the startup process, so you'll see some resolution resizing during the initial screen draw; in some cases panel windows may resize improperly as a result. Second, as this is a per-user setting, it won't affect the resolutions of other users, nor will it alter the resolution on the login screen.

Setting xrandr commands in kdm/gdm startup scripts

Both KDM and GDM have startup scripts that are executed when X is initiated. For GDM, these are in /etc/gdm/ , while for KDM this is done at /etc/kde4/kdm/Xsetup. In either case, you can paste in an xrandr command line string into one of these scripts. For GDM, try putting them right before initctl -q emit login-session-start DISPLAY_MANAGER=gdm in /etc/gdm/Init/Default

This process requires root access and mucking around in system config files, but will take effect earlier in the startup process than using .xprofile, and will apply to all users including the login screen.

Setting resolution changes in xorg.conf

While xorg.conf is largely empty these days, it can still be used for setting up resolutions. For example:

Section "Monitor"
  Identifier      "External DVI"
  Modeline        "1280x1024_60.00"  108.88  1280 1360 1496 1712  1024 1025 1028 1060  -HSync +Vsync
  Option          "PreferredMode" "1280x1024_60.00"
EndSection
Section "Device"
  Identifier      "ATI Technologies, Inc. M22 [Radeon Mobility M300]"
  Driver          "ati"
  Option          "Monitor-DVI-0" "External DVI"
EndSection
Section "Screen"
  Identifier      "Primary Screen"
  Device          "ATI Technologies, Inc. M22 [Radeon Mobility M300]"
  DefaultDepth    24
  SubSection "Display"
      Depth           24
      Modes   "1280x1024" "1024x768" "640x480"
  EndSubSection
EndSection

Section "ServerLayout"
      Identifier      "Default Layout"
      Screen          "Primary Screen"
EndSection

See man xorg.conf for full details on how to craft an xorg.conf file.

Setting resolution changes in xorg.conf -- resolution lower than expected

Try this first

If you video card is recognized but the resolution is lower than you expect, you may try this.

Background: I use Ubuntu 9.0.4 x86, ATI X1550 based video card and two LCD monitors DELL 2408(up to 1920x1200) and Samsung 206BW(up to 1680x1050). Upon first login after installation, the resolution default to 1152x864. xrandr does not list any resolution higher than 1152x864. You may want to try editing /etc/X11/xorg.conf, add a section about virtual screen, logout, login and see if this helps. If not then read on.

Change the default xorg.conf

Section "Device"
      Identifier      "Configured Video Device"
EndSection

Section "Monitor"
      Identifier      "Configured Monitor"
EndSection

Section "Screen"
      Identifier      "Default Screen"
      Monitor         "Configured Monitor"
      Device          "Configured Video Device"
EndSection

Section "Monitor"
      Identifier      "Configured Monitor"
EndSection

Section "Screen"
      Identifier      "Default Screen"
      Monitor         "Configured Monitor"
      Device          "Configured Video Device"
->        SubSection "Display"
->                Virtual 3600 1200
->        EndSubSection
EndSection

Section "Device"
      Identifier      "Configured Video Device"
EndSection

About the numbers: I put DELL on the left and Samsung on the right. So the virtual width is of sum of both LCD width 3600=1920+1680; Height then is figured as the max of them, which is max(1200,1050)=1200. If you put one LCD above the other, use this calculation instead: (max(width1, width2), height1+height2).

If that does not help, here's what I did:

Use cvt/xrandr tool to add the highest mode the LCD can do

The actual order was different, as I tried to add new mode to one LCD at a time. Below is the combined/all-in-one quote

aa@aa-desktop:/$ cvt 1920 1200 60
# 1920x1200 59.88 Hz (CVT 2.30MA) hsync: 74.56 kHz; pclk: 193.25 MHz
Modeline "1920x1200_60.00"  193.25  1920 2056 2256 2592  1200 1203 1209 1245 -hsync +vsync
aa@aa-desktop:/$ cvt 1680 1050 60
# 1680x1050 59.95 Hz (CVT 1.76MA) hsync: 65.29 kHz; pclk: 146.25 MHz
Modeline "1680x1050_60.00"  146.25  1680 1784 1960 2240  1050 1053 1059 1089 -hsync +vsync
aa@aa-desktop:/$ xrandr --newmode "1920x1200_60.00"  193.25  1920 2056 2256 2592  1200 1203 1209 1245 -hsync +vsync
aa@aa-desktop:/$ xrandr --newmode "1680x1050_60.00"  146.25  1680 1784 1960 2240  1050 1053 1059 1089 -hsync +vsync
aa@aa-desktop:/$ xrandr --addmode DVI-1 "1920x1200_60.00"
aa@aa-desktop:/$ xrandr --addmode DVI-0 "1680x1050_60.00"

Preference -> Display">Goto Ubuntu Menu: System -> Preference -> Display

Change one of the LCD's resolution to a lower one, e.g. 800x600. Apply change, then (I don't remember the exact order/wording here:) hopefully the GUI will give you a prompt saying something like "the resolution can be improved but virtual screen has to be enabled, you need to however logout and log back in". I did it and on 2nd login, I am able to find the higher resolution listed for that LCD. After that I follow suite and make similar change to 2nd LCD and am able to get both of them working.

giovedì 4 marzo 2010

Add user ti SUDO

To give a user the ability to use the “sudo” command you must add them to the “sudoers” file. Here’s how. Thanks to ubuntucat (see comment below) for the following suggestion! The easiest way to allow a user to sudo is to simply run the following command from the Terminal:

To open the Terminal:

Applications >> Accessories >> Terminal

Once the Terminal is open type:

sudo adduser username admin

This must be done from an account that already has sudo abilities or else from the root account.

If for some reason you have to manually edit the “sudoers” file keep reading!

Open the file “sudoers” located at /etc/sudoers using your favorite text editor. You must have root permissions to be able to edit this file so you will want to open your editor from the command line.

To use gedit you would do the following:

Open the Terminal and type:

sudo gedit /etc/sudoers

If you want to use vim you can simply enter the following into the Terminal:

sudo visudo

Once you have the sudoers file open, scroll down to the line:

root ALL = (ALL) ALL

Add the folling line below the root line (replacing “user” with the name of the account you wish to give sudo access to)

user ALL = (ALL) ALL

Save and close the file. The new user has now been added to the “sudoers” file and can use the “sudo” command.

Nagios Ubuntu Install

Introduction

This guide is intended to provide you with simple instructions on how to install Nagios from source (code) on Ubuntu and have it monitoring your local machine inside of 20 minutes. No advanced installation options are discussed here - just the basics that will work for 95% of users who want to get started.

These instructions were written based on an Ubuntu 6.10 (desktop) installation. They should work for an Ubuntu 7.10 install as well.

What You'll End Up With

If you follow these instructions, here's what you'll end up with:

Nagios and the plugins will be installed underneath /usr/local/nagios
Nagios will be configured to monitor a few aspects of your local system (CPU load, disk usage, etc.)
The Nagios web interface will be accessible at http://localhost/nagios/

Required Packages

Make sure you've installed the following packages on your Ubuntu installation before continuing.

Apache 2
PHP
GCC compiler and development libraries
GD development libraries

You can use apt-get to install these packages by running the following commands:

sudo apt-get install apache2

sudo apt-get install libapache2-mod-php5

sudo apt-get install build-essential

With Ubuntu 6.10, install the gd2 library with this command:

sudo apt-get install libgd2-dev

With Ubuntu 7.10, the gd2 library name has changed, so you'll need to use the following:

sudo apt-get install libgd2-xpm-dev

1) Create Account Information

Become the root user.

sudo -s

Create a new nagios user account and give it a password.

/usr/sbin/useradd -m -s /bin/bash nagios

passwd nagios

On older Ubuntu server editions (6.01 and earlier), you will need to also add a nagios group (it's not created by default). You should be able to skip this step on desktop, or newer server editions of Ubuntu.

/usr/sbin/groupadd nagios

/usr/sbin/usermod -G nagios nagios

Create a new nagcmd group for allowing external commands to be submitted through the web interface. Add both the nagios user and the apache user to the group.

/usr/sbin/groupadd nagcmd

/usr/sbin/usermod -a -G nagcmd nagios

/usr/sbin/usermod -a -G nagcmd www-data

2) Download Nagios and the Plugins

Create a directory for storing the downloads.

mkdir ~/downloads

cd ~/downloads

Download the source code tarballs of both Nagios and the Nagios plugins (visit http://www.nagios.org/download/ for links to the latest versions). These directions were tested with Nagios 3.1.1 and Nagios Plugins 1.4.11.

wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.2.0.tar.gz

wget http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.11.tar.gz

3) Compile and Install Nagios

Extract the Nagios source code tarball.

cd ~/downloads

tar xzf nagios-3.2.0.tar.gz

cd nagios-3.2.0

Run the Nagios configure script, passing the name of the group you created earlier like so:

./configure --with-command-group=nagcmd

Compile the Nagios source code.

make all

Install binaries, init script, sample config files and set permissions on the external command directory.

make install

make install-init

make install-config

make install-commandmode

Don't start Nagios yet - there's still more that needs to be done...

4) Customize Configuration

Sample configuration files have now been installed in the /usr/local/nagios/etc directory. These sample files should work fine for getting started with Nagios. You'll need to make just one change before you proceed...

Edit the /usr/local/nagios/etc/objects/contacts.cfg config file with your favorite editor and change the email address associated with the nagiosadmin contact definition to the address you'd like to use for receiving alerts.

vi /usr/local/nagios/etc/objects/contacts.cfg

5) Configure the Web Interface

Install the Nagios web config file in the Apache conf.d directory.

make install-webconf

Create a nagiosadmin account for logging into the Nagios web interface. Remember the password you assign to this account - you'll need it later.

htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

Restart Apache to make the new settings take effect.

/etc/init.d/apache2 reload

Note Note: Consider implementing the ehanced CGI security measures described here to ensure that your web authentication credentials are not compromised.

6) Compile and Install the Nagios Plugins

Extract the Nagios plugins source code tarball.

cd ~/downloads

tar xzf nagios-plugins-1.4.11.tar.gz

cd nagios-plugins-1.4.11

Compile and install the plugins.

./configure --with-nagios-user=nagios --with-nagios-group=nagios

make

make install

7) Start Nagios

Configure Nagios to automatically start when the system boots.

ln -s /etc/init.d/nagios /etc/rcS.d/S99nagios

Verify the sample Nagios configuration files.

/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

If there are no errors, start Nagios.

/etc/init.d/nagios start

8) Login to the Web Interface

You should now be able to access the Nagios web interface at the URL below. You'll be prompted for the username (nagiosadmin) and password you specified earlier.

http://localhost/nagios/

Click on the "Service Detail" navbar link to see details of what's being monitored on your local machine. It will take a few minutes for Nagios to check all the services associated with your machine, as the checks are spread out over time.

9) Other Modifications

If you want to receive email notifications for Nagios alerts, you need to install the mailx (Postfix) package.

sudo apt-get install mailx

sudo apt-get install postfix

You'll have to edit the Nagios email notification commands found in /usr/local/nagios/etc/objects/commands.cfg and change any '/bin/mail' references to '/usr/bin/mail'. Once you do that you'll need to restart Nagios to make the configuration changes live.

sudo /etc/init.d/nagios restart

Configuring email notifications is outside the scope of this documentation. Refer to your system documentation, search the web, or look to the Nagios Support Portal or Nagios Community Wiki for specific instructions on configuring your Ubuntu system to send email messages to external addresses.